Is AO-27 Amateur Radio FM Satellite Active?

 If you search for AO-27 on N2YO.COM, it is listed as EYESAT-1 and is shown as active, but there is a snag! Uplink is given as 145.850 MHz and downlink as 436.795 MHz. No beacon is listed and the mode is given as 1200bps AFSK FM! That should be telemetry and not an FM transponder. Now why is it listed as EYESAT-1? PE0SAT has mentioned the history in his blog. AO-27 was originally designed as a commercial satellite known as EYESAT-1, but the project was halted on the way. In fact they had an ambitious plan of a constellation of six EYESAT satellites according to Gunter's Space Page. SatNOGS database also mentions that EYESAT-1 as active and operational.

The halted project was later completed by the Amateur Radio Research and Development Corporation (AMRAD) at the facilities of Interferometrics in McLean, Virginia. That explains the name for the amateur radio payload which was added by them: AMRAD-OSCAR, AO 27, OSCAR 27. It has a crystal controlled FM transmitter with frequencies as mentioned initially. Power output can be set to over 1W, but the normal operation was at 0.5W and sometimes even with 0.1W with exciter only. Uplink antenna is a linearly polarized whip on the top face of the spacecraft, being shared by the commercial payload. Downlink antenna is a quarter wave whip mounted on the bottom face of the satellite. Even though the polarizations are linear, we no that as the satellite spins and tumbles in space, the ideal setup for a ground station would be a circularly polarized antenna to reduce the chance of cross polarization.

A blog post by AB1OC dated 3rd June 2020, mentioned that AO-27 was back on the air and he could have a QSO with AI9IN then. He has mentioned that AO-27 was launched in 1993 and that the satellite's amateur radio payload became inoperative due to an internal communication failure seven years back. That would have been in 2013. N3UC, who was one of the satellite’s original designers could bring it back on air on a limited-time basis for being active for 4 minutes, twice per orbit over the mid latitudes. I checked the waterfall and audio uploaded by  Daniel Ekman on SatNOGS on 26th August 2024. To me the audio was only the hissing noise of an open squelch and the waterfall appeared blank. It is possible that either no one was using the FM transponder in that region at that moment or it was inactive on that pass.

Another interesting piece of information on AO-27 been mentioned by F1NNI on his satellite blog. In July 2007, N3UC and AA4RC could use it to provide the first D-Star via Satellite contact between them. Communications were possible for most of the pass. As the FM repeater on board AO-27 did not have the normal low frequency filtering found in normal FM Repeaters, the Analogue mode would pass the low frequencies required for D-Star. IC-2200 radios were used by both N3UC and AA4RC on the uplink. For downlink, N3UC had used IC-2820 while AA4RC used IC-91AD. N3UC was an AO-27 Control Operator and mentioned that Control Operators fully support and encourage the use of D-Star via Satellite on AO-27. According to the AMRAD schedule, AO-27 was available on daylight passes over the Northern Hemisphere. May be we should try our luck again on such passes, though the AMSAT Live OSCAR Satellite Status Page does not show any recent activity even though the satellite is there on the drop down menu for submission on that page.