Receiving LAPAN A-2 Satellite for the First Time!

LAPAN A-2, also known as IO-86 or Indonesian Oscar 86 is an Indonesian amateur radio satellite launched by ISRO from Sriharikota, India, in 2015,  and has an orbit near the equator. Hence it is accessible mostly from South India only. But the caveat is that voice transponder is activated only towards the end of the pass in this region, and on weekends only. VU3CDK has been able receive it fairly well from Mumbai and VU3DGR has been able to have several contacts through LAPAN A-2 being located more to the South than me. Today morning VU3CDK informed that there are two passes, one in the morning and one in the evening. During the morning pass I could hear only feeble signals towards the end of the satellite pass in my region.

But during the evening pass, to my surprise, the signals were quite loud and I could hear Indonesian Stations working each other. Suddenly VU2DGR came up on the satellite and had contact with one of them! Though it was a pass with more than 40 degree maximum elevation in my region, the transponder was switched on only near the end of the pass giving only three minutes for us. By that time, the satellite was far away for my limited setup with a fixed elevation and azimuth Moxon Yagi, to access it or so I presume. Anyway I am quite happy that I could receive the signals loud and clear and also hear the contact of my ham friend! My friend told me that some time back it used to be switched on earlier and he could work stations from Maldives also. There would be satellite operators coming there for DXpeditions.

The uplink frequency of LAPAN A-2 is 145.880 MHz and needs CTCSS tone of 88.5Hz. Downlink frequency is 435.880 MHz. Doppler correction is needed for both uplink and downlink as satellite is moving towards you initially and later away from you. I use the Argentinian Amsat page for satellite pass displayed on my mobile phone for manual Doppler tuning in IC 2730 full duplex radio during the pass. As I am operating from indoors, it is quite convenient for me. Those operating from outdoors using handheld radios program 3 or 4 four frequency steps up and down and switch the memories during the pass. Still others with sophisticated setup use software like GPredict to control both the radio and the antenna rotator.

You can listen to the signals received from LAPAN A-2 satellite towards the end. The hissing sound heard in between is the noise of the open squelch in the radio. When satellite signals are received, the hissing noise subsides and you can hear the conversation. Callsigns are being expanded in phonetic codes as is usual with amateur radio contacts, especially between long distance stations. Signal intensity is varying because satellite spins and tumbles in orbit changing polarization of satellite antenna with respect to my antenna which has a vertical polarization. If you use an antenna like cross Yagi or Eggbeater antenna with circular polarization, this effect will be minimized.