LSLIDAR CH128X1 - 8.2 Dual Echo Mode

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Each data packet block of the CH128X1 Lidar contains 171 measurement data.
Therefore, the end time interval of each data packet (single echo mode) is
148.428 μs. Assuming that the absolute time of the data packet end is T
Packet_end
,
the steps for calculating the end time of the data block T
Block_end
(N) are as follows:
T
Block_end
(N) = (T
Packet_end
- 0.868 μs*(171-N)). (N = 1, 2, ..., 171).
8.2 Dual Echo Mode
In the dual echo mode, a data packet has a total of 109 measurement data. The
packaging time of the data packet is about 0.868 μs*109~=94.612 μs, and the
data rate is about 1s/94.612 μs ~=10569 data packets/second.
8.2.1 Calculation of Data Packet End Time
The timestamp in the data packet is a relative time in microseconds, which is
defined as the packing time of the laser measurement data of the last channel in
the data packet (packet end time), and its duration is less than 1 second.
Therefore, to calculate the absolute end time of the data packet, it is necessary
to obtain the 1-byte second information and the 4-byte microsecond timestamp
from the data packet first, and then obtain the year, month, day, hour and minute
information of the UTC time from the device package. The combination of the
three will be the exact time when the data packet ends.
8.2.2 Accurate Time Calculation of Channel Data
The precise measurement time of each data can be calculated with the exact
time of the end of the data packet and the light-emitting time interval of the 109
data.
Each data packet block of the CH128X1 Lidar contains 109 measurement data.
Therefore, the end time interval of each data packet (dual echo mode) is 94.612
μs. Assuming that the absolute time of the data packet end is T
Packet_end
, the steps
for calculating the end time of the data block T
Block_end
(N) are as follows:
T
Block_end
(N) = (T
Packet_end
- 0.868 μs*(109-N)). (N = 1, 2, ..., 109).