Velodyne VLP-32C - Figure 6-4 Dual Return with Far Retro-Reflector

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Figure 6-4 Dual Return with Far Retro-Reflector

The dual return function is often used in forestry applications where measurement of the height of trees is desired.

Figure

6-5 on the facing page

indicates a sample response when the laser pulse initially hits the upper canopy, penetrates it, and

eventually hits the ground, producing multiple returns. Which laser return mode would be best in this situation?

36 VLP-32C User Manual

Main Page

default chapter2
- Method2
- Method3
- Table of Contents4
Chapter 1 • about this Manual16
- Manual Scope16
- Prerequisite Knowledge16
- Audience16
- Document Conventions16
- Table 1-1 Document Conventions16
- Figure 2-1 Example 3D Sensing System18
Chapter 2 • VLP-32C Overview 2.1 Overview19
- Product Models19
- Time of Flight19
- Data Interpretation Requirements19
- Table 2-1 3D Sensing System Components19
Chapter 3 • Safety Precautions20
- Warning and Caution Definitions20
- Caution Hazard Alerts20
- Safety Overview20
- Electrical Safety20
- Mechanical Safety20
- Laser Safety20
- Figure 3-1 Class 1 Laser21
Chapter 4 • Unboxing & Verification22
- What's in the Box22
- Variants22
- Verification Procedure22
- Network Setup in Isolation23
- Figure 4-1 Sensor Network Settings23
- Access Sensor's Web Interface24
- Figure 4-2 Interface Box (Power and Data Connections)24
- Figure 4-3 Sample Web Interface Main Configuration Screen25
- Visualize Live Sensor Data with Veloview26
- Veloview Operation27
- Figure 4-4 Veloview Open Sensor Stream27
- Figure 4-5 Veloview Select Sensor Calibration27
- Figure 4-6 Veloview Sensor Stream Display28
Chapter 5 • Installation & Integration29
- Overview29
- Mounting29
- Figure 5-1 Mounting Details29
- Encapsulation, Solar Hats, and Ventilation30
- Connections30
- Interface Box and Cable31
- Operation Without an Interface Box31
- Power31
Chapter 6 • Key Features32
- Calibrated Reflectivity32
- Laser Return Modes32
- Single Return Modes: Strongest, Last32
- Multiple Returns33
- Dual Return Mode33
- Figure 6-1 a Single Return33
- Figure 6-2 Dual Return with Last and Strongest Returns34
- Figure 6-3 Dual Return with Second Strongest Return35
- Figure 6-4 Dual Return with Far Retro-Reflector36
- Phase Locking Multiple Sensors37
- Figure 6-5 Forestry Application Multiple Returns37
- Figure 6-6 Phase Locking Example38
Chapter 7 • Sensor Inputs39
- Power Requirements39
- Interface Box Signals40
- Table 7-1 Interface Box Signals40
- Figure 7-1 Interface Box40
- Ethernet Interface41
- GPS, Pulse Per Second (PPS) and NMEA Sentence41
- GPS Input Signals41
- Electrical Requirements41
- Timing and Polarity Requirements41
- Figure 7-2 Synchronizing PPS with NMEA GPRMC Message41
- Figure 7-3 PPS Signal Closely Followed by NMEA GPRMC Message42
- Figure 7-4 PPS Signal Followed 600 Ms Later by NMEA GPRMC Message42
- Figure 7-5 RS-232 Example Transmission43
- GPS Connection Scenarios44
- Connecting a Garmin 18X LVC GPS Receiver44
- Figure 7-6 Garmin 18X LVC Configuration44
- Figure 7-7 Garmin GPRMC Message45
- Connecting to a Computer's Serial Port46
- Connecting to a Microcomputer's UART46
- Figure 7-8 DB9 Pin-Outs (DTE) and USB-To-Serial Adapter46
- Figure 7-9 Signal Directly from UART (Incorrect Polarity)46
- NMEA Message Formats47
- Pre-NMEA Version 2.3 Message Format47
- Figure 7-10 Inverted Signal from UART (Correct Polarity)47
- NMEA Version 2.3 Message Format48
