Dimiter_Popoff <dp@tgi-sci.com> wrote:
On 10/25/2023 0:34, john larkin wrote:
Tww it the dimensionless factor
(how many parts you tidly-wink and lose) / (how many parts you want)
which, for 0603's, runs 0.6 or so.
Not sure I got what tww is (looked it up, some domino thing so I
guess I get it if so) but 0402 are significantly worse, a lot more
than twice worse. And I have not yet done any 0201...
I highly recommend a good set of curved jaw tweezers, with a tiny binder
clip on the hinge end. That lets you micro-adjust the tension by sliding
the clip, so that they open when you squeeze them edgeways, and close very gently when you release.
On Wed, 25 Oct 2023 01:12:21 +0300, Dimiter_Popoff <dp@tgi-sci.com>
wrote:
On 10/25/2023 0:34, john larkin wrote:
Tww it the dimensionless factor
(how many parts you tidly-wink and lose) / (how many parts you want)
which, for 0603's, runs 0.6 or so.
Not sure I got what tww is (looked it up, some domino thing so I
guess I get it if so) but 0402 are significantly worse, a lot more
than twice worse. And I have not yet done any 0201...
When I first saw 1206's, I thought they were tiny. Ha!
I refuse to use 0402's. I default to 0805s.
I'm tuning the tempco of a 50 MHz triggrered Colpitts oscillator. What
a nuisance. It should have a 3.3 pF N4700 0805 cap, but the layout guy
used all 0603s, so some engineer (who shall not be named) substituted
an 0603 NP0. "NTC" does sound a lot like "NPO" I guess.
The proper 0805 cap was custom brewed for us by Capax.
On 10/25/2023 0:34, john larkin wrote:
Tww it the dimensionless factor
(how many parts you tidly-wink and lose) / (how many parts you want)
which, for 0603's, runs 0.6 or so.
Not sure I got what tww is (looked it up, some domino thing so I
guess I get it if so) but 0402 are significantly worse, a lot more
than twice worse. And I have not yet done any 0201...
On 10/25/2023 0:34, john larkin wrote:
Tww it the dimensionless factor
(how many parts you tidly-wink and lose) / (how many parts you want)
which, for 0603's, runs 0.6 or so.
Not sure I got what tww is (looked it up, some domino thing so I
guess I get it if so) but 0402 are significantly worse, a lot more
than twice worse. And I have not yet done any 0201...
On 10/25/2023 1:51, john larkin wrote:
On Wed, 25 Oct 2023 01:12:21 +0300, Dimiter_Popoff <dp@tgi-sci.com>
wrote:
On 10/25/2023 0:34, john larkin wrote:
Tww it the dimensionless factor
(how many parts you tidly-wink and lose) / (how many parts you want) >>>>
which, for 0603's, runs 0.6 or so.
Not sure I got what tww is (looked it up, some domino thing so I
guess I get it if so) but 0402 are significantly worse, a lot more
than twice worse. And I have not yet done any 0201...
When I first saw 1206's, I thought they were tiny. Ha!
I refuse to use 0402's. I default to 0805s.
I'm tuning the tempco of a 50 MHz triggrered Colpitts oscillator. What
a nuisance. It should have a 3.3 pF N4700 0805 cap, but the layout guy
used all 0603s, so some engineer (who shall not be named) substituted
an 0603 NP0. "NTC" does sound a lot like "NPO" I guess.
The proper 0805 cap was custom brewed for us by Capax.
I often do it the other way around,the 0805 pads I make can also hold
0603. Took me a while to grasp I could do it the first time I could
not find the 0805 I needed...
The temp compensations I typically have to deal with are resistor
tracking. Meanwhile I know which batch of which supply I have
does not track too well with which other.
Tww it the dimensionless factor
(how many parts you tidly-wink and lose) / (how many parts you want)
which, for 0603's, runs 0.6 or so.
On Wed, 25 Oct 2023 07:18:58 +0300, Dimiter_Popoff <d...@tgi-sci.com>
wrote:
On 10/25/2023 1:51, john larkin wrote:
On Wed, 25 Oct 2023 01:12:21 +0300, Dimiter_Popoff <d...@tgi-sci.com>
wrote:
On 10/25/2023 0:34, john larkin wrote:
Tww it the dimensionless factor
(how many parts you tidly-wink and lose) / (how many parts you want) >>>>
which, for 0603's, runs 0.6 or so.
Not sure I got what tww is (looked it up, some domino thing so I
guess I get it if so) but 0402 are significantly worse, a lot more
than twice worse. And I have not yet done any 0201...
When I first saw 1206's, I thought they were tiny. Ha!
I refuse to use 0402's. I default to 0805s.
I'm tuning the tempco of a 50 MHz triggrered Colpitts oscillator. What
a nuisance. It should have a 3.3 pF N4700 0805 cap, but the layout guy
used all 0603s, so some engineer (who shall not be named) substituted
an 0603 NP0. "NTC" does sound a lot like "NPO" I guess.
The proper 0805 cap was custom brewed for us by Capax.
I often do it the other way around,the 0805 pads I make can also hold >0603. Took me a while to grasp I could do it the first time I could
not find the 0805 I needed...
The temp compensations I typically have to deal with are resistor >tracking. Meanwhile I know which batch of which supply I haveWhat I'm fighting right now is the positive TC of the Coilcraft
does not track too well with which other.
Midi-spring inductor (typically +100 PPM/c or so) and the positive TC
of the PCB FR4, typically +900. The combo makes the oscillator have a serious negative TC, which the N4700 cap compensates. I have a series
padder cap, in series with the NTC cap, to trim the oscillator tempco
to near zero, down to the 2nd order parabola.
It's tedious. Tuning takes about an hour per iteration. We have a
gigantic environmental oven in the basement, but using that would take
more like a day per iteration. I made my own benchtop chamber, a
cardboard box with a USB fan inside, used with a heat gun and freeze
spray.
My $5000 Rigol scope is the frequncy counter and USB fan supply.
On Wednesday, October 25, 2023 at 6:40:17?AM UTC-4, John Larkin wrote:
On Wed, 25 Oct 2023 07:18:58 +0300, Dimiter_Popoff <d...@tgi-sci.com>
wrote:
On 10/25/2023 1:51, john larkin wrote:What I'm fighting right now is the positive TC of the Coilcraft
On Wed, 25 Oct 2023 01:12:21 +0300, Dimiter_Popoff <d...@tgi-sci.com>
wrote:
On 10/25/2023 0:34, john larkin wrote:
Tww it the dimensionless factor
(how many parts you tidly-wink and lose) / (how many parts you want)
which, for 0603's, runs 0.6 or so.
Not sure I got what tww is (looked it up, some domino thing so I
guess I get it if so) but 0402 are significantly worse, a lot more
than twice worse. And I have not yet done any 0201...
When I first saw 1206's, I thought they were tiny. Ha!
I refuse to use 0402's. I default to 0805s.
I'm tuning the tempco of a 50 MHz triggrered Colpitts oscillator. What
a nuisance. It should have a 3.3 pF N4700 0805 cap, but the layout guy
used all 0603s, so some engineer (who shall not be named) substituted
an 0603 NP0. "NTC" does sound a lot like "NPO" I guess.
The proper 0805 cap was custom brewed for us by Capax.
I often do it the other way around,the 0805 pads I make can also hold
0603. Took me a while to grasp I could do it the first time I could
not find the 0805 I needed...
The temp compensations I typically have to deal with are resistor
tracking. Meanwhile I know which batch of which supply I have
does not track too well with which other.
Midi-spring inductor (typically +100 PPM/c or so) and the positive TC
of the PCB FR4, typically +900. The combo makes the oscillator have a
serious negative TC, which the N4700 cap compensates. I have a series
padder cap, in series with the NTC cap, to trim the oscillator tempco
to near zero, down to the 2nd order parabola.
It's tedious. Tuning takes about an hour per iteration. We have a
gigantic environmental oven in the basement, but using that would take
more like a day per iteration. I made my own benchtop chamber, a
cardboard box with a USB fan inside, used with a heat gun and freeze
spray.
My $5000 Rigol scope is the frequncy counter and USB fan supply.
You're using an LC tuned Colpitts?
On Wed, 25 Oct 2023 09:23:20 -0700 (PDT), Fred Bloggs <bloggs.fredbloggs.fred@gmail.com> wrote:
On Wednesday, October 25, 2023 at 6:40:17?AM UTC-4, John Larkin wrote:
On Wed, 25 Oct 2023 07:18:58 +0300, Dimiter_Popoff <d...@tgi-sci.com>
wrote:
On 10/25/2023 1:51, john larkin wrote:What I'm fighting right now is the positive TC of the Coilcraft
On Wed, 25 Oct 2023 01:12:21 +0300, Dimiter_Popoff <d...@tgi-sci.com> >>>>> wrote:
On 10/25/2023 0:34, john larkin wrote:
Tww it the dimensionless factor
(how many parts you tidly-wink and lose) / (how many parts you want) >>>>>>>
which, for 0603's, runs 0.6 or so.
Not sure I got what tww is (looked it up, some domino thing so I
guess I get it if so) but 0402 are significantly worse, a lot more >>>>>> than twice worse. And I have not yet done any 0201...
When I first saw 1206's, I thought they were tiny. Ha!
I refuse to use 0402's. I default to 0805s.
I'm tuning the tempco of a 50 MHz triggrered Colpitts oscillator. What >>>>> a nuisance. It should have a 3.3 pF N4700 0805 cap, but the layout guy >>>>> used all 0603s, so some engineer (who shall not be named) substituted >>>>> an 0603 NP0. "NTC" does sound a lot like "NPO" I guess.
The proper 0805 cap was custom brewed for us by Capax.
I often do it the other way around,the 0805 pads I make can also hold
0603. Took me a while to grasp I could do it the first time I could
not find the 0805 I needed...
The temp compensations I typically have to deal with are resistor
tracking. Meanwhile I know which batch of which supply I have
does not track too well with which other.
Midi-spring inductor (typically +100 PPM/c or so) and the positive TC
of the PCB FR4, typically +900. The combo makes the oscillator have a
serious negative TC, which the N4700 cap compensates. I have a series
padder cap, in series with the NTC cap, to trim the oscillator tempco
to near zero, down to the 2nd order parabola.
It's tedious. Tuning takes about an hour per iteration. We have a
gigantic environmental oven in the basement, but using that would take
more like a day per iteration. I made my own benchtop chamber, a
cardboard box with a USB fan inside, used with a heat gun and freeze
spray.
My $5000 Rigol scope is the frequncy counter and USB fan supply.
You're using an LC tuned Colpitts?
Yes. It uses a SAV551 phemt as a source follower driving the usual two
caps back into the tank.
Here's my temp chamber.
https://www.dropbox.com/scl/fi/ncxlgwgyvyoxexzmfqyk3/T660_Temp_Chamber.jpg?rlkey=oud1q89ygu5nafd2i5nym6jii&raw=1
I blast it with a heat gun or freeze spray to evaluate tempco. This
gadget has a pretty narrow pull range PLL to lock the triggered LC
oscillator to a crystal oscillator, and it will fail lock if
temperature changes the LC osc frequency more than maybe 1000 PPM.
We use a digital capacitor to center the frequency to close to 50 MHz
at powerup, but then it's usually cold, and can't drift more than the
1000 PPM after that.
Tedious.
DOGBERRY: But truly, if I were as tedious as a king, I would find it
in my heart to give it all to you, your Worship. LEONATO: All thy
tediousness on me, ah?
On Wed, 25 Oct 2023 09:23:20 -0700 (PDT), Fred Bloggs <bloggs.fred...@gmail.com> wrote:
On Wednesday, October 25, 2023 at 6:40:17?AM UTC-4, John Larkin wrote:
On Wed, 25 Oct 2023 07:18:58 +0300, Dimiter_Popoff <d...@tgi-sci.com>
wrote:
On 10/25/2023 1:51, john larkin wrote:What I'm fighting right now is the positive TC of the Coilcraft
On Wed, 25 Oct 2023 01:12:21 +0300, Dimiter_Popoff <d...@tgi-sci.com> >> >> wrote:
On 10/25/2023 0:34, john larkin wrote:
Tww it the dimensionless factor
(how many parts you tidly-wink and lose) / (how many parts you want) >> >>>>
which, for 0603's, runs 0.6 or so.
Not sure I got what tww is (looked it up, some domino thing so I
guess I get it if so) but 0402 are significantly worse, a lot more
than twice worse. And I have not yet done any 0201...
When I first saw 1206's, I thought they were tiny. Ha!
I refuse to use 0402's. I default to 0805s.
I'm tuning the tempco of a 50 MHz triggrered Colpitts oscillator. What >> >> a nuisance. It should have a 3.3 pF N4700 0805 cap, but the layout guy >> >> used all 0603s, so some engineer (who shall not be named) substituted >> >> an 0603 NP0. "NTC" does sound a lot like "NPO" I guess.
The proper 0805 cap was custom brewed for us by Capax.
I often do it the other way around,the 0805 pads I make can also hold
0603. Took me a while to grasp I could do it the first time I could
not find the 0805 I needed...
The temp compensations I typically have to deal with are resistor
tracking. Meanwhile I know which batch of which supply I have
does not track too well with which other.
Midi-spring inductor (typically +100 PPM/c or so) and the positive TC
of the PCB FR4, typically +900. The combo makes the oscillator have a
serious negative TC, which the N4700 cap compensates. I have a series
padder cap, in series with the NTC cap, to trim the oscillator tempco
to near zero, down to the 2nd order parabola.
It's tedious. Tuning takes about an hour per iteration. We have a
gigantic environmental oven in the basement, but using that would take
more like a day per iteration. I made my own benchtop chamber, a
cardboard box with a USB fan inside, used with a heat gun and freeze
spray.
My $5000 Rigol scope is the frequncy counter and USB fan supply.
You're using an LC tuned Colpitts?Yes. It uses a SAV551 phemt as a source follower driving the usual two
caps back into the tank.
Here's my temp chamber.
https://www.dropbox.com/scl/fi/ncxlgwgyvyoxexzmfqyk3/T660_Temp_Chamber.jpg?rlkey=oud1q89ygu5nafd2i5nym6jii&raw=1
I blast it with a heat gun or freeze spray to evaluate tempco. This
gadget has a pretty narrow pull range PLL to lock the triggered LC oscillator to a crystal oscillator, and it will fail lock if
temperature changes the LC osc frequency more than maybe 1000 PPM.
We use a digital capacitor to center the frequency to close to 50 MHz
at powerup, but then it's usually cold, and can't drift more than the
1000 PPM after that.
Tedious.
DOGBERRY: But truly, if I were as tedious as a king, I would find it
in my heart to give it all to you, your Worship. LEONATO: All thy tediousness on me, ah?
On Wed, 25 Oct 2023 09:23:20 -0700 (PDT), Fred Bloggs <bloggs.fred...@gmail.com> wrote:
On Wednesday, October 25, 2023 at 6:40:17?AM UTC-4, John Larkin wrote:
On Wed, 25 Oct 2023 07:18:58 +0300, Dimiter_Popoff <d...@tgi-sci.com>
wrote:
On 10/25/2023 1:51, john larkin wrote:What I'm fighting right now is the positive TC of the Coilcraft
On Wed, 25 Oct 2023 01:12:21 +0300, Dimiter_Popoff <d...@tgi-sci.com> >> >> wrote:
On 10/25/2023 0:34, john larkin wrote:
Tww it the dimensionless factor
(how many parts you tidly-wink and lose) / (how many parts you want) >> >>>>
which, for 0603's, runs 0.6 or so.
Not sure I got what tww is (looked it up, some domino thing so I
guess I get it if so) but 0402 are significantly worse, a lot more
than twice worse. And I have not yet done any 0201...
When I first saw 1206's, I thought they were tiny. Ha!
I refuse to use 0402's. I default to 0805s.
I'm tuning the tempco of a 50 MHz triggrered Colpitts oscillator. What >> >> a nuisance. It should have a 3.3 pF N4700 0805 cap, but the layout guy >> >> used all 0603s, so some engineer (who shall not be named) substituted >> >> an 0603 NP0. "NTC" does sound a lot like "NPO" I guess.
The proper 0805 cap was custom brewed for us by Capax.
I often do it the other way around,the 0805 pads I make can also hold
0603. Took me a while to grasp I could do it the first time I could
not find the 0805 I needed...
The temp compensations I typically have to deal with are resistor
tracking. Meanwhile I know which batch of which supply I have
does not track too well with which other.
Midi-spring inductor (typically +100 PPM/c or so) and the positive TC
of the PCB FR4, typically +900. The combo makes the oscillator have a
serious negative TC, which the N4700 cap compensates. I have a series
padder cap, in series with the NTC cap, to trim the oscillator tempco
to near zero, down to the 2nd order parabola.
It's tedious. Tuning takes about an hour per iteration. We have a
gigantic environmental oven in the basement, but using that would take
more like a day per iteration. I made my own benchtop chamber, a
cardboard box with a USB fan inside, used with a heat gun and freeze
spray.
My $5000 Rigol scope is the frequncy counter and USB fan supply.
You're using an LC tuned Colpitts?Yes. It uses a SAV551 phemt as a source follower driving the usual two
caps back into the tank.
Here's my temp chamber.
https://www.dropbox.com/scl/fi/ncxlgwgyvyoxexzmfqyk3/T660_Temp_Chamber.jpg?rlkey=oud1q89ygu5nafd2i5nym6jii&raw=1
I blast it with a heat gun or freeze spray to evaluate tempco. This
gadget has a pretty narrow pull range PLL to lock the triggered LC oscillator to a crystal oscillator, and it will fail lock if
temperature changes the LC osc frequency more than maybe 1000 PPM.
We use a digital capacitor to center the frequency to close to 50 MHz
at powerup, but then it's usually cold, and can't drift more than the
1000 PPM after that.
Tedious.
DOGBERRY: But truly, if I were as tedious as a king, I would find it
in my heart to give it all to you, your Worship. LEONATO: All thy tediousness on me, ah?
Dimiter_Popoff <dp@tgi-sci.com> wrote:
On 10/25/2023 0:34, john larkin wrote:
Tww it the dimensionless factor
(how many parts you tidly-wink and lose) / (how many parts you want)
which, for 0603's, runs 0.6 or so.
Not sure I got what tww is (looked it up, some domino thing so I
guess I get it if so) but 0402 are significantly worse, a lot more
than twice worse. And I have not yet done any 0201...
I highly recommend a good set of curved jaw tweezers, with a tiny binder
clip on the hinge end. That lets you micro-adjust the tension by sliding
the clip, so that they open when you squeeze them edgeways, and close very >gently when you release.
Good Medicine.
