[amsat-bb] Re: HF Satellite Relay
ko6th_greg at hotmail.com
Mon Jun 28 22:03:17 PDT 2010
Well, it's finally happened. We've come full circle. They've reinvented Echo-1.
Of course, that one was 10x larger. What makes this a 10m (band) operation? I expect it would work on the higher bands too, especially with the smaller size. What band did they use ~50-ish years ago?
> From: bruninga at usna.edu
> To: amsat-bb at amsat.org
> Date: Mon, 28 Jun 2010 13:44:45 -0400
> Subject: [amsat-bb] HF Satellite Relay
> Heard today of a Passive HF relay satellite being proposed.
> Wondered if Hams could relay off of it.
> It's a 10m diameter sphere.
> I assumed a 10m signal and 1000 Watts
> And antenna gains at both ends of 10 dB.
> Unless I made a dumb error, it looks impossible?
> I get a received signal of -170 dBm
> Compared to a good HF receiver of -122 dBm
> So its 48 dB down in the noise.
> Going to narrow band, could improve things, but the Doppler of
> +/- 600 Hz would make that difficult.
> Anyway, if someone else wants to double check the link budget
> using the radar range equation, go for it.
> The beauty of this system is that it is perfectly spherical, so
> the reflection coefficient would be constant within 1 dB. That
> is the advantage over trying to use the ISS or other large
> rocket body... They vary by 20 dB making communication by
> reflection impossible.
> Oh, and it would be in space for 30 years or more. So with
> something that reliable, it would be worth developing an amateur
> capability to use it.
> It is not designed for comms, but as a calibration sphere for
> over the horizon radars that have LOTS more power and LOTS more
> gain than we do.
> Bob, Wb4APR
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