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Re: LF: Wolf Tests

To: [email protected]
Subject: Re: LF: Wolf Tests
From: "jannsen" <[email protected]>
Date: Wed, 21 Mar 2001 19:02:04 +0100
References: <9881.200103201602@gemini>
Reply-to: [email protected]
Sender: <[email protected]>
James Moritz schrieb:


The obvious problem is how to determine the soundcard error, if you don't have a accurate audio frequency source. I used the reference output of my synthesiser divided doown to 1kHz (and filtered; a fairly clean sine wave seemed to be neccessary to avoid aliasing problems with the soundcard). You could use the RX audio out, but only if you knew what the RX frequency error was to within a small fraction of a Hz.

Cheers, Jim Moritz
73 de M0BMU

Hi Jim and all,
audio qrg source out of ur old PC does it too. take Rik`s QRS-progr, switch setup/sound/dfcw/enable/fill in the qrg u want in both dash- and dot-window the same qrg. hardware: take the speaker output (kill the speaker as Rik suggested), form the needle-waves into sinus-waves (I took out of my junk-box a pot-core 330mH, 1,8mikroF and 100nF for c1 and c2 of a Pi-Filter for transforming 10ohm to abt 6kohm)and measure the qrg. Taking 1000Hz out of my junk-pc (486/66Mhz with the motherboard crystal tempcompensated)in the above described manner the counter shows 1000.0706Hz to 1000.1804Hz constance over 4 hours.
regards
Uwe/dj8wx



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