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Message-ID: <93387A2E760946D699EFF6D2AC56AA97@JimPC>
From: "James Moritz" <james.moritz@btopenworld.com>
To: <rsgb_lf_group@blacksheep.org>
References: <004001cae655$530251b0$4001a8c0@lark> <6B98541B11824CD8B9103C5D243A8264@JimPC>
In-Reply-To: <6B98541B11824CD8B9103C5D243A8264@JimPC>
Date: Wed, 28 Apr 2010 19:38:26 +0100
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Subject: LF: 500kHz WSPR question - non reception of G3XIZ
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...This was one that didn't get through a few days ago:

Dear Roger, LF Group,

G3XIZ seems to be "on the nail" here as far as timing goes. The most common
culprit for WSPR non-reception seems to be sound card sample rate errors.
These can be quite large due to the varagies of sound card clocks and
windows re-sampling oddities. The combined error in TX and RX sound cards
may be enough to prevent reception of some signals while others are OK. You
could try calibrating the sound card with an accurately known audio tone. Or
if one is not available, you could try the trick of waiting until about
halfway through one of G3XIZ's transmissions, then removing the audio input
from the PC for the remaining minute. If it decodes then, you can be pretty
sure ther is a sample rate error in either yours or Chris' sound card.

Cheers, Jim Moritz
73 de M0BMU
----- Original Message ----- 
From: "Roger Lapthorn" <rogerlapthorn@gmail.com>
To: <rsgb_lf_group@blacksheep.org>
Sent: Sunday, April 25, 2010 1:23 PM
Subject: LF: 500kHz WSPR question - non reception of G3XIZ


For some reason I am totally unable to
> copy Chris G3XIZ who is clearly visible at very good strength on the WSPR
> window on 503.850kHz ( see attached screenshot) when others can.