[time-nuts] Yet another GPSDO - locking to 10MHz

[Peter Vince]

Hi Murray,

     Why did you use such a large division factor - or any for that
matter?  Could you not just have used a PLL with very long time
constant running at 10 MHz?

     Peter


On 27 June 2010 20:14, Murray Greenman <Murray.Greenman at rakon.com> wrote:
> I have a design which locks a high performance 10MHz OCXO to a 10MHz
> source which should work equally well with the LEA5, or any source of 5
> or 10MHz.
>
> I designed it for use with a distributed factory GPS reference which has
> picked up noise, hum and phase modulation, in order to deliver a high
> quality but GPS locked reference direct to equipment. The design adds
> nearly three orders of improvement.
>
> Essentially it divides the incoming 10MHz by 16384 and compared the
> phase with a similar division from the OCXO, within an ATTiny2313 micro.
> The phase detector is a D-flip-flop type implemented in software (in
> interrupts), and it delivers a locked reference with ADev around 10e-12
> for Tau between 1s and 20s. The micro also keeps a real time clock and
> does various background monitoring and telemetry tasks. There is PC
> monitoring software as well. There are only four chips in the design.
> While I can't share the code (belongs to my employer), the idea is
> simple enough and I could share the schematic.
>
> Eight of these units have been built. I used the excellent Rakon
> STP2402E OCXO.
>
>
> Regards,
> Murray Greenman ZL1BPU