[Lowfer] Sound Card sample rate For WOLF

[w1tag at charter.net]

Andy,

What you're looking for is an audio (not necessarily RF) source of known 
frequency. Loran-C was really neat for that, but you only occasionally 
hear them testing down there. WWVB is no help, as the carrier frequency 
is too high for most sound card setups. Jay has posted a method using a 
second computer, Spectrum Lab and NAA (or similar VLF source) to create 
a very accurate audio tone generator. See:
http://www.w1vd.com/SoundcardCalibration.html

Myself, I take the 10 MHz output from a GPS receiver (one of those old 
HP's that were on the market 10 years or so ago), and divide down to 1 
kHz. That's a handy output for setting both sampling rate, and for 1 kHz 
markers for receiver calibration. The thing is... the source RF 
frequency doesn't need to have anything close to GPS accuracy. For 
example, you probably only need to have an audio frequency that's within 
1 milliHertz. Now, 1 milliHertz at 1000 Hz is 1 Hz at 1 MHz, and 10 Hz 
at 10 MHz. A 10MHz crystal oscillator that can be netted within 10 Hz of 
WWV for a few minutes is no big trick. So there would be a fairly 
straightforward project involving a 10 mHz crystal, logic gates, and 
dividers down to 1 kHz.

One other approach is to try to use the 440 and 600 Hz audio modulation 
on WWV. You would need to look up the schedule for when the tones are 
transmitted each hour, but it would give you something close to a minute 
for measurements. Just be sure that whatever program you are using to do 
the measurements is running at the same sample rate as WOLF.

John, W1TAG