Hello again.
The manual to my radio states:
Frequency range:
87.5–108.0 MHz (100-kHz step)
Sensitivity:
2.5 μV(IHF)
S/N:
26 dB 2.2 μV
Then this webpage:
https://www.aerialsandtv.com/knowledge/fm-and-dab-radio
says:
"Signal levels for FM & DAB, plus splitting FM/DAB
Some sources say that for FM you should be aiming for a signal level
between 60 and 75dBµV at the tuner input but most tuners will work
fine down to 40dBµV (some even lower) and that includes the
additional signal [15dB or so] that stereo decoders require."
Is the dBuV (decibel microvolts, I know that much, but...) here the same as the uV figure given in the tuner specification?The sensitivity quoted (2ish microvolts) is the signal level required
If so, does this mean I will be laughing with a half wave dipole and 30 or so metres of WF100 from it (at the roof) to the tuner (in the cellar)?
Thanks again you lovely bunch.
If so, does this mean I will be laughing with a half wave dipole and 30 or so metres of WF100 from it (at the roof) to the tuner (in the cellar)?
A good
tuner will do that at around 40-50 dBµV (200-315 µV ).
That's not very much, but to work out your 'RF link budget' you need to
know the field strength of your wanted signal,
the gain of the aerial,
how much of that ends up as a 'voltage' in your coax, and the loss of
the Co-ax. We only know the latter so far. What are you trying to
receive
and how far away is the transmitter from you (this thread could
run and run....)
On Saturday, 5 February 2022 at 17:03:04 UTC, Mark Carver wrote:
A goodWhat is the relationship between these two values? I am truly ignorant of this stuff.
tuner will do that at around 40-50 dBµV (200-315 µV ).
On Saturday, 5 February 2022 at 17:14:49 UTC, Mark Carver wrote:No :-)
That's not very much, but to work out your 'RF link budget' you need toCan I find that out with a multimeter? :D
know the field strength of your wanted signal,
the gain of the aerial,It'll be a half-wave dipole, so whatever that is I suppose.
Radios 1-4, Classic FM. All from Holme Moss as far as I know
However, stop. Why are you wanting to use FM for these stations ? The
days of HiFi quality sound on any FM station are long gone.
You'd be better off (in a fixed receiving environment) using the
internet, satellite, or Freeview for these national stations ?
Is the dBuV (decibel microvolts, I know that much, but...) here the same as the uV figure given in the tuner specification?
If so, does this mean I will be laughing with a half wave dipole and 30 or so metres of WF100 from it (at the roof) to the tuner (in the cellar)?You won't be laughing if you use it to receive a BBC comedy programme on
Thanks again you lovely bunch.How can you tell? Is there a camera on my computer? I do get a lot of
On 05/02/2022 16:45, David Paste wrote:
If so, does this mean I will be laughing with a half wave dipole andI forgot to answer this question.
30 or so metres of WF100 from it (at the roof) to the tuner (in the
cellar)?
WF100 etc has an attenuation at 100 MHz for about 6 or 7dB per 100
metres. Therefore 30 metres will have an attenuation of 2 or 3 dB.
The sensitivity quoted (2ish microvolts) is the signal level required
across the input of the tuner for "full quieting". In other words a
noise(*) free mono signal
You need significantly more than that for clean stereo decoding. A good
tuner will do that at around 40-50 dBµV (200-315 µV ).
For the lowest possible noise in stereo, you need at least 60 dBµV (1 millivolt) However, go above 75 dBµV (about 5mV) and you risk
overloading the tuner,
and introducing intermodulation products and distortion.
* By noise in this context I'm talking about only the noise that's
generated internally by the tuner. In practice, and particularly these
days, trying to listen to a signal that's only 2 microvolts, it'll be interrupted by lots of external electrical interference, and won't be practical .
You won't be laughing if you use it to receive a BBC comedy programme on Radio Four because they aren't funny anymore. But a vertical half wave (centre fed) is to all intents and purposes the best FM aerial there is,
and the loss on 30m of WF100 is about half a dB, so negligible.
