[time-nuts] 1 pps sync'ing

Lester Veenstra m0ycm at veenstras.com
Fri Jun 29 10:10:19 EDT 2018

    Are you with PTS in Littleton ?

Lester B Veenstra  K1YCM  MØYCM  W8YCM   6Y6Y
lester at veenstras.com

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-----Original Message-----
From: time-nuts [mailto:time-nuts-bounces at lists.febo.com] On Behalf Of Martyn Smith
Sent: Friday, June 29, 2018 9:13 AM
To: time-nuts at febo.com
Subject: [time-nuts] 1 pps sync'ing



My colleague Steve asked a question about wanting to generate a 10 MHz and
100 MHz squarewaves with both rising edges aligned to a reference 1 pps input (to within 5ns).


We already have a product that can do this (at 10 MHz), but it is very complicated, and Steve's job is to fine an easier approach.


I'm not trying to achieve 1-5 ns to UTC as that's not possible as already pointed out, just 1 to 5 ns to a reference 1 pps (from Hydrogen Maser).


We definitely need all rising edges synchronised.  Of course, we will have to be very careful with cabling lengths etc otherwise we will lose all this synchronisation.


So starting at 100 MHz and dividing down is a good idea, except the 100 MHz needs to be synchronised in the first place, which brings me back to the first problem.


Our existing product generates 48 bit BCD time code all synchronised to a 1 pps inputs.  This was designed ages ago for a customer.  So, the last bit of the 48 bit is 100ns in time or 10 MHz in frequency. 


So we could use this board and then lock the 100 MHz to the 10 MHz.  


But it's not very elegant!!


Anyway, the research continues.


Best Regards




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