Intermittent picture breakup problem on some channels

clearcomms

Standard Member
I know this forum is not for Sky or Freesat queries, so I hope you agree this isn't really either!

I live in SW France, and I have a professionally installed UK satellite system with the right sized dish.

The dish was moved recently after working perfectly for over 10 years. It now works perfectly a lot of the time, but not all the time. I can't be certain it started at the move, but it didn't occur before it. The problem is not caused by our digibox, as I have tried another one and the same thing happens.

Some evenings (and sometimes for just part of an evening) we get bad picture break-up and even occasional "No signal" messages on some channels - essentially the BBC and other "terrestial-related" channels like Channel 4, ITV1-2-3 etc. Sky channels are not affected.

When I check the signal during these episodes it appears perfectly normal both in strength and quality.

It can be a slight problem, or can render a programme totally unwatchable, it can occur for half an hour or throughout the evening. It rarely happens during the day so far as we know. Sometimes it doesn't happen for two weeks, currently it is happening to some extent most days.

Our installer (who is very knowledgeable and used to UK satellite installations) is due to visit shortly, and is talking about possible polarisation problems - he's sure the dish is aligned with the satellite but appears to think the LNB might be out of vertical alignment (if I understand his French properly!)

Is there anything else I should be asking him, and can anyone give me a likely explanation for this odd and very annoying problem?
 

jim345

Active Member
Evening signal fading is a common issue for those in fringe reception areas such as southern Spain. If your set-up was working well before, then it is probably just a bit out of alignment and should be easy to fix. It's possible there's a problem with the new cable/connector. LNB skew (rotation from vertical) won't have changed: from the site below, I'd say it should be pointing at 1 o'clock, facing the dish.
Satellite Finder / Dish Pointing Calculator with Google Maps | DishPointer.com

It would be a good idea for the installer to come in the evening when the signal starts to fade, though he should be able to maximise signal levels at any time using a meter.
 

pedro2000uk

Distinguished Member
what dish make/ size is it?
 

MartinPickering

Well-known Member
what dish make/ size is it?

Awaiting with interest. Also how far was it moved? Was the LNB changed? Was the same cable used? Was the dish distorted during the move?

I would add that I've come across installations where a dish works perfectly in Portugal and an identical set up in a neighbour's garden doesn't. Ignoring possible variations in LNB manufacture, I put this down to location. Some locations simply get a better signal than others. I don't know whether this is due to the actual radiated pattern from the transponder or local effects such as ground and building reflections causing signal cancellation at specific frequencies. But inexplicable things do happen and the answer is to relocate the dish.
 

clearcomms

Standard Member
As to the dish, I have no idea of the make, and the size is the right one for our area. But as it's been working perfectly for almost 12 years, I can;t see that the dish itself can be the issue.

We're waiting for the engineer to be able to get up on the roof - it's too wet at the moment. But the dish was only moved around 30 feet from one side of the roof to the other. There's nothing in front of our house (we're at the top of a steep slope).

Some new (extra) cable will have been used to get the signal to the end of the cable at the old position, otherwise nothing will have been changed, and it's unlikely anything got damaged or bent!

Thanks for your interest.

Of course we are currently getting the benefit of the "Doctor's Surgery Syndrome", where the moment you call in an expert the problem disappears!
 
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MartinPickering

Well-known Member
Don't join the cable and don't make it longer than previously. Either of those factors alone would explain your problem. In addition, the average life of unprotected cable outdoors in the UK is 5 years. It may be longer or shorter abroad, dependent on the effects of rain and sunlight.

Nobody was suggesting that the dish is the cause (unless it's distorted*). What we're trying to extract from you is the maximum amount of information so we can offer advice based on fact rather than guess work. If you aren't even prepared to divulge the dish size, I'm out of here.

* 1mm distortion would be sufficient to alter reception and could easily occur.
 

clearcomms

Standard Member
>>If you aren't even prepared to divulge the dish size, I'm out of here.<<

Wow. It's not that I won't divulge it. I bought it over 12 years ago, I can't remember the size, and I'm not going onto a wet roof to measure it. I do know that a responsible and experienced professional tells me it is the right size, it has been working perfectly for 12 years, and it is the same size as others in the area, including both my neighbours. If that isn't enough, then I can only apologise.

I mentioned the extra cable because I can see how that could be a problem, at least in theory. Scarcely any of the old cable involved is outside - it entered my roof just a few feet from the old dish position, so almost all the cable is protected.

You also said <<Was the dish distorted during the move.<< Good question - which is why I tried to indicate that I thought this unlikely.

I get the distinct feeling I've upset you somehow, and I'm sorry if that is the case. I have some general technical knowedge of TV (I worked in the industry for over 40 years) and am trying to give the information that seems likely to be relevant when I know it.

If that isn't enough, then I'm sorry to have wasted your time.
 

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