All posts by Chris.SE
Below are all of Chris.SE's postings, with the most recent are at the bottom of the page.
Jonathan Cohen:
All UHF TV channels are 8MHz bandwidth.
The Local multiplex carrying London Live is on 586000kHz (UHF C35) from Crystal Palace and Croydon transmitters. Freeview's ONid: is Hex 233A (Dec:9018)
The London Local mux is TSid: is Hex 800A (Dec:32778) The modulation is QPSK 8K, Code Rate/FEC: 3/4, Guard Interval: 1/32
London Live SID: is Hex 804A (Dec:32842) PMT PID: is Hex 3F2 (Dec:1010)
I'm afraid I don't know the Network ID for Crystal Palace as I'm not in the London area, and there's not a convenient list anywhere that most of us could find! Nor the "Provider" which I wouldn't have thought was critical info anyway!
I would have expected that you could have got all the info from one of you existing Tuner Cards (or most of it from a TV set Tuning section). Another handy source of some of the info is https://www.digitalbitrat…ve=9
Don't forget the the transmitter power for the Local multiplexes is a lot less than the PSBs & most COMs. So make sure you don't have anything is series with the antenna input that might attenuate the signal so it's not found on a search.
32834=8042 Bristol TSid:32770=8002
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Geoff:
LCN70 will never be available from Clacton as it's on COM7 which isn't transmitted at Clacton-on-Sea.
See Channel listings for Industry Professionals | Freeview
The loss of other channels is probably due to "Tropospheric propagation" at present, often associated with High Pressure weather systems.
It causes signals from more distant transmitters to travel a lot further than normal. It is currently affecting different parts of the country by varying degrees and signals can change by the second or remain stable for much longer periods.
In the old "analogue" days there was a lot of talk about "continental" interference often in the summer months, but the interference can come from transmitters anywhere in the UK or Europe and even further afield. At the moment some people are getting DAB radio from the Netherlands and FM Radio from France as well as the interference to DTV previously some coming from Norway.
It is predicted to continue for a couple more days, and you are advise NOT to retune as you will likely lose the correct tuning that you had. The "propagation" can be very frequency dependent, and it can only affected one frequency or several, but it can/will be different for others.
For those that have retuned and lost correct tuning, you will have to try again and it could be hit and miss whilst the unusual propagation continues. If you are able to do a manual tune for the correct UHF channels, you may still receive interference or the wrong programmes.
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A further reminder -
Clacton is no longer a "Light" transmitter as of 1st August 2018, it now broadcasts the 6 main muxes.
PSB1(BBCA) - UHF32; PSB2(D3&4) - UHF34; PSB3(BBCB HD) - UHF45; SDN - UHF40; ARQA - UHF43; ARQB - UHF46. 400W for each Mux. Aerial group K, Horizontal.
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jack:
As you haven't given a full postcode, we don't know if you are referring to reception from Crystal Palace in the Sutton area of London (the Sutton Relay transmitter doesn't have COM7), or whether you mean the Sutton Coldfield transmitter.
Whichever, none of those transmitters are currently listed for Planned Engineering or have any Faults listed that I can find.
Have you changed anything around in your installation when this started?
Make sure you don't have any HDMI leads near unscreened/poorly screened flyleads/aerial leads (ie. not double screened) as HDMI has been known to cause interference, especially to UHF C55 - COM7.
I take it you've checked your aerial and downlead looks intact/undamaged and the aerial still points in the correct direction.
You say it's 30% signal, what is it on the other multiplexes, and what are the Quality (or Error) figures like?
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jack:
If you haven't changed anything and checked all your coax plugs, connections, flyleads and swapped leads etc., have you introduced any new electrical equipment of any type, including lighting?
Do the problems occur at any particular time of day?
I assume that's the Local multiplex you are getting on C48. As for C26, that's not transmitted from Sutton Coldfield, but three other nearby transmitters use it for the BBCA multiplex (as a SFN) - Bromsgrove, Lark Hill & The Wrekin. Without a full postcode, I can't say if you might normally receive any of those, but the current high pressure is causing some periodic and variable tropospheric ducting which is bringing in signals from more distant transmitters. This might cause some interfering signals to affect C48.
But as your initial problem was COM7, as it's a SFN, problems/engineering at other nearby main transmitters with COM7 might have an effect on your reception. Which direction your aerial is pointing might give a clue. Having had a bit of a dig around I've also spotted that Sutton Coldfield was on Planned Engineering for the whole of May!
There were some intervals of tropo over some days in recent weeks as well, just to complicate matters, but that doesn't mean it affected your reception, that's so difficult to predict as it can affect different parts of the country by varying degrees and signals can change by the second or remain stable for much longer periods.
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Stuart:
Whilst what StevensOnln1 has said is correct, Findon and Rowridge are in opposite directions from you, so you must be getting the Findon signals off the back of your aerial - assuming it's still intact and correctly pointing at Rowridge. Findon is also somewhat closer! However manual tuning might be a solution.
Rowridge is at bearing 255 degrees (almost WSW) and Findon is at bearing 66 degrees (almost ENE), Crystal Palace is almost NNE Rowridge transmits signals with both Horizontal and Vertical polarisation, whereas Findon is vertical (Crystal Palace is horizontal). You aren't predicted to get good COM4/5/6 reception from Rowridge with horizontal polarisation (poor to none), it's better vertical.
Are the rods (or squashed Xs) of your aerial vertical, is the reflector of the aerial still intact as well as the other elements and still pointing WSW? The aerial needs to be intact and correctly pointing to reduce interference from other transmitters, but sometimes that is difficult.
Also what will not help matters is that there is currently some tropospheric ducting with the high pressure weather affecting mostly the South/SW of the country by varying degrees and signals can change by the second or remain stable for much longer periods. This can affect different frequencies by differing amounts at different locations, just because one multiplex might be affected doesn't mean another will be.
So you could try the following, first you'll need to clear the current tuning, usually best done by unplugging the aerial and doing a full automatic tune, nothing should be found clearing the old tuning. Plug the aerial back in and find the manual tuning section in the settings.
In the multiplex order PSBs1-3, COMs4-6, manual tune the following UHF channels for Rowridge -
C24, C27, C21, C25, C22, C28. You may have to try several times if there is any interference around.
IF you happen to find that despite the way your aerial points, you get better stable PSB reception from Findon then there shouldn't be any issue with the PSBs tuned to C44, C41, C47 and the COMs from Rowridge, but I don't know if you'd get a different local news variation from Findon.
IF your aerial turns out to have the rods horizontal, the channels are the same but you could try adding C55 for COM7.
Again, you may have to try several times if there is interference around.
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Graham Cox:
If they are still off-air, there is likely to be a fault that is taking time to fix, but you'd be best trying to contact them direct - try 01796 474040 or radio@dctmedia.co.uk if the methods of contact on their website don't do it.
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andy:
I would try anything above UHF C60, so that should be far enough away from C55 (COM7).
Anything lower might give interference if the device produces any harmonics or it or any equipment has strange C+5 or C+9 effects.
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Monday 7 June 2021 12:10PM
Pete williams:
It's because Sony have sold the channels - but not the Sony name!