Cheers
Phil Hobbs
On Wednesday, October 25, 2023 at 2:22:37?PM UTC-4, john larkin wrote:
On Wed, 25 Oct 2023 09:23:20 -0700 (PDT), Fred Bloggs
<bloggs.fred...@gmail.com> wrote:
On Wednesday, October 25, 2023 at 6:40:17?AM UTC-4, John Larkin wrote:Yes. It uses a SAV551 phemt as a source follower driving the usual two
On Wed, 25 Oct 2023 07:18:58 +0300, Dimiter_Popoff <d...@tgi-sci.com>
wrote:
On 10/25/2023 1:51, john larkin wrote:What I'm fighting right now is the positive TC of the Coilcraft
On Wed, 25 Oct 2023 01:12:21 +0300, Dimiter_Popoff <d...@tgi-sci.com> >> >> >> wrote:
On 10/25/2023 0:34, john larkin wrote:
Tww it the dimensionless factor
(how many parts you tidly-wink and lose) / (how many parts you want) >> >> >>>>
which, for 0603's, runs 0.6 or so.
Not sure I got what tww is (looked it up, some domino thing so I
guess I get it if so) but 0402 are significantly worse, a lot more
than twice worse. And I have not yet done any 0201...
When I first saw 1206's, I thought they were tiny. Ha!
I refuse to use 0402's. I default to 0805s.
I'm tuning the tempco of a 50 MHz triggrered Colpitts oscillator. What >> >> >> a nuisance. It should have a 3.3 pF N4700 0805 cap, but the layout guy >> >> >> used all 0603s, so some engineer (who shall not be named) substituted >> >> >> an 0603 NP0. "NTC" does sound a lot like "NPO" I guess.
The proper 0805 cap was custom brewed for us by Capax.
I often do it the other way around,the 0805 pads I make can also hold
0603. Took me a while to grasp I could do it the first time I could
not find the 0805 I needed...
The temp compensations I typically have to deal with are resistor
tracking. Meanwhile I know which batch of which supply I have
does not track too well with which other.
Midi-spring inductor (typically +100 PPM/c or so) and the positive TC
of the PCB FR4, typically +900. The combo makes the oscillator have a
serious negative TC, which the N4700 cap compensates. I have a series
padder cap, in series with the NTC cap, to trim the oscillator tempco
to near zero, down to the 2nd order parabola.
It's tedious. Tuning takes about an hour per iteration. We have a
gigantic environmental oven in the basement, but using that would take
more like a day per iteration. I made my own benchtop chamber, a
cardboard box with a USB fan inside, used with a heat gun and freeze
spray.
My $5000 Rigol scope is the frequncy counter and USB fan supply.
You're using an LC tuned Colpitts?
caps back into the tank.
Here's my temp chamber.
https://www.dropbox.com/scl/fi/ncxlgwgyvyoxexzmfqyk3/T660_Temp_Chamber.jpg?rlkey=oud1q89ygu5nafd2i5nym6jii&raw=1
I blast it with a heat gun or freeze spray to evaluate tempco. This
gadget has a pretty narrow pull range PLL to lock the triggered LC
oscillator to a crystal oscillator, and it will fail lock if
temperature changes the LC osc frequency more than maybe 1000 PPM.
We use a digital capacitor to center the frequency to close to 50 MHz
at powerup, but then it's usually cold, and can't drift more than the
1000 PPM after that.
Tedious.
DOGBERRY: But truly, if I were as tedious as a king, I would find it
in my heart to give it all to you, your Worship. LEONATO: All thy
tediousness on me, ah?
I found this after an exhausting 15-second search. There are tons of others:
https://www.sciencedirect.com/science/article/abs/pii/S0026269216306036
On 25/10/2023 19:22, john larkin wrote:
On Wed, 25 Oct 2023 09:23:20 -0700 (PDT), Fred Bloggs
<bloggs.fredbloggs.fred@gmail.com> wrote:
On Wednesday, October 25, 2023 at 6:40:17?AM UTC-4, John Larkin wrote:
On Wed, 25 Oct 2023 07:18:58 +0300, Dimiter_Popoff <d...@tgi-sci.com>
wrote:
On 10/25/2023 1:51, john larkin wrote:What I'm fighting right now is the positive TC of the Coilcraft
On Wed, 25 Oct 2023 01:12:21 +0300, Dimiter_Popoff <d...@tgi-sci.com> >>>>>> wrote:
On 10/25/2023 0:34, john larkin wrote:
Tww it the dimensionless factor
(how many parts you tidly-wink and lose) / (how many parts you want) >>>>>>>>
which, for 0603's, runs 0.6 or so.
Not sure I got what tww is (looked it up, some domino thing so I >>>>>>> guess I get it if so) but 0402 are significantly worse, a lot more >>>>>>> than twice worse. And I have not yet done any 0201...
When I first saw 1206's, I thought they were tiny. Ha!
I refuse to use 0402's. I default to 0805s.
I'm tuning the tempco of a 50 MHz triggrered Colpitts oscillator. What >>>>>> a nuisance. It should have a 3.3 pF N4700 0805 cap, but the layout guy >>>>>> used all 0603s, so some engineer (who shall not be named) substituted >>>>>> an 0603 NP0. "NTC" does sound a lot like "NPO" I guess.
The proper 0805 cap was custom brewed for us by Capax.
I often do it the other way around,the 0805 pads I make can also hold >>>>> 0603. Took me a while to grasp I could do it the first time I could
not find the 0805 I needed...
The temp compensations I typically have to deal with are resistor
tracking. Meanwhile I know which batch of which supply I have
does not track too well with which other.
Midi-spring inductor (typically +100 PPM/c or so) and the positive TC
of the PCB FR4, typically +900. The combo makes the oscillator have a
serious negative TC, which the N4700 cap compensates. I have a series
padder cap, in series with the NTC cap, to trim the oscillator tempco
to near zero, down to the 2nd order parabola.
It's tedious. Tuning takes about an hour per iteration. We have a
gigantic environmental oven in the basement, but using that would take >>>> more like a day per iteration. I made my own benchtop chamber, a
cardboard box with a USB fan inside, used with a heat gun and freeze
spray.
My $5000 Rigol scope is the frequncy counter and USB fan supply.
You're using an LC tuned Colpitts?
Yes. It uses a SAV551 phemt as a source follower driving the usual two
caps back into the tank.
Here's my temp chamber.
https://www.dropbox.com/scl/fi/ncxlgwgyvyoxexzmfqyk3/T660_Temp_Chamber.jpg?rlkey=oud1q89ygu5nafd2i5nym6jii&raw=1
I blast it with a heat gun or freeze spray to evaluate tempco. This
gadget has a pretty narrow pull range PLL to lock the triggered LC
oscillator to a crystal oscillator, and it will fail lock if
temperature changes the LC osc frequency more than maybe 1000 PPM.
We use a digital capacitor to center the frequency to close to 50 MHz
at powerup, but then it's usually cold, and can't drift more than the
1000 PPM after that.
Tedious.
DOGBERRY: But truly, if I were as tedious as a king, I would find it
in my heart to give it all to you, your Worship. LEONATO: All thy
tediousness on me, ah?
I assume that board has an MCU and with many now including on chip >temperature measurement can you use the digital capacitor to do the temp >compensation in software?
piglet
On Wednesday, October 25, 2023 at 2:22:37?PM UTC-4, john larkin wrote:
On Wed, 25 Oct 2023 09:23:20 -0700 (PDT), Fred Bloggs
<bloggs.fred...@gmail.com> wrote:
On Wednesday, October 25, 2023 at 6:40:17?AM UTC-4, John Larkin wrote:Yes. It uses a SAV551 phemt as a source follower driving the usual two
On Wed, 25 Oct 2023 07:18:58 +0300, Dimiter_Popoff <d...@tgi-sci.com>
wrote:
On 10/25/2023 1:51, john larkin wrote:What I'm fighting right now is the positive TC of the Coilcraft
On Wed, 25 Oct 2023 01:12:21 +0300, Dimiter_Popoff <d...@tgi-sci.com> >> >> >> wrote:
On 10/25/2023 0:34, john larkin wrote:
Tww it the dimensionless factor
(how many parts you tidly-wink and lose) / (how many parts you want) >> >> >>>>
which, for 0603's, runs 0.6 or so.
Not sure I got what tww is (looked it up, some domino thing so I
guess I get it if so) but 0402 are significantly worse, a lot more
than twice worse. And I have not yet done any 0201...
When I first saw 1206's, I thought they were tiny. Ha!
I refuse to use 0402's. I default to 0805s.
I'm tuning the tempco of a 50 MHz triggrered Colpitts oscillator. What >> >> >> a nuisance. It should have a 3.3 pF N4700 0805 cap, but the layout guy >> >> >> used all 0603s, so some engineer (who shall not be named) substituted >> >> >> an 0603 NP0. "NTC" does sound a lot like "NPO" I guess.
The proper 0805 cap was custom brewed for us by Capax.
I often do it the other way around,the 0805 pads I make can also hold
0603. Took me a while to grasp I could do it the first time I could
not find the 0805 I needed...
The temp compensations I typically have to deal with are resistor
tracking. Meanwhile I know which batch of which supply I have
does not track too well with which other.
Midi-spring inductor (typically +100 PPM/c or so) and the positive TC
of the PCB FR4, typically +900. The combo makes the oscillator have a
serious negative TC, which the N4700 cap compensates. I have a series
padder cap, in series with the NTC cap, to trim the oscillator tempco
to near zero, down to the 2nd order parabola.
It's tedious. Tuning takes about an hour per iteration. We have a
gigantic environmental oven in the basement, but using that would take
more like a day per iteration. I made my own benchtop chamber, a
cardboard box with a USB fan inside, used with a heat gun and freeze
spray.
My $5000 Rigol scope is the frequncy counter and USB fan supply.
You're using an LC tuned Colpitts?
caps back into the tank.
Here's my temp chamber.
https://www.dropbox.com/scl/fi/ncxlgwgyvyoxexzmfqyk3/T660_Temp_Chamber.jpg?rlkey=oud1q89ygu5nafd2i5nym6jii&raw=1
I blast it with a heat gun or freeze spray to evaluate tempco. This
gadget has a pretty narrow pull range PLL to lock the triggered LC
oscillator to a crystal oscillator, and it will fail lock if
temperature changes the LC osc frequency more than maybe 1000 PPM.
We use a digital capacitor to center the frequency to close to 50 MHz
at powerup, but then it's usually cold, and can't drift more than the
1000 PPM after that.
You need to re-examine your lock-in idea and make it a coarse/fine tuning one.
Are you using some digital discriminator in an FPGA or something minimal like that?
The trick in a digital delay generator, or at least ours, is to stop
an LC oscillator and start it when we get an external trigger, and
then use it as our timebase. But lock it to an crystal oscillator to
keep long delays accurate.
To do that, I need a pretty stable LC oscillator, hence the tempco
tuning. Capex made us a reel of custom N4700 ceramic caps, which can
be used to compensate the pretty awful inductor and FR4 tempcos.
HP made one delay generator that actually started and stopped a
crystal oscillator. It didn't work very well. A quartz crystal is hard
to kick start and is even worse to stop; it rings like a bell.
On Wed, 25 Oct 2023 21:02:50 +0100, piglet <erichpwagner@hotmail.com>
wrote:
On 25/10/2023 19:22, john larkin wrote:
On Wed, 25 Oct 2023 09:23:20 -0700 (PDT), Fred Bloggs
<bloggs.fredbloggs.fred@gmail.com> wrote:
On Wednesday, October 25, 2023 at 6:40:17?AM UTC-4, John Larkin wrote: >>>>> On Wed, 25 Oct 2023 07:18:58 +0300, Dimiter_Popoff <d...@tgi-sci.com> >>>>> wrote:
On 10/25/2023 1:51, john larkin wrote:What I'm fighting right now is the positive TC of the Coilcraft
On Wed, 25 Oct 2023 01:12:21 +0300, Dimiter_Popoff <d...@tgi-sci.com> >>>>>>> wrote:
On 10/25/2023 0:34, john larkin wrote:
Tww it the dimensionless factor
(how many parts you tidly-wink and lose) / (how many parts you want) >>>>>>>>>
which, for 0603's, runs 0.6 or so.
Not sure I got what tww is (looked it up, some domino thing so I >>>>>>>> guess I get it if so) but 0402 are significantly worse, a lot more >>>>>>>> than twice worse. And I have not yet done any 0201...
When I first saw 1206's, I thought they were tiny. Ha!
I refuse to use 0402's. I default to 0805s.
I'm tuning the tempco of a 50 MHz triggrered Colpitts oscillator. What >>>>>>> a nuisance. It should have a 3.3 pF N4700 0805 cap, but the layout guy >>>>>>> used all 0603s, so some engineer (who shall not be named) substituted >>>>>>> an 0603 NP0. "NTC" does sound a lot like "NPO" I guess.
The proper 0805 cap was custom brewed for us by Capax.
I often do it the other way around,the 0805 pads I make can also hold >>>>>> 0603. Took me a while to grasp I could do it the first time I could >>>>>> not find the 0805 I needed...
The temp compensations I typically have to deal with are resistor
tracking. Meanwhile I know which batch of which supply I have
does not track too well with which other.
Midi-spring inductor (typically +100 PPM/c or so) and the positive TC >>>>> of the PCB FR4, typically +900. The combo makes the oscillator have a >>>>> serious negative TC, which the N4700 cap compensates. I have a series >>>>> padder cap, in series with the NTC cap, to trim the oscillator tempco >>>>> to near zero, down to the 2nd order parabola.
It's tedious. Tuning takes about an hour per iteration. We have a
gigantic environmental oven in the basement, but using that would take >>>>> more like a day per iteration. I made my own benchtop chamber, a
cardboard box with a USB fan inside, used with a heat gun and freeze >>>>> spray.
My $5000 Rigol scope is the frequncy counter and USB fan supply.
You're using an LC tuned Colpitts?
Yes. It uses a SAV551 phemt as a source follower driving the usual two
caps back into the tank.
Here's my temp chamber.
https://www.dropbox.com/scl/fi/ncxlgwgyvyoxexzmfqyk3/T660_Temp_Chamber.jpg?rlkey=oud1q89ygu5nafd2i5nym6jii&raw=1
I blast it with a heat gun or freeze spray to evaluate tempco. This
gadget has a pretty narrow pull range PLL to lock the triggered LC
oscillator to a crystal oscillator, and it will fail lock if
temperature changes the LC osc frequency more than maybe 1000 PPM.
We use a digital capacitor to center the frequency to close to 50 MHz
at powerup, but then it's usually cold, and can't drift more than the
1000 PPM after that.
Tedious.
DOGBERRY: But truly, if I were as tedious as a king, I would find it
in my heart to give it all to you, your Worship. LEONATO: All thy
tediousness on me, ah?
I assume that board has an MCU and with many now including on chip
temperature measurement can you use the digital capacitor to do the temp
compensation in software?
piglet
No. We don't know when we might get a trigger, and tuning the digital
cap would disrupt a timing cycle. There is a dac+varicap for fine
tuning, and that is used for locking the LC oscillator to the XO.
The trick in a digital delay generator is to get crystal oscillator
accuracy, but not quantize timings to the clock edges.
There's a wikipedia article about various ways to accomplish that
trick; I wrote some of it.
On 26/10/2023 04:34, John Larkin wrote:
On Wed, 25 Oct 2023 21:02:50 +0100, piglet <erichp...@hotmail.com>
wrote:
On 25/10/2023 19:22, john larkin wrote:
On Wed, 25 Oct 2023 09:23:20 -0700 (PDT), Fred Bloggs
<bloggs.fred...@gmail.com> wrote:
On Wednesday, October 25, 2023 at 6:40:17?AM UTC-4, John Larkin wrote: >>>>> On Wed, 25 Oct 2023 07:18:58 +0300, Dimiter_Popoff <d...@tgi-sci.com> >>>>> wrote:
On 10/25/2023 1:51, john larkin wrote:What I'm fighting right now is the positive TC of the Coilcraft
On Wed, 25 Oct 2023 01:12:21 +0300, Dimiter_Popoff <d...@tgi-sci.com>
wrote:
On 10/25/2023 0:34, john larkin wrote:
Tww it the dimensionless factor
(how many parts you tidly-wink and lose) / (how many parts you want)
which, for 0603's, runs 0.6 or so.
Not sure I got what tww is (looked it up, some domino thing so I >>>>>>>> guess I get it if so) but 0402 are significantly worse, a lot more >>>>>>>> than twice worse. And I have not yet done any 0201...
When I first saw 1206's, I thought they were tiny. Ha!
I refuse to use 0402's. I default to 0805s.
I'm tuning the tempco of a 50 MHz triggrered Colpitts oscillator. What
a nuisance. It should have a 3.3 pF N4700 0805 cap, but the layout guy
used all 0603s, so some engineer (who shall not be named) substituted
an 0603 NP0. "NTC" does sound a lot like "NPO" I guess.
The proper 0805 cap was custom brewed for us by Capax.
I often do it the other way around,the 0805 pads I make can also hold >>>>>> 0603. Took me a while to grasp I could do it the first time I could >>>>>> not find the 0805 I needed...
The temp compensations I typically have to deal with are resistor >>>>>> tracking. Meanwhile I know which batch of which supply I have
does not track too well with which other.
Midi-spring inductor (typically +100 PPM/c or so) and the positive TC >>>>> of the PCB FR4, typically +900. The combo makes the oscillator have a >>>>> serious negative TC, which the N4700 cap compensates. I have a series >>>>> padder cap, in series with the NTC cap, to trim the oscillator tempco >>>>> to near zero, down to the 2nd order parabola.
It's tedious. Tuning takes about an hour per iteration. We have a >>>>> gigantic environmental oven in the basement, but using that would take >>>>> more like a day per iteration. I made my own benchtop chamber, a
cardboard box with a USB fan inside, used with a heat gun and freeze >>>>> spray.
My $5000 Rigol scope is the frequncy counter and USB fan supply.
You're using an LC tuned Colpitts?
Yes. It uses a SAV551 phemt as a source follower driving the usual two >>> caps back into the tank.
Here's my temp chamber.
https://www.dropbox.com/scl/fi/ncxlgwgyvyoxexzmfqyk3/T660_Temp_Chamber.jpg?rlkey=oud1q89ygu5nafd2i5nym6jii&raw=1
I blast it with a heat gun or freeze spray to evaluate tempco. This
gadget has a pretty narrow pull range PLL to lock the triggered LC
oscillator to a crystal oscillator, and it will fail lock if
temperature changes the LC osc frequency more than maybe 1000 PPM.
We use a digital capacitor to center the frequency to close to 50 MHz >>> at powerup, but then it's usually cold, and can't drift more than the >>> 1000 PPM after that.
Tedious.
I assume that board has an MCU and with many now including on chip temperature measurement can you use the digital capacitor to do the temp compensation in software?
No. We don't know when we might get a trigger, and tuning the digital
cap would disrupt a timing cycle. There is a dac+varicap for fine
tuning, and that is used for locking the LC oscillator to the XO.
The trick in a digital delay generator is to get crystal oscillator accuracy, but not quantize timings to the clock edges.
There's a wikipedia article about various ways to accomplish that
trick; I wrote some of it.
You know your project far better than me but I don't understand why the
temp tuning varicap or digi-cap can't make tiny slow changes while the oscillator is running - after all you can't very well stop the N4700 cap from shifting value during an oscillator run?
