[amsat-bb] Re: HF Satellite Relay

[Joe]

Looks like freqs used were right around 2 gig and just above 2 meters 
too.  according to this book
http://books.google.com/books?id=_azf94TByF8C&pg=PA4&lpg=PA4&dq=frequencies+used+in+project+echo&source=bl&ots=FmCl7J7Mix&sig=eUfFCrcaFQ4lz-5gBS7nt1JLBfg&hl=en&ei=t4IpTOryEsL_nAfjp52MAQ&sa=X&oi=book_result&ct=result&resnum=4&ved=0CCoQ6AEwAw#v=onepage&q=frequencies%20used%20in%20project%20echo&f=false

Joe WB9SBD
Near Space Sciences

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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.
> http://en.wikipedia.org/wiki/Project_Echo
>
> 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
>>      
>      Cancel
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>> 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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