February 2007 - AMSAT-BB - mailman.amsat.org

RAFT radar Detection and Southern Ground Stations
by Robert Bruninga 08 Feb '07

08 Feb '07

The RAFT Radar Transponder has been detected. See plot: http://www.ew.usna.edu/~bruninga/craft/XP217-PE1ITR4feb07.JPG Although the 4 milliwatt RAFT Radar Fence oscillator was designed to be heard by the collosal 2 mile long 30 dB gain receive antenna of the Radar Fence across the southern USA, PE1ITR was able to detect the oscillator on his own ground station. We are still welcoming GOOD OSCAR class AMSAT stations near the RADAR fence across the southern USA (Arizona through Texas to Georgia) who have good 2 meter beams, to command on the RAFT Radar fence transponder so that we can make our first Radar Fence detection. RAFT requires a good 2m beam station to operate it. The primary objective is for RAFT's radar xponder to HEAR the radar fence as it flies through it. Since this is not detectible here at USNA due to our latitude, we are dependent on volunteer ground stations in the southern USA to activate the RAFT transponder at precisely the correct time to make this detection. There is only one good pass per station in the evening hours and so it is slow going. But the detection above, gives great confidence in the primary objective.. For more on RAFT's radar Fence Transponder which is a model for future small satellites to be able to detect their own passage through the fence, see the main RAFT web page about half way down the page: http://www.ew.usna.edu/~bruninga/raft.html To see the overall ANDE-RAFT and MARScom operations page see: http://www.ew.usna.edu/~bruninga/ande-raft-ops.html And we still need good ANDE data from the Southern Hemisphere so we can detect the spin rate. Right now, ANDE is in the dark in the Northern Hemisphere. We need data from the Southern Hemisphere. ANDE only wakes 2 seconds every 16 seconds to listen for activity. IF it hears any packets, then it will stay awake for the next minute. While it is awake, it can be used just like PCSAT-1 as an APRS digipeater by all users. And while it is awake, we will also be able to hear telemetry which is what we need. Hopefully all the 145.825 Igates are listening. Bob, WB4APR USNA Satellite Lab

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Old Topic
by Norman W Osborne VE3CJE 07 Feb '07

07 Feb '07

Where do I find a replacement for the Yaesu 5500 rotor plug in connector? Norman

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RAFT in GF15AC
by Carlos Guillermo Vahnovan 07 Feb '07

07 Feb '07

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 07/02/07 Loc: GF15AC Frec: 145.825khz Equipment: IC-271A, KPC9612 TNC, half wave cross-dipoles turnstile with ground plane at 15 meters over the ground Orbit 774 19:43:51R RAFT>BEACON,SGATE Port=1 <UI Len=39>: T#931,088,100,040,052,095,00000000,999 19:44:21R RAFT>BEACON,SGATE Port=1 <UI Len=39>: T#934,087,103,040,055,096,00000000,999 19:44:22R RAFT>BEACON,SGATE Port=1 <UI Len=38>: >RAFT is on 145.825 US Naval Academy 73's - -- Carlos Guillermo Vahnovan LW1EXU http://www.lw1exu.com.ar http://gacw.no-ip.org -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.5 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFFyjEDIjwYD/uz16kRAjS8AJ90ABOQDlnFCmsg5+8a8lVSog/qcACgzxem 0wINKjWq6w9xTglfClZXt74= =WTJX -----END PGP SIGNATURE-----

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Re: RX only satellite?
by G0MRF＠aol.com 07 Feb '07

07 Feb '07

Weird idea number 2. You mention "no transmitters" But thinking out of the box a little....If you carried forward your idea of the Laser beacons from your earlier project, then it may be possible to "transmit" something after all. - How about one of the new Hi power LEDs? 5 Watts to 20W are available now. Just run it at whatever power suits the power budget. Have the onbard RX activate the LED for a limited period on receipt of a command. Two simple methods of data transfer come to mind. 1) Switch the LED on and off at an audio rate with a 1:1 square wave. Then turn that signal on and off with a CW generated message. Simple but effective. We know that works over 150 miles from recent reports from Australia. Receive using software from weaksignals.com 2) Much nicer. - Switch the LED on / off at some spot frequency between 12 - 20kHz. But arrange for the waveform to be pulse width modulated. Easy ! One comparator and a rectangular wave at 20kHz. - Audio on the other input. You can send anything generated at audio including PSK31 speech, JT65, Domino, etc. I imagine the sat will be attached to the ISS. Tracking is easy too. Pick a night or early morning when a visible pass will occur. Track the ISS while it is in sunlight then when it reaches the terminator, activate the LED transmitter. Your tracking should be spot on and the signal can be received with very modest equipment. The receiver on the ground is a magnifying glass lens about 4 - 6inches across. - Or a small telescope. A BPW34 Pin photodiode followed by a low pass filter to remove the 20kHz. What comes out is audio. - That can be fed to a computer soundcard. 73 David

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RX only satellite?
by Robert Bruninga 07 Feb '07