On 05/02/2022 17:03, Mark Carver wrote:
The sensitivity quoted (2ish microvolts) is the signal level required across the input of the tuner for "full quieting". In other words a noise(*) free mono signal
To be honest I've never encountered a tuner that would give anything
like noise free-reception on such a low signal. Not in the real world.
But 6dBuV -- no. 15 to 20dBuV I'd say yes, with a following wind. Maybe external noise has always been the limiting factor, because when I've
been struggling with this it's usually been somewhere noisy, and with
other signals at around 60dBuV.
You need significantly more than that for clean stereo decoding. A good tuner will do that at around 40-50 dBµV (200-315 µV ).
Agreed.
For the lowest possible noise in stereo, you need at least 60 dBµV (1 millivolt) However, go above 75 dBµV (about 5mV) and you risk
overloading the tuner,
and introducing intermodulation products and distortion.
It always used to be a problem when the hi-fi buffs insisted on a six
element aerial when you could see nearby Holme Moss from the roof.
Still, it sold "these special things that reduce the strength without spoiling the quality" at a fiver each. It was great when the 50p gold coloured ones came out...
* By noise in this context I'm talking about only the noise that's generated internally by the tuner. In practice, and particularly these days, trying to listen to a signal that's only 2 microvolts, it'll be interrupted by lots of external electrical interference, and won't be practical .
Yes.
I've often said the same thing about UHF TV reception when the city is compared to the country.
Bill
The sensitivity quoted (2ish microvolts) is the signal level required
across the input of the tuner for "full quieting".
However, stop. Why are you wanting to use FM for these stations ? The
days of HiFi quality sound on any FM station are long gone. You'd be
better off (in a fixed receiving environment) using the internet,
satellite, or Freeview for these national stations ?
On 05/02/2022 17:03, Mark Carver wrote:
The sensitivity quoted (2ish microvolts) is the signal level required
across the input of the tuner for "full quieting". In other words a
noise(*) free mono signal
To be honest I've never encountered a tuner that would give anything
like noise free-reception on such a low signal. Not in the real world.
But 6dBuV -- no. 15 to 20dBuV I'd say yes, with a following wind.
Maybe external noise has always been the limiting factor, because when
I've been struggling with this it's usually been somewhere noisy, and
with other signals at around 60dBuV.
You need significantly more than that for clean stereo decoding. A
good tuner will do that at around 40-50 dBµV (100-315 µV ).
Agreed.
When I was a lad, I used to receive Capital, LBC, and BBC R London at
about 40 dBµV, (45 miles west of London using a three element yagi,
looking at Croydon/CP)
On 06/02/2022 13:34, Mark Carver wrote:
When I was a lad, I used to receive Capital, LBC, and BBC R London at
about 40 dBµV, (45 miles west of London using a three element yagi,
looking at Croydon/CP)
Ha! That's nowt! When I were a lad I used to receive Capital, LBC, and BBC
R London on a one element yagi!
Ha! You should be so lucky! When I were a lad I used to receive Capital,
LBC, and BBC R London on a bit of wet string!
We used to live in a tiny tumble down house with no electricity so the
only way to receive Capital, LBC, and BBC R London was with a crystal set.
We were poor but we were happy!
We were happy because we were poor! We couldn't afford a crystal set so
(cont p92)
Decibels are meaningless unless referenced, so the unit dBµV, are an expression of voltage referenced to 1 microvolt.
For a voltage ratio, the value is 20log(V2/V1). So say something 1000
times a microvolt, (i.e 1 millivolt) that's 20log(1/1000) or 60dBuV
Actually, I cocked up with my 40-50 dBuV example, I'd referenced the
40dB figure at 2uV and not 1uV, so 40 dBuV relates to 100uV, but 50 dBuV
is indeed 315uV)
However, stop. Why are you wanting to use FM for these stations ? The
days of HiFi quality sound on any FM station are long gone.
You'd be better off (in a fixed receiving environment) using the
internet, satellite, or Freeview for these national stations ?
Yes, much better to use GetIPlayer to download the 320kbps versions of
the BBC's music output.
