[amsat-bb] Re: BBsat Call for ideas
vk3jed at gmail.com
Mon Nov 24 18:38:03 PST 2008
At 01:01 PM 11/25/2008, Andrew Glasbrenner wrote:
>On the drive home from the symposium in Atlanta, I was thinking about a
>cubesat with a "hybrid" voice repeater. My idea would use a 435 FM uplink
>because it's easy to generate power enough on the ground, and the Doppler
>shift moves QRM out of the uplink fast, it's FM and not picky about tuning,
>and there aren't any illegal telephones that work on the uplink AFAIK. We'd
>use a 2m SSB downlink, for a few reasons. 2m path loss is less, so given
>similar antennas we'll get a better downlink. SSB is more efficient than FM,
>and we also save power by not transmitting unless there is audio on the
>uplink, a squelch of sorts.
Interesting idea, except I do have one quibble - normally when there
is no signal on FM, there would be the background noise at high
level. You would need to have squelch on the bird to cut the Tx power to zero.
>No computer on my satellite either! We'd have some sort of hardware timer
>that has to be reset every few days to keep the repeater running, so we
>could meet FCC rules on control. Maybe PL or DTMF?
>Wouldn't it be neat to have one of these sitting on the shelf in case a
>empty spot on a PPOD became available?
Could be neat to have a simple bird to throw up at the drop of a
hat. Also there are more 2m SSB radios than 70cm ones in service
down this way, so this is a goer in my book. :)
73 de VK3JED
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