[amsat-bb] Re: HF Satellite Relay
nss at mwt.net
Mon Jun 28 22:24:29 PDT 2010
Looks like freqs used were right around 2 gig and just above 2 meters
too. according to this book
Near Space Sciences
The Original Rolling Ball Clock
On 6/29/2010 12:03 AM, Greg D. wrote:
> 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?
> Greg KO6TH
>> 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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