But a vertical half wave
(centre fed) is to all intents and purposes the best FM aerial there is,
Thanks again you lovely bunch.How can you tell? Is there a camera on my computer? I do get a lot of messages saying that people can see me indulging in self abuse, come to
think of it.
Slight cavil on that. Although for serious 'sit and listen' I tend to
prefer R3 via iplayer 320k, I find that R3/FM on a decent tuner sound very good. The way the level compression, etc, is applied actually make it sound warmer and easier to hear.
Jim
When I was a lad, I used to receive Capital, LBC, and BBC R London at
about 40 dBµV, (45 miles west of London using a three element yagi,
looking at Croydon/CP)
On Sunday, 6 February 2022 at 13:34:32 UTC, Mark Carver wrote:
When I was a lad, I used to receive Capital, LBC, and BBC R London at
about 40 dBµV, (45 miles west of London using a three element yagi,
looking at Croydon/CP)
How do you measure this? Do you need a special meter?
On Sunday, 6 February 2022 at 13:34:32 UTC, Mark Carver wrote:
When I was a lad, I used to receive Capital, LBC, and BBC R London at
about 40 dBµV, (45 miles west of London using a three element yagi,
looking at Croydon/CP)
How do you measure this? Do you need a special meter?
On 07/02/2022 19:36, David Paste wrote:
On Sunday, 6 February 2022 at 13:34:32 UTC, Mark Carver wrote:
When I was a lad, I used to receive Capital, LBC, and BBC R London at
about 40 dBµV, (45 miles west of London using a three element yagi,
looking at Croydon/CP)
How do you measure this? Do you need a special meter?
Yes.
Bill
then there was the Tandy Tuners which turned of the AFC while you
gripped the tuning knob and turned it on when you let go.
We used to live in a tiny tumble down house with no electricity so the
only way to receive Capital, LBC, and BBC R London was with a crystal
set. We were poor but we were happy!
One has to also beware of published specs. I bought a Rotel tuner which
got good reviews on its performance both in sensitivity, and its strong signal handling, but although it was fine for both of these and also
s/N, it sounded leaden, no matter what you did when put against a
Pioneer or Armstrong at the time. I eventually sold it on, and bought a Pioneer which lasted for many years till it started to have
semiconductor failures in the small signal parts and the over complex
string dial and lights failed.
It turned out the problem was the very aggressive filtering of the
bandwidth giving phase distortions, a bit like an audio noth filter can
ring.
On Sunday, 6 February 2022 at 13:34:32 UTC, Mark Carver wrote:Yep, borrowed from the MoD, but that's quite another story !
When I was a lad, I used to receive Capital, LBC, and BBC R London atHow do you measure this? Do you need a special meter?
about 40 dBµV, (45 miles west of London using a three element yagi,
looking at Croydon/CP)
I had to sort through the coal in every sack till I found one which functioned as a crystal, it was the cats whiskers of course.
OK enough silliness.
Does anyone recall those early cassette stereo portables with the image width control. The idea I think was that as you progressed from wide, ie anti phase to mono, completely in phase and joined the his could be reduced the nearer you got to mono.
Another Philips gimmick. I remember some of their stereo systems of the 70s had very good turntables and some kind of illumination of the dial that subtly changed colour with signal strength, then there was the Tandy Tuners which turned of the AFC while you gripped the tuning knob and turned it on when you let go.
Brian
--
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...
bri...@blueyonder.co.uk
Blind user, so no pictures please
Note this Signature is meaningless.!
"williamwright" <wrights...@f2s.com> wrote in message news:j6aro2...@mid.individual.net...
On 06/02/2022 13:34, Mark Carver wrote:
When I was a lad, I used to receive Capital, LBC, and BBC R London at
about 40 dBµV, (45 miles west of London using a three element yagi,
looking at Croydon/CP)
Ha! That's nowt! When I were a lad I used to receive Capital, LBC, and BBC R London on a one element yagi!
Ha! You should be so lucky! When I were a lad I used to receive Capital, LBC, and BBC R London on a bit of wet string!