On 26/10/2023 04:34, John Larkin wrote:
On Wed, 25 Oct 2023 21:02:50 +0100, piglet <erichpwagner@hotmail.com>
wrote:
On 25/10/2023 19:22, john larkin wrote:
On Wed, 25 Oct 2023 09:23:20 -0700 (PDT), Fred Bloggs
<bloggs.fredbloggs.fred@gmail.com> wrote:
On Wednesday, October 25, 2023 at 6:40:17?AM UTC-4, John Larkin wrote: >>>>>> On Wed, 25 Oct 2023 07:18:58 +0300, Dimiter_Popoff <d...@tgi-sci.com> >>>>>> wrote:
On 10/25/2023 1:51, john larkin wrote:What I'm fighting right now is the positive TC of the Coilcraft
On Wed, 25 Oct 2023 01:12:21 +0300, Dimiter_Popoff <d...@tgi-sci.com> >>>>>>>> wrote:
On 10/25/2023 0:34, john larkin wrote:
Tww it the dimensionless factor
(how many parts you tidly-wink and lose) / (how many parts you want) >>>>>>>>>>
which, for 0603's, runs 0.6 or so.
Not sure I got what tww is (looked it up, some domino thing so I >>>>>>>>> guess I get it if so) but 0402 are significantly worse, a lot more >>>>>>>>> than twice worse. And I have not yet done any 0201...
When I first saw 1206's, I thought they were tiny. Ha!
I refuse to use 0402's. I default to 0805s.
I'm tuning the tempco of a 50 MHz triggrered Colpitts oscillator. What >>>>>>>> a nuisance. It should have a 3.3 pF N4700 0805 cap, but the layout guy >>>>>>>> used all 0603s, so some engineer (who shall not be named) substituted >>>>>>>> an 0603 NP0. "NTC" does sound a lot like "NPO" I guess.
The proper 0805 cap was custom brewed for us by Capax.
I often do it the other way around,the 0805 pads I make can also hold >>>>>>> 0603. Took me a while to grasp I could do it the first time I could >>>>>>> not find the 0805 I needed...
The temp compensations I typically have to deal with are resistor >>>>>>> tracking. Meanwhile I know which batch of which supply I have
does not track too well with which other.
Midi-spring inductor (typically +100 PPM/c or so) and the positive TC >>>>>> of the PCB FR4, typically +900. The combo makes the oscillator have a >>>>>> serious negative TC, which the N4700 cap compensates. I have a series >>>>>> padder cap, in series with the NTC cap, to trim the oscillator tempco >>>>>> to near zero, down to the 2nd order parabola.
It's tedious. Tuning takes about an hour per iteration. We have a
gigantic environmental oven in the basement, but using that would take >>>>>> more like a day per iteration. I made my own benchtop chamber, a
cardboard box with a USB fan inside, used with a heat gun and freeze >>>>>> spray.
My $5000 Rigol scope is the frequncy counter and USB fan supply.
You're using an LC tuned Colpitts?
Yes. It uses a SAV551 phemt as a source follower driving the usual two >>>> caps back into the tank.
Here's my temp chamber.
https://www.dropbox.com/scl/fi/ncxlgwgyvyoxexzmfqyk3/T660_Temp_Chamber.jpg?rlkey=oud1q89ygu5nafd2i5nym6jii&raw=1
I blast it with a heat gun or freeze spray to evaluate tempco. This
gadget has a pretty narrow pull range PLL to lock the triggered LC
oscillator to a crystal oscillator, and it will fail lock if
temperature changes the LC osc frequency more than maybe 1000 PPM.
We use a digital capacitor to center the frequency to close to 50 MHz
at powerup, but then it's usually cold, and can't drift more than the
1000 PPM after that.
Tedious.
DOGBERRY: But truly, if I were as tedious as a king, I would find it
in my heart to give it all to you, your Worship. LEONATO: All thy
tediousness on me, ah?
I assume that board has an MCU and with many now including on chip
temperature measurement can you use the digital capacitor to do the temp >>> compensation in software?
piglet
No. We don't know when we might get a trigger, and tuning the digital
cap would disrupt a timing cycle. There is a dac+varicap for fine
tuning, and that is used for locking the LC oscillator to the XO.
The trick in a digital delay generator is to get crystal oscillator
accuracy, but not quantize timings to the clock edges.
There's a wikipedia article about various ways to accomplish that
trick; I wrote some of it.
You know your project far better than me but I don't understand why the
temp tuning varicap or digi-cap can't make tiny slow changes while the >oscillator is running - after all you can't very well stop the N4700 cap
from shifting value during an oscillator run?
piglet
On a sunny day (Wed, 25 Oct 2023 20:45:52 -0700) it happened John Larkin ><jl@997PotHill.com> wrote in <hknjjih3rp87naoq2o2pefergou2deg7i4@4ax.com>:
The trick in a digital delay generator, or at least ours, is to stop
an LC oscillator and start it when we get an external trigger, and
then use it as our timebase. But lock it to an crystal oscillator to
keep long delays accurate.
To do that, I need a pretty stable LC oscillator, hence the tempco
tuning. Capex made us a reel of custom N4700 ceramic caps, which can
be used to compensate the pretty awful inductor and FR4 tempcos.
HP made one delay generator that actually started and stopped a
crystal oscillator. It didn't work very well. A quartz crystal is hard
to kick start and is even worse to stop; it rings like a bell.
All this makes me think about a 4046 and PLL.
On Thu, 26 Oct 2023 05:06:21 GMT, Jan Panteltje <al...@comet.invalid>
wrote:
On a sunny day (Wed, 25 Oct 2023 20:45:52 -0700) it happened John Larkin ><j...@997PotHill.com> wrote in <hknjjih3rp87naoq2...@4ax.com>:
The trick in a digital delay generator, or at least ours, is to stop
an LC oscillator and start it when we get an external trigger, and
then use it as our timebase. But lock it to an crystal oscillator to >>keep long delays accurate.
To do that, I need a pretty stable LC oscillator, hence the tempco >>tuning. Capex made us a reel of custom N4700 ceramic caps, which can
be used to compensate the pretty awful inductor and FR4 tempcos.
HP made one delay generator that actually started and stopped a
crystal oscillator. It didn't work very well. A quartz crystal is hard >>to kick start and is even worse to stop; it rings like a bell.
All this makes me think about a 4046 and PLL.The 4046 has a terrible phase detector.
On Thu, 26 Oct 2023 05:06:21 GMT, Jan Panteltje <alien@comet.invalid>
wrote:
On a sunny day (Wed, 25 Oct 2023 20:45:52 -0700) it happened John Larkin >><jl@997PotHill.com> wrote in <hknjjih3rp87naoq2o2pefergou2deg7i4@4ax.com>:
The trick in a digital delay generator, or at least ours, is to stop
an LC oscillator and start it when we get an external trigger, and
then use it as our timebase. But lock it to an crystal oscillator to
keep long delays accurate.
To do that, I need a pretty stable LC oscillator, hence the tempco >>>tuning. Capex made us a reel of custom N4700 ceramic caps, which can
be used to compensate the pretty awful inductor and FR4 tempcos.
HP made one delay generator that actually started and stopped a
crystal oscillator. It didn't work very well. A quartz crystal is hard
to kick start and is even worse to stop; it rings like a bell.
All this makes me think about a 4046 and PLL.
The 4046 has a terrible phase detector.
On a sunny day (Fri, 27 Oct 2023 15:53:31 -0700) it happened john larkin <j...@650pot.com> wrote in <6qfojihekda4aobmg...@4ax.com>:
On Thu, 26 Oct 2023 05:06:21 GMT, Jan Panteltje <al...@comet.invalid> wrote:
On a sunny day (Wed, 25 Oct 2023 20:45:52 -0700) it happened John Larkin <j...@997PotHill.com> wrote in <hknjjih3rp87naoq2...@4ax.com>:
The 4046 has a terrible phase detector.HCT4046 has 3 phase detectors.
1 xor gate
2 A digital memory network. It consists of four flip–flops and some gating logic,
a three state output and a phase pulse output.
This comparator acts only on the positive edges of the input signals and is independent of duty cycle.
3 A digital four flip–flops and some gating logic a 3 state output and a phase pulse output
See datasheet
So what's your problem :-)
I have used the 4046 for many things, nice chip.
On a sunny day (Fri, 27 Oct 2023 15:53:31 -0700) it happened john larkin ><jl@650pot.com> wrote in <6qfojihekda4aobmgnq71rbf493sa454q0@4ax.com>:
On Thu, 26 Oct 2023 05:06:21 GMT, Jan Panteltje <alien@comet.invalid> >>wrote:
On a sunny day (Wed, 25 Oct 2023 20:45:52 -0700) it happened John Larkin >>><jl@997PotHill.com> wrote in <hknjjih3rp87naoq2o2pefergou2deg7i4@4ax.com>: >>>
The trick in a digital delay generator, or at least ours, is to stop
an LC oscillator and start it when we get an external trigger, and
then use it as our timebase. But lock it to an crystal oscillator to >>>>keep long delays accurate.
To do that, I need a pretty stable LC oscillator, hence the tempco >>>>tuning. Capex made us a reel of custom N4700 ceramic caps, which can
be used to compensate the pretty awful inductor and FR4 tempcos.
HP made one delay generator that actually started and stopped a
crystal oscillator. It didn't work very well. A quartz crystal is hard >>>>to kick start and is even worse to stop; it rings like a bell.
All this makes me think about a 4046 and PLL.
The 4046 has a terrible phase detector.
HCT4046 has 3 phase detectors.
1 xor gate
2 A digital memory network. It consists of four flip–flops and some gating logic,
a three state output and a phase pulse output.
This comparator acts only on the positive edges of the input signals and is independent of duty cycle.
3 A digital four flip–flops and some gating logic a 3 state output and a phase pulse output
See dataseet
So what's your problem :-)
I have used the 4046 for many things, nice chip.
On Wed, 25 Oct 2023 13:50:35 -0700 (PDT), Fred Bloggs <bloggs.fred...@gmail.com> wrote:
On Wednesday, October 25, 2023 at 2:22:37?PM UTC-4, john larkin wrote:
On Wed, 25 Oct 2023 09:23:20 -0700 (PDT), Fred Bloggs
<bloggs.fred...@gmail.com> wrote:
On Wednesday, October 25, 2023 at 6:40:17?AM UTC-4, John Larkin wrote: >> >> On Wed, 25 Oct 2023 07:18:58 +0300, Dimiter_Popoff <d...@tgi-sci.com> >> >> wrote:Yes. It uses a SAV551 phemt as a source follower driving the usual two
On 10/25/2023 1:51, john larkin wrote:What I'm fighting right now is the positive TC of the Coilcraft
On Wed, 25 Oct 2023 01:12:21 +0300, Dimiter_Popoff <d...@tgi-sci.com>
wrote:
On 10/25/2023 0:34, john larkin wrote:
Tww it the dimensionless factor
(how many parts you tidly-wink and lose) / (how many parts you want)
which, for 0603's, runs 0.6 or so.
Not sure I got what tww is (looked it up, some domino thing so I >> >> >>> guess I get it if so) but 0402 are significantly worse, a lot more >> >> >>> than twice worse. And I have not yet done any 0201...
When I first saw 1206's, I thought they were tiny. Ha!
I refuse to use 0402's. I default to 0805s.
I'm tuning the tempco of a 50 MHz triggrered Colpitts oscillator. What
a nuisance. It should have a 3.3 pF N4700 0805 cap, but the layout guy
used all 0603s, so some engineer (who shall not be named) substituted
an 0603 NP0. "NTC" does sound a lot like "NPO" I guess.
The proper 0805 cap was custom brewed for us by Capax.
I often do it the other way around,the 0805 pads I make can also hold >> >> >0603. Took me a while to grasp I could do it the first time I could >> >> >not find the 0805 I needed...
The temp compensations I typically have to deal with are resistor
tracking. Meanwhile I know which batch of which supply I have
does not track too well with which other.
Midi-spring inductor (typically +100 PPM/c or so) and the positive TC >> >> of the PCB FR4, typically +900. The combo makes the oscillator have a >> >> serious negative TC, which the N4700 cap compensates. I have a series >> >> padder cap, in series with the NTC cap, to trim the oscillator tempco >> >> to near zero, down to the 2nd order parabola.
It's tedious. Tuning takes about an hour per iteration. We have a
gigantic environmental oven in the basement, but using that would take >> >> more like a day per iteration. I made my own benchtop chamber, a
cardboard box with a USB fan inside, used with a heat gun and freeze >> >> spray.
My $5000 Rigol scope is the frequncy counter and USB fan supply.
You're using an LC tuned Colpitts?
caps back into the tank.
Here's my temp chamber.
https://www.dropbox.com/scl/fi/ncxlgwgyvyoxexzmfqyk3/T660_Temp_Chamber.jpg?rlkey=oud1q89ygu5nafd2i5nym6jii&raw=1
I blast it with a heat gun or freeze spray to evaluate tempco. This
gadget has a pretty narrow pull range PLL to lock the triggered LC
oscillator to a crystal oscillator, and it will fail lock if
temperature changes the LC osc frequency more than maybe 1000 PPM.
We use a digital capacitor to center the frequency to close to 50 MHz
at powerup, but then it's usually cold, and can't drift more than the
1000 PPM after that.
Tedious.
DOGBERRY: But truly, if I were as tedious as a king, I would find it
in my heart to give it all to you, your Worship. LEONATO: All thy
tediousness on me, ah?
I found this after an exhausting 15-second search. There are tons of others:
https://www.sciencedirect.com/science/article/abs/pii/S0026269216306036The trick in a digital delay generator, or at least ours, is to stop
an LC oscillator and start it when we get an external trigger, and
then use it as our timebase. But lock it to an crystal oscillator to
keep long delays accurate.
To do that, I need a pretty stable LC oscillator, hence the tempco
tuning. Capex made us a reel of custom N4700 ceramic caps, which can
be used to compensate the pretty awful inductor and FR4 tempcos.
HP made one delay generator that actually started and stopped a
crystal oscillator. It didn't work very well. A quartz crystal is hard
to kick start and is even worse to stop; it rings like a bell.
On Sat, 28 Oct 2023 04:26:51 GMT, Jan Panteltje <al...@comet.invalid>
wrote:
On a sunny day (Fri, 27 Oct 2023 15:53:31 -0700) it happened john larkin ><j...@650pot.com> wrote in <6qfojihekda4aobmg...@4ax.com>:
On Thu, 26 Oct 2023 05:06:21 GMT, Jan Panteltje <al...@comet.invalid> >>wrote:
On a sunny day (Wed, 25 Oct 2023 20:45:52 -0700) it happened John Larkin >>><j...@997PotHill.com> wrote in <hknjjih3rp87naoq2...@4ax.com>:
The trick in a digital delay generator, or at least ours, is to stop >>>>an LC oscillator and start it when we get an external trigger, and >>>>then use it as our timebase. But lock it to an crystal oscillator to >>>>keep long delays accurate.
To do that, I need a pretty stable LC oscillator, hence the tempco >>>>tuning. Capex made us a reel of custom N4700 ceramic caps, which can >>>>be used to compensate the pretty awful inductor and FR4 tempcos.
HP made one delay generator that actually started and stopped a >>>>crystal oscillator. It didn't work very well. A quartz crystal is hard >>>>to kick start and is even worse to stop; it rings like a bell.
All this makes me think about a 4046 and PLL.
The 4046 has a terrible phase detector.
HCT4046 has 3 phase detectors.
1 xor gate
2 A digital memory network. It consists of four flip–flops and some gating logic,
a three state output and a phase pulse output.
This comparator acts only on the positive edges of the input signals and is independent of duty cycle.
3 A digital four flip–flops and some gating logic a 3 state output and a phase pulse output
See dataseet
So what's your problem :-)
I have used the 4046 for many things, nice chip.
OK, my mistake, the 4046 has three terrible phase detectors. And one terrible VCO.
On Wednesday, October 25, 2023 at 11:46:17?PM UTC-4, John Larkin wrote:
On Wed, 25 Oct 2023 13:50:35 -0700 (PDT), Fred Bloggs
<bloggs.fred...@gmail.com> wrote:
On Wednesday, October 25, 2023 at 2:22:37?PM UTC-4, john larkin wrote:The trick in a digital delay generator, or at least ours, is to stop
On Wed, 25 Oct 2023 09:23:20 -0700 (PDT), Fred Bloggs
<bloggs.fred...@gmail.com> wrote:
On Wednesday, October 25, 2023 at 6:40:17?AM UTC-4, John Larkin wrote: >> >> >> On Wed, 25 Oct 2023 07:18:58 +0300, Dimiter_Popoff <d...@tgi-sci.com> >> >> >> wrote:Yes. It uses a SAV551 phemt as a source follower driving the usual two
On 10/25/2023 1:51, john larkin wrote:What I'm fighting right now is the positive TC of the Coilcraft
On Wed, 25 Oct 2023 01:12:21 +0300, Dimiter_Popoff <d...@tgi-sci.com>
wrote:
On 10/25/2023 0:34, john larkin wrote:
Tww it the dimensionless factor
(how many parts you tidly-wink and lose) / (how many parts you want)
which, for 0603's, runs 0.6 or so.
Not sure I got what tww is (looked it up, some domino thing so I >> >> >> >>> guess I get it if so) but 0402 are significantly worse, a lot more >> >> >> >>> than twice worse. And I have not yet done any 0201...
When I first saw 1206's, I thought they were tiny. Ha!
I refuse to use 0402's. I default to 0805s.
I'm tuning the tempco of a 50 MHz triggrered Colpitts oscillator. What
a nuisance. It should have a 3.3 pF N4700 0805 cap, but the layout guy
used all 0603s, so some engineer (who shall not be named) substituted
an 0603 NP0. "NTC" does sound a lot like "NPO" I guess.
The proper 0805 cap was custom brewed for us by Capax.
I often do it the other way around,the 0805 pads I make can also hold >> >> >> >0603. Took me a while to grasp I could do it the first time I could >> >> >> >not find the 0805 I needed...
The temp compensations I typically have to deal with are resistor
tracking. Meanwhile I know which batch of which supply I have
does not track too well with which other.
Midi-spring inductor (typically +100 PPM/c or so) and the positive TC >> >> >> of the PCB FR4, typically +900. The combo makes the oscillator have a >> >> >> serious negative TC, which the N4700 cap compensates. I have a series >> >> >> padder cap, in series with the NTC cap, to trim the oscillator tempco >> >> >> to near zero, down to the 2nd order parabola.
It's tedious. Tuning takes about an hour per iteration. We have a
gigantic environmental oven in the basement, but using that would take >> >> >> more like a day per iteration. I made my own benchtop chamber, a
cardboard box with a USB fan inside, used with a heat gun and freeze >> >> >> spray.
My $5000 Rigol scope is the frequncy counter and USB fan supply.
You're using an LC tuned Colpitts?
caps back into the tank.
