Monday, March 04, 2013

Classic WSPR vs WSPR-X

Are you a fan of WSPR mode? Have you tried K1JT's new program WSPR-X yet?

Comparing classic WSPR to WSPR-X
I decided to switch to the newer program as the older 'classic' version won't work with VSPE virtual serial ports. But I had a sneaky feeling that WSPR-X was not decoding some of the traces it should. So I decided to run both programs in parallel, using the same sound card, the same radio, the same data source. Sure enough, WSPR-X is missing about 1 decode in 10 compared to WSPR 2.11. There is no apparent common factor between the signals it missed. They are not at the extremes of the frequency range, close to the limit of timing error nor especially faint.

Look at the screenshot above and look at the decodes for 1540. Classic WSPR has decoded two signals for this interval whilst WSPR-X has decoded only one. The signal from W3CSW was missed. Later signals from the same station were decoded. That is just one example. I only needed to wait a few minutes to find another.

I set the older WSPR to save .wav files and when these were processed by WSPR-X using its File Open option the result was the same as when the signals were received off-air. The same transmission was missed in each case.

WSPR-X seems a bit faster to run the decodes than WSPR. It prints them up on the screen before classic WSPR does. There are sometimes slight differences in the dB and DT figures, but not enough to worry about. Has anyone else noticed this?
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