[time-nuts] Generating a solid PPS from 10Mhz source - finetuned start

Bob Camp kb8tq at n1k.org
Mon Jan 25 18:06:15 EST 2016


Hi

> On Jan 25, 2016, at 8:55 AM, Xavier Bestel <xavier.bestel at free.fr> wrote:
> 
> Hi Guys,
> 
> Le mercredi 13 janvier 2016 à 09:22 +0000, Jerome Blaha a écrit :
>> Hey Guys,
>> 
>> Is there an easy circuit to build that can consistently deliver a 1
>> PPS from a 10MHz source with excellent resolution and
>> repeatability?  My first application is to test different 10MHz
>> oscillators without a TIC always attached and then compare the PPS
>> output change over time against a master GPSDO PPS with an HP53132A.
>> 
>> The circuit used for PPS generation would have to deliver consistent
>> PPS output with preferably not more than 100ps noise or jitter,
>> assuming a perfect source.  I'm totally guessing that for this
>> resolution, the PPS would have to be generated and accurate to within
>> 0.001Hz every second.  If this is too difficult, maybe the
>> integration time can be increased to generate one pulse every
>> 10second or every 100,000,000.00 cycles?
>> 
>> Finally, is a square 10Mhz reference any better in this case than a
>> sinusoidal input for generating the PPS?
> 
> What would it take to make that PPS adjustable with a step <= 1ns ?
> I see that the PIC solution has a mean of "arming" the 1PPS to let it
> start at the desired time, but the granularity would be of course
> 10MHz. For example are there easy-to-use programmable delays to reach
> the missing precision ?

The question is (as always) why? 

If you are trying to get to low temperature coef and low jitter and good long term stability ….

No, they really aren’t good enough. 

Bob


> 
> 	Xav
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