Livox Avia
User Manual
©
2020 Livox Tech. All Rights Reserved.
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Tags: indicate the return type of the laser and if the point detected is a noise. The format of the tag is as shown
below:
bit7 bit6 bit5
bit4
bit3
bit2
bit1
bit0
Reserved Return number:
00: return 0
01: return 1
10: return 2
11: return 3
Point property based on intensity:
00: Normal
01: High confidence level of noise
10: Moderate confidence level of noise
11: Reserved
Point property based on spatial position:
00: Normal
01: High confidence level of noise
10: Moderate confidence level of noise
11: Low confidence level of noise
Each tag is composed of one byte. In this byte, bit7, and bit6 are Group 1, bit5 and bit4 are Group 2, bit3 and
bit2 are Group 3 while bit1 and bit0 are Group 4.
Group 2 indicates the return sequence of the sampling point. Featuring a coaxial optical path, the Avia itself
will generate a laser return even if there is no detectable object around. This return is recorded as return 0. After
that, if there is any object within the detectable range, the first laser that returns to the Avia is recorded as return 1,
and then return 2, and so on. If the object is too close to the Avia, such as 1.5 m away, the first effective return
will be merged into return 0, and be recorded as return 0.
Group 3 indicates if the sampling point is noise based on the intensity of the return. Normally, the intensity of the
returns of the noise generated due to the interference of atmosphere particles such as dust, rain, fog, and snow
is quite low. Therefore, noise is divided into two categories based on the intensity of the return received. "01"
represents a low intensity return, indicating that the samples have a high possibility of being noise such as dust;
“10” represents a moderate intensity return, indicating that the samples have a moderate possibility of being noise
such as rain and fog. The lower the confidence level of the sample is, the lower the possibility that it is noise.
Group 4 indicates if the sampling point is noise based on its spatial position. Normally, when the Avia LiDAR
sensors detect two objects in close proximity of each other, there will be some thread-like noise between the
two objects. Noise is divided into three categories. The lower the confidence level of noise is, the lower the
possibility that it is noise.
Note: Point property based on intensity and point property based on spatial position are not yet available for
Avia. Contact Livox if you require either.
Timestamp
Both point cloud data and IMU data have timestamp information. There are three ways to synchronize data with
the Avia: IEEE 1588-2008, Pulse Per Second (PPS), and GPS (PPS+UTC).
IEEE 1588-2008: IEEE 1588-2008 is the Precision Time Protocol (PTP) enabling precise synchronization of
clocks in measurement and control systems by Ethernet. Livox LiDAR sensors, as the ordinary clock in the PTP,
only support UDP/IPV4 for PTP. Livox LiDAR sensors support the following message events: Sync, Follow_up,
Delay_req, Delay_resp.
PPS: PPS uses the sync cable for data synchronization. Refer to the Cables section for more information. The
synchronization logic is shown in the figure below. The pulse interval in PPS is 1s (t0 = 1000 ms) while the
continuous time of high-level voltage is from 20 ms to 200 ms (20 ms <t1< 200ms). The rising edge of PPS
resets the timestamp to zero, so the timestamp of the point cloud data indicates the duration between the point
cloud sampling and the PPS rising edge.
Pulse Per
Second (PPS)
t0
t1
t0=1000 ms
20 ms < t1 <200 ms
Figure 5.2.2.1 Pulse Per Second
Содержание LIVOX LIDAR AVIA
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