07 Feb '07

There may be a Satellite opportunity for a ham radio RX only payload. No TX allowed. Any ideas? It will be recoverd one year later. All I can come up with is a satellite band moniitor that scans the satellte bands and makes a one year survey of QRM and stores it in flash. That is, recording frequency and signal strength and position for a year. Problem is, I cannot figure out how we could use the data to tell the good guys from the bad guys so it wouldn't tell us much I don't think? Any other ideas for a RX only space application? Of educational interest? Anyone interesetd in developing the band monitor payload? Bob, WB4APR

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AMSAT-UK Colloquium 2007 - Call for Papers
by David Johnson 07 Feb '07

07 Feb '07

This is the first call for speakers for the 22nd Amsat-UK Colloquium which will be held at Surrey University, Guildford, Surrey, U.K., from Friday 20 July to Sunday 22 July 2007. Amsat-UK invite speakers, about amateur radio space and associated activities, for this event. They are also invited to submit papers for the "Proceedings" document which will be published at the same time but printed papers are not mandatory. We normally prefer authors to present talks themselves rather than having someone else give them in the authors' absence. We also welcome "unpresented" papers for the Proceedings document. Offers of talks should be submitted as soon as possible; the final date for full documents to be received is mid-June 2007 in order that the "Proceedings" document be available to participants. Submissions should be sent *ONLY* to G4DPZ, via the following routes: e-mail: dave at g4dpz.me.uk Terrestrial mail: QTHR www.qrz.com AMSAT-UK also invite anyone with requests for Program Topics to submit them as soon as possible to G4DPZ. Invitations for any papers on specific subjects will be included in the future call. Likewise if anyone knows of a good speaker, please send contact and other information to G4DPZ. Additionally, Amsat-UK will be running sessions specifically for beginners to amateur satellite operating on the Friday and Saturday afternoons. Details of the colloquium can be found at: http://www.uk.amsat.org 73 Dave, G4DPZ

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AMSAT Groups Make Donation to Facilitate Completion of P3E
by Trevor 07 Feb '07

07 Feb '07

See http://www.uk.amsat.org/ 73 Trevor M5AKA ___________________________________________________________ The all-new Yahoo! Mail goes wherever you go - free your email address from your Internet provider. http://uk.docs.yahoo.com/nowyoucan.html

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RX only satellite?
by James Duffey 07 Feb '07

07 Feb '07

It would be interesting to look at the NCDXCC HF beacons from space to get an idea of ionospheric absorption. These have predictable times and variable predictable power levels, so path losses can be easily calculated. Monitoring the 10M frequency at 28.200 might provide useful information for future Mode A applications. With beacons all around the world, broadcasting every 3 minutes at known power levels, a 28.2 MHz receiver could provide a wealth of information. The beacons ID themselves, so data analysis should be easy; all that would be required is some sort of time tagging. I suspect that the satellite would never be out of range of a beacon. How much data storage is available? I need to calculate how much data you would need to obtain. It would be interesting to launch these satellites at various points in the solar cycle. - Duffey KK6MC/5

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RAFT in Packet-Voice mode
by Robert Bruninga 06 Feb '07

06 Feb '07

Henk, PA3GUO, reports that he has just -enabled- RAFT VOICE mode. Enabled, this means that any station may TURN ON voice mode over his country with a single CONNECT RAFT packet. The voice synthesizer will remain on for 90 seconds. Only the CONNECT packet is required of that station. After his connect packet brings up RAFT, then he can fore a disconnect so he can try an APRS MESSAGE to TALK. Once the VOICE synthesizer is on, then anyone can send a UI APRS formatted MESSAGE to the callsign of "TALK" and RAFT will speak it (if it decodes it)... RAFT is very weak and hard to hear except on HIGH overhead passes, even with beams. Please do NOT attempt to turn on RAFT or to send TALK messages if you cannot hear it. You may be QRMing other stations. Thanks Bob Bruninga, WB4APR US Naval Academy Satellite Lab

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Re: RX only satellite?
by G0MRF＠aol.com 06 Feb '07

06 Feb '07

In a message dated 06/02/2007 17:47:35 GMT Standard Time, bruninga(a)usna.edu writes: There may be a Satellite opportunity for a ham radio RX only payload. No TX allowed. Any ideas? It will be recoverd one year later. Hi Bob. I guess this is attached to the ISS so no oportunity to have attitude control. OK, Long time in orbit so lots of data. How about one or more of the cheap USB memory sticks for storage? 1GB+ is small and cheap these days. To interface the USB to the real world you can use an interface chip with PIC microcontroller. I'm sure that would normally be a wholelot of design all by itself, except you can buy the USB intefaced to a PIC16F877 off the shelf for about $50 limited driver software included _http://www.dlpdesign.com/usb/dlp-2232pbv15.pdf_ (http://www.dlpdesign.com/usb/dlp-2232pbv15.pdf) That gives you 16 I/O lines and some A-D conversion to play with. As for payloads? Well spectrum monitoring is good but GPS data to give the location would be an advantage so you know where you are. Bands to monitor. 2.4 is the most controversial, but the proposed uplink band of 5.6G would give valuable insight for future projects. Or, one of the new power to voltage converters from Analog Devices. Monitoring the radar fence output or other High radar signals could be interesting. Or camera that can take pics on your command. - I can almost see the picture of your QTH on the wall of your office. Taken on a clear day when you know the lens is pointing in the right direction. 73 David G0MRF www.sseti.net

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