[amsat-bb] Re: Geostationary Satellites

Bob Bruninga bruninga at usna.edu
Tue Oct 11 17:02:29 PDT 2011

> Question, what is the closest spacing for geo 
> satellites to share the same slot?  
> Is this theoretically practical and or possible?

I think someone already said that there are no such thing as physical slots.  Slots are FREQUENCY based.  Meaning their separation only has to be as great as the beamwidth of the grouind based antennas that will use them IF they are on he SAME frequency.

So "C" band satellites were originally at 4 degree separation (10 foot dishes) then went to 2 degree separation by making evrey other TV channel be oppositely polarized.

Such spacing only applies to large constellatiosn of birds on the SAME identical frequency plans.  (such as consumer TV downlinks).

If we had ground receive antennas that had beamwidths the width of the moon, then we couild have nearly 720 slots (each 0.5 deg wide).  If a GEO constellation used laser communications links, with user ground stations using OPTICAL telescopes, there could be a million slots because the telescopes could resolve them down to .0003 degrees?

Oh, for HAMS with an OSCAR array and beamwidths of say 30 degrees, then there could be 12 slots.


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