On 17/05/2022 15:02, The Other John wrote:
I've recently been getting break-up and freezing on some Freeview
channels
even though I'm about 1.5 miles line of sight from the Reigate
transmitter. The channels affected are all on the mux on UHF 24 and are
mainly the Sky channels. I did a spectrum analysis using my RTL-SDR
stick
and it shows there's a massive dip starting on UHF23 and pushing 24
right
down.
The scan can be seen here: <https://www.dropbox.com/s/sh7b3fdyabnadll/
Scan%20470.0-592.0MHz%20lounge.png?dl=0>
The aerial is a standard 18 element yagi which might be group C/D as it
was for Reigate analogue, although it could be group A if the previous
owner used to receive Crystal Palace before Reigate opened. Either way
what do you think would cause such a drop in the middle of the band?
Nothing has been changed recently but the coax is over 40 years old,
could
it be causing some kind of cancellation due to standing waves or summat?
If that co-ax is 40 years old, it is not 100% screened.
If any of it is exposed to the elements, the outer sheath will have
long perished and rain water will have ingressed into it.
a kink in the cable can cause a standing wave if its not rainwater
ingress.
I'd personally put up a new aerial and new CT100/WF100 co-ax and be
done with it.
Getting 40 years out of a co-ax is very good going though and that
cable doesn't owe you anything :-)
I've recently been getting break-up and freezing on some Freeview channels even though I'm about 1.5 miles line of sight from the Reigate
transmitter. The channels affected are all on the mux on UHF 24 and are mainly the Sky channels. I did a spectrum analysis using my RTL-SDR stick and it shows there's a massive dip starting on UHF23 and pushing 24 right down.
The scan can be seen here: <https://www.dropbox.com/s/sh7b3fdyabnadll/ Scan%20470.0-592.0MHz%20lounge.png?dl=0>
The aerial is a standard 18 element yagi which might be group C/D as it
was for Reigate analogue, although it could be group A if the previous
owner used to receive Crystal Palace before Reigate opened. Either way
what do you think would cause such a drop in the middle of the band?
Nothing has been changed recently but the coax is over 40 years old, could
it be causing some kind of cancellation due to standing waves or summat?
I've recently been getting break-up and freezing on some Freeview channels even though I'm about 1.5 miles line of sight from the Reigate
transmitter. The channels affected are all on the mux on UHF 24 and are mainly the Sky channels. I did a spectrum analysis using my RTL-SDR stick and it shows there's a massive dip starting on UHF23 and pushing 24 right down.
The scan can be seen here: <https://www.dropbox.com/s/sh7b3fdyabnadll/ Scan%20470.0-592.0MHz%20lounge.png?dl=0>
The aerial is a standard 18 element yagi which might be group C/D as it
was for Reigate analogue, although it could be group A if the previous
owner used to receive Crystal Palace before Reigate opened. Either way
what do you think would cause such a drop in the middle of the band?
Nothing has been changed recently but the coax is over 40 years old, could
it be causing some kind of cancellation due to standing waves or summat?
I've recently been getting break-up and freezing on some Freeview channels even though I'm about 1.5 miles line of sight from the Reigate
transmitter. The channels affected are all on the mux on UHF 24 and are mainly the Sky channels. I did a spectrum analysis using my RTL-SDR stick and it shows there's a massive dip starting on UHF23 and pushing 24 right down.
The scan can be seen here: <https://www.dropbox.com/s/sh7b3fdyabnadll/ Scan%20470.0-592.0MHz%20lounge.png?dl=0>
The aerial is a standard 18 element yagi which might be group C/D as it
was for Reigate analogue, although it could be group A if the previous
owner used to receive Crystal Palace before Reigate opened. Either way
what do you think would cause such a drop in the middle of the band?
Nothing has been changed recently but the coax is over 40 years old, could
it be causing some kind of cancellation due to standing waves or summat?
The Other John wrote:
The channels affected are all on the mux on UHF 24 and are
mainly the Sky channels. I did a spectrum analysis using my RTL-SDR
stick
and it shows there's a massive dip starting on UHF23 and pushing 24 right
down.
The scan can be seen here:
Have you tried the spectrum scan at different speeds? or with smoothing options?
You have quite a slope on several of the muxes, I seem to remember
getting similar ... possible RTL AGC issue?
