Can you explain a bit more please, does that apply to weak Sky signals on Astra 2D - eek!
CASE 580G digger with the starting problem is fixed by the way, thanks for all the original replies and suggestions.
-- Holly, in France Gite to let in Dordogne, now with pool.
Hi,
Try painting the joints with a few coats of zinc rich primer; zinc is used to protect aluminium hulls and fittings in seawater so should protect the aluminium. In any case it will create another conductive path between the joints.
cheers, Pete.
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Terrestrial digital is being transmitted on low power at the moment so as not to interfere with the existing analogue channels. When the analogue channels are switched off the digital channels will be transmitted at increased power. This means that digital coverage will be greatly improved.
Interesting, however I gather that the TV companies want to chage the MPEG coding from 2 to 4 so as to squeeze more channels in, so any investment in terrestrial TV is likely to be a recurring event.
The transmission of the digital data can be pretty complicated, but the basic situation is simple enough. The receiver can either distinguish a '0' from a '1', or it can't. You either get a perfect copy of the transmission, or you get nothing.
There's various trade-offs in the detail, and the slower the transmission speed the easier it is to pick out the signal. The problem for ground-based TV transmitters is that, to squeeze the extra frequencies in without messing up existing TV signals, it has to be transmitted at lower power. A satellite doesn't have that problem.
A satellite only has the power available from it's solar panels. Typically tens of watts is all.
Satellites work better in terrestrially marginal areas because they have a very broad beam, not focussed to high population areas and always require a much more efficient antenna system than TV.
Yes, terrestrial digital is lower power than conventional UHF transmitters, but it still sends out 100W-10kW. Analogue sends out 1kW right up to 1MW(!)
The main problem terrestrial digital has is that in order to squeeze in as many channels as possible they have cut down the bitrate and error redundancy to a bare minimum - so a signal with 'a bit of snow' on an analogue channel is a frozen blocky nightmare on DVB-T.
follow alt.satellite.tv.europe.sky, and alt.satellite.tv.europe where there several people very knowledgeable about getting the SKY channels in Europe. Jim Watt
Yes, satellites are low power, but with a better antenna system.
The digital terrestrial channels use the same receiver antenna as the analog channels, but are transmitted at lower power. Bitrate and error correction are issues, but it's the relative power level which gives people problems. Use the same power as analogue and the other differences don't matter.
Bitrate and error-correction are linked. The lower the bitrate (and the more compression), the more effect a single-bit error has. But to get a "frozen blocky nightmare" is a sign of a lousy signal. It's a lot of errors needed to do that.
As I said, but no one noticed, you can solder Ali with the right flux...
Because Sats do not interfere with each other, the beam of the dish generally only picks up significant signal from one group of related satelites.
Indeed around the same as a domestic light bulb.
Beam width is variable, can be only a few square miles to most of Europe. Antenna may be more efficient but it is easier to stamp out dishes that assemble yagi arrays.
All or nothing is a function of digital systems wherever you find them. Humans are analogue, a hint of a hungry tiger is better than nothing.
Or interference.
I have a good digital signal, at least after installing preamps (it was acceptable before that). However I also periodically get significant interference (seen on analogue). When this interference is present the digital picture is a "frozen blocky nightmare", or disappears completely, but the digital signal strength remains good.
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