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Re: LF: Re: WOLF/WSPR Sound card issues

To: <[email protected]>
Subject: Re: LF: Re: WOLF/WSPR Sound card issues
From: "James Moritz" <[email protected]>
Date: Sat, 12 Sep 2009 20:18:17 +0100
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Dear Graham, LF Group,

If an error in sample rate was causing the error in the transmission timing, it would also lead to an error of the same percentage in the audio frequencies being generated during transmission. I.e. if transmission was about 2% short, the transmitted frequency would be about 30Hz higher than the nominal value, with an audio frequency around 1500Hz. Likewise the reported frequencies on receive would be about 30Hz lower than expected. Do you recall if this was the case?

Cheers, Jim Moritz
73 de M0BMU

----- Original Message ----- From: "Graham" <[email protected]>
To: <[email protected]>
Sent: Saturday, September 12, 2009 3:08 PM
Subject: Re: LF: Re: WOLF/WSPR Sound card issues


Jim,

Re the  size of error

With the delta-4 card, the tx frame could be observed to be some 2 or more seconds short of the expected time window

1 % ~ 1.2 seconds , 2 % ~ 2.4 seconds, assumedly indicating the clock on the card runs fast, but as to the influence of the system by the software, dma, irq etc Im not sure, one problem is I expect is the soundcards are not designed to be the interface for a accurate frequency meter / generator and as such compromises 'must' exist ...



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