User's Manual

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3.2 GPS Data Packet
GPS Data Packets are triggered every second. All the multi-byte values are unsigned and in little endian format.
Before $GPRMC messages are available from the external GPS module
Each rising edge of the LiDAR’s internal 1 Hz signal triggers a GPS Data Packet.
The time and date in the GPS Data Packets are unreal, starting from 00 01 01 00 00 00 (year, month, day, hour, minute, second) and increasing with the
internal 1 Hz signal.
Once the LiDAR receives the PPS (pulse-per-second) signal and $GPRMC messages
The internal 1 Hz signal will be locked to the PPS. Each rising edge still triggers a GPS Data Packet.
Meanwhile, the LiDAR will extract the actual UTC time and date from $GPRMC messages, and stamp them into both Point Cloud Data Packets and GPS
Data Packets.
• Point Cloud Data Packets: 6-byte UTC Time (year, month, day, hour, minute, second) in decimal
• GPS Data Packets: 6-byte Date (year, month, day) and 6-byte Time (second, minute, hour) in ASCII
The GPS module sends first the PPS signal and then the $GPRMC message. At the rising edge of the PPS pulse, the corresponding $GPRMC message is not
yet available. Therefore, the LiDAR extracts UTC information from the previous $GPRMC message and automatically adds 1 full second. Users need not
worry.
When GPS signal is lost
The LiDAR will still trigger GPS Data Packets by the rising edge of the internal 1 Hz signal. However, the GPS time in the packets will be counted by the
internal 1 Hz signal and will drift from the actual GPS time.
3.2.1 Ethernet Header
The source IP is 192.168.1.201 by default. The destination IP address is 0xFF FF FF FF and in broadcast form.