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www.southgatearc.org
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Amateur Radio Satellite AO-16 reconfiguredAO-16 has been reconfigured to provide Radio Amateurs with a novel FM to SSB satellite transponder. The satellite was launched 18 years ago on 22nd January 1990 and it is testimony to the high standards of Amateur Radio satellite design and construction that it is still operating after all these years. Commercial Low-Earth orbit satellites typically have a lifetime of just a few years. The long lifetime of Amateur Satellites is one reason why the Amateur Satellite Service needs the assurance of access to low-noise floor spectrum for several decades after a satellite is launched. None of the Amateur Satellite Service allocations between 435 MHz and 24 GHz are Primary and the existing secondary allocations have seen significant increases in the noise floor or sell-offs to other users, which jeopardises missions. Amateurs are currently committing significant resources to developing new pioneering satellites for the Microwave bands with no guarantee that the frequencies will remain usable for the lifetime of the satellite. AO-16 was a Digital satellite running an AX.25 protocol store-and-forward communications system. Since that aspect of the system has now reached the end of its days the dedicated team of AMSAT volunteers has successfully reconfigured the satellite to give it a new lease of life as a voice transponder. Drew KO4MA, AMSAT-NA Vice President of Operations, has issued this report on the reconfiguration of AO-16: 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 ao16@amsat.org . 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
AO-16 Information: http://www.amsat.org/amsat/sats/n7hpr/ao16.html AMSAT-NA: http://www.amsat.org/ AMSAT-UK: http://www.uk.amsat.org/ Join now online at https://secure.amsat.org.uk/subscription/ The United Kingdom Amateur Satellite organisation AMSAT-UK publishes a
quarterly newsletter full of the latest information on Amateur Satellites.
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