Since AO-16 was recovered approximately 6 months ago, the command team has attempted to reload the satellite software almost a dozen times without success. Subsequently a series of memory tests were performed which points towards a hardware failure which prevents restarting the spacecraft software successfully. This team included Bruce Rahn WB9ANQ and Jim White WD0E advising Mark Hammond N8MH as the primary groundstation. Mark put in many early hours during the multiple reloads and test sessions, with Bruce, Jim, and others advising. Thank you to all involved for your hard work.
After the conclusion that the spacecraft computer system was damaged and as discussions about decommissioning were taking place, Jim recalled a series of low level commands included in the spacecraft design by Tom Clark, K3IO during construction. One of these commands allows an uplink receiver to be directly tied to a downlink transmitter. The twist is that the uplink is regular FM but the downlink via the BPSK transmitter is DSB (Double Sideband). Mark placed the satellite in this mode early this week and some testing was undertaken. The satellite hears VERY well, and the reduced bandwidth by using either USB or LSB on the groundstation receiver allows for a very robust downlink. Tuning the downlink is just like on a linear transponder, meaning it is tight and with fast Doppler. Uplink tuning is not required, just as with the FM mode V/U satellites. QSOs were made between N8MH, WD4ASW, KO4MA, K5QXJ, and WA6FWF. My personal observations include being able to access and hear the satellite within one degree of the horizon, much lower than any other current bird for my QTH. This should be an easy satellite with omni antennas and a 70cm preamp.
With that explanation, I'm happy to open the satellite to general use on voice for a test period. Please submit reports either to the -bb or to [email protected] . The uplink is 145.920 FM, and the downlink is 437.026 SSB +/- Doppler shift. Please restrict your uplink power to a reasonable level, and do not transmit without being able to hear the downlink. All the general single-channel guidelines apply. Enjoy this bird's new life!
73, Drew KO4MA AMSAT-NA VP Operations
Magnificent effort... monitored the downlink on the 21:20Z pass over EN19. Seemed to get best reception on USB downlink. When it was well into the Cold Great White North and the traffic quieted down I tried to hear myself and it may take a couple more passes to get SatPC32 TX/RX splits right on.
Thanks to the AO-16 team on a job well done.
73, Alan VE4YZ EN19kw AMSAT LM 2352
-----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Andrew Glasbrenner Sent: January 22, 2008 12:48 PM To: [email protected]; [email protected] Cc: [email protected]; ans-editor Subject: [amsat-bb] AO-16 reconfigured.
Since AO-16 was recovered approximately 6 months ago, the command team has attempted to reload the satellite software almost a dozen times without success. Subsequently a series of memory tests were performed which points towards a hardware failure which prevents restarting the spacecraft software successfully. This team included Bruce Rahn WB9ANQ and Jim White WD0E advising Mark Hammond N8MH as the primary groundstation. Mark put in many early hours during the multiple reloads and test sessions, with Bruce, Jim, and others advising. Thank you to all involved for your hard work.
After the conclusion that the spacecraft computer system was damaged and as discussions about decommissioning were taking place, Jim recalled a series of low level commands included in the spacecraft design by Tom Clark, K3IO during construction. One of these commands allows an uplink receiver to be directly tied to a downlink transmitter. The twist is that the uplink is regular FM but the downlink via the BPSK transmitter is DSB (Double Sideband). Mark placed the satellite in this mode early this week and some testing was undertaken. The satellite hears VERY well, and the reduced bandwidth by using either USB or LSB on the groundstation receiver allows for a very robust downlink. Tuning the downlink is just like on a linear transponder, meaning it is tight and with fast Doppler. Uplink tuning is not required, just as with the FM mode V/U satellites. QSOs were made between N8MH, WD4ASW, KO4MA, K5QXJ, and WA6FWF. My personal observations include being able to access and hear the satellite within one degree of the horizon, much lower than any other current bird for my QTH. This should be an easy satellite with omni antennas and a 70cm preamp.
With that explanation, I'm happy to open the satellite to general use on voice for a test period. Please submit reports either to the -bb or to [email protected] . The uplink is 145.920 FM, and the downlink is 437.026 SSB +/- Doppler shift. Please restrict your uplink power to a reasonable +level, and do not transmit without being able to hear the downlink. All the general single-channel guidelines apply. Enjoy this bird's new life!
73, Drew KO4MA AMSAT-NA VP Operations
_______________________________________________ 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
Hi!
With that explanation, I'm happy to open the satellite to general use on voice for a test period. Please submit reports either to the -bb or to [email protected] . The uplink is 145.920 FM, and the downlink is 437.026 SSB +/- Doppler shift. Please restrict your uplink power to a reasonable level, and do not transmit without being able to hear the downlink. All the general single-channel guidelines apply. Enjoy this bird's new life!
I tried on 2 AO-16 passes Saturday afternoon (26 January, 2221-2234 and 2359-0014 UTC). Very easy to hear, sometimes hard to get through, but fun. All of this was done without computer control, with the gear in the back of my truck parked in grid DM44ha in north-central Arizona, holding the antenna in one hand while holding and mic and adjusting the receiver with the other.
For the first pass, I used an IC-2720H mobile radio at 5W for TX and an FT-817ND as RX, connected directly to the respective feedpoints on my Arrow Antennas handheld 2m/70cm Yagi. I already had the IC-2720H out for AO-27 passes around this time, so I just stayed with that. I could have put an HT in place of the mobile radio, but at its lowest power level (5W) I didn't bother with swapping it out with another radio.
I could hear the satellite from about 1-2 degrees above the horizon, but as the first pass covered most of North America it was crowded and I didn't make any QSOs. Still, a fun time trying to work an SSB downlink for the first time, although a single-channel SSB downlink. I was switching between USB and LSB, finding USB easier to understand although I could follow the Doppler easier on LSB while tuning down manually. I could hear it until the last minute of the pass, when the satellite was around 2 degrees elevation.
Later, for the pass around 0000 UTC, a slightly-different setup. Same antenna, same TX radio, but now using narrow FM on the IC-2720H. I didn't do that on the earlier pass. I changed radios for the RX side, now trying an AOR AR8200Mk2 handheld 100kHz-2GHz all-mode receiver. Again, an easy-to-copy pass, but not as crowded as the earlier pass. I ended up using LSB on the receiver, which helped me hear where to put the radio as I adjusted for Doppler, and made 5 quick contacts during the pass.
This was fun, and now I have added motivation to get a portable setup for the SSB/CW satellites. The AOR receiver worked well on anything I tried except for SO-50's weak downlink. I had used it on an AO-51 and an SO-50 pass in the morning, plus two VO-52 passes (heard the satellite OK, heard myself through it, but no QSOs during those passes), before AO-16's passes this afternoon.
73!
Patrick WD9EWK/VA7EWK http://www.wd9ewk.net/
participants (3)
-
Alan -
Andrew Glasbrenner -
Patrick STODDARD (WD9EWK/VA7EWK)