Here's my temp chamber.
https://www.dropbox.com/scl/fi/ncxlgwgyvyoxexzmfqyk3/T660_Temp_Chamber.jpg?rlkey=oud1q89ygu5nafd2i5nym6jii&raw=1
I blast it with a heat gun or freeze spray to evaluate tempco. This
gadget has a pretty narrow pull range PLL to lock the triggered LC
oscillator to a crystal oscillator, and it will fail lock if
temperature changes the LC osc frequency more than maybe 1000 PPM.
We use a digital capacitor to center the frequency to close to 50 MHz
at powerup, but then it's usually cold, and can't drift more than the
1000 PPM after that.
Tedious.
DOGBERRY: But truly, if I were as tedious as a king, I would find it
in my heart to give it all to you, your Worship. LEONATO: All thy
tediousness on me, ah?
I found this after an exhausting 15-second search. There are tons of others:
https://www.sciencedirect.com/science/article/abs/pii/S0026269216306036
an LC oscillator and start it when we get an external trigger, and
then use it as our timebase. But lock it to an crystal oscillator to
keep long delays accurate.
To do that, I need a pretty stable LC oscillator, hence the tempco
tuning. Capex made us a reel of custom N4700 ceramic caps, which can
be used to compensate the pretty awful inductor and FR4 tempcos.
HP made one delay generator that actually started and stopped a
crystal oscillator. It didn't work very well. A quartz crystal is hard
to kick start and is even worse to stop; it rings like a bell.
There was a line of monolithic delay line oscillators expressly made for fast start stop, don't recall any of them were tunable either. but may not have the long term stability, you're after. Aside form that it sounds generally like a DLL.
On Sat, 28 Oct 2023 04:26:51 GMT, Jan Panteltje <alien@comet.invalid>
wrote:
On a sunny day (Fri, 27 Oct 2023 15:53:31 -0700) it happened john larkin >><jl@650pot.com> wrote in <6qfojihekda4aobmgnq71rbf493sa454q0@4ax.com>:
On Thu, 26 Oct 2023 05:06:21 GMT, Jan Panteltje <alien@comet.invalid> >>>wrote:
On a sunny day (Wed, 25 Oct 2023 20:45:52 -0700) it happened John Larkin >>>><jl@997PotHill.com> wrote in <hknjjih3rp87naoq2o2pefergou2deg7i4@4ax.com>: >>>>
The trick in a digital delay generator, or at least ours, is to stop >>>>>an LC oscillator and start it when we get an external trigger, and >>>>>then use it as our timebase. But lock it to an crystal oscillator to >>>>>keep long delays accurate.
To do that, I need a pretty stable LC oscillator, hence the tempco >>>>>tuning. Capex made us a reel of custom N4700 ceramic caps, which can >>>>>be used to compensate the pretty awful inductor and FR4 tempcos.
HP made one delay generator that actually started and stopped a >>>>>crystal oscillator. It didn't work very well. A quartz crystal is hard >>>>>to kick start and is even worse to stop; it rings like a bell.
All this makes me think about a 4046 and PLL.
The 4046 has a terrible phase detector.
HCT4046 has 3 phase detectors.
1 xor gate
2 A digital memory network. It consists of four flip–flops and some gating logic,
a three state output and a phase pulse output.
This comparator acts only on the positive edges of the input signals and is independent of duty cycle.
3 A digital four flip–flops and some gating logic a 3 state output and a phase pulse output
See dataseet
So what's your problem :-)
I have used the 4046 for many things, nice chip.
OK, my mistake, the 4046 has three terrible phase detectors. And one
terrible VCO.
On Wed, 25 Oct 2023 07:18:58 +0300, Dimiter_Popoff <dp@tgi-sci.com>
wrote:
On 10/25/2023 1:51, john larkin wrote:
On Wed, 25 Oct 2023 01:12:21 +0300, Dimiter_Popoff <dp@tgi-sci.com>
wrote:
On 10/25/2023 0:34, john larkin wrote:
Tww it the dimensionless factor
(how many parts you tidly-wink and lose) / (how many parts you want) >>>>>
which, for 0603's, runs 0.6 or so.
Not sure I got what tww is (looked it up, some domino thing so I
guess I get it if so) but 0402 are significantly worse, a lot more
than twice worse. And I have not yet done any 0201...
When I first saw 1206's, I thought they were tiny. Ha!
I refuse to use 0402's. I default to 0805s.
I'm tuning the tempco of a 50 MHz triggrered Colpitts oscillator. What
a nuisance. It should have a 3.3 pF N4700 0805 cap, but the layout guy
used all 0603s, so some engineer (who shall not be named) substituted
an 0603 NP0. "NTC" does sound a lot like "NPO" I guess.
The proper 0805 cap was custom brewed for us by Capax.
I often do it the other way around,the 0805 pads I make can also hold
0603. Took me a while to grasp I could do it the first time I could
not find the 0805 I needed...
The temp compensations I typically have to deal with are resistor
tracking. Meanwhile I know which batch of which supply I have
does not track too well with which other.
What I'm fighting right now is the positive TC of the Coilcraft
Midi-spring inductor (typically +100 PPM/c or so) and the positive TC
of the PCB FR4, typically +900. The combo makes the oscillator have a
serious negative TC, which the N4700 cap compensates. I have a series
padder cap, in series with the NTC cap, to trim the oscillator tempco
to near zero, down to the 2nd order parabola.
It's tedious. Tuning takes about an hour per iteration. We have a
gigantic environmental oven in the basement, but using that would take
more like a day per iteration. I made my own benchtop chamber, a
cardboard box with a USB fan inside, used with a heat gun and freeze
spray.
My $5000 Rigol scope is the frequncy counter and USB fan supply.
On 10/25/2023 1:40, Phil Hobbs wrote:
Dimiter_Popoff <dp@tgi-sci.com> wrote:
On 10/25/2023 0:34, john larkin wrote:
Tww it the dimensionless factor
(how many parts you tidly-wink and lose)Â /Â (how many parts you want) >>>>
which, for 0603's, runs 0.6 or so.
Not sure I got what tww is (looked it up, some domino thing so I
guess I get it if so) but 0402 are significantly worse, a lot more
than twice worse. And I have not yet done any 0201...
I highly recommend a good set of curved jaw tweezers, with a tiny binder
clip on the hinge end. That lets you micro-adjust the tension by sliding >> the clip, so that they open when you squeeze them edgeways, and close
very
gently when you release.
This sounds interesting, would you please post a photo?
I manage with my normal tweezers, two of those I have are good enough
to get me through placing placing a lot of 0402-s, not too hard
especially if the paste has not begun to dry so they stick. But
yours might be helpful on less standard operations...
Dimiter_Popoff <dp@tgi-sci.com> wrote:
On 10/25/2023 0:34, john larkin wrote:
Tww it the dimensionless factor
(how many parts you tidly-wink and lose) / (how many parts you want)
which, for 0603's, runs 0.6 or so.
Not sure I got what tww is (looked it up, some domino thing so I
guess I get it if so) but 0402 are significantly worse, a lot more
than twice worse. And I have not yet done any 0201...
I highly recommend a good set of curved jaw tweezers, with a tiny binder
clip on the hinge end. That lets you micro-adjust the tension by sliding
the clip, so that they open when you squeeze them edgeways, and close very >gently when you release.
Good Medicine.
Cheers
Phil Hobbs
On a sunny day (Sat, 28 Oct 2023 07:49:21 -0700) it happened John Larkin ><jl@997PotHill.com> wrote in <no7qji5c7ak2m46cmmuq7misqaqlrt4nkr@4ax.com>:
On Sat, 28 Oct 2023 04:26:51 GMT, Jan Panteltje <alien@comet.invalid> >>wrote:
On a sunny day (Fri, 27 Oct 2023 15:53:31 -0700) it happened john larkin >>><jl@650pot.com> wrote in <6qfojihekda4aobmgnq71rbf493sa454q0@4ax.com>:
On Thu, 26 Oct 2023 05:06:21 GMT, Jan Panteltje <alien@comet.invalid> >>>>wrote:
On a sunny day (Wed, 25 Oct 2023 20:45:52 -0700) it happened John Larkin >>>>><jl@997PotHill.com> wrote in <hknjjih3rp87naoq2o2pefergou2deg7i4@4ax.com>: >>>>>
The trick in a digital delay generator, or at least ours, is to stop >>>>>>an LC oscillator and start it when we get an external trigger, and >>>>>>then use it as our timebase. But lock it to an crystal oscillator to >>>>>>keep long delays accurate.
To do that, I need a pretty stable LC oscillator, hence the tempco >>>>>>tuning. Capex made us a reel of custom N4700 ceramic caps, which can >>>>>>be used to compensate the pretty awful inductor and FR4 tempcos.
HP made one delay generator that actually started and stopped a >>>>>>crystal oscillator. It didn't work very well. A quartz crystal is hard >>>>>>to kick start and is even worse to stop; it rings like a bell.
All this makes me think about a 4046 and PLL.
The 4046 has a terrible phase detector.
HCT4046 has 3 phase detectors.
1 xor gate
2 A digital memory network. It consists of four flip–flops and some gating logic,
a three state output and a phase pulse output.
This comparator acts only on the positive edges of the input signals and is independent of duty cycle.
3 A digital four flip–flops and some gating logic a 3 state output and a phase pulse output
See dataseet
So what's your problem :-)
I have used the 4046 for many things, nice chip.
OK, my mistake, the 4046 has three terrible phase detectors. And one >>terrible VCO.
Well, opinions are still allowed (I hope see https://arstechnica.com/tech-policy/2023/10/the-uks-problematic-online-safety-act-is-now-law/ )
But it depends on what you call 'terrible'
I have sued 4046 (going back to the old CMOS since the seventies?) for things like FM audio modulation, demodulation,
data clock recovery, what not.
So do I understand it right if you wanted to sync an LC oscillator with an external pulse, have it restart (so phase shifted) in an instant?
If all you need is phase shift and no frequency shift then a variable delay would work?
Bit like summer winter time here, got up one hour early it seems....
LC oscillators are (due the the Q (even higher Q for xtal based oscillators) ) not so easy to adjust in a 'flash'.
On 2023-10-25 06:39, John Larkin wrote:
On Wed, 25 Oct 2023 07:18:58 +0300, Dimiter_Popoff <dp@tgi-sci.com>Seems like with a little math you could take one measurement, calculate
wrote:
On 10/25/2023 1:51, john larkin wrote:
On Wed, 25 Oct 2023 01:12:21 +0300, Dimiter_Popoff <dp@tgi-sci.com>
wrote:
On 10/25/2023 0:34, john larkin wrote:
Tww it the dimensionless factor
(how many parts you tidly-wink and lose) / (how many parts you want) >>>>>>
which, for 0603's, runs 0.6 or so.
Not sure I got what tww is (looked it up, some domino thing so I
guess I get it if so) but 0402 are significantly worse, a lot more
than twice worse. And I have not yet done any 0201...
When I first saw 1206's, I thought they were tiny. Ha!
I refuse to use 0402's. I default to 0805s.
I'm tuning the tempco of a 50 MHz triggrered Colpitts oscillator. What >>>> a nuisance. It should have a 3.3 pF N4700 0805 cap, but the layout guy >>>> used all 0603s, so some engineer (who shall not be named) substituted
an 0603 NP0. "NTC" does sound a lot like "NPO" I guess.
The proper 0805 cap was custom brewed for us by Capax.
I often do it the other way around,the 0805 pads I make can also hold
0603. Took me a while to grasp I could do it the first time I could
not find the 0805 I needed...
The temp compensations I typically have to deal with are resistor
tracking. Meanwhile I know which batch of which supply I have
does not track too well with which other.
What I'm fighting right now is the positive TC of the Coilcraft
Midi-spring inductor (typically +100 PPM/c or so) and the positive TC
of the PCB FR4, typically +900. The combo makes the oscillator have a
serious negative TC, which the N4700 cap compensates. I have a series
padder cap, in series with the NTC cap, to trim the oscillator tempco
to near zero, down to the 2nd order parabola.
It's tedious. Tuning takes about an hour per iteration. We have a
gigantic environmental oven in the basement, but using that would take
more like a day per iteration. I made my own benchtop chamber, a
cardboard box with a USB fan inside, used with a heat gun and freeze
spray.
My $5000 Rigol scope is the frequncy counter and USB fan supply.
the correct pad cap value, and be done. Of course NTC caps' tempcos are >notoriously variable (typically +- 30%), so it's hard to get away from >cut-and-try altogether.
You got a reel of custom ones made--do you know how tight their tempco >matching is?
Cheers
Phil Hobbs
On Sun, 29 Oct 2023 05:15:08 GMT, Jan Panteltje <alien@comet.invalid>
wrote:
On a sunny day (Sat, 28 Oct 2023 07:49:21 -0700) it happened John Larkin >><jl@997PotHill.com> wrote in <no7qji5c7ak2m46cmmuq7misqaqlrt4nkr@4ax.com>:
On Sat, 28 Oct 2023 04:26:51 GMT, Jan Panteltje <alien@comet.invalid> >>>wrote:
On a sunny day (Fri, 27 Oct 2023 15:53:31 -0700) it happened john larkin >>>><jl@650pot.com> wrote in <6qfojihekda4aobmgnq71rbf493sa454q0@4ax.com>:
On Thu, 26 Oct 2023 05:06:21 GMT, Jan Panteltje <alien@comet.invalid> >>>>>wrote:
On a sunny day (Wed, 25 Oct 2023 20:45:52 -0700) it happened John Larkin >>>>>><jl@997PotHill.com> wrote in <hknjjih3rp87naoq2o2pefergou2deg7i4@4ax.com>:
The trick in a digital delay generator, or at least ours, is to stop >>>>>>>an LC oscillator and start it when we get an external trigger, and >>>>>>>then use it as our timebase. But lock it to an crystal oscillator to >>>>>>>keep long delays accurate.
To do that, I need a pretty stable LC oscillator, hence the tempco >>>>>>>tuning. Capex made us a reel of custom N4700 ceramic caps, which can >>>>>>>be used to compensate the pretty awful inductor and FR4 tempcos.
HP made one delay generator that actually started and stopped a >>>>>>>crystal oscillator. It didn't work very well. A quartz crystal is hard >>>>>>>to kick start and is even worse to stop; it rings like a bell.
All this makes me think about a 4046 and PLL.
The 4046 has a terrible phase detector.
HCT4046 has 3 phase detectors.
1 xor gate
2 A digital memory network. It consists of four flip–flops and some gating logic,
a three state output and a phase pulse output.
This comparator acts only on the positive edges of the input signals and is independent of duty cycle.
3 A digital four flip–flops and some gating logic a 3 state output and a phase pulse output
See dataseet
So what's your problem :-)
I have used the 4046 for many things, nice chip.
OK, my mistake, the 4046 has three terrible phase detectors. And one >>>terrible VCO.
Well, opinions are still allowed (I hope see >>https://arstechnica.com/tech-policy/2023/10/the-uks-problematic-online-safety-act-is-now-law/ )
But it depends on what you call 'terrible'
I have sued 4046 (going back to the old CMOS since the seventies?) for things like FM audio modulation, demodulation,
data clock recovery, what not.
The phase-frequency detector has a nanoseconds-wide deadband. That
makes for lots of time error and jitter.
The XOR detector is just a slow, sloppy XOR gate.
So do I understand it right if you wanted to sync an LC oscillator with an external pulse, have it restart (so phase shifted)
in an instant?
My 50 MHz LC oscillator is the coarse count for a triggred delay
generator, like this one:
http://www.highlandtechnology.com/DSS/P500DS.shtml
(We're designing a small embedded version now.)
The oscillator is quiescently quenched and kicked off when we get an
extrnal trigger. Then it counts off time in 20 ns ticks. That's OK for
a microsecond or so, but isn't accurate much longer. So the trick is
to phase-lock it to a good XO but preserve its realtionship to the
trigger, namely preserve its random phase relationship to the XO.
If all you need is phase shift and no frequency shift then a variable delay would work?
The SRS DDG does that, but it's complex and adds a lot of insertion
delay.
Bit like summer winter time here, got up one hour early it seems....
LC oscillators are (due the the Q (even higher Q for xtal based oscillators) ) not so easy to adjust in a 'flash'.
Our LC oscillator outputs its first edge a few ns after the trigger,
than ticks faithfully every 20 ns after that. Just a little calculus.
On a sunny day (Sun, 29 Oct 2023 08:28:08 -0700) it happened John Larkin ><jl@997PotHill.com> wrote in <lvtsjihq7q40l12e41r5vdppfvblsa4sis@4ax.com>:
On Sun, 29 Oct 2023 05:15:08 GMT, Jan Panteltje <alien@comet.invalid> >>wrote:
On a sunny day (Sat, 28 Oct 2023 07:49:21 -0700) it happened John Larkin >>><jl@997PotHill.com> wrote in <no7qji5c7ak2m46cmmuq7misqaqlrt4nkr@4ax.com>: >>>
On Sat, 28 Oct 2023 04:26:51 GMT, Jan Panteltje <alien@comet.invalid> >>>>wrote:
On a sunny day (Fri, 27 Oct 2023 15:53:31 -0700) it happened john larkin >>>>><jl@650pot.com> wrote in <6qfojihekda4aobmgnq71rbf493sa454q0@4ax.com>: >>>>>
On Thu, 26 Oct 2023 05:06:21 GMT, Jan Panteltje <alien@comet.invalid> >>>>>>wrote:
On a sunny day (Wed, 25 Oct 2023 20:45:52 -0700) it happened John Larkin >>>>>>><jl@997PotHill.com> wrote in <hknjjih3rp87naoq2o2pefergou2deg7i4@4ax.com>:
The trick in a digital delay generator, or at least ours, is to stop >>>>>>>>an LC oscillator and start it when we get an external trigger, and >>>>>>>>then use it as our timebase. But lock it to an crystal oscillator to >>>>>>>>keep long delays accurate.
To do that, I need a pretty stable LC oscillator, hence the tempco >>>>>>>>tuning. Capex made us a reel of custom N4700 ceramic caps, which can >>>>>>>>be used to compensate the pretty awful inductor and FR4 tempcos. >>>>>>>>
HP made one delay generator that actually started and stopped a >>>>>>>>crystal oscillator. It didn't work very well. A quartz crystal is hard >>>>>>>>to kick start and is even worse to stop; it rings like a bell.
All this makes me think about a 4046 and PLL.
The 4046 has a terrible phase detector.
HCT4046 has 3 phase detectors.
1 xor gate
2 A digital memory network. It consists of four flip–flops and some gating logic,
a three state output and a phase pulse output.
This comparator acts only on the positive edges of the input signals and is independent of duty cycle.
3 A digital four flip–flops and some gating logic a 3 state output and a phase pulse output
See dataseet
So what's your problem :-)
I have used the 4046 for many things, nice chip.
OK, my mistake, the 4046 has three terrible phase detectors. And one >>>>terrible VCO.
Well, opinions are still allowed (I hope see >>>https://arstechnica.com/tech-policy/2023/10/the-uks-problematic-online-safety-act-is-now-law/ )
But it depends on what you call 'terrible'
I have sued 4046 (going back to the old CMOS since the seventies?) for things like FM audio modulation, demodulation,
data clock recovery, what not.
