[amsat-bb] HEO opertunity

Ross Whenmouth ross at topwire.co.nz
Tue Oct 25 06:19:56 UTC 2016


I am thinking along the lines of K.I.S.S - a simple "bent pipe" linear 
transponder, with as little to go wrong as possible (the bird will be in 
GTO for a very long time). Power and link budget permitting (eg a 5 GHz 
/ 10 GHz machine), a wideband transponder would permit ranging 
experiments, high speed data and video modes in addition to CW & SSB...

Can the attitude of a 1U cubesat in GTO be passively stabilised (gravity 
gradient?) to keep the antennae pointing towards nadir?

Is a microprocessor (or any digital logic) strictly required? simply 
having the transponder run whenever the arming pin is out (pulled by 
ejection from the cubesat canister) and the DC volts are high enough, 
would eliminate the need for a rad-hard processor. As far as I am aware, 
the RF circuits in a "rock locked" (no PLL) linear transponder are not 
as prone to SEU induced latchup as digital circuitry.

Ross Whenmouth

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