[time-nuts] Progress on the FE-5680A serial commands!
beale at bealecorner.com
Fri Jan 20 01:28:40 EST 2012
On 1/19/2012 9:52 PM, Scott Newell wrote:
> This assumes that the reply from the undoc command 0x5a is the raw counts
> from the 4 channel 12 bit ADC. I think channel 3 is a temp sensor. What
> would channel 4 be? Photodiode output?
Great detective work Scott! I'll bet Channel 4 is voltage to the VCXO. It
is driven up and down at startup searching for the lock, then it settles
down, but the oscillator components are also affected by temperature so the
VCO voltage would logically track the temperature too. At least it seems a
For example, look at this plot of the 10 MHz output frequency after
powerup. It has a similar look to your Channel 4, except for the post-lock
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