The phase-frequency detector has a nanoseconds-wide deadband. That
makes for lots of time error and jitter.
The XOR detector is just a slow, sloppy XOR gate.
So do I understand it right if you wanted to sync an LC oscillator with an external pulse, have it restart (so phase shifted)
in an instant?
My 50 MHz LC oscillator is the coarse count for a triggred delay
generator, like this one:
http://www.highlandtechnology.com/DSS/P500DS.shtml
(We're designing a small embedded version now.)
Impressive, my hat off to that!
Have not done any picosecond timing work myself... 1 ps resolution is like 1000 GHz???
The oscillator is quiescently quenched and kicked off when we get an >>extrnal trigger. Then it counts off time in 20 ns ticks. That's OK for
a microsecond or so, but isn't accurate much longer. So the trick is
to phase-lock it to a good XO but preserve its realtionship to the
trigger, namely preserve its random phase relationship to the XO.
If all you need is phase shift and no frequency shift then a variable delay would work?
The SRS DDG does that, but it's complex and adds a lot of insertion
delay.
Bit like summer winter time here, got up one hour early it seems....
LC oscillators are (due the the Q (even higher Q for xtal based oscillators) ) not so easy to adjust in a 'flash'.
Our LC oscillator outputs its first edge a few ns after the trigger,
than ticks faithfully every 20 ns after that. Just a little calculus.
OK I see.
On Sun, 29 Oct 2023 05:15:08 GMT, Jan Panteltje <alien@comet.invalid>
wrote:
On a sunny day (Sat, 28 Oct 2023 07:49:21 -0700) it happened John Larkin
<jl@997PotHill.com> wrote in <no7qji5c7ak2m46cmmuq7misqaqlrt4nkr@4ax.com>: >>
On Sat, 28 Oct 2023 04:26:51 GMT, Jan Panteltje <alien@comet.invalid>
wrote:
On a sunny day (Fri, 27 Oct 2023 15:53:31 -0700) it happened john larkin >>>> <jl@650pot.com> wrote in <6qfojihekda4aobmgnq71rbf493sa454q0@4ax.com>: >>>>
On Thu, 26 Oct 2023 05:06:21 GMT, Jan Panteltje <alien@comet.invalid> >>>>> wrote:
On a sunny day (Wed, 25 Oct 2023 20:45:52 -0700) it happened John Larkin >>>>>> <jl@997PotHill.com> wrote in <hknjjih3rp87naoq2o2pefergou2deg7i4@4ax.com>:
The trick in a digital delay generator, or at least ours, is to stop >>>>>>> an LC oscillator and start it when we get an external trigger, and >>>>>>> then use it as our timebase. But lock it to an crystal oscillator to >>>>>>> keep long delays accurate.
To do that, I need a pretty stable LC oscillator, hence the tempco >>>>>>> tuning. Capex made us a reel of custom N4700 ceramic caps, which can >>>>>>> be used to compensate the pretty awful inductor and FR4 tempcos. >>>>>>>
HP made one delay generator that actually started and stopped a
crystal oscillator. It didn't work very well. A quartz crystal is hard >>>>>>> to kick start and is even worse to stop; it rings like a bell.
All this makes me think about a 4046 and PLL.
The 4046 has a terrible phase detector.
HCT4046 has 3 phase detectors.
1 xor gate
2 A digital memory network. It consists of four flip–flops and some gating logic,
a three state output and a phase pulse output.
This comparator acts only on the positive edges of the input signals and is independent of duty cycle.
3 A digital four flip–flops and some gating logic a 3 state output and a phase pulse output
See dataseet
So what's your problem :-)
I have used the 4046 for many things, nice chip.
OK, my mistake, the 4046 has three terrible phase detectors. And one
terrible VCO.
Well, opinions are still allowed (I hope see https://arstechnica.com/tech-policy/2023/10/the-uks-problematic-online-safety-act-is-now-law/ )
But it depends on what you call 'terrible'
I have sued 4046 (going back to the old CMOS since the seventies?) for things like FM audio modulation, demodulation,
data clock recovery, what not.
The phase-frequency detector has a nanoseconds-wide deadband. That
makes for lots of time error and jitter.
The XOR detector is just a slow, sloppy XOR gate.
So do I understand it right if you wanted to sync an LC oscillator with an external pulse, have it restart (so phase shifted) in an instant?
My 50 MHz LC oscillator is the coarse count for a triggred delay
generator, like this one:
http://www.highlandtechnology.com/DSS/P500DS.shtml
(We're designing a small embedded version now.)
The oscillator is quiescently quenched and kicked off when we get an
extrnal trigger. Then it counts off time in 20 ns ticks. That's OK for
a microsecond or so, but isn't accurate much longer. So the trick is
to phase-lock it to a good XO but preserve its realtionship to the
trigger, namely preserve its random phase relationship to the XO.
[...]
On 10/29/23 16:28, John Larkin wrote:
On Sun, 29 Oct 2023 05:15:08 GMT, Jan Panteltje <alien@comet.invalid>
wrote:
On a sunny day (Sat, 28 Oct 2023 07:49:21 -0700) it happened John Larkin >>> <jl@997PotHill.com> wrote in <no7qji5c7ak2m46cmmuq7misqaqlrt4nkr@4ax.com>: >>>
On Sat, 28 Oct 2023 04:26:51 GMT, Jan Panteltje <alien@comet.invalid>
wrote:
On a sunny day (Fri, 27 Oct 2023 15:53:31 -0700) it happened john larkin >>>>> <jl@650pot.com> wrote in <6qfojihekda4aobmgnq71rbf493sa454q0@4ax.com>: >>>>>
On Thu, 26 Oct 2023 05:06:21 GMT, Jan Panteltje <alien@comet.invalid> >>>>>> wrote:
On a sunny day (Wed, 25 Oct 2023 20:45:52 -0700) it happened John Larkin
<jl@997PotHill.com> wrote in <hknjjih3rp87naoq2o2pefergou2deg7i4@4ax.com>:
The trick in a digital delay generator, or at least ours, is to stop >>>>>>>> an LC oscillator and start it when we get an external trigger, and >>>>>>>> then use it as our timebase. But lock it to an crystal oscillator to >>>>>>>> keep long delays accurate.
To do that, I need a pretty stable LC oscillator, hence the tempco >>>>>>>> tuning. Capex made us a reel of custom N4700 ceramic caps, which can >>>>>>>> be used to compensate the pretty awful inductor and FR4 tempcos. >>>>>>>>
HP made one delay generator that actually started and stopped a >>>>>>>> crystal oscillator. It didn't work very well. A quartz crystal is hard >>>>>>>> to kick start and is even worse to stop; it rings like a bell.
All this makes me think about a 4046 and PLL.
The 4046 has a terrible phase detector.
HCT4046 has 3 phase detectors.
1 xor gate
2 A digital memory network. It consists of four flip–flops and some gating logic,
a three state output and a phase pulse output.
This comparator acts only on the positive edges of the input signals and is independent of duty cycle.
3 A digital four flip–flops and some gating logic a 3 state output and a phase pulse output
See dataseet
So what's your problem :-)
I have used the 4046 for many things, nice chip.
OK, my mistake, the 4046 has three terrible phase detectors. And one
terrible VCO.
Well, opinions are still allowed (I hope see https://arstechnica.com/tech-policy/2023/10/the-uks-problematic-online-safety-act-is-now-law/ )
But it depends on what you call 'terrible'
I have sued 4046 (going back to the old CMOS since the seventies?) for things like FM audio modulation, demodulation,
data clock recovery, what not.
The phase-frequency detector has a nanoseconds-wide deadband. That
makes for lots of time error and jitter.
The XOR detector is just a slow, sloppy XOR gate.
So do I understand it right if you wanted to sync an LC oscillator with an external pulse, have it restart (so phase shifted) in an instant?
My 50 MHz LC oscillator is the coarse count for a triggred delay
generator, like this one:
http://www.highlandtechnology.com/DSS/P500DS.shtml
(We're designing a small embedded version now.)
The oscillator is quiescently quenched and kicked off when we get an
extrnal trigger. Then it counts off time in 20 ns ticks. That's OK for
a microsecond or so, but isn't accurate much longer. So the trick is
to phase-lock it to a good XO but preserve its realtionship to the
trigger, namely preserve its random phase relationship to the XO.
[...]
How do you do that?
Jeroen Belleman
On Sat, 28 Oct 2023 04:26:51 GMT, Jan Panteltje <al...@comet.invalid>
wrote:
On a sunny day (Fri, 27 Oct 2023 15:53:31 -0700) it happened john larkin ><j...@650pot.com> wrote in <6qfojihekda4aobmg...@4ax.com>:
The 4046 has a terrible phase detector.
HCT4046 has 3 phase detectors.
1 xor gate
2 A digital memory network. It consists of four flip–flops and some gating logic,
a three state output and a phase pulse output.
This comparator acts only on the positive edges of the input signals and is independent of duty cycle.
3 A digital four flip–flops and some gating logic a 3 state output and a phase pulse output
See dataseet
So what's your problem :-)
I have used the 4046 for many things, nice chip.
OK, my mistake, the 4046 has three terrible phase detectors. And one terrible VCO.
On Sun, 29 Oct 2023 08:56:07 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
On 2023-10-25 06:39, John Larkin wrote:
On Wed, 25 Oct 2023 07:18:58 +0300, Dimiter_Popoff <dp@tgi-sci.com>Seems like with a little math you could take one measurement, calculate
wrote:
On 10/25/2023 1:51, john larkin wrote:
On Wed, 25 Oct 2023 01:12:21 +0300, Dimiter_Popoff <dp@tgi-sci.com>
wrote:
On 10/25/2023 0:34, john larkin wrote:
Tww it the dimensionless factor
(how many parts you tidly-wink and lose) / (how many parts you want) >>>>>>>
which, for 0603's, runs 0.6 or so.
Not sure I got what tww is (looked it up, some domino thing so I
guess I get it if so) but 0402 are significantly worse, a lot more >>>>>> than twice worse. And I have not yet done any 0201...
When I first saw 1206's, I thought they were tiny. Ha!
I refuse to use 0402's. I default to 0805s.
I'm tuning the tempco of a 50 MHz triggrered Colpitts oscillator. What >>>>> a nuisance. It should have a 3.3 pF N4700 0805 cap, but the layout guy >>>>> used all 0603s, so some engineer (who shall not be named) substituted >>>>> an 0603 NP0. "NTC" does sound a lot like "NPO" I guess.
The proper 0805 cap was custom brewed for us by Capax.
I often do it the other way around,the 0805 pads I make can also hold
0603. Took me a while to grasp I could do it the first time I could
not find the 0805 I needed...
The temp compensations I typically have to deal with are resistor
tracking. Meanwhile I know which batch of which supply I have
does not track too well with which other.
What I'm fighting right now is the positive TC of the Coilcraft
Midi-spring inductor (typically +100 PPM/c or so) and the positive TC
of the PCB FR4, typically +900. The combo makes the oscillator have a
serious negative TC, which the N4700 cap compensates. I have a series
padder cap, in series with the NTC cap, to trim the oscillator tempco
to near zero, down to the 2nd order parabola.
It's tedious. Tuning takes about an hour per iteration. We have a
gigantic environmental oven in the basement, but using that would take
more like a day per iteration. I made my own benchtop chamber, a
cardboard box with a USB fan inside, used with a heat gun and freeze
spray.
My $5000 Rigol scope is the frequncy counter and USB fan supply.
the correct pad cap value, and be done. Of course NTC caps' tempcos are
notoriously variable (typically +- 30%), so it's hard to get away from
cut-and-try altogether.
What one measurement? I typically take 5 or so termperature:frequency
points and graph that to get an average slope, which generally looks
pretty good. The bummer is that the padder caps only come in coarse
steps, and the value of the padder has some 2nd order effects.
You got a reel of custom ones made--do you know how tight their tempco
matching is?
I've only measured a few but they look pretty good. The uncorrected
tempco of the oscillator is something like 150 PPM, and I can live
with 25 or so, so the correction need not be perfect.
What's scary is that most of the TC is in the PCB dielectric,
composition and thickness, and that can vary from board batch to
batch.
On Sun, 29 Oct 2023 08:56:07 -0400, Phil Hobbs <pcdhSpamM...@electrooptical.net> wrote:
On 2023-10-25 06:39, John Larkin wrote:
On Wed, 25 Oct 2023 07:18:58 +0300, Dimiter_Popoff <d...@tgi-sci.com> wrote:
On 10/25/2023 1:51, john larkin wrote:
On Wed, 25 Oct 2023 01:12:21 +0300, Dimiter_Popoff <d...@tgi-sci.com> wrote:
On 10/25/2023 0:34, john larkin wrote:
with 25 or so, so the correction need not be perfect.You got a reel of custom ones made--do you know how tight their tempco matching is?
I've only measured a few but they look pretty good. The uncorrected tempco of the oscillator is something like 150 PPM, and I can live
What's scary is that most of the TC is in the PCB dielectric, composition and thickness, and that can vary from board batch to batch.
On Saturday, October 28, 2023 at 7:49:49 AM UTC-7, John Larkin wrot=
e:
On Sat, 28 Oct 2023 04:26:51 GMT, Jan Panteltje <al...@comet.invalid>
wrote:
On a sunny day (Fri, 27 Oct 2023 15:53:31 -0700) it happened john larkin=
<j...@650pot.com> wrote in <6qfojihekda4aobmg...@4ax.com>:
ome gating logic,The 4046 has a terrible phase detector.
HCT4046 has 3 phase detectors.
1 xor gate
2 A digital memory network. It consists of four flip–flops and s=
ut and a phase pulse outputa three state output and a phase pulse output.
This comparator acts only on the positive edges of the input signals an= >d is independent of duty cycle.
3 A digital four flip–flops and some gating logic a 3 state outp=
See dataseet
So what's your problem :-)
I have used the 4046 for many things, nice chip.
OK, my mistake, the 4046 has three terrible phase detectors. And one
terrible VCO.
The three-detector wasn't the CD4046, but a later 74HC prefixed unit
For the purpose of a start-now oscillator, none of the 4046 phase detectors=
matter,
only the 'enable' feature, the pin #5 switch for its current sources.
Ramping up/down my stepping motors with a 4046 was graceful and easy to acc= >omplish.
On Sun, 29 Oct 2023 22:47:23 +0100, Jeroen Belleman
<jeroen@nospam.please> wrote:
On 10/29/23 16:28, John Larkin wrote:
On Sun, 29 Oct 2023 05:15:08 GMT, Jan Panteltje <alien@comet.invalid>
wrote:
On a sunny day (Sat, 28 Oct 2023 07:49:21 -0700) it happened John Larkin >>>> <jl@997PotHill.com> wrote in <no7qji5c7ak2m46cmmuq7misqaqlrt4nkr@4ax.com>: >>>>
On Sat, 28 Oct 2023 04:26:51 GMT, Jan Panteltje <alien@comet.invalid> >>>>> wrote:
On a sunny day (Fri, 27 Oct 2023 15:53:31 -0700) it happened john larkin >>>>>> <jl@650pot.com> wrote in <6qfojihekda4aobmgnq71rbf493sa454q0@4ax.com>: >>>>>>
On Thu, 26 Oct 2023 05:06:21 GMT, Jan Panteltje <alien@comet.invalid> >>>>>>> wrote:
On a sunny day (Wed, 25 Oct 2023 20:45:52 -0700) it happened John Larkin
<jl@997PotHill.com> wrote in <hknjjih3rp87naoq2o2pefergou2deg7i4@4ax.com>:
The trick in a digital delay generator, or at least ours, is to stop >>>>>>>>> an LC oscillator and start it when we get an external trigger, and >>>>>>>>> then use it as our timebase. But lock it to an crystal oscillator to >>>>>>>>> keep long delays accurate.All this makes me think about a 4046 and PLL.
To do that, I need a pretty stable LC oscillator, hence the tempco >>>>>>>>> tuning. Capex made us a reel of custom N4700 ceramic caps, which can >>>>>>>>> be used to compensate the pretty awful inductor and FR4 tempcos. >>>>>>>>>
HP made one delay generator that actually started and stopped a >>>>>>>>> crystal oscillator. It didn't work very well. A quartz crystal is hard
to kick start and is even worse to stop; it rings like a bell. >>>>>>>>
The 4046 has a terrible phase detector.
HCT4046 has 3 phase detectors.
1 xor gate
2 A digital memory network. It consists of four flip–flops and some gating logic,
a three state output and a phase pulse output.
This comparator acts only on the positive edges of the input signals and is independent of duty cycle.
3 A digital four flip–flops and some gating logic a 3 state output and a phase pulse output
See dataseet
So what's your problem :-)
I have used the 4046 for many things, nice chip.
OK, my mistake, the 4046 has three terrible phase detectors. And one >>>>> terrible VCO.
Well, opinions are still allowed (I hope see https://arstechnica.com/tech-policy/2023/10/the-uks-problematic-online-safety-act-is-now-law/ )
But it depends on what you call 'terrible'
I have sued 4046 (going back to the old CMOS since the seventies?) for things like FM audio modulation, demodulation,
data clock recovery, what not.
The phase-frequency detector has a nanoseconds-wide deadband. That
makes for lots of time error and jitter.
The XOR detector is just a slow, sloppy XOR gate.
So do I understand it right if you wanted to sync an LC oscillator with an external pulse, have it restart (so phase shifted) in an instant?
My 50 MHz LC oscillator is the coarse count for a triggred delay
generator, like this one:
http://www.highlandtechnology.com/DSS/P500DS.shtml
(We're designing a small embedded version now.)
The oscillator is quiescently quenched and kicked off when we get an
extrnal trigger. Then it counts off time in 20 ns ticks. That's OK for
a microsecond or so, but isn't accurate much longer. So the trick is
to phase-lock it to a good XO but preserve its realtionship to the
trigger, namely preserve its random phase relationship to the XO.
[...]
How do you do that?
Jeroen Belleman
Digitize the LC oscillator waveform with an ADC that's clocked by the crystal, and do FPGA math on that to tune a varicap to lock in the
phase relationship.
The LC is drifting after trigger, so it's prudent to start locking in
under a microsecond.
Older designs, like the HP 5359A Time Synthesizer and such, didn't
have the advantages that we have now, cheap video ADCs and FPGAs and
phemts and such. But their old manuals are worth studying.
SRS used to have schematics in their manuals, so I studied them too.
