[time-nuts] Simple solution for disciplining OCXO with 1 PPS

Nick Sayer nsayer at kfu.com
Mon May 23 12:46:20 EDT 2016


> 
>> If that sounds too weird, I am open to receive advises for a microcontroller based solution.
> 
> If you want to go that way, probably the simplest solution would be to
> take one of Nick Sayers boards, pull out the GPS receiver and feed the
> PPS input from your GPS receiver.

It’d be kind of an awkward fit. For the OCXO/TCXO, you’d need to pull the oscillator as well as the GPS (I believe you said you had an oscillator already), and your EFC would be 1.65 volts wide centered on 1.65 volts. That’s unlikely to be absolutely correct for your oscillator. You could change around the Vref for the DAC, but at that point I’d consider redesigning the board for your purposes instead.

That said, I think it’d be easy to adapt the circuit and code for a more arbitrary setup. And I believe my system is good down to the ADEV 10E-11 level at tau 1s or so. I don’t know how much better it can do, as I’ve simply not tried to go below that (and I likely couldn’t properly measure the results anyway).

There’s also the FE-5680 board, but it has an RS-232 level shifter in place of the DAC. On the other hand, it does have a very nice 2A @ 15V power supply, which likely is very close to what you’d need for a really good OCXO. A mash-up of that with the DAC put back in might be closer. But either way, you’re designing a new board, I think.


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