James Moritz wrote:
> Eventually, I realised that the
> difference was that your transmissions are a few seconds shorter than
> the locally generated signals


Dear Jim, LF,

that is a clear evidence of a soundcard sampling rate error. I am quite sure
that all timing in the WSPR software is derived from the sampling frequency and,
if memory serves me, the WSPR program uses a sampling rate of 12kHz. If the
soundcard does not support this rate and/or has a "physical" sampling rate that
is not a multiple of 12kHz (for example 44.1 kHz), then the driver or window$
will kick in a "resampler" between the soundcard and the WSPR application which
is asking for 12kHz. Many such resamplers are known to be inaccurate...

73
Johan SM6LKM