[time-nuts] Re: Compairing the phase drifts between two PPS signals

[Mayukh Bagchi]

Hello John
This is interesting! Thanks

Mayukh

Mayukh Bagchi (He/Him), MSc
Graduate Student
Department of Physics, Engineering Physics, and Astronomy

mayukh.bagchi at queensu.ca<mailto:mayukh.bagchi at queensu.ca>
[Queen's University Logo]<https://www.queensu.ca/>
________________________________
From: John Ackermann N8UR via time-nuts <time-nuts at lists.febo.com>
Sent: Monday, October 3, 2022 4:59 PM
To: time-nuts at lists.febo.com <time-nuts at lists.febo.com>
Cc: John Ackermann N8UR <jra at febo.com>
Subject: [time-nuts] Re: Compairing the phase drifts between two PPS signals

The "TICC" timestamping counter available from TAPR
(https://can01.safelinks.protection.outlook.com/?url=https%3A%2F%2Ftapr.org%2Fproduct%2Ftapr-ticc%2F&data=05%7C01%7Cmayukh.bagchi%40queensu.ca%7C884c8cefb71841b1025408daa5841091%7Cd61ecb3b38b142d582c4efb2838b925c%7C1%7C0%7C638004283874376111%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=gssMZnxezpilblySN9M0HytdBx2K0ve0GW09kg5W%2FDA%3D&reserved=0) uses the TDC7200 to do this.

The "gotcha" is that the TDC7200 has a limited measurement range.  There
are two operating modes: in one it measures from 12 ns to 500 ns, and in
the other from 250 ns to 8 ms.  That is a problem if the two devices
you're measuring are too far apart in intial phase, or if they are too
close together, or if there is drift between them that crosses the
boundaries.

To get around that, the TICC uses two TDC7200s operating more or less
independently, but sharing a common internal timescale.  It calculates
time interval by subtracting the timescale value of the pulse on the
"start" channel from that of the pulse on the stop channel, and as a
result the measurement range is from a very large negative number to a
very large positive number, with no dead zone around 0 seconds.

It can also output raw timestamps from either or both channels for
external processing, which in many cases is more versatile than using a
traditional time interval measurement.

Hope this helps,
John
----

On 10/3/22 16:33, Mayukh Bagchi via time-nuts wrote:
> Hello,
>
> I am trying to compare the phase drifts between a 1PPS signal generated by a GPS receiver with a 1PPS from an OCXO( using a frequency divider to convert 10MHz to 1 PPS).
> I was thinking of using a TDC like the texas instruments TDC7200 boards.
> Do any of you have an idea for doing this?
>
> Let me know if you need more background on the kind of work I am trying to achieve.
>
> Thanks,
> Mayukh
>
> Mayukh Bagchi (He/Him), MSc
> Graduate Student
> Department of Physics, Engineering Physics, and Astronomy
>
> mayukh.bagchi at queensu.ca<mailto:mayukh.bagchi at queensu.ca>
> [Queen's University Logo]<https://www.queensu.ca/>
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