- Table 7-2 Pre-NMEA Version 2.3 Message Format48
- Table 7-3 Post-NMEA Version 2.3 Message Format48
- Accepting NMEA Messages Via Ethernet49
Chapter 8 • Sensor Operation50
- Firing Sequence50
- Throughput Calculations50
- Data Packet Rate50
- Figure 8-1 Firing Sequence Timing50
- Position Packet Rate51
- Total Packet Rate51
- Laser Measurements Per Second51
- Single Return Mode (Strongest, Last)51
- Dual Return Mode51
- Rotation Speed (RPM)51
- Horizontal Angular (Azimuth) Resolution51
- Rotation Speed Fluctuation and Point Density52
- Table 8-1 Rotation Speed Vs Resolution52
- Figure 8-2 Point Density Example52
Chapter 9 • Sensor Data53
- Sensor Origin and Frame of Reference53
- Calculating X,Y,Z Coordinates from Collected Spherical Data53
- Packet Types and Definitions54
- Definitions54
- Figure 9-1 VLP-32C Sensor Coordinate System54
- Firing Sequence55
- Laser Channel55
- Data Point55
- Azimuth55
- Data Block55
- Time Stamp55
- Factory Bytes56
- Data Packet Structure56
- Table 9-1 Factory Byte Values56
- Figure 9-2 VLP-32 Single Return Mode Data Structure57
- Table 9-2 VLP-32C Data Order in Data Block58
- Figure 9-3 VLP-32 Dual Return Mode Data Structure58
- Position Packet Structure59
- Table 9-3 Position Packet Structure Field Offsets59
- Table 9-4 PPS Status Byte Values61
- Figure 9-4 Wireshark Position Packet Trace61
- Discreet Point Timing Calculation62
- Table 9-5 VLP-32C's Lasers Fire in Pairs62
- Figure 9-5 Firing Sequence Timing62
- Figure 9-6 Example Data Point Timing Calculation64
- Figure 9-7 Single Return Mode Timing Offsets (in Μs)65
- Precision Azimuth Calculation66
- Table 9-6 VLP-32C Azimuth Offsets by Elevation66
- Figure 9-8 Dual Return Mode Timing Offsets (in Μs)66
- Converting PCAP Files to Point Cloud Formats69
Chapter 10 • Sensor Communication70
- Web Interface70
- Configuration Screen71
- Table 10-1 Configuration Screen Functionality and Features71
- Figure 10-1 VLP-32C Configuration Screen71
- MAC Address73
- Correctly Reset MAC Address to Factory MAC Address73
- System Screen74
- Table 10-2 System Screen Functionality and Features74
- Figure 10-2 VLP-32C System Screen74
- Info Screen75
- Table 10-3 Info Screen Functionality and Features75
- Figure 10-3 VLP-32C Info Screen75
- Diagnostics Screen77
- Table 10-4 System Screen Functionality and Features77
- Figure 10-4 VLP-32C Diagnostics Screen77
- Sensor Control with Curl78
- Using Curl with Velodyne Lidar Sensors78
- Curl Command Parameters78
- Command Line Curl Examples79
- Get Diagnostic Data79
- Conversion Formulas80
- Interpret Diagnostic Data80
- Top:hv80
- Top:lm20_Temp81
- Top:pwr_5V81
- Top:pwr_2_5V81
- Top:pwr_3_3V81
- Top:pwr_Raw82
- Top:pwr_Vccint82
- Bot:i_Out82
- Bot:lm20_Temp82
- Bot:pwr_V_In84
- Get Snapshot84
- Get Sensor Status84
- Set Motor RPM84
- Set Field of View85
- Set Return Type (Strongest, Last, Dual)85
- Save Configuration85
- Reset System85
- Network Configuration86
- Set Host (Destination) IP Address86
- Set Data Port86
- Set Telemetry Port86
- Set Network (Sensor) IP Address86
- Set Netmask86
- Set Gateway86
- Set DHCP86
- Curl Example Using Python87
Chapter 11 • Troubleshooting89
- Troubleshooting Process89
- Table 11-1 Common Problems and Resolutions89
- Turned DHCP On, Lost Contact with Sensor90
- Service and Maintenance91
- Fuse Replacement91
- Technical Support92
- Purchased through a Distributor92
- Factory Support92
- Support Desk92
- Return Merchandise Authorization (RMA)92
Appendix A • Sensor Specifications93