<http://andyburns.uk/misc/CH21-CH68.png>
On 17/05/2022 15:02, The Other John wrote:
I've recently been getting break-up and freezing on some Freeview
channels
even though I'm about 1.5 miles line of sight from the Reigate
transmitter. The channels affected are all on the mux on UHF 24 and are
mainly the Sky channels. I did a spectrum analysis using my RTL-SDR
stick
and it shows there's a massive dip starting on UHF23 and pushing 24 right
down.
The scan can be seen here: <https://www.dropbox.com/s/sh7b3fdyabnadll/
Scan%20470.0-592.0MHz%20lounge.png?dl=0>
The aerial is a standard 18 element yagi which might be group C/D as it
was for Reigate analogue, although it could be group A if the previous
owner used to receive Crystal Palace before Reigate opened. Either way
what do you think would cause such a drop in the middle of the band?
Nothing has been changed recently but the coax is over 40 years old,
could
it be causing some kind of cancellation due to standing waves or summat?
The aerial and the cable need to be replaced. The new aerial should be a
log periodic, but not one of the little ones that are only about a foot
long. The cable should be CT100-type, copper foil/copper braid.
The aerial fixings will need to be replaced most likely.
The channels affected are all on the mux on UHF 24 and are
mainly the Sky channels. I did a spectrum analysis using my RTL-SDR stick and it shows there's a massive dip starting on UHF23 and pushing 24 right down.
The scan can be seen here:
Correct me if I am mistaken, but doesn't CT100 have an aluminium foil
under copper braid? I have used WF100 (dual copper) from Screwfix for
years.
On 17/05/2022 16:51, Woody wrote:
Copper foil
Correct me if I am mistaken, but doesn't CT100 have an aluminium foil
under copper braid? I have used WF100 (dual copper) from Screwfix for
years.
https://www.cablemonkey.co.uk/data-sheet?id_attachment=37103
On 17/05/2022 16:59, Mark Carver wrote:
On 17/05/2022 16:57, Mark Carver wrote:
On 17/05/2022 16:51, Woody wrote:
Copper foil
Correct me if I am mistaken, but doesn't CT100 have an aluminium
foil under copper braid? I have used WF100 (dual copper) from
Screwfix for years.
https://www.cablemonkey.co.uk/data-sheet?id_attachment=37103
....with al ?
Weird. The picture looks like copper but the description says "Al Foil".
On 17/05/2022 16:57, Mark Carver wrote:
On 17/05/2022 16:51, Woody wrote:
Copper foil
Correct me if I am mistaken, but doesn't CT100 have an aluminium foil
under copper braid? I have used WF100 (dual copper) from Screwfix for
years.
https://www.cablemonkey.co.uk/data-sheet?id_attachment=37103
....with al ?
On 17/05/2022 17:21, Brian Gregory wrote:
On 17/05/2022 16:59, Mark Carver wrote:Whenever I've used some I'm quite sure it's pure(?) copper ?
On 17/05/2022 16:57, Mark Carver wrote:
On 17/05/2022 16:51, Woody wrote:
Copper foil
Correct me if I am mistaken, but doesn't CT100 have an aluminium
foil under copper braid? I have used WF100 (dual copper) from
Screwfix for years.
https://www.cablemonkey.co.uk/data-sheet?id_attachment=37103
....with al ?
Weird. The picture looks like copper but the description says "Al Foil".
Get your bins out and have a look at the colour of the plugs in the ends
of the aerial boom. In theory (note - theory - Marky!) it should be red
for a group A, yellow for a group and one of a number of colours
including green, brown, and black if it is C/D or wideband.
The aerial and the cable need to be replaced. The new aerial should be a
log periodic, but not one of the little ones that are only about a foot
long. The cable should be CT100-type, copper foil/copper braid.
The aerial fixings will need to be replaced most likely.
Brian Gregory wrote:
The picture looks like copper but the description says "Al Foil".Whenever I've used some I'm quite sure it's pure(?) copper ?
If any of it is exposed to the elements, the outer sheath will have long perished and rain water will have ingressed into it.
a kink in the cable can cause a standing wave if its not rainwater
ingress.
On 17/05/2022 19:32, The Other John wrote:
None of the neighbours has got a logWell, by your report that's exactly what you may well have, and
periodic and as we're only 1.5 miles from the TX a bit of wet string
would
probably work :)
clearly it isn't working !
Have you tried the spectrum scan at different speeds? or with smoothing options?
You have quite a slope on several of the muxes, I seem to remember
getting similar ... possible RTL AGC issue?
None of the neighbours has got a log
periodic and as we're only 1.5 miles from the TX a bit of wet string would probably work :)
I know nothing about spectrum scanners, but your graph is completely unbelievable with such cliff-edge drops and rises.
