NMEA status Date and time (accurate
to the second)
Lidar behavior
Locked Synchronized At each rising edge of the internal 1 Hz signal, the lidar obtains the actual date and time by
performing these two steps:
1. Extract the date and time from the previous NMEA message.
2. Add 1 full second.
•
When Require PPS Lock is ON:
Only when both NMEA and PPS are locked, NMEA messages are used to update
the date and time; when PPS is not locked, NMEA messages are considered
untrustworthy and thus not used.
•
Require PPS Lock can be set using web control (see Require PPS Lock) or
HTTP/PTC API (see the API Reference Manuals).
Unlocked (Lost) Drifting When the lidar goes from Locked to Unlocked, it starts counting from the last
synchronized time using the lidar's internal 1 Hz signal.
This absolute time will gradually drift from the actual GPS time.
PPS status μs time Lidar behavior
Unlocked (Initial) Not synchronized The lidar's internal 1 Hz signal is not aligned with the GPS second.
Locked Synchronized The rising edge of the lidar's internal 1 Hz signal is aligned with the rising edge of the PPS
signal (i.e. the start of each GPS second).
Unlocked (Lost) Drifting The lidar counts the absolute time using the internal 1 Hz signal.
This absolute time will gradually drift from the actual GPS second.
B.1.2. PTP as the clock source
The lidar connects to a third-party PTP master to obtain the absolute time.
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General