Quoting Graham Shirville g.shirville@btinternet.com:
Delfi C3 will have a linear Mode B transponder - a triple cubesat scheduled for launch in June. See http://www.delfic3.nl/ for details
To have one in a single cubesat would be a big challenge, especially if it needs to share power with other on-board experiments. If we could fund/develop an amateur only cubesat then it could be a fun project!
still dreaming!
73
Graham G3VZV
The amateur-only cubesat model is a very exciting one since it reduces the cost of launch considerably and provides the builders with a likely launch scenario early in the process. Delfi C3 is really leading the way in this field, and some of the compromises it makes are instructive. It has a transmitter power of, 400mW, 6 to 10dB below what we are used to in LEO linear birds. It also has no batteries, and will therefore work only when illuminated.
I expect that the power trade-off will be acceptable and that a fixed-elevation directional antenna with LNPA will still work well, though CW might be more popular on this bird :-)
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' :-)
73, Bruce VE9QRP
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.'
participants (2)
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Bruce Robertson -
Jonathan Wagner