Hello,
I’m observing an issue where the seconds field (ref_sec) in $PSTMPPSDATA and $PSTMTRAIMSTATUS NMEA messages sometimes skips values instead of incrementing by 1 each second.
For example, in the log below the ref_sec jumps from 48 directly to 50, skipping 49:
2026-03-11 10:07:47.973322637 $PSTMPPSDATA,1,1,1,0,0,1,0.500000,0,633,420,420,633,0,1,1,10,0,48,3,5,18,0,-2,0,1.128e-08,65473939.64,25999992.58,2*3A
ref_sec = 48
2026-03-11 10:07:48.990959770 $PSTMPPSDATA,1,1,1,0,0,1,0.500000,0,633,420,420,633,0,1,1,10,0,50,3,6,18,0,-2,0,8.651e-09,65473939.64,25999992.58,2*31
ref_sec = 50
As you can see, the host-side timestamps are ~1 second apart, which is expected, but the ref_sec field inside the message jumps by 2 (from 48 to 50). The message for second 49 appears to be missing entirely.
Questions:
- What could cause the module to skip a second in these proprietary timing messages?
- Is this related to internal PPS/timing recalibration?
- Is there a recommended way to handle such gaps?
Any insight would be appreciated. Thank you.