I could try different speeds but that wouldn't change the big dip would
it? There isn't a similar dip on the adjacent channels 26 and 27. The
AGC was switched off for the scan.
By the way, in which direction is the mast from you ?
The reason I ask is the Tx antenna is cardioid towards the SSE, so
basically if you're north of the M25, don't expect too much reliable
signal (even at 1.5 miles)
On 17/05/2022 20:25, Dave W wrote:
I know nothing about spectrum scanners, but your graph is completely
unbelievable with such cliff-edge drops and rises.
The sharp edges are the boundaries between digital multiplexes. There
is a very small one in the middle because there has to be a small
separation between multiplexes. The other ones are transitions to empty channels, where the fuzzy horizontal lines represent the system noise
floor.
Digital TV uses spectrum much more efficiently than analogue TV, so you expect a flat top for the multiplex and then a large fall off.
On Tue, 17 May 2022 16:21:17 +0100, williamwright wrote:
The aerial and the cable need to be replaced. The new aerial should be a
log periodic, but not one of the little ones that are only about a foot
long. The cable should be CT100-type, copper foil/copper braid.
The aerial fixings will need to be replaced most likely.
I was afraid you'd say that! None of the neighbours has got a log
periodic and as we're only 1.5 miles from the TX a bit of wet string would probably work :)
On 17/05/2022 16:51, Woody wrote:
Copper foil
Correct me if I am mistaken, but doesn't CT100 have an aluminium foil
under copper braid? I have used WF100 (dual copper) from Screwfix for
years.
https://www.cablemonkey.co.uk/data-sheet?id_attachment=37103
Maybe different manufacturers use the CT100 label for slightly different things.
Correct me if I am mistaken, but doesn't CT100 have an aluminium foil
under copper braid? I have used WF100 (dual copper) from Screwfix for
years.
The aerial fixings will need to be replaced most likely.I was afraid you'd say that! None of the neighbours has got a log
periodic and as we're only 1.5 miles from the TX a bit of wet string would probably work:)
I could try different speeds but that wouldn't change the big dip would
it? There isn't a similar dip on the adjacent channels 26 and 27. The
AGC was switched off for the scan.
I know nothing about spectrum scanners, but your graph is completely unbelievable with such cliff-edge drops and rises.
And probably work if the aerial is in the loft. A log periodic is an
ideal physical package for loft installation.
Anyway it's been fine for
years but just recently developed the breaking up and freezing but only on the mux on UHF24.
Here's one done in a different way: https://www.brian-gregory.me.uk/GDL/spectrumspy-2020_03_10__04_03_33.png
It has numerous spurious spikes all over the place.
I've recently been getting break-up and freezing on some Freeview channels even though I'm about 1.5 miles line of sight from the Reigate
transmitter. The channels affected are all on the mux on UHF 24 and are mainly the Sky channels. I did a spectrum analysis using my RTL-SDR stick and it shows there's a massive dip starting on UHF23 and pushing 24 right down.
The scan can be seen here: <https://www.dropbox.com/s/sh7b3fdyabnadll/ Scan%20470.0-592.0MHz%20lounge.png?dl=0>
The aerial is a standard 18 element yagi which might be group C/D as it
was for Reigate analogue, although it could be group A if the previous
owner used to receive Crystal Palace before Reigate opened. Either way
what do you think would cause such a drop in the middle of the band?
Nothing has been changed recently but the coax is over 40 years old, could
it be causing some kind of cancellation due to standing waves or summat?
On Tue, 17 May 2022 20:14:59 +0100, Mark Carver wrote:
By the way, in which direction is the mast from you ?Roughly NNW, so I should be in the SSE lobe. Anyway it's been fine for
The reason I ask is the Tx antenna is cardioid towards the SSE, so
basically if you're north of the M25, don't expect too much reliable
signal (even at 1.5 miles)
years but just recently developed the breaking up and freezing but only on the mux on UHF24.
On 17/05/2022 23:25, alan_m wrote:
And probably work if the aerial is in the loft. A log periodic is an
ideal physical package for loft installation.
No no no! Loft aerials last for ever! What about the poor starving
children of future aerial men?
Ah, I know more or less where you are (I've probably used your road as a
rat run, when that bloody level crossing in the centre of Reigate has
had a mega queue). High up, with a good view to the south ?
Me: Your aerial isn't working properly.
Customer: Hurumph! It's worked fine for the last thirty years!
