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Link Analysis criteria


My questions for the day.

My link analysis spreadsheets are growing with equipment tradeoffs. But
they are using several criteria that I don't fully understand.

The first set of numbers are Frank Sperber, DL6DBN set published in The
AMSAT Journal and elsewhere. Are these signal powers at the satellite
subpoint and what appogee?  Do we need several dB extra margin for
atmospheric loss at edge of footprint and off-axis in the satellites antenna? 

The second set of criteria are those of Zack Lau published in the ARRL
Handbook (page 23.18 of the 1998 Handbook) where he gives antenna gain
(power ratio) to system receiver noise temperature (kelvin) ratios for
various bands (ranging from 0.008 on 2m to 0.53 on 13cm). What is being
optimized here?

On 13cm downlink, I seem to get great Signal to Noise margins (22dB) but
only get 0.30 g/T instead of greater than 0.53. I need another 3dB antenna
gain to meet this criteria.

Jerry, W6IHG
Dr. Jerry R. Pixton, PIXOS Designs LLC
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