Dear Johan, Graham, LF Group,
If the shorter frame length is due to a sample rate error, there should also
be a corresponding upward shift in the audio output frequencies. If we take
M0LMH's figure of 1.5 seconds shorter, the M0BMU PC as being correct, and a
frame length around 110s this implies a sample rate error of about 1.4%.
This means that the audio coming out of Graham's PC at around 1500Hz should
be about 20Hz higher than the nominal value. Is there actually a significant
frequency error, Graham?
Cheers, Jim Moritz
73 de M0BMU
----- Original Message -----
From: "Johan H. Bodin" <[email protected]>
To: <[email protected]>
Sent: Thursday, January 29, 2009 9:26 AM
Subject: Re: LF: WSPR - G0NBD
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
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