On Sun, 2009-09-27 at 16:02 -0300, Bruce Robertson wrote: > In a recent conversation on this list, I did the math and > conservatively estimated that 125 1U cubesats could be launched for > the current quoted price of a HEO launch alone.
I think Bob Bruniga mentioned something like $400 to build a packet satellite. If that's correct - $400 per unit - then I will split in $100 to get the first one started (and more, if the exchange rate swings in my favour again). > The problem, as I think Bob has noted before, is momentum: a > constellation of these is very useful; one of them is much less so. > The group that puts up the first of them, then, is not doing much of > interest and hopes that others will follow to increase the 'network > effect'. For this reason, we cannot expect (most) university cubesat > missions to look merely like this, unless their institution has a > special interest in emergency communications, as Bob's uniquely is. I personally have no interest in emergency comms, but I would like to see useful packet satellites. If they're that cheap to build, then we should have a big stack of them ready to fly. > KD6OZH's mentioning of a 1200 bps voice codec is very interesting, > too. I see that DSTAR's AMBE is down to 2000 with error correction, > and Speex operates down to 2000, too, though I think without error > correction. (I find the latter much more engaging as a ham, since it > is open source.) It would be a hoot to do a voice conference over the > Internet using a sample of low bitrate codecs and just get a sense of > what might be possible. One downside of voice is that it would occupy > the transponder far more than messaging, and Bob's favorable power > calculations would need to be estimated downwards. Would the packet satellite be capable of bent-pipe operation though? You'd need to transmit and receive simultaneously to get that working. I'd far prefer to use Speex rather than the locked-down proprietary AMBE codecs. > I guess another aspect of the cubesat approach is that the cost of > failure is much lower. If a low bitrate audio codec doesn't really > work well, it would be a less expensive enterprise and easier to chalk > up to experience. You could also just blow new firmware on it remotely. If it bricked, that's a shame but at least you tried... Gordon MM0YEQ _______________________________________________ Sent via amsat...@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
