All posts by Chris.SE
Below are all of Chris.SE's postings, with the most recent are at the bottom of the page.
jj:
I'm afraid that 50kW doesn't always guarantee good reception even if reasonably close.
Reported elsewhere, on Monday eg. at Ventnor I-O-W, reception of the BBCA mux was wiped out in the evening, and the D3&4 the following morning. There was good reception of some French muxes on other UHF channels.
Transmitters have always had to share frequencies, but they are generally allocated around the country so as not to cause problems in the predicted reception areas under normal conditions, and the same principle goes for coastal areas (eg. S. coast and France, E. coast and Belgium etc.) as well as the use of directional transmission where possible. The higher the power the more likely there'll be unwanted interference.
Because priority is given to ensuring that as much of the country as possible can receive the 3 PSB muxes, that has a limiting effect on available frequencies & powers for the other muxes. There are over 1100 transmitters in the UK, just over 80 are main transmitters, the rest are relays carrying just the 3 PSBs (apart from one welsh one which has SDN as well!). So at the end of the day, it's a bit of a balancing act and unfortunately there will be some locations that lose out on some muxes due to co-channel interference, good directional aerial installations may help in some places but not everywhere.
Turning up the power would just cause additional interference to many, so unfortunately that isn't an option.
You may happen to be in a poor spot for some of those COM muxes anyway.
| link to this comment |
Debbie Al Amiley:
I can see why you are confused. As you may be aware some programmes have a +1 channel as well, which means they are an hour later than the main channel.
In this case Sony Movies Classic is on LCN50 and is transmitted on a local multiplex, unusually there are 3 at the main Winter Hill transmitter - one for Liverpool, one for Manchester, and one for Preston and they are directionally transmitted so it depends on where you are as to which (if any) you may receive (a full postcode is needed to look at predicted reception for your location).
The Sony Movies Classic +1 programme is on the G-MAN (or GI) multiplex which is a separate commercial service with several channels, and the programme is on LCN62. Again whether you can receive the G-MAN multiplex depends on location.
If you can do manual tuning on your set, not knowing your postcode you could try for each multiplex and see what you can get. They are on UHF channels as follows C21, C24, C40 & C27 that is in the order L-LIV, L-MAN, L-PTN & G-MAN.
Otherwise, if you provide a full postcode we can check the predicted reception at your location.
| link to this comment |
Alison Foster:
Apart from mentioning the BBC channels you haven't given details of the other channels that are problematic as well as those that are ok. Without a full postcode we can't advise on the predicted reception at your location.
That said, before this last change in August were you watching the BBC channels at LCNs 751 and up in your EPG?
The first of these final changes was made by Freeview last February where the BBC main multiplex was moved to UHF C32 with programmes at the normal LCNs 1,2,9 etc but the old one on UHF C50 was left simulcasting with the programmes at 751 et seq. Whilst a lot of people would be (and did) get satisfactory reception of C32, this was so that people who weren't getting satisfactory reception on C32 (which is generally due to having an old Group C/D aerial), had time to arrange for the free support for aerial replacement before the last change which was due in April but postponed until August due to covid-19.
(Since the changes you need a Group T/Wideband to get all multiplexes if you are predicted to get them all).
I assume you can no longer get any of the local multiplexes either (on lower channels than C32, although if you are in the Preston area you might as that one is on C40) but again without knowing the full postcode I couldn't be certain. My guess is not, as you mention about getting reception from Wales.
Just to make matters worse at this moment, there is some interference to signals due to "tropospheric ducting" (see Effect of tropospheric ducting on Freeview | Help receiving TV and radio for a simplistic explanation) This can be quite variable and will come and go, so a further retune to get Winter Hill back may help if signals are more stable.
However, to resolve the primary problem, providing you don't have cable or satellite (I again guess not from your comments) and it your own aerial on your home you can get free help from Freeview. You need to ring them on 0808-100-0288 and tell them that since the August changes you've had pixellation on the BBC and other channels, you had problems with the BBC channels since February, that you've retuned several times to no effect (and you've currently lost Winter Hill channels) and have been advised that your aerial needs replacing because it's an old Group C/D. They should put you through to DMSL who will arrange the free aerial replacement with you.
| link to this comment |
PETER LITTLE:
It's unlikely to be your box, there's been a lot of "Tropospheric Ducting" around causing interference, see Effect of tropospheric ducting on Freeview | RTIS for a simplistic explanation. It's likely to continue for a day or two more.