On Sun, 29 Oct 2023 22:47:23 +0100, Jeroen Belleman
<jeroen@nospam.please> wrote:
On 10/29/23 16:28, John Larkin wrote:
On Sun, 29 Oct 2023 05:15:08 GMT, Jan Panteltje <alien@comet.invalid>
wrote:
On a sunny day (Sat, 28 Oct 2023 07:49:21 -0700) it happened John Larkin >>>> <jl@997PotHill.com> wrote in <no7qji5c7ak2m46cmmuq7misqaqlrt4nkr@4ax.com>: >>>>
On Sat, 28 Oct 2023 04:26:51 GMT, Jan Panteltje <alien@comet.invalid> >>>>> wrote:
On a sunny day (Fri, 27 Oct 2023 15:53:31 -0700) it happened john larkin >>>>>> <jl@650pot.com> wrote in <6qfojihekda4aobmgnq71rbf493sa454q0@4ax.com>: >>>>>>
On Thu, 26 Oct 2023 05:06:21 GMT, Jan Panteltje <alien@comet.invalid> >>>>>>> wrote:
On a sunny day (Wed, 25 Oct 2023 20:45:52 -0700) it happened John Larkin
<jl@997PotHill.com> wrote in <hknjjih3rp87naoq2o2pefergou2deg7i4@4ax.com>:
The trick in a digital delay generator, or at least ours, is to stop >>>>>>>>> an LC oscillator and start it when we get an external trigger, and >>>>>>>>> then use it as our timebase. But lock it to an crystal oscillator to >>>>>>>>> keep long delays accurate.All this makes me think about a 4046 and PLL.
To do that, I need a pretty stable LC oscillator, hence the tempco >>>>>>>>> tuning. Capex made us a reel of custom N4700 ceramic caps, which can >>>>>>>>> be used to compensate the pretty awful inductor and FR4 tempcos. >>>>>>>>>
HP made one delay generator that actually started and stopped a >>>>>>>>> crystal oscillator. It didn't work very well. A quartz crystal is hard
to kick start and is even worse to stop; it rings like a bell. >>>>>>>>
The 4046 has a terrible phase detector.
HCT4046 has 3 phase detectors.
1 xor gate
2 A digital memory network. It consists of four flip–flops and some gating logic,
a three state output and a phase pulse output.
This comparator acts only on the positive edges of the input signals and is independent of duty cycle.
3 A digital four flip–flops and some gating logic a 3 state output and a phase pulse output
See dataseet
So what's your problem :-)
I have used the 4046 for many things, nice chip.
OK, my mistake, the 4046 has three terrible phase detectors. And one >>>>> terrible VCO.
Well, opinions are still allowed (I hope see https://arstechnica.com/tech-policy/2023/10/the-uks-problematic-online-safety-act-is-now-law/ )
But it depends on what you call 'terrible'
I have sued 4046 (going back to the old CMOS since the seventies?) for things like FM audio modulation, demodulation,
data clock recovery, what not.
The phase-frequency detector has a nanoseconds-wide deadband. That
makes for lots of time error and jitter.
The XOR detector is just a slow, sloppy XOR gate.
So do I understand it right if you wanted to sync an LC oscillator with an external pulse, have it restart (so phase shifted) in an instant?
My 50 MHz LC oscillator is the coarse count for a triggred delay
generator, like this one:
http://www.highlandtechnology.com/DSS/P500DS.shtml
(We're designing a small embedded version now.)
The oscillator is quiescently quenched and kicked off when we get an
extrnal trigger. Then it counts off time in 20 ns ticks. That's OK for
a microsecond or so, but isn't accurate much longer. So the trick is
to phase-lock it to a good XO but preserve its realtionship to the
trigger, namely preserve its random phase relationship to the XO.
[...]
How do you do that?
Jeroen Belleman
Digitize the LC oscillator waveform with an ADC that's clocked by the crystal, and do FPGA math on that to tune a varicap to lock in the
phase relationship.
The LC is drifting after trigger, so it's prudent to start locking in
under a microsecond.
Older designs, like the HP 5359A Time Synthesizer and such, didn't
have the advantages that we have now, cheap video ADCs and FPGAs and
phemts and such. But their old manuals are worth studying.
SRS used to have schematics in their manuals, so I studied them too.
On 10/29/23 23:37, John Larkin wrote:
On Sun, 29 Oct 2023 22:47:23 +0100, Jeroen Belleman
<jeroen@nospam.please> wrote:
On 10/29/23 16:28, John Larkin wrote:
On Sun, 29 Oct 2023 05:15:08 GMT, Jan Panteltje <alien@comet.invalid>
wrote:
On a sunny day (Sat, 28 Oct 2023 07:49:21 -0700) it happened John Larkin >>>>> <jl@997PotHill.com> wrote in <no7qji5c7ak2m46cmmuq7misqaqlrt4nkr@4ax.com>:
On Sat, 28 Oct 2023 04:26:51 GMT, Jan Panteltje <alien@comet.invalid> >>>>>> wrote:
On a sunny day (Fri, 27 Oct 2023 15:53:31 -0700) it happened john larkin
<jl@650pot.com> wrote in <6qfojihekda4aobmgnq71rbf493sa454q0@4ax.com>: >>>>>>>
On Thu, 26 Oct 2023 05:06:21 GMT, Jan Panteltje <alien@comet.invalid> >>>>>>>> wrote:
On a sunny day (Wed, 25 Oct 2023 20:45:52 -0700) it happened John Larkin
<jl@997PotHill.com> wrote in <hknjjih3rp87naoq2o2pefergou2deg7i4@4ax.com>:
The trick in a digital delay generator, or at least ours, is to stop >>>>>>>>>> an LC oscillator and start it when we get an external trigger, and >>>>>>>>>> then use it as our timebase. But lock it to an crystal oscillator to >>>>>>>>>> keep long delays accurate.All this makes me think about a 4046 and PLL.
To do that, I need a pretty stable LC oscillator, hence the tempco >>>>>>>>>> tuning. Capex made us a reel of custom N4700 ceramic caps, which can >>>>>>>>>> be used to compensate the pretty awful inductor and FR4 tempcos. >>>>>>>>>>
HP made one delay generator that actually started and stopped a >>>>>>>>>> crystal oscillator. It didn't work very well. A quartz crystal is hard
to kick start and is even worse to stop; it rings like a bell. >>>>>>>>>
The 4046 has a terrible phase detector.
HCT4046 has 3 phase detectors.
1 xor gate
2 A digital memory network. It consists of four flip–flops and some gating logic,
a three state output and a phase pulse output.
This comparator acts only on the positive edges of the input signals and is independent of duty cycle.
3 A digital four flip–flops and some gating logic a 3 state output and a phase pulse output
See dataseet
So what's your problem :-)
I have used the 4046 for many things, nice chip.
OK, my mistake, the 4046 has three terrible phase detectors. And one >>>>>> terrible VCO.
Well, opinions are still allowed (I hope see https://arstechnica.com/tech-policy/2023/10/the-uks-problematic-online-safety-act-is-now-law/ )
But it depends on what you call 'terrible'
I have sued 4046 (going back to the old CMOS since the seventies?) for things like FM audio modulation, demodulation,
data clock recovery, what not.
The phase-frequency detector has a nanoseconds-wide deadband. That
makes for lots of time error and jitter.
The XOR detector is just a slow, sloppy XOR gate.
So do I understand it right if you wanted to sync an LC oscillator with an external pulse, have it restart (so phase shifted) in an instant?
My 50 MHz LC oscillator is the coarse count for a triggred delay
generator, like this one:
http://www.highlandtechnology.com/DSS/P500DS.shtml
(We're designing a small embedded version now.)
The oscillator is quiescently quenched and kicked off when we get an
extrnal trigger. Then it counts off time in 20 ns ticks. That's OK for >>>> a microsecond or so, but isn't accurate much longer. So the trick is
to phase-lock it to a good XO but preserve its realtionship to the
trigger, namely preserve its random phase relationship to the XO.
[...]
How do you do that?
Jeroen Belleman
Digitize the LC oscillator waveform with an ADC that's clocked by the
crystal, and do FPGA math on that to tune a varicap to lock in the
phase relationship.
The LC is drifting after trigger, so it's prudent to start locking in
under a microsecond.
OK, though I won't pretend I understand how you get to picosecond
resolution from that.
Older designs, like the HP 5359A Time Synthesizer and such, didn't
have the advantages that we have now, cheap video ADCs and FPGAs and
phemts and such. But their old manuals are worth studying.
SRS used to have schematics in their manuals, so I studied them too.
Our ancestors sometimes did amazing things, considering the means they
had...
Jeroen Belleman
I highly recommend a good set of curved jaw tweezers, with a tiny
binder clip on the hinge end.¶ÿ That lets you micro-adjust the tension
by sliding the clip, so that they open when you squeeze them edgeways,
and close very gently when you release.
This sounds interesting, would you please post a photo?
I manage with my normal tweezers, two of those I have are good enough
to get me through placing placing a lot of 0402-s, not too hard
especially if the paste has not begun to dry so they stick. But
yours might be helpful on less standard operations...
Something like these:
<https://www.amazon.com/Officemate-Micro-Binder-Clips-31030/dp/B003U4U3YQ
.
You take off the silver handles and just use the black spring part.
That and a little jar of acetone for cleaning flux off the tweezers
makes an excellent combination that reduces the tiddly-wink problem by a
lot.
Cheers
Phil Hobbs
Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:<snip>
I highly recommend a good set of curved jaw tweezers, with a tiny
binder clip on the hinge end.¶ÿ That lets you micro-adjust the tension >>>> by sliding the clip, so that they open when you squeeze them edgeways, >>>> and close very gently when you release.
This sounds interesting, would you please post a photo?
I manage with my normal tweezers, two of those I have are good enough
to get me through placing placing a lot of 0402-s, not too hard
especially if the paste has not begun to dry so they stick. But
yours might be helpful on less standard operations...
Something like these:
<https://www.amazon.com/Officemate-Micro-Binder-Clips-31030/dp/B003U4U3YQ >>> .
You take off the silver handles and just use the black spring part.
That and a little jar of acetone for cleaning flux off the tweezers
makes an excellent combination that reduces the tiddly-wink problem by a
lot.
Cheers
Phil Hobbs
Tweezers can still lose the parts, and may have some difficulty removing parts from the tape. The binder clips require two hands, and fumbling
around trying to get the part aligned with the mounting point may case it
to pop out of the tweezers and get lost.
What is needed is a method that firmly fixes the component while it is
being transported from the tape to the pcb, provides easy 360 degree
rotation of the part for alignment, and only requires one hand for
operation.
A simple vacuum system seems to be ideal. Here is probably the simplest:
DIY Vacuum Pen
https://www.youtube.com/watch?v=sYZ2oqnYb3s
I cordially dislike vacuum pens, though I know some folks like them a
lot. I have one, but rarely use it. You have to change tips to go
from doing chips to doing small parts, or else your 0402s get sucked
right up the hose. A pain.
Dumping a couple of parts out of a tape is pretty simple--the issue is holding them in the right position and orientation long enough to get at least one lead soldered down.
Cheers
Phil Hobbs
Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
I cordially dislike vacuum pens, though I know some folks like them a
lot. I have one, but rarely use it. You have to change tips to go
from doing chips to doing small parts, or else your 0402s get sucked
right up the hose. A pain.
Dumping a couple of parts out of a tape is pretty simple--the issue is
holding them in the right position and orientation long enough to get at
least one lead soldered down.
How do you handle ic's such as tssop, soic, tsop, etc. With tweezers, there is a risk of mangling the leads. The vacuum approach does not touch the leads.
On 2023-10-30 20:19, Mike Monett VE3BTI wrote:
Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:<snip>
I highly recommend a good set of curved jaw tweezers, with a tiny
binder clip on the hinge end.¶ÿ That lets you micro-adjust the tension >>>>> by sliding the clip, so that they open when you squeeze them edgeways, >>>>> and close very gently when you release.
This sounds interesting, would you please post a photo?
I manage with my normal tweezers, two of those I have are good enough
to get me through placing placing a lot of 0402-s, not too hard
especially if the paste has not begun to dry so they stick. But
yours might be helpful on less standard operations...
Something like these:
<https://www.amazon.com/Officemate-Micro-Binder-Clips-31030/dp/B003U4U3YQ >>>> .
You take off the silver handles and just use the black spring part.
That and a little jar of acetone for cleaning flux off the tweezers
makes an excellent combination that reduces the tiddly-wink problem by a >>> lot.
Cheers
Phil Hobbs
Tweezers can still lose the parts, and may have some difficulty removing
parts from the tape. The binder clips require two hands, and fumbling
around trying to get the part aligned with the mounting point may case it
to pop out of the tweezers and get lost.
What is needed is a method that firmly fixes the component while it is
being transported from the tape to the pcb, provides easy 360 degree
rotation of the part for alignment, and only requires one hand for
operation.
A simple vacuum system seems to be ideal. Here is probably the simplest:
DIY Vacuum Pen
https://www.youtube.com/watch?v=sYZ2oqnYb3s
I cordially dislike vacuum pens, though I know some folks like them a
lot. I have one, but rarely use it. You have to change tips to go
from doing chips to doing small parts, or else your 0402s get sucked
right up the hose. A pain.
Dumping a couple of parts out of a tape is pretty simple--the issue is >holding them in the right position and orientation long enough to get at >least one lead soldered down.
The HP5370 time-interval counter had/has 20 ps picosecond resolution
and about a 30 ps RMS noise floor. The new Keysight equivalent is, as
I recall, about twice as good on jitter. After 40 years!
The 5370 is astounding. It does amazing measurements with an MC6800
CPU, less compute power than a toaster has nowadays. The user
interface is wonderful too.
The Keysight 53200 will not display an N-sample running jitter
measurement! The 5370 did that.
On a sunny day (Mon, 30 Oct 2023 09:04:03 -0700) it happened John Larkin <jl@997PotHill.com> wrote in <egkvjih16kc0bu4crm5vk6g1cu32s1rge2@4ax.com>:
The HP5370 time-interval counter had/has 20 ps picosecond resolution
and about a 30 ps RMS noise floor. The new Keysight equivalent is, as
I recall, about twice as good on jitter. After 40 years!
The 5370 is astounding. It does amazing measurements with an MC6800
CPU, less compute power than a toaster has nowadays. The user
interface is wonderful too.
The Keysight 53200 will not display an N-sample running jitter
measurement! The 5370 did that.
I just keep wondering, if I do light speed divided by time I get
300,000,000 * 10^-12 = 0.000300 meter
.3 mm in vacuum as distance the signal travels in a pico second, a lot less in cables,
even if you bended a cable it would vary significally,
Temperature changes changing cable length would create pico second delay changes too.
How did you measure that 1 ps, seems just sales crap to me?
Video digitizers have jitter depending on clock frequency..
I have worked with those.
No wonder they cannot get fussion or was it fusion to work.
;-)
Seems you need a 1 THz reference ? and likely locked to some 10 MHz atomic Rubidium thing?
even than 10^12 / 10^7 = 10^5 increase in jitter and drift of the rub-it-in-dium..
Drift over 1000 seconds???
On 31/10/2023 4:01 am, Jan Panteltje wrote:
On a sunny day (Mon, 30 Oct 2023 09:04:03 -0700) it happened John Larkin <j...@997PotHill.com> wrote in <egkvjih16kc0bu4cr...@4ax.com>:
The HP5370 time-interval counter had/has 20 ps picosecond resolution
and about a 30 ps RMS noise floor. The new Keysight equivalent is, as
I recall, about twice as good on jitter. After 40 years!
The 5370 is astounding. It does amazing measurements with an MC6800
CPU, less compute power than a toaster has nowadays. The user
interface is wonderful too.
The Keysight 53200 will not display an N-sample running jitter
measurement! The 5370 did that.
I just keep wondering, if I do light speed divided by time I get 300,000,000 * 10^-12 = 0.000300 meter
.3 mm in vacuum as distance the signal travels in a pico second, a lot less in cables,
even if you bended a cable it would vary significally,
Temperature changes changing cable length would create pico second delay changes too.
How did you measure that 1 ps, seems just sales crap to me?
Video digitizers have jitter depending on clock frequency..
I have worked with those.
No wonder they cannot get fussion or was it fusion to work.
;-)
Seems you need a 1 THz reference ? and likely locked to some 10 MHz atomic Rubidium thing?
even than 10^12 / 10^7 = 10^5 increase in jitter and drift of the rub-it-in-dium..
Drift over 1000 seconds???
This HP Journal is great reading;
<https://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1978-08.pdf>
How do you handle ic's such as tssop, soic, tsop, etc. With tweezers,
there is a risk of mangling the leads. The vacuum approach does not
touch the leads.
Never recall having a problem with that. I normally hold them by the
ends, where there aren't any leads. Of course those parts are big
enough that you can just place them with the tweezers and then press
them down on the board (usually with the closed jaws) while soldering.
I still lose parts, of course, but not nearly as many as I used to.
Cheers
Phil Hobbs
On 2023-10-30 21:31, Mike Monett VE3BTI wrote:
Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
I cordially dislike vacuum pens, though I know some folks like them a
lot. I have one, but rarely use it. You have to change tips to go
from doing chips to doing small parts, or else your 0402s get sucked
right up the hose. A pain.
Dumping a couple of parts out of a tape is pretty simple--the issue is
holding them in the right position and orientation long enough to get at >>> least one lead soldered down.
How do you handle ic's such as tssop, soic, tsop, etc. With tweezers, there >> is a risk of mangling the leads. The vacuum approach does not touch the
leads.
Never recall having a problem with that. I normally hold them by the
ends, where there aren't any leads. Of course those parts are big
enough that you can just place them with the tweezers and then press
them down on the board (usually with the closed jaws) while soldering.
I still lose parts, of course, but not nearly as many as I used to.
Cheers
Phil Hobbs
On Tuesday, October 31, 2023 at 6:51:41 PM UTC+11, piglet wrote:generated 800MHz clocked edges and subtract that that offset from the delay from the appropriate clock edge to the output edge.
On 31/10/2023 4:01 am, Jan Panteltje wrote:
On a sunny day (Mon, 30 Oct 2023 09:04:03 -0700) it happened John Larkin >>> <j...@997PotHill.com> wrote in <egkvjih16kc0bu4cr...@4ax.com>:This HP Journal is great reading;
The HP5370 time-interval counter had/has 20 ps picosecond resolution
and about a 30 ps RMS noise floor. The new Keysight equivalent is, as
I recall, about twice as good on jitter. After 40 years!
The 5370 is astounding. It does amazing measurements with an MC6800
CPU, less compute power than a toaster has nowadays. The user
interface is wonderful too.
The Keysight 53200 will not display an N-sample running jitter
measurement! The 5370 did that.
I just keep wondering, if I do light speed divided by time I get
300,000,000 * 10^-12 = 0.000300 meter
.3 mm in vacuum as distance the signal travels in a pico second, a lot less in cables,
even if you bended a cable it would vary significally,
Temperature changes changing cable length would create pico second delay changes too.
How did you measure that 1 ps, seems just sales crap to me?
Video digitizers have jitter depending on clock frequency..
I have worked with those.
No wonder they cannot get fussion or was it fusion to work.
;-)
Seems you need a 1 THz reference ? and likely locked to some 10 MHz atomic Rubidium thing?
even than 10^12 / 10^7 = 10^5 increase in jitter and drift of the rub-it-in-dium..
Drift over 1000 seconds???
<https://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1978-08.pdf>
But it's from 1978. When we tackled much the same problem at Cambridge Instruments in 1988 we had more options.
