[amsat-bb] Re: Receiving RAFT on 216.98 MHz ?

David Goncalves davegoncalves at gmail.com
Thu Dec 7 14:05:53 PST 2006


If you look at the description on the RAFT1 website, you will notice that the
radar transponder, as it flies over the radar beam, will be downconverting the
216.98 (+/- doppler shift) radar signal to an audio tone on the 2
meter downlink.
This is the intended way to hear the 'ping'. You must be well timed
with your receiver, as the radar transponder is on a 1 minute timer
that must be commanded on by a command station. Hopefully, following
testing, a schedule can be setup so that many folks get a chance to
try this radar transponder out.

Heaingr the direct radar reflection 'ping' from off of the satellite
body is challenging for NAVSPASUR; for such a small cross section, I
don't know that it is likely that a amatuer would be able to do this -
but do try! Others may try hearing strong radar pings with the ISS,
Space Shuttle or other large orbiting bodies (like the moon!).

Lastly, one may listen to the 216.98 (+/- doppler shift) signal
transmitted from the radar transponder itself. There is no ping, just
a CW tone. AA2TX and others have determined that one may hear the 6mW
CW signal with a good omnidirectional antenna and a reasonably quiet
and sensitive receiver. A small group of us in the Boston area that
built the transponder eagerly await the launch, release and testing of
the satellite to listen to our creation. We are using a preamp, as a
weak signal will not impress my girlfriend :-)

Personally, I've a IC-375 220 allmode to hear it, but I live in a very
poor location for satellite reception. :-( One could also purchase and
rework a Hamtronics downconverter to use their 2M radio to hear the
signal. Hurry - the satellite will not be in orbit for long...

Hope this helps.

David Goncalves

On 12/7/06, Douglas Quagliana <dquagliana at aol.com> wrote:
> A quick check around my radio shack confirms
> that none of my receivers will receive at or
> near 216.980 MHz.
> What were other amateurs planning to use to
> receive the pings from RAFT on 216.98? Is
> there a bargain-basement no-frills way to
> kludge something together to receive the
> signals?
> Douglas KA2UPW/5
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David Goncalves

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