[time-nuts] Soundcard sampling Re: Picking a good HP 10811

[Stanley Reynolds]

<snip>
Thus
for a 1kHz input and 100dB SNR the input clock jitter should be < 18ns rms.

for a 10kHz input and 100dB SNR the input clock jitter should be < 1.8ns
rms.

It is very likely that the differential sampling clock jitter
contribution of a high end sound card to the ADEV noise floor will in
around 1E-15 or less at Tau = 100sec.

Bruce

So offset each DUT to prevent injection lock within the 20 Hz range, and get relaxed spec on mixers and buffers. The retail was about 12 US$ for the surface mount and 50 US$ for the BNC mini-circuit mixers. Home made buffer amps and mixers sounds possible for me.

Use a 10Mhz +-10Khz offset common oscillator to put beat in the sound card range, just because jitter of 1.8ns sounds better than 18ns.

Slave two cards to one oscillator for 4 channels run test, post data / wave files.

Any reason to upgrade the sound card sample clock, I have a clock-block ? 

What would be a reasonable common LO oscillator, sine wave XO module ?

Stanley

I have several HP-8708a NOS that are full of parts they have a 20Mhz XO that would phase lock to the lab standard and provide a voltage of 1 volt per Mhz for an input signal that was the result of another mixer from the Ghz range which I do not have. Thinking of using them one for each DUT. They use the same connector for the backplane as the 10811 but each board is in a smaller compartment, could take three of the six slots but it would require much work and the front part of the case has space. 

Does anyone have any info on this 8709A option HU8 Synchronizer ? Think it was made about 1987.