it's not true that broadcasting digitally means a smaller dishsize is required than for analogue, but it is true that many of the modern digital broadcasts can be picked up on smaller dishes than used to be the case for the analogue stuff. This is not however related to the broadcast standard (digital vs. analogue) - it is down to factors such as greater signal strength from more powerful transponders on the modern satellites.
In fact, for a given signal strength and dish size, you are more likely to get a watchable picture from analogue transmissions than you are from digital. This is because the digital technology equates to "all or nothing" reception - a slightly too-weak signal (eg as experienced in heavy rain) results in severe blocking and very quickly in complete loss of picture. Under the same conditions, an analogue picture would usually still be watchable albeit with "sparklies" (dots and picture/sound degredation).
You also need to be aware that Hotbird is not a single beam (it isn't even a single satellite). The Hotbird cluster transmits its signals using several different beams, and they have different footpints, with different signal strengths. In general, to know the size of dish you need requires that you have identified the channels you want to watch, the specific beam that carries them, and the signal strength of that beam at your location (if indeed it is aimed at your location at all).
This kind of information is available for all satellites at Lyngsat.
See for example: http://www.lyngsat.com/hotbird.shtml
You will see that each satellite in the Hotbird cluster carries a couple of beams ("wide", "super", etc.)
Now in practise, in this case, it turns out that all of their footprints cover London, and even the weakest of them arrives there with a strength of 49dbW.
Several sites allow a rough "translation" of such figures to a dish size. Here is one such site:
http://sat-digital-tv.provider.pl/oprac/dbwtootm.html
Here you can finally conclude that you will need a dish size of 75cm diameter or bigger.
2old
