Receiving the Morse Code Beacon of Amateur Radio on International Space Station

Receiving the Morse Code Beacon of Amateur Radio on International Space Station

Yesterday I had posted about receiving the voice beacon of AO-91 amateur radio satellite. Today I decided to check a relatively lower elevation pass of International Space Station to see if I could make any contacts through the voice transponder of ARISS. I was using my Moxon dual band VHF/UHF yagi at about 6 m from the ground, hardly 2 feet above the fencing on first floor terrace. It was a 15 degree maximum elevation pass along the Western side.

After posting the planned activation on hams.at, I checked the SatMatch link to see the direction of the pass as seen in the image shown. The maximum elevation of the pass was in the South West direction. So I set the antenna in that direction just before the pass. It is at a fixed elevation of about 15 degrees and I do not have an antenna rotator. Antenna mast is rotated manually prior to the pass as mentioned. Doppler tuning of my radio was done as per the display on Argentinian Amsat webpage, as described earlier. The pass was at around 10 am local time.

When the satellite was passing down from its point of closest approach (TCA), I could clearly hear the callsign of ARISS being announced in Morse Code.

What you heard just now, is the callsign of ARISS, NA1SS in Morse Code. Unlike the Morse Code you hear on HF or on linear amateur radio satellites, it is not the keying of radiofrequency carrier. Instead it is frequency modulation of the carrier with an audio tone like the tone you hear from a Code Practice Oscillator. If carrier is being keyed, FM radio will not be able to make it audible, instead you will hear like closing of the open squelch when the signal is received and open squelch hissing sound when the signal is not being received.