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
Doug,
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 W1EUJ
On 12/7/06, Douglas Quagliana [email protected] 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 _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
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
You don't need a receiver. Just listen on 145.825 RAFT downlink and you will hear the Radar ping on RAFT's downlink. RAFT has a 216.98 MHz direct conversion receiver and so it will hear a tone proportional to the Doppler as it flies through the radar fence. This should last about a second.
And it is not really a ping. It is an 80 meggawatt CW transmitter that is on all the time. When we fly through it, you will simply hear a tone for a second or so. The pitch of the tone will be constant, but its actual frequency will depend on the angle that our spacecraft path makes with the intersectino with the beam.
A SECOND experiment for those inclined is to listen on 216.98 MHz and see if you can hear our 4 milliwatt 216.98 oscillator. A lot of work and not much gained. Of course if you do have an SSB receiver that can listen to 216.98, you can be entertained by any of the other 10,000 pieces of space material that also flies through the fence. If you live in the Southern states, a simple dipole receiver will hear severl things a day. Particularly listen during meteor showers and it is like rain on a tin roof... (that is an exaggeration, but compared to one ping a day from ISS, it makes the point)...
Read about the fence on the RAFT web page: http://www.ew.usna.edu/~bruninga/raft.html
Bob, WB4APR
At 04:00 PM 12/7/2006, Douglas Quagliana 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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Hi Douglas,
In the Sept/Oct 2005 AMSAT Journal, there is an article aout how to build a simple frequency converter for about $5 using a pair of 1N914 diodes and a TTL clock oscillator. The circuit was not designed for 217 MHz but it would be pretty simple to adapt it, just change coils L1, L2 and L3. Using a 35 MHz oscillator, 216.98 would be converted to 146.98 MHz.
This would not be nearly sensitive enough to hear the 4 mW beacon on RAFT1 but if you have a spare VHF TV preamp to use in front of it, this would probably be good enough especially if you use a TV antenna with a little gain and point it at the satellite.
73, Tony AA2TX
participants (4)
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Anthony Monteiro -
David Goncalves -
Douglas Quagliana -
Robert Bruninga