April 8th, 2013

Another test tonight with the experience of the one two days ago, was more efficient in finding the reflections. The ISS passed south of our QTHs. So I could track the whole pass from rise to set. Jan´s signal could be detected most of the time during his window. The picture shows his signal shortly after the rise of the ISS. Caused by the doppler effect it moves from right to left. The shift in this detail varied between 47 kHz and 38 kHz, while PA3FXB was transmitting on 1296.300 MHz in CW.  By a length of about 25 seconds there was a variation of 400 to 500 Hz per second.

PA3FXB shortly after rise without QRG tracking

PA3FXB shortly after rise

PA3FXB shortly after rise with manual QRG tracking

Jan was transmitting his callsign “PA3FXB” followed by “T”s. The variation of the pitch in the first audio file is caused by manually tracking the signal. The second audio file gives an impression of the speed of the doppler variation. An effective  compensation of the doppler effect seems to be most important.

There have been earlier attempts to realize QSOs by reflections on the ISS. SM2CEW reports about nearly completing QSOs on 144 MHz with SM7WSJ in 2007 and he tried also with SV3AAF (more). DF2ZC claims the first ever QSO via ISS scatter on 2 m with DH7FB on December 9, 2007. They completed three more QSOs in 2008. It seems that these were the only four QSOs via ISS bounce since then. VA7MM reports about tests on ISS bounce with VE7BBG on 23 cm in 2004. PE1ITR tried with DK3WN in 2007.