[amsat-bb] Re: New Satellite Downlink?
ka3hsw at att.net
Fri Aug 27 16:28:02 PDT 2010
Question: since there is no amateur radio allocation at 149.985, "we"
(hams) would be asking the Navy, to whom the downlink frequency is
allocated, to transmit one-way amateur communications thru this satellite,
Doesn't anyone else see potential legal problems involved here?
----- Original Message -----
From: "Robert Bruninga" <bruninga at usna.edu>
To: <amsat-bb at amsat.org>
Sent: Wednesday, August 25, 2010 11:27 AM
Subject: [amsat-bb] New Satellite Downlink?
> Possible new AMSAT Application?
> We may have access to two old TRANSIT navigation satellites with
> a 50 baud downlink at 149.985 (and 400 MHz). (presently coming
> over in the mid afternoon). My problem is, coming up with any
> meaningful application to use them for communications that would
> capture the interest of students, hams or volunteers in support
> of education, public service or emergency comms or just plain
> The downlink can be heard on an OMNI antenna (though I would
> suggest a 3/4 wave (55") vertical) and could be decoded by a
> simple software only application with a sound card. (someone has
> to write it)...
> The total useful message capability is about 500 bytes
> transmitted every 2 minutes (at 50 baud). The uplink is very
> specialized and can ONLY BE DONE from one (or two) very special
> commmand stations. These satellites of course were the original
> Navy Navigation satellite system (also called OSCARS) and so the
> message would be in-place of the normal navigation data. SO in
> a sense, this is a downlink BROADCAST application. Since ham
> radio is two way, I'm stumped for applications.
> The total message capability of 500 Bytes can contain one long
> ARRL bulletin, or 20 APRS position/status reports, or say 20 or
> so APRS text messages, or say 50 "callsign exchanges" or maybe
> even 1 thumbnail image... but what's the application?
> Even if we allow say, INTERNET link to the command station for
> "anyone" to contribute to the twice per-day upload, then
> everyone's receiver application can receive them... For what?
> So Im looking for ideas. All I can come up with so far is:
> 1) ARRL Bulletins? (I don't even know how often ARRL sends
> 2) Navy/Army/AF MARS broadcast bulletins...
> 3) Internet message in-to-command-upload-to message RF downlink.
> Two stations do this to each other and it counts as a two-way
> 4) ...
> Every scenario of interest usually begins with the much higher
> value of UPLINK from the individual field station, not
> downlink.. Hence I am stumped.
> HUMMH... Maybe purely educational? If the software can run on
> any PC with a sound card connected to any scanner... Then every
> school can use it as a satellite downlink signal of interest..
> What kind of thumbnail image can fit in 500 bytes? Send in your
> picture and get it downlinked on a given day?
> Will need a DSP volunteer to write the sound card decoder.
> Bob, WB4APR
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