[time-nuts] Re: PRS-10 sawtooth correction with microcontroller

[ew]

This is all it takes. I would leave the GPS unit separate since so many choices are available including a 9T and 250 and 500 psec chips are readily available now Analog Devices. At the time I did publish it there was no interest today I am to old but be glad to help off list                                                             
Bert Kehren
In a message dated 12/25/2022 6:32:49 PM Eastern Standard Time, time-nuts at lists.febo.com writes:Â 
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.
>Â  
>> 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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