WSPR Spurious signals?

I have noted that "strong" wspr signals (in this case SNR=6) is accompanied with spurious signals 76 Hz above and below the nominal frequency. A friend of mine also noted this, and compared with his IC-7800 on which no spuriosa is noted. I can't imagine that the signal itself would overload the Kiwi, so perhaps a software issue? The screendump shows SM0MDG which is the strongest wspr station here (5 watts at 1336 km). 

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Comments

  • Yes, this is a known problem with other WSPR programs as well. Although I always thought it seemed to be worse in my implementation. In the WSPR code I started from there is actually some code to prevent the double-reporting of strong signals with images.

    One of the last changes I added was some input resampling to handle a change to the audio sample rate of the Kiwi. It is quite possible that I'm not filtering the resampling properly. I'll add it to the bug list.

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