All
I asked Joe K1JT , this question a short time ago, below is the reply
G ..
Q : Is there a means to
compensate for the sound card sampling rate? ,
No, but I think an even better feature. The sample rate in WSPR 2.0
will always be 48000 Hz. This will prevent a problem that occurs in a
few systems that insist on sampling at 44100 Hz and then resampling (in
the driver) to the 12000 Hz requested by WSPR 1.2 ... and doing a *very*
poor job of the resampling.
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From: "Andy Talbot" <[email protected]>
Sent: Thursday, November 19, 2009 5:29 PM
To: <[email protected]>
Subject: Re: LF: WSPR 2.0 is now available
It has a calibration procedure built in, but as far as I can make out,
is aimed at solving frequency offset / tuning errors. I may have
missed something, but there seems to be no facility to calibrate for
soundcard errors in the same way as WSJT does, which can affect symbol
timing . As we found in discussion on theis reflector a year or so
ago. Sample rate timing error is enough to destroy WSPR decoding
even when signals are strong.
May be wrong, and will go and re read the appendices associated with
calibration, but no mention is made, specifically, of soundcard
sampling rate error - only refrences to frequency error.
FOrtunately, as WSPR is designed around 12000Hz sampling, this is
rarely out by more than a few ppm in most modern cards. See my
Column in the latest RadCom for some soundcard sampling rate
measurements - and how bad some are
Andy
www.g4jnt.com
This email has been scanned for damaging side-effects by the health
and safety police
2009/11/19 Johan Bodin <[email protected]>:
http://physics.princeton.edu/pulsar/K1JT/
73
Johan SM6LKM
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