We used to live in a tiny tumble down house with no electricity so the only way to receive Capital, LBC, and BBC R London was with a crystal set. We were poor but we were happy!
We were happy because we were poor! We couldn't afford a crystal set so
(cont p92)
Yep, borrowed from the MoD, but that's quite another story !
On Saturday, 5 February 2022 at 18:15:06 UTC, Mark Carver wrote:
Decibels are meaningless unless referenced, so the unit dBµV, are an
expression of voltage referenced to 1 microvolt.
For a voltage ratio, the value is 20log(V2/V1). So say something 1000
times a microvolt, (i.e 1 millivolt) that's 20log(1/1000) or 60dBuV
Actually, I cocked up with my 40-50 dBuV example, I'd referenced the
40dB figure at 2uV and not 1uV, so 40 dBuV relates to 100uV, but 50 dBuV
is indeed 315uV)
*nods along blankly* ;) Thanks for the effort though!
On Tuesday, 8 February 2022 at 16:49:33 UTC, Mark Carver wrote:How long have you got ?
Yep, borrowed from the MoD, but that's quite another story !How do they work?
Hello again.
The manual to my radio states:
Frequency range:
87.5–108.0 MHz (100-kHz step)
Sensitivity:
2.5 μV(IHF)
S/N:
26 dB 2.2 μV
Then this webpage:
https://www.aerialsandtv.com/knowledge/fm-and-dab-radio
says:
"Signal levels for FM & DAB, plus splitting FM/DAB
Some sources say that for FM you should be aiming for a signal level
between 60 and 75dBµV at the tuner input but most tuners will work
fine down to 40dBµV (some even lower) and that includes the
additional signal [15dB or so] that stereo decoders require."
Is the dBuV (decibel microvolts, I know that much, but...) here the same as the uV figure given in the tuner specification?
If so, does this mean I will be laughing with a half wave dipole and 30 or so metres of WF100 from it (at the roof) to the tuner (in the cellar)?
Thanks again you lovely bunch.
On 08/02/2022 22:10, David Paste wrote:
On Tuesday, 8 February 2022 at 16:49:33 UTC, Mark Carver wrote:How long have you got ?
Yep, borrowed from the MoD, but that's quite another story !How do they work?
The most basic model is simply a normal receiver, but with a moving coil meter fed off of the AGC control line (Automatic Gain Control)
In fact lots of FM tuners back in the day had a little moving coil meter
for signal strength indication. The key to it is for it to have
meaningful calibration, which I don't recall any tuner had ?
Present day TVs and DAB radios have bar-graphs for signal strength, same principle, except they have nonsense calibration, such as using
percentages (of what ?)
Don't get confused with the Signal _Quality_ meters they also have,
those are a measure in some way of error correction that's being applied.
For digital reception alignment and set up, you really need a proper
spectrum analyser, as it's not just about raw signal strength.
Internet rabbit hole:-
https://www.promaxelectronics.com/ing/
In article <stqis5$c4j$1@dont-email.me>, Brian Gaff \(Sofa\) ><briang1@blueyonder.co.uk> wrote:
then there was the Tandy Tuners which turned of the AFC while you
gripped the tuning knob and turned it on when you let go.
The Yamaha CT7000 also does that. Superb FM tuner.
Jim
On 05/02/2022 17:39, David Paste wrote:
On Saturday, 5 February 2022 at 17:14:49 UTC, Mark Carver wrote:No :-)
That's not very much, but to work out your 'RF link budget' you need toCan I find that out with a multimeter? :D
know the field strength of your wanted signal,
the gain of the aerial,It'll be a half-wave dipole, so whatever that is I suppose.
Well, that's used as a 0dB reference for specifying yagi gain, if for
sake of argument we say that it translates a 60dBuv/m field into 60 dBuV
of signal (it doesn't, Bill Wright can give us chapter and verse on real >world figures) then if you're only 30 miles from Holme Moss, you're
likely to be on that contour, so after the feeder loss you're going to
end up with 56 or 57 dBuV at the tuner, not quite the magic 60 figure,
but probably good enough.
