[time-nuts] I've been thinking about a GPS receiver experiment

Bob Martin aphid1 at comcast.net
Wed Oct 25 19:46:32 EDT 2017

   The holdover state is a DAC set to the last value of the analog 
control voltage that adjusts the oscillator frequency. Some designs
use an analog control loop and switch the DAC into the control loop.
Others use the DAC to set the control voltage at all times. This can 
result in a steps in the control voltage (output frequency).
I've used both methods and prefer the latter.

Bob M

On 10/25/2017 5:30 PM, Mark Sims wrote:
>>   No, you set up an oscillator so that is why you have that problem.
> I hooked the two rubidiums together just to see what would happen.   It pretty much did what I expected... chaos...   the time-nut equivalent of a naughty schoolboy putting a microphone up to the speaker of the public address system.  I't's a tough job, but somebody gotta do it  ;-)
>>   No, not really. The rubidium would be the real hold-over clock.
> Symmetricom calls the disciplining state where it can't lock to the 1PPS signal the "holdover" state.  It's sort of like a GPSDO holdover state.  Their discipline firmware does let you set the time constant and damping values.  I tried a little playing around with them, but never found any settings that worked consistently well with the LEA-5T.
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