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Faulty Live TV Signal

DelboyMacbooth
On our wavelength

We have a Faulty Live TV Signal.

On some channels the pictures and sound are breaking up.

Each TV channel's SNR value and its % Signal Strength can be seen within the V6 Menus.

Some of the high frequency channels are only showing 91% signal and 36dB.

Does anyone know what dB and % we need to have to get a proper signal on these channels?

19 REPLIES 19

japitts
Very Insightful Person
Very Insightful Person

@DelboyMacbooth wrote:

Not being immensely impressed!


With what?

I don't believe the recommended SNR values are documented anywhere, it's only on the broadband boards where those details are more "relevant".

If you're having service problems, then the quickest way to resolve that is to call in and report your fault. If you start quoting SNR & dB values at most CS agents - offshore especially - it's not going to get you anywhere, frankly. Save that for the techs that attend, and treat the CS call as a means to an end.

Staff do generally respond on these boards, if you have service issues that aren't being resolved by phone - then we can give the thread a nudge if it's been missed.

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nodrogd
Very Insightful Person
Very Insightful Person

@DelboyMacbooth wrote:

Its been a couple of months now since we Last asked.

Not being immensely impressed! we took advice from an independant engineer 🙂

So for the benefit of anyone Searching the Community, the advice we've had is.....

- For a channel to have 100% Signal, the frequency's SNR has to be at least 40dB but no more than 42dB.

- Any channel with an SNR of 38dB or Less (with a Signal of 97% or less) is probably going to have reception problems.

Don't know if this is 'Virgin Correct' but seems reasonable.


Whether you get problems or not are determined by two things. Signal strength & signal quality. Signal strength is determined by the voltage received at the input socket. For Freeview DVB services this is somewhere between 650 & 1000 microvolts. Cable systems are a little more stringent as all the adjacent frequencies carrying the broadcast muxes are in use. Hence overloading the tuner circuit is more likely than with an off-air set up. Signal strength on a cable system would therefore top out at around 800 microvolts. However, a 600 microvolt signal would still be sufficient if the noise level in the cable is low. So signal quality is a balance of signal strength versus noise. It would be quite possible for signal strength to reduce to 75-80% & still not have issues if noise is low. Conversely even with low noise, if the signal level exceeds 800 microvolts (100%) you will again see poor signal quality. VM boxes don’t show signal quality figures, unlike Satellite & Terrestrial based DVB boxes.

These were easy to spot with analogue TV signals in the earlier days of cable TV, as they gave visibly different symptoms. But with DVB the data corruption is very similar, so further technical investigation is required.

VM BB TV Landline. Vonage 2nd line. Freeview/Freesat HD, ASDA/Tesco PAYG Mobile. Customer since 1993

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Nodrogd.....

Firstly thanks for reading my words. For me at least, that counts.

As I said, exploring the technical side has (eventually) become of interest.

Amazing isn't it that what comes miles and miles through the air for Freeview is actually a form of very low voltage artificial electricity (electromagnetic waves of which light itself is part).

Anyway... I take your point about off-air set ups, certainly adds to my view.

Also the point about exceeding 800 microvolts, sounds to perhaps confirm the idea that there is such a thing as bad reception because a signal is too strong? (even though it won't show on V6 as 103% etc)

As a matter of interest, do you think its possible to take the V6 box SNR as in some way an indication of signal quality - that being that 37dB is low quality, 40dB is good quality and 43dB is so good its bad.

nodrogd
Very Insightful Person
Very Insightful Person

@DelboyMacbooth wrote:

Nodrogd.....

Firstly thanks for reading my words. For me at least, that counts.

As I said, exploring the technical side has (eventually) become of interest.

Amazing isn't it that what comes miles and miles through the air for Freeview is actually a form of very low voltage artificial electricity (electromagnetic waves of which light itself is part).

Anyway... I take your point about off-air set ups, certainly adds to my view.

Also the point about exceeding 800 microvolts, sounds to perhaps confirm the idea that there is such a thing as bad reception because a signal is too strong? (even though it won't show on V6 as 103% etc)

As a matter of interest, do you think its possible to take the V6 box SNR as in some way an indication of signal quality - that being that 37dB is low quality, 40dB is good quality and 43dB is so good its bad.


What you have to accept is that these figures are just a guide that points to a possible problem. They don’t tell you what the problem is. SNR is just a ratio. Signal strength just a figure.

