Re: [amsat-bb] Coverage Area of 10Ghz

[Richard@xxxxxxxxxxxxxxxxx (Richard W L Limebear)]

James Clay French KD4DLA writes:

> Also wondering how bad the doppler shift would be using different modes 
(SSB, CW, FM)? Also on two point four, three, and five point seven GHZ?

1973 ARRL Technical Symposium on Space Communications contains the following
info - I find it invaluable for ballpark estimation.

Given: Satellite altitude 900 statute miles. Maximum Doppler from centre 
frequency (ie on an overhead pass) is:
Band (MHz):    21    29    145   435   1296   2304   24GHz
Doppler (KHz): 0.4   0.6   2.8   8.5    25     45     470

Interpolating from the above, the ballpark starts at +/- 90 KHz for 5.7 GHz.

Most amateur satellites are at lower altitudes these days; this will 
increase the doppler (we usually expect about +/- 11 KHz on 435 from current 
LEO birds). Of course, on P3D, they'll usually run the GHz stuff *away* from
perigee, where the doppler will be lower, otherwise we'd all need electric 
motors on the tuning dials.

73
Richard W L Limebear G3RWL
g3rwl@amsat.org
FOC # 1188

          So many beautiful girls ..... (sob) so little time
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