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RS-Ruby Lite Users’ Manual
9
5.1.1 Header
The 80-byte Header is used to mark the start position of data, return mode setting, sensor
temperature and timestamp. The detail of the header is as shown in Table 4.
Table 4: Format of Header.
Header (80bytes)
Header Resv Wave_mode Temp Time Resv
4bytes 3bytes 1byte 2bytes 10bytes 60bytes
Header
: this can be used for packets identification: 0x55, 0xAA, 0x05, 0x5A (Default Value)
Wave_mode : Big-Endian mode, lower 4 bits are used to represent the return mode of the
LiDAR, for instance:00000001 stands for that first return mode is chosen.
Temp : the temperature of device;
Time : it is used to save the timestamp. In the defined timestamp the system time is recorded,
resolution is 1us, the definition of time can be found in the appendix B.11.
Resv : those bytes are reserved.
5.1.2 Data Field
The value of measurement result is saved in the data field, in total 976 byte. It consists of 4
data blocks, the length of each data block is 244 bytes. Each block stands for a complete
round of distance measuring for all 80 channels. The definition is shown as follow:
Table 5: Data Block Definition.
Data block n (244bytes)
Symbol Ret_id Azimuth Channel1_data ... Channel80_data
1byte 1byte 2bytes 3bytes ... 3bytes
Symbol : identification bit, default value: 0xFE;
Ret_id : it is used to represent which echo measurement is for this block;
Azimuth : the information of horizontal rotation angle. This angle information will be used to
calculate the 3D coordinate with all following 80-channel data in the same block. In following
section, it will be completely explained.
Channel data : the length of each channel data is 3 bytes, each block includes 80-channel
data (further details could be seen in Table 6). (The relationship between the number of
channel and vertical angle can be found in chapter 8.)
5.1.2.1 Calculation of the Azimuth
In each data block the value of azimuth is measured once and this azimuth corresponds to the
first position of the first laser emission (the first channel data in this block). The rotation angle is
recorded by angle encoder. The zero position of angle encoder is the zero degree of azimuth.
The resolution of angle is 0.01°.
For instance, in Figure 6, the azimuth value is calculated as follow:
Get azimuth values (HEX): 0x59, 0x39
Combine to a 16-bit, unsigned integer (HEX): 0x 5939
Convert the value to decimal (DEC): 22841
Divided by 100 (DEC): 228.41°