Signal Quality issue

the groundsman

Active Member
I'm pretty ignorant about TVs :)

My daughter just moved into a flat in Chelmsford around 25 miles away from the Sudbury Transmitter. She bought a new LG TV and I gave her an old Coaxial cable so she could get started. The flat is ground floor in a small 4 story block. She's waiting for a broadband connection so just has the TV for entertainment at the moment.

Problem is with the HD Channels which are unwatchable and the TV removes them from the listed channels frequently. The signal strength seems good at nearly 100%. Not quite 100% so I think that might mean the usual diagnosis of over amplified signal is not that likely. Signal Quality however is very low- dropping to 0. She has cable coming in from somewhere- I assume a shared aerial on the roof. This feeds a Grey box via one of 2 inputs. There are 4 outputs that presumably feed the wall sockets in the flat ( though I can only find 3 wall sockets, despite 4 wires disappearing into the walls).

She's tried a different coaxial cable to the TV but no improvement.

Any ideas what she can do. I think if all else fails once the broadband turns up she can get all her TV via a streaming box.
 

Rodders53

Distinguished Member
Block of four flats: quite likely to be separate aerials for each dwelling (although T&C Planning deprecates that).

IF a communal system then there will be an amplifier already and the grey box (VHF/DAB in plus UHF in??) will be a cascaded amplifier and is not a ideal thing. Quite likely to over-amplify. The description of quality drop out when signal level high is typical of overload.

First thing is to connect the incoming aerial feed direct to this TV (using joiners if necessary) rather than using this 4-way distribution amplifier. (Make and model off the grey box would help).

If things then work fine, reconsider how signals are sent to the other 3 cables and if they are even wanted. A passive 2-way loses 4dB of signal.

If the coax is not hand-made, double screened coax try alternatives?

Crystal Palace is predicted to serve and be used in parts of Chelmsford, so be sure the correct transmitter is tuned in and aerial points the correct way.
 

the groundsman

Active Member
Thanks - lots to try there. Will pass on the info and follow up - probably needs to wait until I'm visiting next unfortunately.
 

mikej

Well-known Member
Yes - eliminating the 'grey box' and internal cabling as a cause of the problem is the first thing I would try, too. If there are still issues then the fault will presumably lie with the external aerial, any cabling in-between or any distribution system that may be in place if aerials are shared.

It's possible that the installation has suffered as a result of the weather, especially if it's an old installation on an older building. There have also been many frequency changes to Freeview in recent years and it's possible that the aerial is no longer optimised for the frequencies currently used (ie. it's no longer suitable). I would check with the neighbours and see what their reception is like.

If you want to get an idea of what reception should be like in theory in that location, put the postcode and house/flat number into the checker on this Freeview site, hit 'check' and it'll give you some useful troubleshooting info, including a table with the most likely transmitters and other alternatives, the recommended aerial type and separate tables of the frequencies they broadcast at, which can be useful when tuning manually. Note that the 'most likely' transmitter tends to be the closest, but this may not necessarily be the one you're aligned to. It also won't take into account factors like nearby tall trees or buildings that could affect the signal.

Which HD channels is she having issues with ? Sudbury looks to broadcast in the range UHF 29 to 47, with 47 being used for the BBC B 'mux' which carries Channels 1-5 in HD and others.

If it's BBC Four HD and BBC News HD she's having issues with, then those are on the 'COM 7' mux and you may find you're actually aligned to the Crystal Palace transmitter as the transmitter at Sudbury doesn't broadcast those channels. COM 7 cause problems for a lot of people (myself included) but it's due to be switched off by the end of June 2022, so not really worth worrying about.
 

the groundsman

Active Member
It's quite a modern 4-story block of 12 flats. I'd guess at it being around 20 years old. Problems are on all the HD channels bbc1 bbc2 itv and c4

We'll try to figure it out over a video call tomorrow and I'll let you know how we get on.

Many thanks
 

CatsWithThumbs

Active Member
I'm pretty ignorant about TVs :)

My daughter just moved into a flat in Chelmsford around 25 miles away from the Sudbury Transmitter. She bought a new LG TV and I gave her an old Coaxial cable so she could get started. The flat is ground floor in a small 4 story block. She's waiting for a broadband connection so just has the TV for entertainment at the moment.

Problem is with the HD Channels which are unwatchable and the TV removes them from the listed channels frequently. The signal strength seems good at nearly 100%. Not quite 100% so I think that might mean the usual diagnosis of over amplified signal is not that likely. Signal Quality however is very low- dropping to 0. She has cable coming in from somewhere- I assume a shared aerial on the roof. This feeds a Grey box via one of 2 inputs. There are 4 outputs that presumably feed the wall sockets in the flat ( though I can only find 3 wall sockets, despite 4 wires disappearing into the walls).

She's tried a different coaxial cable to the TV but no improvement.

Any ideas what she can do. I think if all else fails once the broadband turns up she can get all her TV via a streaming box.

You mention the TV removes the marginal channels from the guide; this is likely because the TV automatically rescans overnight to pick up any changes. (I found out the hard way, connected to a YouVIew box which went into low-power standby overnight, resulting in no signal passed through to the TV, resulting in all tuning being deleted every night).

You should be able to turn this auto scanning off. Whilst it won't fix the reception, you at least don't lose them from the guide once you have them. My LG is a few years old now but assuming not massively different, go to Settings > Programmes > Programme Tuning & Settings > turn off "Programme List Update". You will still get an on screen prompt when new channels are available.
 

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