Freeview channels missing on some devices

SiliconChip

I'm in the process of giving up on Virgin Media, I have just taken out a Three 5G home broadband contract which so far is working fine. My issue is with replacing the Virgin TV channels with Freeview.

I have 2 TVs and an inherited Humax Freeview DVR.

TV1 (Panasonic TX32CS510B) upstairs has been using Freeview from new and has a full complement of channels as far as I'm aware.

TV2 (Panasonic TXL42E6B) downstairs has always been connected to Virgin Media, having connected it to the aerial and done an automatic scan the EPG shows some channels but not all (for example, E4 is missing)

Humax box (HDR-2000T 500GB) has been unused since my mum died 2 years ago but I plugged it into the same aerial lead as I tried with TV2 and it has loaded the same channels as TV2 found. Thinking it might be an issue with the lead from the aerial to downstairs I repeated the scan using the aerial upstairs, but it still only found the same subset of channels (in fact, the first time I scanned it failed to find any HD channels, but a second scan added those). After seeing a suggestion on the Freeview site I did a scan with the aerial disconnected to clear the box memory then scanned again but it made no difference.

Clearly the aerial is receiving all channels, as shown by TV1, can anyone suggest a reason why TV2 and the Humax box are failing to find the same list of channels as TV1?

Rodders53

Different receivers have different 'sensitivity' to the signals presented them.
So if a signal is 'marginal' one TV may work fine while another is unable to 'see' the weaker signal.

Where is the aerial? 
How is the aerial split to feed the two locations?

A passive splitter loses half the signal. 
A low gain mains aerial distribution amplifier will double the signal (or a lot more if higher gain but such a one can cause overload issues, too.

The 2000T will have a signal level and quality meter that can help. 
So will the Panasonic TVs (but most give a post auto gain and error correction figures so are less helpful).

First though, go over all the cables plugs and sockets with a fine toothed comb.  Re-make or replace any suspect and all hand-made TV plugs.

SiliconChip

Thanks @Rodders53, you may be onto something. The 2000T reports the following signal strength and quality:

Channel 39 - 74% and 100% respectively

Channel 40 - 77% and 100%

Channel 42 - 54% and 100%

Channel 43 - 49% and 100%

I don't know whether those strength figures could be a possible cause of the issue.

I can't see anywhere in the Panasonic menu that would give me any similar information for the TV.

The aerial is on a pole on the roof, and I believe it will be using the Sutton Coldfield transmitter (it's certainly pointing in that direction). I have no idea how or where the aerial is split, it was in place when I bought the house 8 years ago and because the signal was fine on the TV that used it I didn't need to investigate before now.

Rodders53

Sutton Coldfield transmits the main 6 muxes on:

BBC A: 43

D3&4: 46

BBC B: 40

SDN: 42

Arq A: 45

Arq B: 39

 all at the same radiated power. {Plus 36 and 48 for lower power Local TV transmit beams.} 

Those S numbers ought not vary that much, my Humax HDR-Fox-T2 shows S76 to S68 across the 6 I receive (the lowest is the highest frequency) from Sandy Heath.  Your two missing ones are highest frequencies, 45 and 46.

Panasonic:  Ensure you are in Freeview watching mode: Menu-- System -- Freeview Tuning --- Signal Condition (or similar).
You can go up/down channel via the button to see other frequencies.

Having done that on my new Panny OLED (to find 'how') I find I need to fettle my own connections as some poor Q numbers are showing!

You need to find where the cable or cables from the aerial go ... and if there is a splitter involved in loft, behind a TV or even outside in a waterproof box. Or even if someone has joined three cables by twisting them together with some tape to hold them together.

I'm suspecting either:
   A faulty/damaged aerial where the output is dropping off fast at higher frequencies.
or
   Cable or connection issues giving the same frequency dependent result.

FYI Tuning to
BBC ONE (SD) (LCN 1) will measure the BBC A multiplex levels. 
ITV 1 (SD) (LCN 3) will measure D3&4 mux. 
BBC ONE HD (LCN 101) will measure BBC B mux.
QVC (LCN 16) will measure the SDN mux. 
SKY MIX (LCN 11) will measure Arqiva A mux. 
QUEST (LCN 12) will measure Arqiva B mux.

SiliconChip

Thanks for the additional information, I'll try to investigate a bit further in the morning, including trying to find where the cable splitter is. I suspect I'm going to have to get someone in to resolve this as it's already getting beyond my technical capability and it's likely to exceed the physical ability of my dodgy knees, but at least if I have some idea of what the cause might be I can try to make sense of it to someone who is able to fix it.

One other thing to add is that on Friday morning during the bad weather my upstairs TV lost the Freeview signal completely (I was watching BBC1HD when everything disappeared without warning). I though at the time that perhaps the aerial had been shifted by the wind, but a few hours later the channels were all back again so I dismissed that as the cause and thought that maybe there had been a transmitter fault. However, perhaps something has happened to the aerial as per your first suspicion.

brewerdave

You will probably find that the builders/previous owners have just manually spliced the cables together in the loft ! That was certainly my experience in the past when I had two feeds fed from one rooftop aerial.

SiliconChip

Here are the results of this morning's research.

I had a look in the loft but I can see no sign of any TV cable inside so I'm guessing that the split happens outside, which perhaps means that water ingress is a potential additional cause of poor signal.

Signal condition figures from the Panasonic TVs (out of 10, estimated from bar display where number is not 10)

Downstairs TV:

BBC1 SD Signal Quality 10 Signal Strength 10

BBC1 HD 10/8

ITV1 SD Not present in channel list

QVC 10/5

Sky Mix Not present in channel list

Quest 10/8

Upstairs TV:

BBC1 SD 10/5

BBC1 HD 10/10

ITV1 SD In list but no service, 2/0.5

QVC 10/5

Sky Mix Not present in channel list

Quest 10/10

As a test I took the upstairs TV downstairs and connected it to the aerial cable there and rescanned, the resulting channel list was the same as the downstairs TV with similar signal condition figures except BBC1 HD and Quest (both 10/10).

It looks to me like both of the possible issues you've highlighted may be present: a faulty connection (or maybe aerial) and differing levels of sensitivity on the devices. I can't do much about the latter (although I might replace the Humax as it seems quite slow and some of the buttons on the remote appear not to be working) but I think some maintenance/repair/replacement on the aerial and cables may resolve the problems.

SiliconChip

I've now had to chance to examine the vicinity of the aerial with binoculars (it's quite a tricky place to see) and it appears that a box is hanging from the frame that attaches the aerial to the chimney stack. I'm fairly sure that's where the cable split is, and I suspect that it may have become disloged when the signal was lost during stormy weather on Friday. So my first step will be to get someone in to resecure the box, if necessary remake the connection, check that the aerial is functioning correctly, and if the issue persists maybe get an amplifier fitted. I'll update once it's been looked at.

SiliconChip

Just to conclude the thread, I got someone in today to investigate, access was a bit tricky so we had to remove a neighbour's fence panel in order to get the ladder at an acceptable angle. He removed the dangling box, which had water in it and a lot of corrosion on the enclosed amplifier. He fitted a new amplifier/splitter box, reconnected the aerial and the TV cables, but was unable to get a signal when testing. Turns out that there was no power supply in place for either of the co-ax cables, so he was a bit stumped as to how it had ever worked! He then fitted a power supply to the downstairs co-ax, and I'm now getting a full complement of channels on both TVs and the Humax box (after turning down the level on the amplifier as the gain was too high at first).

Total time on site was just over an hour, cost for his time and the replacement parts was £120, which I thought was not unreasonable.

Thanks for the advice from everyone who responded.