There are no reported transmitter faults either.
Your most likely transmitter is predicted to be Pontop Pike, Chatton would be a good second choice. Bilsdale is a possibility but not a good as the other two especially for COMs4-6.
You can look in your box's tuning section to see what UHF channels you are tuned to, I'll list them for you in a moment, but some simple checks - If you get a local station at LCN7 in your EPG and it's Newcastle, then it's Pontop Pike you are getting. If your box is HD, if you are getting BBC News HD at LCN107 the you are getting COM7 which isn't broadcast from Chatton.
Middlesbrough is the Local station from Bilsdale.
You can also check which way your aerial is pointing, at your location, directions as follows -
Bearing 190 degrees - 10 degrees W of due S, it's Pontop Pike
Bearing 326 degrees - 11 degrees N of NW, it's Chatton
Bearing 164 degrees - 16 degrees E of Due S, it's Bilsdale.
UHF channels as follows, in the order PSB1/BBCA, PSB2/D3&4, PSB3/BBCB HD, COM4/SDN, COM5/ArqA, COM6/ArqB, COM7, Local
Pontop Pike C39, C42, C45, C32, C34, C35, C55, C33
Chatton C41, C44, C47, C29, C31, C37
Bilsdale C27, C24, C21, C43, C46, C40, C55, C30
The "Tropo" is the most likely cause of problems right now.
| link to this comment |
Ray:
Without a full postcode we can't advise what the predicted reception is likely to be at your location.
If this is a recent problem this last few days then there's two things that might be causing your problems.
The Rowridge transmitter is currently listed for Planned Engineering with "Possible weak signal".
Also there's been a lot of "Tropospheric Ducting" around causing interference, see Effect of tropospheric ducting on Freeview | RTIS for a simplistic explanation.
It's likely to continue for a day or two more.
| link to this comment |
Sue:
The problem explained in the posts previous to yours are more generally about people having problems with the normal BBC and ITV etc SD channels since the changes in August. Even if you didn't have those problems and also had an old Group C/D aerial, that old aerial picks up C55 COM7 with no problem.
The issue is more likely to be due to a lot of "Tropospheric Ducting" around causing interference, see Effect of tropospheric ducting on Freeview | RTIS for a simplistic explanation. Signals can travel from distant transmitters in Europe or the UK and "knock out" local signals for periods of time. It's likely to continue for a day or two more on current predictions.
Dave:
The "Tropo" is the most likely cause.
Andy:
Tropospheric Ducting can accompany High Pressure, but it's not high pressure per se that's the cause. Nor is it directly due to Sutton Coldfield being on the same channel, as COM7 operates as a "Single Frequency Network" (SFN) where the signals are synchronised, and the 25 main transmitters in the UK that transmit COM7 all use C55. The atmospheric conditions described can also disrupt that synchronisation so any transmitter could cause interference with others in some locations, but it can/will be quite variable.
| link to this comment |
Richard:
An increase in power is highly unlikely. COM7 operates as a "Single Frequency Network" and power changes would cause different problems in different locations.
Also to make matters worse at present, there's been a lot of "Tropospheric Ducting" around causing interference, see Effect of tropospheric ducting on Freeview | RTIS for a simplistic explanation.
It's likely to continue for a day or two more.
| link to this comment |
Roger Boysen:
Normally you should have any problem with reception of any of the multiplexes from Sandy Heath, or the Local one from Madingley at your location (should be within the beamwidth of your aerial).
See further comments below.
Gavin:
There's been a lot of "Tropospheric Ducting" around causing interference, see Effect of tropospheric ducting on Freeview | RTIS for a simplistic explanation.
It's likely to continue for a day or two more.
| link to this comment |
Thursday 17 September 2020 2:47PM
Karl:
No, COM7 is still there. BUT there has been/is some significant "tropospheric ducting" around (see Effect of tropospheric ducting on Freeview | Help receiving TV and radio for a simplistic explanation) causing disruption in various parts of the country at different times and unfortunately it is likely to be around over the next few days. However, predictions, like weather forecasts, could change!
If you can do a manual tune on UHF C55 that may be the best way to get correctly tuned without the possibility of disrupting the other multiplexes as the "tropo" could affect them as well, although your set will be able to cope with limited interference it may baulk a bit on a total retune at any given time, then you'd have to go through the process again when signals are more stable.