Satellite TV problem.

[None of the above]

A few weeks ago I bought a new TV and Freesat satellite box (Humax Foxsat). The previous installation was a Sky Digibox and mini-dish. I connected the dish antenna to the new set up and it worked perfectly.
Over the past couple of weeks there have been frequent appearances of a dialogue box announcing 'No, or bad, signal'. There then follows a couple of seconds of the picture freezing and/or pixellating and then things return to normal.
Looking at the diagnostic display, it shows signal strength as 100% and quality as 80%. Of course when I look at the diagnostic screen the TV is behaving normally. It occurs to me that the LNB might be showing signs of departing this world for the next, or possibly that the satbox has a fault of some sort or another. I'm keen to avoid the hassle of returning the box only to find that it is pronounced 'fit and healthy'.
The dish antenna has a good unobstructed view of the sky and at first it occurred to me that an aircraft might have briefly 'broken' the beam but given the number of occasions on which the fault has manifested itself, I think that this theory can be disregarded. Additionally, weather would not appear to be playing a part in this. There has been no heavy precipitation to absorb the signal.

Now............. does anyone have an idea what the problem might be, and if so, please would you be kind enough to share it with the wider world?:)

Thanks,

N o t a:ok:

PS I suppose that there could be a malfunctioning transponder behind this, however that would be likely to have created something of a stir.

[dazdaz]

Hi
I've a Bush FreeSat box, As far as I know, The system is uploading software updates/new channels. That's what happens to me when the screen goes blank.

Good old 'rule of thumb' Turn off and reboot. I've read on forums here, it's the done thing with Airbus pilots.:p

[green granite]

Unplug the antenna and then try resetting the box back to 'factory settings' in the set up menu, sw off re-plug the antenna in and then re-install from scratch. It cleared my problems.

[None of the above]

Thank you, Gentlemen, for your replies.

I've tried the re-booting option, in particular the version as laid down by Green Granite.

I thought we'd struck gold as the TV behaved itself faultlessly for twenty-five minutes and then............ well, you know the rest!
It isn't a particularly serious problem, but it is very irritating. I have a feeling it must be the LNB. I think those supplied with the Sky mini-dish are of a non-standard variety and care is required in purchasing a replacement.

Retires to scratch one's head.:ok:

Thanks chaps,

N o t a

[The Flying Pram]

Yes, I believe the Sky LNB's are a clip in type and not the standard 40 mm collar. Check the connection at the LNB - try moving it about while someone watches the TV. I don't know whether you can see from the display if the problem occurs with Vertically or Horizontally polarised channels, or even which frequency is affected. The polarisation is selected by either 14 volts or 18 volts fed up the LNB cable, and the frequency band is also split in two and determined by a 22Khz signal, so a fault can just affect certain channels.

[None of the above]

Thanks, Flying Pram (That conjures up a wonderful picture!).

I don't watch a great deal of TV at the moment but recently my principal viewing has been the BBC News Channel.

I'll try to do some viewing on other channels over the weekend and I hope to be able to give you some more information in two or three days.

I know little of transponder allocations or polarisations, but is there a hard and fast rule, eg: are all BBC transmissions on the same transponder with the same polarisation?

Thanks again,

N o t a:ok:

[The Flying Pram]

BBC News is high band Horizontal, though most of the regional channels are low band. See if it the drop out is only on certain channels, and if so let me know which ones. I can look them up and see if there is a pattern forming. LNB's can fail only on certain parameters. If you can, check the dish, LNB, and mounting for security, it won't take much movement (a gust of wind for example) to cause problems if anything can move.

[None of the above]

OK, thanks FP.

All other things being equal, I'll do some research over the weekend and get back to you.

I'm presently looking after my dad (83) who has just come out of hospital and his recovery has been far from straightforward. If no further problems manifest themselves in the next couple of days, I should have time to make the necessary observations.

Thanks again,

N o t a

[None of the above]

Good morning, Flying Pram,

I've made a few observations in respect of signal strength/quality on various satellite channels. The signal strength in all cases has been 100% but the quality varies - see below:

10788 V Quality 100% BBC E Mids

10817 V Quality 100% BBC Oxford

12523 H Quality 30-40% Daystar (Not my usual viewing)

11953 H Quality 70% BBC News

10847 V Quality 100% BBC HD

............and in non-Freesat mode:

12051 V Quality 70% CNN

12207 V Quality 90-100% Sky News

A couple of points which might help:


(1) The dish is just below the gutter of this bungalow, but the local topography is such that it has a good 'take-off' in the required direction. I examined the installation a little earlier and there was minor play in the LNB. Manipulation of the component varied the quality on BBC News by -10%.

(2) The LNB is about seven or eight years old. I remember a few years ago when the BBC shifted some or all of its channels to a different satellite within the Astra cluster, that they were lost and the only way of retrieving them was by selecting Ch 303 (Yes, Sky Comedy!) before selecting the required BBC channel. I think that this was a recognised 'work around'. The problem disappeared when I disposed of the Panasonic Digibox in favour of the Humax box.

(3) The 'No, or bad, signal' banner appears more frequently on the poorer quality streams. Eg: the Daystar picture was particularly prone to breaking up.

I hope that there is now something to go on and that I haven't muddied the waters still further!

