On Fri, March 23, 2007 12:32 pm, Bruce Robertson wrote:
There seem to be many AMSAT operators who use large Az/El systems for LEOs; perhaps, then, an even weaker transmitter on 2m might be acceptable. My vote would be for an S-band downlink. It would be possible to put a patch antenna on one face, but some of this gain is eaten up in increased 'path loss'. Such a bird could be called a 'HardSat' in contrast to the so-called FM 'EasySats' :-)
Bruce,
I think there is more and more talk about an S-band downlink. Some of the guys on CAPE-2 have mentioned using S-band for high speed telemetry with a FEC scheme based on the Voyager and AO-40 methods (Viterbi and Reed-Solomon combo). The biggest problem with a patch antenna is the lack of attitude control on these small sats. Many developers are still playing with ideas on how to achieve this well and some interesting concepts have come up (for instance, one of Cal-Poly's sats CP3 or CP4 has magnetotorquers made by passing current through a PCB trace in the inner signal layers of a 4-layer PCB which also serves as a solar panel).
Also, having spent the last few years working on CAPE-1, a very simple satellite in many ways, I don't think it's fair to call any sat an 'EasySat,' they're all 'HardSats' and 'HarderSats.'