a const time offset ahead

Lin Zhao <[email protected]>
Newsgroups gmane.comp.time.chrony.user
Message-ID <CAF4Vr9Rmc=E2ToudKszy8P67-b2_5k+eq+hh4_ZeVTAHQN1fbg@mail.gmail.com>
Hi,

I am using a microcontroller to generate PPS and NMEA string to time sync
an Nvidia Jetson computer using gpsd and chrony for the GPS-denied
environment.  PPS and NMEA are verified as good.

When I started time synchronization process, chrony always like:
*#* PPS                           0   0   1     0    -894ms[  -894ms] +/-
1000ns*

I tried a lot of times, chrony always considers PPS time is ahead
around 890 ms. But I checked the NMEA time data is right. When the computer
is synchronized,  system time is ahead of NMEA time. Before the time
synchronization, both of them are verified the same.

After the 1 hour test, time is synchronized, but with this const offset.

Could you tell me how to debug this? Thanks for your help.

Best regards,

-------------------------------------------------
*Lin Zhao*

*Research** Assistant @ Graduate School of Oceanography *
*Ph.D. Student @ Department of Ocean Engineering*
*University of Rhode Island*

*Room 2, Horn Lab*

*215 South Ferry RoadNarragansett RI 02882*
*Phone: 401-771-4661*
*E-mail: [email protected] <[email protected]>*
*Personal*: [email protected]
*Lab: https://soslab.wordpress.com/ <https://soslab.wordpress.com/>*
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