Recorded the Morse Code Beacon of Diwata-2 (PO-101) Amateur Radio Satellite!
Diwata-2 (PO-101) was designated as Philippines-OSCAR 101 by AMSAT, the Radio Amateur Satellite Corporation, headquartered in Washington, D.C. I have been hearing the FM voice transponder of PO-101 occasionally and it has been tough to work this satellite as it is U/V satllite with uplink on UHF and downlink on VHF, unlike the popular amateur radio satellite FM transponder on the Space Station which is V/U. Occasionally I have been hearing Morse Code (CW) like signals on the downlink of PO-101. But unlike the CW beacon of ARISS which comes as a modulated signal on the FM downlink, the CW signals on PO-101 downlink seemed to be carrier switching like the usual CW we send on the HF bands.
Usual CW on HF bands will not have an audible tone unless a beat frequency signal is introduced within your receiver. In my yester years of homebrew radios, we would use a Beat Frequency Oscillator which works on slightly different frequency from the Intermediate Frequency (IF) of the radio, to produce an audible note when the CW signal is received. In my FT-710 radio, I just have to select the CW mode for me to hear the audible tone while receiving CW signals. Things are quite different in my IC 2730 which is FM only. If it was IC 705 which is all mode, all band, I think I could have chosen the CW mode and heard the nice CW tone for PO-101. But as I was listening with IC 2730 with squelch open, I could only hear the change in the received FM carrier when PO-101 was transmitting its beacon in CW.
Details about the type of beacon transmissions from PO-101 is available from the Diwata-2 (PO-101) Amateur Radio Unit: Information and Usage page. While the transponder is on FM repeater mode, it sends Morse Code CW beacons every two minutes and it takes one minute to complete. Then there will be one minute without a beacon. So there will be about 5-6 CW beacons sent in a typical pass of PO-101. Heard that these beacons will not interfere with the use of the FM transponder, unlike in the case of ARISS, where we stop transmissions as soon as we hear the beacon. But the tone modulated CW on ARISS is not that frequent and you might hear it only once in a pass. When PO-101 is in the APRS mode, it sends out packets every 30 seconds and each packet is sent in 1-2 seconds. That would mean 20 APRS beacons could be received in a pass. But I have never tried to receive APRS beacons from PO-101.
When I looked at the details on the CW beacon, it is mind boggling, unlike just the callsign NA1SS announced by ARISS. It starts with MABUHAY _ PILIPINAS _ DW4TA, of which the last is the callsign of the satellite. That is followed by a string of characters which encodes a lot of information including the status of VHF and UHF antennas, battery voltage, supply current, ambient temperature and many more parameters. Of course I will not be able to read the full message in a rather fast CW transmission, that too without the audio tone in my FM only IC 2730. At least, recording the beacon was an eye opener for me to the amount of information which can be transmitted down by the satellite in its beacon.