What the HP article doesn't seem to mention is the minimum delay available. Our system couldn't produce an output edge earlier than about 40nsec after the input edge - it took that long to work out where the input edge was vis-a-vis our continuously
It was bit more complicated but offered slightly better performance. The main driver was the boss's insistance on being able to offer 10psec granularity - which was bit silly when positioning a 500psec wide pulse, but the boss sold the machine himself.and knew what sales spiels worked.
Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
How do you handle ic's such as tssop, soic, tsop, etc. With tweezers,
there is a risk of mangling the leads. The vacuum approach does not
touch the leads.
Never recall having a problem with that. I normally hold them by the
ends, where there aren't any leads. Of course those parts are big
enough that you can just place them with the tweezers and then press
them down on the board (usually with the closed jaws) while soldering.
I still lose parts, of course, but not nearly as many as I used to.
Tweezers don't help with Quad Flat Package (QFP).
Vacuum pickup handles all packages, needs only one hand, and loses fewer parts.
On 31/10/2023 12:32 pm, Anthony William Sloman wrote:
On Tuesday, October 31, 2023 at 6:51:41 PM UTC+11, piglet wrote:
On 31/10/2023 4:01 am, Jan Panteltje wrote:
On a sunny day (Mon, 30 Oct 2023 09:04:03 -0700) it happened John Larkin >>>> <j...@997PotHill.com> wrote in <egkvjih16kc0bu4cr...@4ax.com>:This HP Journal is great reading;
The HP5370 time-interval counter had/has 20 ps picosecond resolution >>>>> and about a 30 ps RMS noise floor. The new Keysight equivalent is, as >>>>> I recall, about twice as good on jitter. After 40 years!
The 5370 is astounding. It does amazing measurements with an MC6800
CPU, less compute power than a toaster has nowadays. The user
interface is wonderful too.
The Keysight 53200 will not display an N-sample running jitter
measurement! The 5370 did that.
I just keep wondering, if I do light speed divided by time I get
300,000,000 * 10^-12 = 0.000300 meter
.3 mm in vacuum as distance the signal travels in a pico second, a lot less in cables,
even if you bended a cable it would vary significally,
Temperature changes changing cable length would create pico second delay changes too.
How did you measure that 1 ps, seems just sales crap to me?
Video digitizers have jitter depending on clock frequency..
I have worked with those.
No wonder they cannot get fussion or was it fusion to work.
;-)
Seems you need a 1 THz reference ? and likely locked to some 10 MHz
atomic Rubidium thing?
even than 10^12 / 10^7 = 10^5 increase in jitter and drift of the rub-it-in-dium..
Drift over 1000 seconds???
<https://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1978-08.pdf>
But it's from 1978. When we tackled much the same problem at Cambridge
Instruments in 1988 we had more options.
What the HP article doesn't seem to mention is the minimum delay
available. Our system couldn't produce an output edge earlier than about
40nsec after the input edge - it took that long to work out where the
input edge was vis-a-vis our continuously generated 800MHz clocked
edges and subtract that that offset from the delay from the appropriate
clock edge to the output edge.
It was bit more complicated but offered slightly better performance. The
main driver was the boss's insistance on being able to offer 10psec
granularity - which was bit silly when positioning a 500psec wide pulse,
but the boss sold the machine himself. and knew what sales spiels worked.
Yes, but Jan Panteltje was asking how one can get 20ps resolution
without needing a 50GHz timebase.
piglet
Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
We try not to use QFNs because of iterated problems with
soldering.(JLCPCB is great, but for some reason gives us problems with
de-wets on QFN packages.) QFNs are also unreliable in vibration
environments, which we encounter a fair amount.
Cheers
Phil Hobbs
Good info. Thanks
Why is vibration a problem? Seems it has more legs to attach to the pcb.
We try not to use QFNs because of iterated problems with
soldering.(JLCPCB is great, but for some reason gives us problems with de-wets on QFN packages.) QFNs are also unreliable in vibration environments, which we encounter a fair amount.
Cheers
Phil Hobbs
Why is vibration a problem? Seems it has more legs to attach to the pcb.
I believe that itƒ Ts that the flexible leads relieve the stress on the solder joints, extending their fatigue life.
Cheers
Phil Hobbs
How did you measure that 1 ps, seems just sales crap to me?
Video digitizers have jitter depending on clock frequency..
I have worked with those.
Mike Monett VE3BTI <spamme@not.com> wrote:
Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
We try not to use QFNs because of iterated problems with
soldering.(JLCPCB is great, but for some reason gives us problems with
de-wets on QFN packages.) QFNs are also unreliable in vibration
environments, which we encounter a fair amount.
Cheers
Phil Hobbs
Good info. Thanks
Why is vibration a problem? Seems it has more legs to attach to the pcb.
I believe that it’s that the flexible leads relieve the stress on the
solder joints, extending their fatigue life.
On a sunny day (Mon, 30 Oct 2023 09:04:03 -0700) it happened John Larkin ><jl@997PotHill.com> wrote in <egkvjih16kc0bu4crm5vk6g1cu32s1rge2@4ax.com>:
The HP5370 time-interval counter had/has 20 ps picosecond resolution
and about a 30 ps RMS noise floor. The new Keysight equivalent is, as
I recall, about twice as good on jitter. After 40 years!
The 5370 is astounding. It does amazing measurements with an MC6800
CPU, less compute power than a toaster has nowadays. The user
interface is wonderful too.
The Keysight 53200 will not display an N-sample running jitter
measurement! The 5370 did that.
I just keep wondering, if I do light speed divided by time I get
300,000,000 * 10^-12 = 0.000300 meter
.3 mm in vacuum as distance the signal travels in a pico second, a lot less in cables,
even if you bended a cable it would vary significally,
Temperature changes changing cable length would create pico second delay changes too.
How did you measure that 1 ps, seems just sales crap to me?
Video digitizers have jitter depending on clock frequency..
I have worked with those.
No wonder they cannot get fussion or was it fusion to work.
;-)
Seems you need a 1 THz reference ? and likely locked to some 10 MHz atomic Rubidium thing?
even than 10^12 / 10^7 = 10^5 increase in jitter and drift of the rub-it-in-dium..
Drift over 1000 seconds???
On 31/10/2023 12:32 pm, Anthony William Sloman wrote:generated 800MHz clocked edges and subtract that that offset from the delay from the appropriate clock edge to the output edge.
On Tuesday, October 31, 2023 at 6:51:41 PM UTC+11, piglet wrote:
On 31/10/2023 4:01 am, Jan Panteltje wrote:
On a sunny day (Mon, 30 Oct 2023 09:04:03 -0700) it happened John Larkin >>> <j...@997PotHill.com> wrote in <egkvjih16kc0bu4cr...@4ax.com>:This HP Journal is great reading;
The HP5370 time-interval counter had/has 20 ps picosecond resolution >>>> and about a 30 ps RMS noise floor. The new Keysight equivalent is, as >>>> I recall, about twice as good on jitter. After 40 years!
The 5370 is astounding. It does amazing measurements with an MC6800 >>>> CPU, less compute power than a toaster has nowadays. The user
interface is wonderful too.
The Keysight 53200 will not display an N-sample running jitter
measurement! The 5370 did that.
I just keep wondering, if I do light speed divided by time I get
300,000,000 * 10^-12 = 0.000300 meter
.3 mm in vacuum as distance the signal travels in a pico second, a lot less in cables,
even if you bended a cable it would vary significally,
Temperature changes changing cable length would create pico second delay changes too.
How did you measure that 1 ps, seems just sales crap to me?
Video digitizers have jitter depending on clock frequency..
I have worked with those.
No wonder they cannot get fussion or was it fusion to work.
;-)
Seems you need a 1 THz reference ? and likely locked to some 10 MHz atomic Rubidium thing?
even than 10^12 / 10^7 = 10^5 increase in jitter and drift of the rub-it-in-dium..
Drift over 1000 seconds???
<https://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1978-08.pdf>
But it's from 1978. When we tackled much the same problem at Cambridge Instruments in 1988 we had more options.
What the HP article doesn't seem to mention is the minimum delay available. Our system couldn't produce an output edge earlier than about 40nsec after the input edge - it took that long to work out where the input edge was vis-a-vis our continuously
himself. and knew what sales spiels worked.It was bit more complicated but offered slightly better performance. The main driver was the boss's insistance on being able to offer 10psec granularity - which was bit silly when positioning a 500psec wide pulse, but the boss sold the machine
Yes, but Jan Panteltje was asking how one can get 20ps resolution
without needing a 50GHz timebase.
On 31/10/2023 4:01 am, Jan Panteltje wrote:
On a sunny day (Mon, 30 Oct 2023 09:04:03 -0700) it happened John Larkin
<jl@997PotHill.com> wrote in <egkvjih16kc0bu4crm5vk6g1cu32s1rge2@4ax.com>: >>
The HP5370 time-interval counter had/has 20 ps picosecond resolution
and about a 30 ps RMS noise floor. The new Keysight equivalent is, as
I recall, about twice as good on jitter. After 40 years!
The 5370 is astounding. It does amazing measurements with an MC6800
CPU, less compute power than a toaster has nowadays. The user
interface is wonderful too.
The Keysight 53200 will not display an N-sample running jitter
measurement! The 5370 did that.
I just keep wondering, if I do light speed divided by time I get
300,000,000 * 10^-12 = 0.000300 meter
.3 mm in vacuum as distance the signal travels in a pico second, a lot less in cables,
even if you bended a cable it would vary significally,
Temperature changes changing cable length would create pico second delay changes too.
How did you measure that 1 ps, seems just sales crap to me?
Video digitizers have jitter depending on clock frequency..
I have worked with those.
No wonder they cannot get fussion or was it fusion to work.
;-)
Seems you need a 1 THz reference ? and likely locked to some 10 MHz atomic Rubidium thing?
even than 10^12 / 10^7 = 10^5 increase in jitter and drift of the rub-it-in-dium..
Drift over 1000 seconds???
This HP Journal is great reading;
<https://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1978-08.pdf>
On Tue, 31 Oct 2023 04:01:09 GMT, Jan Panteltje <alien@comet.invalid>
wrote:
On a sunny day (Mon, 30 Oct 2023 09:04:03 -0700) it happened John Larkin >><jl@997PotHill.com> wrote in <egkvjih16kc0bu4crm5vk6g1cu32s1rge2@4ax.com>:
The HP5370 time-interval counter had/has 20 ps picosecond resolution
and about a 30 ps RMS noise floor. The new Keysight equivalent is, as
I recall, about twice as good on jitter. After 40 years!
The 5370 is astounding. It does amazing measurements with an MC6800
CPU, less compute power than a toaster has nowadays. The user
interface is wonderful too.
The Keysight 53200 will not display an N-sample running jitter >>>measurement! The 5370 did that.
I just keep wondering, if I do light speed divided by time I get
300,000,000 * 10^-12 = 0.000300 meter
.3 mm in vacuum as distance the signal travels in a pico second, a lot less in cables,
even if you bended a cable it would vary significally,
Temperature changes changing cable length would create pico second delay changes too.
How did you measure that 1 ps, seems just sales crap to me?
Video digitizers have jitter depending on clock frequency..
I have worked with those.
There are lots of oscilloscopes and time-interval counters that will
resolve under a ps, with some signal averaging.
Our old Tek 11801C scopes have a jitter noise floor around 2 ps RMS.
Our giant LeCroy scope claims some absurd jitter like 100 fs.
A good crystal oscillator will have short-term jitter measured in fs,
and maybe 1 ps of jitter one second out.
No wonder they cannot get fussion or was it fusion to work.
NIF is getting fusion yield over unity, measured as blast energy out
over light energy in. We supplied the master timing system and two >generations of the beam modulators. They are great people to work
with.
;-)
Seems you need a 1 THz reference ? and likely locked to some 10 MHz atomic Rubidium thing?
even than 10^12 / 10^7 = 10^5 increase in jitter and drift of the rub-it-in-dium..
Drift over 1000 seconds???
Our timing modules use a 155.52 MHz clock to time delays in 6.4 ns
ticks, and analog ramp vernier delays to get sub-ps resolution.
They all phase-lock to the NIF master timing system which is
GPS-based.
What really matters is that the roughly 2000 "client" devices use the
same time reference so the 192 lasers whack the target in sync.
On a sunny day (Tue, 31 Oct 2023 17:49:57 -0700) it happened John Larkin ><jl@997PotHill.com> wrote in <6c73kiprdslaj899vv92sm26n58r73s2au@4ax.com>:
On Tue, 31 Oct 2023 04:01:09 GMT, Jan Panteltje <alien@comet.invalid> >>wrote:
On a sunny day (Mon, 30 Oct 2023 09:04:03 -0700) it happened John Larkin >>><jl@997PotHill.com> wrote in <egkvjih16kc0bu4crm5vk6g1cu32s1rge2@4ax.com>: >>>
The HP5370 time-interval counter had/has 20 ps picosecond resolution >>>>and about a 30 ps RMS noise floor. The new Keysight equivalent is, as
I recall, about twice as good on jitter. After 40 years!
The 5370 is astounding. It does amazing measurements with an MC6800 >>>>CPU, less compute power than a toaster has nowadays. The user
interface is wonderful too.
The Keysight 53200 will not display an N-sample running jitter >>>>measurement! The 5370 did that.
I just keep wondering, if I do light speed divided by time I get
300,000,000 * 10^-12 = 0.000300 meter
.3 mm in vacuum as distance the signal travels in a pico second, a lot less in cables,
even if you bended a cable it would vary significally,
Temperature changes changing cable length would create pico second delay changes too.
How did you measure that 1 ps, seems just sales crap to me?
Video digitizers have jitter depending on clock frequency..
I have worked with those.
There are lots of oscilloscopes and time-interval counters that will >>resolve under a ps, with some signal averaging.
Our old Tek 11801C scopes have a jitter noise floor around 2 ps RMS.
Our giant LeCroy scope claims some absurd jitter like 100 fs.
A good crystal oscillator will have short-term jitter measured in fs,
and maybe 1 ps of jitter one second out.
No wonder they cannot get fussion or was it fusion to work.
NIF is getting fusion yield over unity, measured as blast energy out
over light energy in. We supplied the master timing system and two >>generations of the beam modulators. They are great people to work
with.
;-)
Seems you need a 1 THz reference ? and likely locked to some 10 MHz atomic Rubidium thing?
even than 10^12 / 10^7 = 10^5 increase in jitter and drift of the rub-it-in-dium..
Drift over 1000 seconds???
Our timing modules use a 155.52 MHz clock to time delays in 6.4 ns
ticks, and analog ramp vernier delays to get sub-ps resolution.
They all phase-lock to the NIF master timing system which is
GPS-based.
What really matters is that the roughly 2000 "client" devices use the
same time reference so the 192 lasers whack the target in sync.
My apologies..
I have now read the HP journal paper and are that much wiser now :-)
On Monday, October 30, 2023 at 9:01:17 PM UTC-7, Jan Panteltje wrote:
How did you measure that 1 ps, seems just sales crap to me?Digitize the delayed and original undelayed signals with a common clock, then downconvert them to baseband I/Q with a complex DDS, then
Video digitizers have jitter depending on clock frequency..
I have worked with those.
band-limit the heck out of them. Then atan2() and unwrap them, and finally subtract them to get the phase difference.
The band-limiting step is the important one, as it gets rid of noise that would
otherwise show up as phase uncertainty. Once you get the measurement BW
down to a few Hz, picoseconds are trivial to resolve.
Here's a paper about the NIF timing system.
https://www.slac.stanford.edu/econf/C011127/TUAP069.pdf
The biggest error is the prop delay tempco of the fiberoptics, around
15 PPM/degC. The facility is BIG.
https://en.wikipedia.org/wiki/National_Ignition_Facility
I don't expect that laser fusion will ever be a practical power
source. NIF is actually mainly for weapons research.
On a sunny day (Wed, 01 Nov 2023 07:56:13 -0700) it happened John Larkin ><jl@997PotHill.com> wrote in <0cp4ki1ui592aul2674qhmk85de16s8c3a@4ax.com>:
Here's a paper about the NIF timing system.
https://www.slac.stanford.edu/econf/C011127/TUAP069.pdf
The biggest error is the prop delay tempco of the fiberoptics, around
15 PPM/degC. The facility is BIG.
https://en.wikipedia.org/wiki/National_Ignition_Facility
I don't expect that laser fusion will ever be a practical power
source. NIF is actually mainly for weapons research.
Thank you for the links.
Billions of dollars it did cost I read...
And the management knew it was crap...
Example of the US Military Industrial Complex.
As to fusion power, I am not even sure ITER will work this time...
Probably needs to be rebuild a little bigger :-)
Politics, job creation...
On Monday, October 30, 2023 at 9:01:17?PM UTC-7, Jan Panteltje wrote:
How did you measure that 1 ps, seems just sales crap to me?
Video digitizers have jitter depending on clock frequency..
I have worked with those.
Digitize the delayed and original undelayed signals with a common clock,
then downconvert them to baseband I/Q with a complex DDS, then
band-limit the heck out of them. Then atan2() and unwrap them, and finally >subtract them to get the phase difference.
The band-limiting step is the important one, as it gets rid of noise that would
otherwise show up as phase uncertainty. Once you get the measurement BW
down to a few Hz, picoseconds are trivial to resolve.
-- john
On Thu, 02 Nov 2023 04:16:52 GMT, Jan Panteltje <alien@comet.invalid>
wrote:
On a sunny day (Wed, 01 Nov 2023 07:56:13 -0700) it happened John Larkin >><jl@997PotHill.com> wrote in <0cp4ki1ui592aul2674qhmk85de16s8c3a@4ax.com>:
Here's a paper about the NIF timing system.
https://www.slac.stanford.edu/econf/C011127/TUAP069.pdf
The biggest error is the prop delay tempco of the fiberoptics, around
15 PPM/degC. The facility is BIG.
https://en.wikipedia.org/wiki/National_Ignition_Facility
I don't expect that laser fusion will ever be a practical power
source. NIF is actually mainly for weapons research.
Thank you for the links.
Billions of dollars it did cost I read...
And the management knew it was crap...
It's expensive but it works for the untended uses. It cost a fraction
of ISS and some other things I could name.
Example of the US Military Industrial Complex.
One use is to keep a number of researchers busy understanding the
dynamics of nuclear weapons, refining simulations, now that we can't
test them any more.
One thing I have noticed is that the big-science and space programs
seem to deliberately seek out small businesses as suppliers, and take
a chance on them.
As to fusion power, I am not even sure ITER will work this time...
Probably needs to be rebuild a little bigger :-)
Politics, job creation...
Inefficient, but has at least some upside. I could name more expensive >programs that are flat destructive.
