How to sync Time Pulse to NMEA output

Q&A forumCategory: QuestionsHow to sync Time Pulse to NMEA output
Strohhut asked 2 weeks ago

Hello,
I do have an F9P board and for my application, I need the PPS signal and NMEA messages from it at the same time.

The Idea ist:
Every time the PPS is received, the UART Port is opened and the new NMEA message with the current Data is read.
PPS and NMEA output are both set to 10Hz.
The problem is, that I can’t find a proper way to sync both Signals … or are they synced once both are set to 10Hz?
Does anyone know and can help me with this?
Thanks!

Ardusimple Staff replied 2 weeks ago

You can configure the timepulse via UBX-CFG-TP5 message.

1 Answers
clive1 answered 2 weeks ago

They aren’t synchronized in the truest sense.
The TIMEPULSE is independently generated, whilst the NMEA data is based on the measurement time tied to the internal integration clock, which gets slewed occasionally as the bias gets +/- a millisecond or two.
The TIMEPULSE is designed for YOUR MCU to establish a timeline, with a synchronized top-of-second. The NMEA data reports the time-of-measurement, allowing you to pull that into the current time based on you knowing what that is.
The TIMEMARK (EVENTIN) allows you to get a GNSS time-stamp for a signal you provide, allowing a two-way time transfer, or establish a shutter time for photogrammetry type applications.