TV tuners are not manufactured identical. Most have a tolerance of 5 - 8% of an optimum value, so some will be more sensitive than others. Having been in the aerial rigging trade many years ago when there were tolerances of up to 15%, I would go to a customer with a grainy weak picture on their TV put a meter on the aerial to test it only to find it would show as receiving an adequate signal. So I would still have to make modifications because of the particular TV set.

Noise is also an anomaly. If I had a tone generator & set it at the same frequency & volume as my voice, you would have problems hearing me. However, if I changed that frequency even by a small amount my voice would become more audible. There is still the same level of noise, some volume, but the quality of the wanted signal (my voice) has increased. RF noise can take many forms. Electrical interference. Other types of RF from mobile phones. All of which affect the wanted signal in different ways. So the signal quality indication is the best guide, as this takes into account the tuner error rate & hence how it is coping with what it’s receiving. Why don’t cable boxes have this? I’ve never managed to work it out.

VM BB TV Landline. Vonage 2nd line. Freeview/Freesat HD, ASDA/Tesco PAYG Mobile. Customer since 1993

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Ok, I hear you - Indications being what we asked and as you say you've seen lots of that professionally.

Thanks for your info about noise etc - much appreciated.

So signal quality Indication is the best Guide and the V6 box doesn't display it..!

That said, to be fair, our view is that the V6s are generally good kit.

The main V6 problem being that Resolving Issues with Virgin as your Supplier is akin to watching paint dry, pulling teeth? or prehaps a very patient day dream about how good your V6 would look if it was in the garden 😉

Its the second V6 box that's never really cut it.

And the Circus has been in town a few times...
On the orginal installation day, a member of the magic circle installed a trans-atlantic length coax which he coiled behind the lounge's big TV cabinet.
Then when we got the second V6, another entertainer installed a moon length of coax and stored that considerately behind the big TV cabinet upstairs.
Most recently an engineer popped up from nowhere saying he'd come to convert our phone to VoIP, I'll bite my lip on describing what he did and left us with!

In addition, we've also had two Virgin call outs in recent years to specifically sort out the second V6 box but that didn't sort it and long term marriage is a wonderful thing but these days people want to watch different things in different rooms.

So we'd like the second V6 to run with a similar coax signal as downstairs.

We've spelt out what we want Virgin to do in writing months ago, we asked them for new cable and a forward path equaliser but their response as usual was abrupt and chasing them for answers by phone has resulted in nothing.

We've also been here as many do, as a final straw and whilst there are obviously some top class posters, mostly what you see here is evidence of why Virgin are Ofcom's most complained about TV company.

Whilst virgin continue to be cagey etc. we've been considering other options - roku, sky. Also - background reading on kit in general has been eye opening but not quite conclusive as of yet.

For now, can anyone tell us as a guide how much Virgin might seek to charge if we could get them to send an engineer to:
1. Replace all the internal coax with short, sensible, non coiled cable.
2. Supply and install a 4, 12 or 15dB Forward Path Equaliser so that the live TV signal on the upstairs box is similarly as good as the downstairs box.

japitts
Very Insightful Person
Very Insightful Person

@DelboyMacbooth wrote:

For now, can anyone tell us as a guide how much Virgin might seek to charge if we could get them to send an engineer to:


All fault callouts and repair works are free of charge within your monthly subscription.

All non-fault works are a flat fee of £25

In either case, whatever works are required - the VM tech will do so.

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sorry community - just remembered...

earlier, meant to say we won't be calling out a giddy van unless we know how much the two things we want cost.

so how bout it virgin!!? 😉

could someone pop up from nowhere and say in a Non Cagey way how much it will cost for the two things above

❤️

japitts
Very Insightful Person
Very Insightful Person

VM don't operate in this way, but I may have confused 

If you report a service fault, VM will rectify that FOC - with whatever replacement kit the tech deems necessary.

The £25 charge is for non-fault callouts, such as requests to move connection points.

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Adri_G
Forum Team (Retired)
Forum Team (Retired)

Hey DellboyMacbooth, thanks for all your posts and replies on our help forum and this thread.

Sorry to see you've had issues with your TV signal and broadcasting recently and good to see they've been restored now.
Thanks for your questions too, we'd love to assist with any queries or concerns you might have.

Regarding our technician visits, we'd like to explain we do offer a faults visit free of cost to all customers as long as our diagnostics find an issue with the equipment or service however there are options such as relocating your home equipment which is a chargeable visit instead.
All external work and network maintenance is also done at our own cost.

You may have a read on our price guide here for more on our appointments and charges, for your reference.
Let us know if you have more questions and we're eager to advise.

Adri
Forum Team

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