Appendix B • Firmware Update94
- Firmware Update Procedure94
- Figure B-1 Velodyne Downloads Page94
- Figure B-2 Compare Firmware Versions95
- Figure B-3 Select New Firmware Image96
- Figure B-4 Upload New Firmware Image97
- Figure B-5 Firmware Update Complete Page98
- Figure B-6 Finalize Firmware Update99
- Special Procedure to Update Firmware100
- Figure B-7 Verify Firmware Versions100
- If an Error Occurs101
Appendix C • Mechanical Diagrams102
- Interface Box Mechanical Drawing103
- Figure C-1 Interface Box Mechanical Drawing 50-6001 Rev a103
- VLP-32C Mechanical Drawing104
- Figure C-2 VLP-32C Mechanical Drawing 86-0130 Rev 1104
Appendix D • Wiring Diagrams105
- Interface Box Wiring Diagram106
- Figure D-1 Interface Box Wiring Diagram 86-0107A106
- Interface Box Schematic107
- Figure D-2 Interface Box Schematic 69-8230A107
Appendix E • Veloview108
- Features108
- Install Veloview109
- Visualize Streaming Sensor Data109
- Figure E-1 Veloview Open Sensor Stream109
- Figure E-2 Veloview Select Sensor Calibration110
- Capture Streaming Sensor Data to PCAP File111
- Figure E-3 Veloview Sensor Stream Display111
- Replay Captured Sensor Data from PCAP File112
- Figure E-4 Veloview Record Button112
- Figure E-5 Veloview Open Capture File113
- Figure E-6 Veloview Play Button113
- Figure E-7 Veloview Spreadsheet Tool114
- Figure E-8 Veloview Data Point Table114
- Figure E-9 Veloview Show Only Selected Elements115
- Figure E-10 Veloview Select All Points115
- Figure E-11 Veloview List Selected Points116
Appendix F • Laser Pulse117
- The Semiconductor Laser Diode117
- Figure F-1 Laser Diode Concept117
- Laser Patterns118
- Laser Spot Pattern118
- Laser Scan Pattern118
- Figure F-2 Laser Spot Shape118
- Beam Divergence119
- Figure F-3 Laser Spots on a Wall119
- Table F-1 VLP-32C Beam Divergence120
Appendix G • Time Synchronization121
- Introduction121
- Background121
- Figure G-1 Web Interface PPS and GPS Qualifier Option Selections121
- PPS Qualifier122
- Require GPS Receiver Valid122
- Require PPS Lock122
- Figure G-2 Top of Hour Counters122
- Delay123
- GPS Qualifier123
- Application123
- Logic Tables123
- Figure G-3 Sub-Second Counter Behavior123
- Figure G-4 Minutes and Seconds Counter Behavior124
Appendix H • Phase Lock125
- Phase Lock125
- Setting the Phase Lock125
- Figure H-1 Direction of Laser Firing125
- Application Scenarios126
- Figure H-2 Configuration Screen - Phase Lock126
- Figure H-3 Right and Left Sensor Phase Offset127
- Figure H-4 Fore and Aft Sensor Phase Offset127
- Field of View128
- Figure H-5 Sensor Data Shadows128
Appendix I • Sensor Care129
- Cleaning the Sensor129
- Required Materials129
- Determine Method of Cleaning the Ring Lens129
- Cleaning Tips130
- Method130
- Cleaning Non-Optical Sensor Surfaces131
Appendix J • Network Configuration132
- Ethernet and Network Setup132
- Defaults132
- Establishing Communication Via Ethernet132
- Network Considerations133
- Throughput Requirements133
- Figure J-1 Sensor Network Settings133
- Single Sensor Transmitting to a Broadcast Address134
- Multiple Sensors in the same Network134
- Multiple Sensors Transmitting to a Broadcast Address134
- Figure J-2 Single Sensor Broadcasting on a Simple Network134
- Multiple Sensors Transmitting to a Specific Address135
- Figure J-3 Multiple Sensors - Improper Network Setup135
- Figure J-4 Multiple Sensors - Proper Network Setup135

Velodyne VLP-32C - Figure 6-4 Dual Return with Far Retro-Reflector

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