Message-ID: <3A6CB502.177290BC@usa.net>
Date: Mon, 22 Jan 2001 23:32:34 +0100
From: "Alberto di Bene" <dibene@usa.net>
Organization: Undisclosed
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To: rsgb_lf_group@blacksheep.org
Subject: Re: LF: Accuracy of Soundcards, programs, and related stuff
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DL4YHF@aol.com wrote:

> Hello Alberto, hello group,
>
> Concering the accuracy of the soundcard's crystal referency: There has been a
> discussion about this before, and I do not want to trigger that again.
> Here are the results from a few tests I did on that. They do not have to be
> 100% true for "your" PC, but I hope they are worth thinking about:
> [snip]

Hi Wolf and the group,
        basically I am in agreement with what you say, Wolf.
To check the accuracy of the sound card clock, perhaps there is a simpler method,
that doesn't require you to bring a TV near your computer. In my case this would
be a bit difficult, as my shack is in the basement, and the TV is upstairs...
If you tune an FM radio to a stereo station, there is a pilot signal at 19 kHz that is
used to regenerate the carrier used for the left - right separation. At least this is true
for Europe, don't know for the US. This reduced-amplitude pilot signal is clearly
visible with any spectrogram-like program. I think its accuracy is comparable to that
of the line synch of the TV signal, and needs only a lightweight portable FM radio.

> to your the soundcard or -better- try to get one of those rare DSP boards.

The DSP boards (I have three of them, the DSKC50, the DSKC30 and the EVM56002)
use normal crystals, without oven, nor temperature compensated, so the only advantage
is that they are not into the PC case, and the temperature excursion is lower.

About the .INI vs. Registry issue, I think each method has its pros and cons.
Personally, I prefer the Registry, but this is just a matter of personal preferences.
Perhaps a right way could be to give the user the possibility to export (and import)
the Registry settings to a text file, so that he can manually edit them, if need be.

73   Alberto    I2PHD