However, stop. Why are you wanting to use FM for these stations ? The
Radios 1-4, Classic FM. All from Holme Moss as far as I know
days of HiFi quality sound on any FM station are long gone.
You'd be better off (in a fixed receiving environment) using the
internet, satellite, or Freeview for these national stations ?
On 07/02/2022 19:36, David Paste wrote:
On Sunday, 6 February 2022 at 13:34:32 UTC, Mark Carver wrote:Yep, borrowed from the MoD, but that's quite another story !
When I was a lad, I used to receive Capital, LBC, and BBC R London atHow do you measure this? Do you need a special meter?
about 40 dB0 >>> looking at Croydon/CP)
Wrotham R2/3/4; 20 miles further away, in more or less the same
direction (for something as blunt as a 3 element yagi) but at 240kW
(rather than 2 kW) so
10Log(240/2) = 20dB higher power, was about 48 dBuV I think.
In article <j6fl8qF2onvU1@mid.individual.net>, Mark Carver <mark.carver@invalid.invalid> scribeth thus
On 07/02/2022 19:36, David Paste wrote:Wouldn't argue with my Hon friend but that 240 kW is the sum of Vertical
On Sunday, 6 February 2022 at 13:34:32 UTC, Mark Carver wrote:Yep, borrowed from the MoD, but that's quite another story !
When I was a lad, I used to receive Capital, LBC, and BBC R London atHow do you measure this? Do you need a special meter?
about 40 dB0 >>> looking at Croydon/CP)
Wrotham R2/3/4; 20 miles further away, in more or less the same
direction (for something as blunt as a 3 element yagi) but at 240kW
(rather than 2 kW) so
10Log(240/2) = 20dB higher power, was about 48 dBuV I think.
and horizontal components ..
On 05/02/2022 17:36, David Paste wrote:
On Saturday, 5 February 2022 at 17:03:04 UTC, Mark Carver wrote:Decibels are meaningless unless referenced, so the unit dBµV, are an expression of voltage referenced to 1 microvolt.
A goodWhat is the relationship between these two values? I am truly ignorant
tuner will do that at around 40-50 dBµV (200-315 µV ).
of this stuff.
For a voltage ratio, the value is 20log(V2/V1). So say something 1000
times a microvolt, (i.e 1 millivolt) that's 20log(1/1000) or 60dBuV
Actually, I cocked up with my 40-50 dBuV example, I'd referenced the
40dB figure at 2uV and not 1uV, so 40 dBuV relates to 100uV, but 50 dBuV
is indeed 315uV)
Op 5-2-2022 om 19:15 schreef Mark Carver:
On 05/02/2022 17:36, David Paste wrote:
On Saturday, 5 February 2022 at 17:03:04 UTC, Mark Carver wrote:Decibels are meaningless unless referenced, so the unit dBµV, are an
A goodWhat is the relationship between these two values? I am truly
tuner will do that at around 40-50 dBµV (200-315 µV ).
ignorant of this stuff.
expression of voltage referenced to 1 microvolt.
For a voltage ratio, the value is 20log(V2/V1). So say something 1000
times a microvolt, (i.e 1 millivolt) that's 20log(1/1000) or 60dBuV
20log(1000/1)Â Â I think?
On 05/03/2022 17:22, Rink wrote:
Op 5-2-2022 om 19:15 schreef Mark Carver:
On 05/02/2022 17:36, David Paste wrote:
On Saturday, 5 February 2022 at 17:03:04 UTC, Mark Carver wrote:Decibels are meaningless unless referenced, so the unit dBµV, are an
A good tuner will do that at around 40-50 dBµV (200-315 µV ).What is the relationship between these two values? I am truly
ignorant of this stuff.
expression of voltage referenced to 1 microvolt.
For a voltage ratio, the value is 20log(V2/V1). So say something 1000
times a microvolt, (i.e 1 millivolt) that's 20log(1/1000) or 60dBuV
20log(1000/1) I think?
Yes, I was upside down !
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