Me: It isn't working properly now though, because a fault has appeared. Customer: Hurumph!
And probably work if the aerial is in the loft. A log periodic is an
ideal physical package for loft installation.
No no no! Loft aerials last for ever! What about the poor starving
children of future aerial men?
On 17/05/2022 23:25, alan_m wrote:
And probably work if the aerial is in the loft. A log periodic is an
ideal physical package for loft installation.
No no no! Loft aerials last for ever! What about the poor starving
children of future aerial men?
Bill
No no no! Loft aerials last for ever! What about the poor starving
children of future aerial men?
On 17/05/2022 19:37, The Other John wrote:
I could try different speeds but that wouldn't change the big dip would
it? There isn't a similar dip on the adjacent channels 26 and 27. The
AGC was switched off for the scan.
In America your 'big dip' is called 'suck out'. The Americans often use >colourful expressions to describe mundane things.
Bill
On Wed, 18 May 2022 08:24:47 +0100, Mark Carver wrote:
Ah, I know more or less where you are (I've probably used your road as aAbout 400 yds from the level crossing in a slight hollow and our road is mostly used as a car park by students at the local college!
rat run, when that bloody level crossing in the centre of Reigate has
had a mega queue). High up, with a good view to the south ?
On 17/05/2022 19:32, The Other John wrote:
The aerial fixings will need to be replaced most likely.I was afraid you'd say that! None of the neighbours has got a log
periodic and as we're only 1.5 miles from the TX a bit of wet string
would
probably work:)
Even close to the tx the directional properties of a log could be
helpful. Also a log has flat response across the band.
I once had a Vision(??) branded log periodic in my loft where the rod elements were just a poor interference fit into the boom.
On 18/05/2022 09:23, alan_m wrote:
I once had a Vision(??) branded log periodic in my loft where the rod
elements were just a poor interference fit into the boom.
There was a whole rash of these mebbe ten years ago.
On 17/05/2022 19:32, The Other John wrote:
The aerial fixings will need to be replaced most likely.I was afraid you'd say that! None of the neighbours has got a log
periodic and as we're only 1.5 miles from the TX a bit of wet string
would
probably work:)
Even close to the tx the directional properties of a log could be
helpful. Also a log has flat response across the band.
On 17/05/2022 23:52, Brian Gregory wrote:
Here's one done in a different way: https://www.brian-gregory.me.uk/GDL/spectrumspy-2020_03_10__04_03_33.png
It has numerous spurious spikes all over the place.
It's nice though. You can make the same spectrum look completely
different by: - Altering the scan bandwidth (makes a massive difference)
- Altering the scan speed - Altering the start and stop frequencies - Altering the dynamic range - Setting 'hold maximum' or 'hold minimum'.
On 17/05/2022 23:25, alan_m wrote:
And probably work if the aerial is in the loft. A log periodic is an
ideal physical package for loft installation.
No no no! Loft aerials last for ever! What about the poor starving
children of future aerial men?
On 18/05/2022 00:00, williamwright wrote:
On 17/05/2022 19:32, The Other John wrote:
The aerial fixings will need to be replaced most likely.I was afraid you'd say that! None of the neighbours has got a log
periodic and as we're only 1.5 miles from the TX a bit of wet string
would
probably work:)
Even close to the tx the directional properties of a log could be
helpful. Also a log has flat response across the band.
Log periodics probably more likely to stay directional when loft
mounted. My limited experience with loft mounted yagis suggests they
can be so detuned by damp roof tiles and felt that they end up almost omnidirectional.
On 18/05/2022 21:26, Brian Gregory wrote:
On 18/05/2022 00:00, williamwright wrote:I had the luxury opportunity of comparing the results from my Log P in
On 17/05/2022 19:32, The Other John wrote:
The aerial fixings will need to be replaced most likely.I was afraid you'd say that! None of the neighbours has got a log
periodic and as we're only 1.5 miles from the TX a bit of wet string
would
probably work:)
Even close to the tx the directional properties of a log could be
helpful. Also a log has flat response across the band.
Log periodics probably more likely to stay directional when loft
mounted. My limited experience with loft mounted yagis suggests they
can be so detuned by damp roof tiles and felt that they end up almost
omnidirectional.
the loft, without any roof tiles and then with them. The difference was
about 6 to 8 dB.
It still delivers 60-65 dBuV across the muxes in the loft, so I kept it
there
If the OP could find one, one of those flying bedsteads of years ago
would work very well in the loft.
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