No subject

Testing them all is not super tough to do. Implement each of them and note if the 1 second ADEV
gets better or worse. One of the four *should* stand out as the winner …..

Bob

> On Dec 25, 2022, at 4:51 PM, Brooke Clarke via time-nuts <time-nuts at lists.febo.com> wrote:
> 
> Hi Matthias:
> 
> Here's a hardware GPS sawtooth corrector I made some time ago:
> https://prc68.com/I/timefreq.shtml#Sawtoooth
> Although it did not work on the Motorola GPS it would give you some idea of what parts are needed.
> https://prc68.com/I/PRS10.shtml
> 
> -- 
> Have Fun,
> 
> Brooke Clarke
> https://www.PRC68.com
> axioms:
> 1. The extent to which you can fix or improve something will be limited by how well you understand how it works.
> 2. Everybody, with no exceptions, holds false beliefs.
> 
> -------- Original Message --------
>> On Donnerstag, 22. Dezember 2022 00:22:37 CET James Wilson via time-nuts
>> wrote:
>>> After running in many of the familiar problems of connecting a GPS timing
>>> module 1PPS signal to a PRS-10, I want try building a software sawtooth
>>> correction board. I’ve seen previous discussion of some of the commands to
>>> use for adjusting the PLL and PPS control on the PRS-10 and getting the
>>> sawtooth error from ublox GNSS modules, but not a start-to-finish
>>> description of how to put everything together.
>>  
>>> My idea to use a microcontroller with multiple UART ports; one connected to
>>> the ublox module and the other connected to the PRS-10, with level shifters
>>> as needed. The microcontroller sits between the two devices, and gets the
>>> PPS sawtooth correction info from the ublox (specifically via the
>>> UBX-TIM-TP message and its qErr field), and then adjusts the PRS-10’s PPS
>>> time offset by this value to null out the sawtooth for the next pulse.
>> I suggest you try correcting the 1PPS pulse of the timing module itself, using
>> a variable delay line. I don't have a particular part in mind, Maxim might
>> have something.
>> 
>> There was a very elaborate GPSDO project discussed last year on this list that
>> used this technique.
>> 
>> BR,
>> Matthias
>> 
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