On a sunny day (Thu, 02 Nov 2023 07:39:42 -0700) it happened John Larkin <j...@997PotHill.com> wrote in <snc7ki56n28ua94ck...@4ax.com>:
On Thu, 02 Nov 2023 04:16:52 GMT, Jan Panteltje <al...@comet.invalid> >wrote:
On a sunny day (Wed, 01 Nov 2023 07:56:13 -0700) it happened John Larkin >><j...@997PotHill.com> wrote in <0cp4ki1ui592aul26...@4ax.com>:
Here's a paper about the NIF timing system.
https://www.slac.stanford.edu/econf/C011127/TUAP069.pdf
The biggest error is the prop delay tempco of the fiberoptics, around >>>15 PPM/degC. The facility is BIG.
https://en.wikipedia.org/wiki/National_Ignition_Facility
I don't expect that laser fusion will ever be a practical power >>>source. NIF is actually mainly for weapons research.
Thank you for the links.
Billions of dollars it did cost I read...
And the management knew it was crap...
It's expensive but it works for the untended uses. It cost a fraction
of ISS and some other things I could name.
Example of the US Military Industrial Complex.
One use is to keep a number of researchers busy understanding the
dynamics of nuclear weapons, refining simulations, now that we can't
test them any more.
One thing I have noticed is that the big-science and space programs
seem to deliberately seek out small businesses as suppliers, and take
a chance on them.
Sure, some new ideas can come in handy.
As to fusion power, I am not even sure ITER will work this time... >>Probably needs to be rebuild a little bigger :-)
Politics, job creation...
Inefficient, but has at least some upside. I could name more expensive programs that are flat destructive.
Fighting climate change :-) ?
On a sunny day (Thu, 02 Nov 2023 07:39:42 -0700) it happened John Larkin ><jl@997PotHill.com> wrote in <snc7ki56n28ua94ck0hg20906kg0oejvi4@4ax.com>:
On Thu, 02 Nov 2023 04:16:52 GMT, Jan Panteltje <alien@comet.invalid> >>wrote:
On a sunny day (Wed, 01 Nov 2023 07:56:13 -0700) it happened John Larkin >>><jl@997PotHill.com> wrote in <0cp4ki1ui592aul2674qhmk85de16s8c3a@4ax.com>: >>>
Here's a paper about the NIF timing system.
https://www.slac.stanford.edu/econf/C011127/TUAP069.pdf
The biggest error is the prop delay tempco of the fiberoptics, around >>>>15 PPM/degC. The facility is BIG.
https://en.wikipedia.org/wiki/National_Ignition_Facility
I don't expect that laser fusion will ever be a practical power
source. NIF is actually mainly for weapons research.
Thank you for the links.
Billions of dollars it did cost I read...
And the management knew it was crap...
It's expensive but it works for the untended uses. It cost a fraction
of ISS and some other things I could name.
Example of the US Military Industrial Complex.
One use is to keep a number of researchers busy understanding the
dynamics of nuclear weapons, refining simulations, now that we can't
test them any more.
One thing I have noticed is that the big-science and space programs
seem to deliberately seek out small businesses as suppliers, and take
a chance on them.
Sure, some new ideas can come in handy.
As to fusion power, I am not even sure ITER will work this time... >>>Probably needs to be rebuild a little bigger :-)
Politics, job creation...
Inefficient, but has at least some upside. I could name more expensive >>programs that are flat destructive.
Fighting climate change :-) ?
As to timing, and I remember we discussed this before many years ago,
in the sixties in the TV studio where I had to keep things running, it was all about timing.
Mostly tubes in that old studio, some transistors.
When a video link from a remote location was used
it needed to be precisely in sync with the studio so they could cross-fade. >So you have a complex in time signal, vertical interval, horizontal sync, color burst and for color 4.43 MHz here.
To get things in sync we send carrier via one of the FM radio stations back to the remote location
that steered their clock generator until both frame and horizontal sync were aligned at out place.
Then we could cross-fade.
As you likely need sync at only one point, where the laser beams hit, one could use a low power laser and a detector
and use a complex signal that could be compared to adjust any remote electronics so the pulses at the 'blast'
place would be guaranteed to be in sync.
Fifties, sixties..
Not been there since it all went digital, now it is easy to store and delay one of more frames digitally...
In the sixties we went color and look up Ampex 'amtec' and 'colortec', basically variable delay lines,
the first to adjust the horizontal sync and the second to adjust the color carrier phase for signals coming from video tape recorders.
There were many of those and ALL needed to be in sync to nano seconds (a few degrees of the 4.43MHz carrier) at the control panel so they could cross fade
and that sync, for PAL takes several frames as it flips phase every frame, >For 2 degrees color error at 4.43 MHz time error is (1 / 4.43e6) / 180 = 1.25408e-09 say about 1.3 nS from any remote location / video source (tape recorder for example).
Even more so for the US NTSC system (short for Never Twice The Same Color as the joke goes), PAL did compensate for small phase / color differences using a delay line.)
sixties.....
Anyways such a remote steering system compensates for any path delays dynamically and has proved itself.
On Fri, 03 Nov 2023 05:22:04 GMT, Jan Panteltje <al...@comet.invalid>wrote: >On a sunny day (Thu, 02 Nov 2023 07:39:42 -0700) it happened John Larkin <j...@997PotHill.com> wrote in <snc7ki56n28ua94ck...@4ax.com>:
On Thu, 02 Nov 2023 04:16:52 GMT, Jan Panteltje <al...@comet.invalid> wrote:
On a sunny day (Wed, 01 Nov 2023 07:56:13 -0700) it happened John Larkin <j...@997PotHill.com> wrote in <0cp4ki1ui592aul26...@4ax.com>:
There is a pretty little town north of I80 in eastern California called Grass Valley. It was the place where the Grass Valley Group started and has become a mini-Silicon Valley.
https://en.wikipedia.org/wiki/Grass_Valley,_California
https://en.wikipedia.org/wiki/Grass_Valley_(company)
I think they pioneered digital video storage and resyncing.
It's appealing, high technology in a small town the Sierra foothills.
On Fri, 03 Nov 2023 05:22:04 GMT, Jan Panteltje <alien@comet.invalid>
wrote:
On a sunny day (Thu, 02 Nov 2023 07:39:42 -0700) it happened John Larkin >><jl@997PotHill.com> wrote in <snc7ki56n28ua94ck0hg20906kg0oejvi4@4ax.com>:
On Thu, 02 Nov 2023 04:16:52 GMT, Jan Panteltje <alien@comet.invalid> >>>wrote:
On a sunny day (Wed, 01 Nov 2023 07:56:13 -0700) it happened John Larkin >>>><jl@997PotHill.com> wrote in <0cp4ki1ui592aul2674qhmk85de16s8c3a@4ax.com>: >>>>
Here's a paper about the NIF timing system.
https://www.slac.stanford.edu/econf/C011127/TUAP069.pdf
The biggest error is the prop delay tempco of the fiberoptics, around >>>>>15 PPM/degC. The facility is BIG.
https://en.wikipedia.org/wiki/National_Ignition_Facility
I don't expect that laser fusion will ever be a practical power >>>>>source. NIF is actually mainly for weapons research.
Thank you for the links.
Billions of dollars it did cost I read...
And the management knew it was crap...
It's expensive but it works for the untended uses. It cost a fraction
of ISS and some other things I could name.
Example of the US Military Industrial Complex.
One use is to keep a number of researchers busy understanding the >>>dynamics of nuclear weapons, refining simulations, now that we can't
test them any more.
One thing I have noticed is that the big-science and space programs
seem to deliberately seek out small businesses as suppliers, and take
a chance on them.
Sure, some new ideas can come in handy.
As to fusion power, I am not even sure ITER will work this time... >>>>Probably needs to be rebuild a little bigger :-)
Politics, job creation...
Inefficient, but has at least some upside. I could name more expensive >>>programs that are flat destructive.
Fighting climate change :-) ?
As to timing, and I remember we discussed this before many years ago,
in the sixties in the TV studio where I had to keep things running, it was all about timing.
Mostly tubes in that old studio, some transistors.
When a video link from a remote location was used
it needed to be precisely in sync with the studio so they could cross-fade. >>So you have a complex in time signal, vertical interval, horizontal sync, color burst and for color 4.43 MHz here.
To get things in sync we send carrier via one of the FM radio stations back to the remote location
that steered their clock generator until both frame and horizontal sync were aligned at out place.
Then we could cross-fade.
As you likely need sync at only one point, where the laser beams hit, one could use a low power laser and a detector
and use a complex signal that could be compared to adjust any remote electronics so the pulses at the 'blast'
place would be guaranteed to be in sync.
Fifties, sixties..
Not been there since it all went digital, now it is easy to store and delay one of more frames digitally...
In the sixties we went color and look up Ampex 'amtec' and 'colortec', basically variable delay lines,
the first to adjust the horizontal sync and the second to adjust the color carrier phase for signals coming from video tape
recorders.
There were many of those and ALL needed to be in sync to nano seconds (a few degrees of the 4.43MHz carrier) at the control
panel so they could cross fade
and that sync, for PAL takes several frames as it flips phase every frame, >>For 2 degrees color error at 4.43 MHz time error is (1 / 4.43e6) / 180 = 1.25408e-09 say about 1.3 nS from any remote location
/ video source (tape recorder for example).
Even more so for the US NTSC system (short for Never Twice The Same Color as the joke goes), PAL did compensate for small phase
/ color differences using a delay line.)
sixties.....
Anyways such a remote steering system compensates for any path delays dynamically and has proved itself.
There is a pretty little town north of I80 in eastern California
called Grass Valley. It was the place where the Grass Valley Group
started and has become a mini-Silicon Valley.
https://en.wikipedia.org/wiki/Grass_Valley,_California
https://en.wikipedia.org/wiki/Grass_Valley_(company)
I think they pioneered digital video storage and resyncing.
It's appealing, high technology in a small town the Sierra foothills.
On a sunny day (Fri, 03 Nov 2023 07:32:12 -0700) it happened John Larkin ><jl@997PotHill.com> wrote in <1l0akipp3mla2hoqh3i04vd9njp41onrat@4ax.com>:
On Fri, 03 Nov 2023 05:22:04 GMT, Jan Panteltje <alien@comet.invalid> >>wrote:
On a sunny day (Thu, 02 Nov 2023 07:39:42 -0700) it happened John Larkin >>><jl@997PotHill.com> wrote in <snc7ki56n28ua94ck0hg20906kg0oejvi4@4ax.com>: >>>
On Thu, 02 Nov 2023 04:16:52 GMT, Jan Panteltje <alien@comet.invalid> >>>>wrote:
On a sunny day (Wed, 01 Nov 2023 07:56:13 -0700) it happened John Larkin >>>>><jl@997PotHill.com> wrote in <0cp4ki1ui592aul2674qhmk85de16s8c3a@4ax.com>: >>>>>
Here's a paper about the NIF timing system.
https://www.slac.stanford.edu/econf/C011127/TUAP069.pdf
The biggest error is the prop delay tempco of the fiberoptics, around >>>>>>15 PPM/degC. The facility is BIG.
https://en.wikipedia.org/wiki/National_Ignition_Facility
I don't expect that laser fusion will ever be a practical power >>>>>>source. NIF is actually mainly for weapons research.
Thank you for the links.
Billions of dollars it did cost I read...
And the management knew it was crap...
It's expensive but it works for the untended uses. It cost a fraction >>>>of ISS and some other things I could name.
Example of the US Military Industrial Complex.
One use is to keep a number of researchers busy understanding the >>>>dynamics of nuclear weapons, refining simulations, now that we can't >>>>test them any more.
One thing I have noticed is that the big-science and space programs >>>>seem to deliberately seek out small businesses as suppliers, and take
a chance on them.
Sure, some new ideas can come in handy.
As to fusion power, I am not even sure ITER will work this time... >>>>>Probably needs to be rebuild a little bigger :-)
Politics, job creation...
Inefficient, but has at least some upside. I could name more expensive >>>>programs that are flat destructive.
Fighting climate change :-) ?
As to timing, and I remember we discussed this before many years ago,
in the sixties in the TV studio where I had to keep things running, it was all about timing.
Mostly tubes in that old studio, some transistors.
When a video link from a remote location was used
it needed to be precisely in sync with the studio so they could cross-fade. >>>So you have a complex in time signal, vertical interval, horizontal sync, color burst and for color 4.43 MHz here.
To get things in sync we send carrier via one of the FM radio stations back to the remote location
that steered their clock generator until both frame and horizontal sync were aligned at out place.
Then we could cross-fade.
As you likely need sync at only one point, where the laser beams hit, one could use a low power laser and a detector
and use a complex signal that could be compared to adjust any remote electronics so the pulses at the 'blast'
place would be guaranteed to be in sync.
Fifties, sixties..
Not been there since it all went digital, now it is easy to store and delay one of more frames digitally...
In the sixties we went color and look up Ampex 'amtec' and 'colortec', basically variable delay lines,
the first to adjust the horizontal sync and the second to adjust the color carrier phase for signals coming from video tape
recorders.
There were many of those and ALL needed to be in sync to nano seconds (a few degrees of the 4.43MHz carrier) at the control
panel so they could cross fade
and that sync, for PAL takes several frames as it flips phase every frame, >>>For 2 degrees color error at 4.43 MHz time error is (1 / 4.43e6) / 180 = 1.25408e-09 say about 1.3 nS from any remote location
/ video source (tape recorder for example).
Even more so for the US NTSC system (short for Never Twice The Same Color as the joke goes), PAL did compensate for small phase
/ color differences using a delay line.)
sixties.....
Anyways such a remote steering system compensates for any path delays dynamically and has proved itself.
There is a pretty little town north of I80 in eastern California
called Grass Valley. It was the place where the Grass Valley Group
started and has become a mini-Silicon Valley.
https://en.wikipedia.org/wiki/Grass_Valley,_California
Seems it can get very hot there, litte rain also in summer.
We just had a severe storm, and it has been raining for days.. Glad my satellite dish is still aligned.
https://en.wikipedia.org/wiki/Grass_Valley_(company)
I think they pioneered digital video storage and resyncing.
Things move fast in that field, lots is possible with ever more powerful electronics.
When I left TV in 1976 or so we had equipment from Fernseh Gmbh:
https://en.m.wikipedia.org/wiki/Fernseh
and Ampex., also color cameras from Philips (plumbican based)..
Ampex quadruplex video tape recorders did cost millions...
Been to Ampex for traning a few times.
Now with digital electronics things can be much smaller and cheaper, solid state camera sensors.
Anybody can start a TV studio with little money.
Youtube an example, some channels have millions of viewers..
It's appealing, high technology in a small town the Sierra foothills.
It's a moving target, very interesting.
I am into music now, playing the keyboard...
Select trumpet, play 'Moon river'
in the sixties I had a real trumpet, keyboards is different..
Thinking about making a big OLED or e-ink paper touch display for the notes.
On Tuesday, October 31, 2023 at 4:14:41 PM UTC-7, John Miles, KE5FX wrote:
On Monday, October 30, 2023 at 9:01:17 PM UTC-7, Jan Panteltje wrote:
How did you measure that 1 ps, seems just sales crap to me?Digitize the delayed and original undelayed signals with a common clock,
Video digitizers have jitter depending on clock frequency..
I have worked with those.
then downconvert them to baseband I/Q with a complex DDS, then
band-limit the heck out of them. Then atan2() and unwrap them, and finally >> subtract them to get the phase difference.
The band-limiting step is the important one, as it gets rid of noise that would
otherwise show up as phase uncertainty. Once you get the measurement BW
down to a few Hz, picoseconds are trivial to resolve.
Band-limiting is guaranteed if you FFT and look at a peak (initial process in most
FFT work involves a Hamming window, which spreads a narrow frequency
input into a few more channels) with correct statistical weighting.
The "average" phase shift is the weighted average, and low-amplitude
channels have high phase noise estimates, so the reciprocal of the
square of the noise becomes a weight function for the averaging,
and basically ignores off-peak values.
On 2023-11-01 21:48, whit3rd wrote:
On Tuesday, October 31, 2023 at 4:14:41 PM UTC-7, John Miles, KE5FX wrote:
On Monday, October 30, 2023 at 9:01:17 PM UTC-7, Jan Panteltje wrote: >>> How did you measure that 1 ps, seems just sales crap to me?
Video digitizers have jitter depending on clock frequency..Digitize the delayed and original undelayed signals with a common clock, >> then downconvert them to baseband I/Q with a complex DDS, then
I have worked with those.
band-limit the heck out of them. Then atan2() and unwrap them, and finally
subtract them to get the phase difference.
The band-limiting step is the important one, as it gets rid of noise that would
otherwise show up as phase uncertainty. Once you get the measurement BW >> down to a few Hz, picoseconds are trivial to resolve.
Band-limiting is guaranteed if you FFT and look at a peak (initial process in most
FFT work involves a Hamming window, which spreads a narrow frequency
input into a few more channels) with correct statistical weighting.
The "average" phase shift is the weighted average, and low-amplitude channels have high phase noise estimates, so the reciprocal of the
square of the noise becomes a weight function for the averaging,
and basically ignores off-peak values.
Once you've done the sampling, it's band-limited, all right, because all
the aliasing has happened already. Whether the transform resembles that
of the function you sampled depends on the function and how you filtered
it before sampling.
Applying a window to the samples before taking the DFT just changes the shape of the passband corresponding to each sample, _within_ the
fundamental interval.
On Sunday, November 5, 2023 at 11:51:23 AM UTC-8, Phil Hobbs wrote:
On 2023-11-01 21:48, whit3rd wrote:
On Tuesday, October 31, 2023 at 4:14:41 PM UTC-7, John Miles, KE5FX wrote:Once you've done the sampling, it's band-limited, all right, because all
On Monday, October 30, 2023 at 9:01:17 PM UTC-7, Jan Panteltje wrote: >>>>> How did you measure that 1 ps, seems just sales crap to me?
Video digitizers have jitter depending on clock frequency..Digitize the delayed and original undelayed signals with a common clock, >>>> then downconvert them to baseband I/Q with a complex DDS, then
I have worked with those.
band-limit the heck out of them. Then atan2() and unwrap them, and finally >>>> subtract them to get the phase difference.
The band-limiting step is the important one, as it gets rid of noise that would
otherwise show up as phase uncertainty. Once you get the measurement BW >>>> down to a few Hz, picoseconds are trivial to resolve.
Band-limiting is guaranteed if you FFT and look at a peak (initial process in most
FFT work involves a Hamming window, which spreads a narrow frequency
input into a few more channels) with correct statistical weighting.
The "average" phase shift is the weighted average, and low-amplitude
channels have high phase noise estimates, so the reciprocal of the
square of the noise becomes a weight function for the averaging,
and basically ignores off-peak values.
the aliasing has happened already. Whether the transform resembles that
of the function you sampled depends on the function and how you filtered
it before sampling.
Applying a window to the samples before taking the DFT just changes the
shape of the passband corresponding to each sample, _within_ the
fundamental interval.
I'd say it does more than that; the time-series data fed into an FFT will pick up things like slow offset drifts in the input, which causes a step
when the sample #1 is adjacent to sample #1024 (due to the discrete
Fourier transform having a circular boundary condition).
A sampling-time boundary step will contribute to lots of frequencies (all of them, in fact, because
a step is the integral of a delta function). Those artifacts ought not
to contribute to a phase measurement, and lopping off half the samples' amplitudes with a Hamming window is the usual way to reject them.
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