Severn said:
Thanks, Analoguesat, but that means there'd only be 120 slots. Surely there are a multitude more than 120 active geostationary satellites (never mind the dead ones)?
Did you mean 3 minutes? That would allow for more than 7000 slots and put them 30 or 40 km apart, if my maths is correct.
I wonder why the UK was late.
No - 3 degrees (moving towards 2 degrees in places like America where the skies are very crowded)
The limiting factor is the acceptance angle of the dish on the house. Dishes dont just accept signals from "straight in front" of the the dish, you can also get usable reception from signals coming in from the side. A normal domestic dish accepts signals from about 2 degrees either side of its lnb arm. Therefore any signals transmitted off a closely located satellite transmitting into the same geographic region and using the same frequencies will cause awful interference.
Theres no problem where the birds are transmittinbg into different areas. Look at the European situation - this of course is generalising and making a lot of assumptions but is approximately true
5E - Europe
7E - Europe
9E - Europe (different frequency bands are used between the 4 slots)
10E - Europe
13E - Europe
16E - eastern Europe (same bands used - 3 degree seperation)
19E - Europe
21E - middle east
23E - Europe
26E - middle east (different target areas using the same freqs across this section of space)
28E - UK/Europe
30/31E - Turkey & Eastern Europe.
33E - Europe