[amsat-bb] Re: CubeSat launch 27Mar07 6:46:35UT

Bruce Robertson broberts at mta.ca
Fri Mar 23 09:32:20 PST 2007

Quoting Graham Shirville <g.shirville at 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

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 

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