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6.3 Lidar Internal Timing
When there is no GPS and other equipment to synchronize, the Lidar uses 1 hour
(360*10
6
μs) as the cycle. With the microsecond as the timing unit, the timing value is
output as the timestamp of the data packet. At this time, there is no UTC reference. If
UTC is required, it must be written in the configuration package, otherwise the UTC
output information of the device package is invalid.
7. Angle and Coordinate Calculation
7.1 Horizontal Angle
The first 4 bits of Byte 1
represents the line number.
The last 4 bits of Byte 1, together
with Byte 2 and Byte 3
form the horizontal angle, the most significant byte of which
is stored at the smallest memory address and the least significant byte at the largest.
The unit is 0.001°. For example, 0x11AD=4525, that is 4.525°.
7.2 Distance Value
Byte 4
,
Byte 5
, and
Byte 6
represent the distance value of the first echo, the most
significant byte of which is stored at the smallest memory address and the least
significant byte at the largest. The two high-order bytes are the integer part, whose unit
is “cm”; and the last byte is the decimal part, whose unit is 1/256 cm. To analyze the
distance value, for example: the distance value in the obtained data packet is
represented by the hexadecimal number 0x02, 0x18, 0x32, and the first two bytes are
composed of 16-bit unsigned data, that is: 0x0218, which is converted to decimal
distance value: 536 cm. The last byte is the decimal part, 0x32 equals 50 in decimal,
that is, 50*1/256 cm=0.1953125 cm. Then the two parts add up to 536. 1953125 cm.
Byte 7
represents the first echo strength, and the value range is 0-255. (Echo strength
can reflect the energy reflection characteristics of the measured object in the actual
measurement environment. Therefore, the echo strength can be used to distinguish
objects with different reflection characteristics.)
Byte 8, Byte 9 and Byte 10
represent the distance value of the second echo, the most
significant byte of which is stored at the smallest memory address and the least
significant byte at the largest. The two high-order bytes are the integer part, whose unit
is “cm”; and the last byte is the decimal part, whose unit is 1/256 cm. To analyze the
distance value, for example: the distance value in the obtained data packet is
represented by the hexadecimal number 0x02, 0x18, 0x32, and the first two bytes are
composed of 16-bit unsigned data, that is: 0x0218, which is converted to decimal
distance value: 536 cm. The last byte is the decimal part, 0x32 equals 50 in decimal,
that is, 50*1/256 cm = 0.1953125 cm. Then the two parts add up to 536. 1953125 cm.