Dish size for Hotbird in London

Genie

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DM800 with 320GB HDD running Nabilosat 0.12
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#1
Hi, sorry about the silly question,

I am a newbie and would like to know what size dish I would need to receive digital broadcasts from Hotbird at 13 Deg east.

I read somewhere that digital broadcast would require a smaller dish.
 

2old4this

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#3
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
 

Genie

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My Satellite Setup
DM800 with 320GB HDD running Nabilosat 0.12
1 metre motorised dish. Intel core i7 920 PC
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#4
Thanks 2old.

I was hoping I could use my old 60cm dish, but I suppose I should get an 80cm one, but I'll give it a try first.

regards
 

rolfw

Believe it when I see it Admin.
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Berkshire
#5
If you decide to opt for the 80cm dish, you can then take a secondary LNB focus to pick up an acceptable 19.2e as well.

Rolf
 

2old4this

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#6
Genie
you may well find that the 60cm dish gives you reception on at least most of the Hotbird channels, but that depends on other factors too - the quality of the cabling, the noise-level of the LNB, the sensitivity of the satellite tuner... and the weather. Maybe you'd get a picture in fine weather but quickly lose it in rain, for example. Point is, it'd be marginal.
2old
 

Genie

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My Satellite Setup
DM800 with 320GB HDD running Nabilosat 0.12
1 metre motorised dish. Intel core i7 920 PC
My Location
London
#7
Thanks all.

I've decided to ditch the 60 cm and buy myself a new 80cm, maybe even get 2 lnbs one for Astra 19.2 and one for Hotbird using an offset arm of course.

I'm gonna connect it up to my Hauppauge DVB-s PC card. That should do it.

cheers
 
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