At 03:40 AM 4/24/2007, Bruce Robertson wrote:
I can't speak for the rest of the world, but I'd say that in this neck of the woods, this approach has worked very well. I've only once or twice heard an FM signal on VO-52, no more often than other birds, and rare enough that I can assume it was by accident or ignorance.
I haven't checked this bird myself, because I lack 70cm SSB gear. Australia is in probably a more unusual situation. We have a relatively high penetration of VHF SSB gear, and a smaller, but significant amount of 70cm SSB radios out there. However, we also have a very low population density, compared to the US or Europe. I know when I was working RS-12/13, the only QSOs I had were those I had pre-arranged with local operators. It's much easier to find someone on FM. I believe there are some working Hamsat on SSB, from time to time, so it might be getting use here in SSB. I doubt there's much, if any FM activity on this bird, I think the convention for this part of the world is SSB.
Given VO-52 success in this score, I wonder: a) if the operators of other, future, LEO linear birds should likewise permit their use in FM over appropriate regions of the globe. Since FM is such a high duty cycle mode, I suspect usage and battery load statistics from Hamsat might be helpful in guiding others' choices in this matter.
Looks like there will be some useful lessons in here.
b) what advantage there is in launching a FM-only bird when a linear one can be used in both modes. I assume there must be reasons of efficiency, etc. since the designers of KiwiSat, for example, are making circuitry for both modes.
Indeed, though we would need to formalise arrangements a bit more then. For this part of the world, FM birds do serve a purpose, and that would need to be reflected in the local bandplan for any future linear satellites, if FM was going to be phased out. In other words, a CW/SSB/FM transponder bandplan in a 40-50 kHz bandwidth might be needed here. I'm sure a single FM QSO, 2 or 3 SSB QSOs and one or 2 in CW would happily coexist at the same time down here. Might also be room to experiment with managing the power sharing on a SDX as well.
Just thinking out loud...
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