29 Apr 2015

More aircraft reflections on 6m WSPR

M0YOU (116km) has been spotted again on 6m WSPR at a strong -9dB S/N. What is interesting is that all his recent signals have shown multiple reflections off planes (up to 5 at one time in the 2 minute TX window) but, so far, just one successful decode. Clearly these planes need to be flying in the right direction for a successful WSPR decode to take place. The reflected signals are strong but the WSPR TX burst is too long. A shorter TX burst would be better for this propagation mode.
M0YOU - catching reflections off planes in the Heathrow stack?
I suppose the Doppler would be less of an issue on 10m but far more of an issue on 2m. G3WKW (134km) and I managed to exchange 2-way WSPR on 2m last year, but it took a whole day to catch that right moment as I recall. Also as you go higher in frequency, rig drift becomes far more of an issue, so it can be more difficult again. For 70cms WSPR this becomes super-critical and an external reference frequency is all but essential so that you can know your frequency precisely.

G4FGJ (44km) has spotted me this afternoon but I think this was plain simple tropo as no Doppler was apparent. He was very strong with me at -2dB S/N.

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