-59-
Calculation
The absolute time of a Point Cloud Data Packet is calculated as the sum of date, time (accurate to the second) and μs time.
· Date and Time can be retrieved either from the current Point Cloud Data Packet (6 bytes, year, month, date, hour, minute, second), or from
the previous GPS Data Packet (6 bytes of Date and 6 bytes of time).
· μs time can be retrieved from the current Point Cloud Data Packet (4 bytes of Timestamp)
NOTE The calculation of absolute time is different when PTP protocol is used. See Appendix III (PTP Protocol).
■ Start Time of Each Block
Assuming that the absolute time of a Point Cloud Data Packet is t0, the start time of each block (the time when the first firing starts) can be
calculated.
Single Return Mode
Block
Start Time (μs)
Block 8
t0 + 3.28
Block N
t0 + 3.28 - 50 * (8 - N)
Block 3
t0 + 3.28 - 50 * 5
Block 2
t0 + 3.28 - 50 * 6
Block 1
t0 + 3.28 - 50 * 7
Dual Return Mode
Block
Start Time (μs)
Block 8 & Block 7
t0 + 3.28
Block 6 & Block 5
t0 + 3.28 - 50 * 1
Block 4 & Block 3
t0 + 3.28 - 50 * 2
Block 2 & Block 1
t0 + 3.28 - 50 * 3