Thanks,

N o t a

[The Flying Pram]

Well you've not got a switching problem since you have both high & low, V & H channels. I have checked those on my receiver and get similar variations in quality. However I am using a dedicated satellite box (a Technomate TM 1500) and a motorised 80cm dish. This has a more accurate and quicker responding signal & quality display than the typical domestic boxes. My parents used to have similar picture break up with their Sky system despite it showing good signal readings. I connected my box to the minidish and found by a careful bit of "tweaking" of dish aim that I got a noticeable improvement in quality, and they've not had any problems since. The best way to do this is with a professional meter, but they are £200 or so! If you want to have a play there are a couple of things to try.

1/ Replace the LNB - If it's the standard "clip in" Sky one you will need to either use the same type, or get a conversion kit from Maplin and fit a standard "Universal" LNB. Chose a low noise figure, they are only slightly more expensive but will help to make the best of your signal.
P.S. These can be moved in & out and also rotated in the clamp - you will need to "skew" (rotate) it anticlockwise looking from behind 5-10 degrees or so, and also experiment with the position since this is like focusing a torch to get the best beam.

2/ Try adjusting the dish aim. This is obviously a bit tricky with out the proper kit, but the normal DIY method is to rig up a TV where you can see it from the dish (upstairs bedroom perhaps?) and also have the signal display showing. The alternative is to have someone shout to you, but that introduces a delay! I would carefully mark the bracket to dish joints with a marker pen so you know where it is at the moment. Then loosen the clamp and rotate the dish slightly to left & right to see if there's any improvement. Wait for a few seconds each time for the readings to stabilise. Obviously aim for the best result, although the quality reading is far more important with digital systems. Then also try the vertical aim - this tends to be more critical. A good tip when doing this is to chose a weak signal rather than a good one since any failings will show up much quicker.

I trust you realise that the dish is actually "looking" up from where it seems to be pointing - most small domestic dishes are "offset feed" types rather than prime focus such as the huge uplink site antennas. The Astra 2A,B,C,D & Eurobird 1 satellites at 28.2 degrees East are at an elevation of about 25 degrees above the horizontal in the SE of England.

Looking out the window, today is probably not the best time to be climbing a ladder, so I will wait to hear what you've decided to do.

[None of the above]

Thanks once again, FP.

I'll probably take the replacement LNB route. As the dish is at head height on the bungalow wall, it won't have to be a death defying stunt at the top of a ladder. (For this relief much thanks!)

I think that a like for like swap of the LNB is likely to be the best bet.
I don't want to change the alignment of the dish or replace the LNB with a different piece of kit and introduce too many variables into the equation, at least at first.

Given that the dish has been in the same well protected spot for some time, I think it unlikely that it has been moved out of alignment but I acknowledge the very real possibility of having to eat my words later on.:hmm:

I note that Screwfix - an unlikely source - stock Sky LNBs so I'll call in there on Monday while aged dad is at the hospital. Parking at the hospital is well nigh impossible, so I might as well use the time wisely.

Thanks,:ok:

N o t a

PS Yes, I am aware that the dish is of the 'offset feed' variety.
In the early days of satellite TV I was puzzled that dishes always appeared to point at the horizon. Eventually, the penny dropped.

[The Flying Pram]

Parents Sky dish had never been touched since installation and all fixings were secure. So either 5 satellites have moved without anyone noticing, or Sky installers are not to be trusted. I know which one my money's on!!


You might consider replacing the Co-ax if it's the cheap (and nasty) aluminium foil screened variety. Decent CT100 should have both a copper core, and copper braid & foil screen. This also greatly reduces the risk of corrosion through dissimilar metals in contact with each other. Do make sure you seal the cable connection with some self amalgamating tape stretched tightly, and overlapped 50%. Hopefully Screwfix will be able to sell you some.

[None of the above]

Parents Sky dish had never been touched since installation and all fixings were secure. So either 5 satellites have moved without anyone noticing, or Sky installers are not to be trusted. I know which one my money's on!!

I take your point!

Just out of interest, are all the Freesat channels on the same satellite or are they spread over two or more craft?
I seem to remember reading that the cluster is contained within an 'eighty mile cube' so to speak.
I just wondered if transmissions being spread over a number of satellites ever caused reception problems.

N o t a

[The Flying Pram]

In the order you posted them: 2D, 2D, Eurobird 1, 2A, 2D, 2A, 2D.
Even 80 miles apart will appear as the same point when you consider that they are all some 22,000 miles distant! The focus of a small dish like that isn't anywhere good enough to separate them out. That's the main reason for the very large dishes used at the uplink sites - to enable individual satellites to be selected, and accurately track their movements. None of them stay in exactly the same spot, they wander about and need regular corrections made. This is done by small thrusters, and the limited fuel for these is the main reason limiting a satellites life.

If you want to know more about all the satellites out there and what they carry "Lyngsat" is worth a visit. Select either "Europe" or "Atlantic" under "Frequencies" and chose a satellite. Then you can click on the relevant footprint map under "Beam" and see what's pointing where. These are only a guide, there can be variations from one transponder to another, but it is a very useful resource for explaining to other "enthusiasts" why they can't get a signal that someone else in another part of the country can.