[time-nuts] HP-3586B SSB L.O. Mods...

[Bob Camp]

Hi

My assumption is that to do any of this, some sort of calibrated clock on the sound card would be needed. Either a mod to the card, or some luck with the built in clock source. It's going to be needed weather you use an FFT or some other DSP process. For a "fully locked" system, mod the sound card for an external clock and whip up a phase locked loop to drive it. 

The mix down source would likely be purely digital. Inserted after you had the sample stream. My first choice would be to use a 2 KHz "stupid clock" (0 1 0 -1)  with an 8 KHz sample rate. Pretty simple math. 

Bob


On Mar 22, 2011, at 6:23 PM, Alberto di Bene wrote:

> On 3/22/2011 5:24 PM, Bob Camp wrote:
>> The other approach would be to simply take the samples, do a mix down, and
>> get the phase from an ATAN calculation on the I/Q results. That would give
>> you pure phase and thus frequency.
> How do you intend to generate the numeric LO stream to use for the mix down ? It must have a sampling rate
> with a precision comparable to what you intend to measure...
> 
> 73  Alberto  I2PHD
> 
> 
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