Velodyne VLP-16 - Discreet Point Timing Calculation

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Figure 9-6 Wireshark Position Packet Trace

Legend:

light blue: Ethernet+IP+UDP packet header (42 bytes)

orange: Timestamp (4 bytes)

red: PPS status (1 byte)

green: NMEA GPRMC sentence (length varies)

9.4 Discreet Point Timing Calculation

For the purpose of geo-referencing LiDAR data, it is helpful to calculate the exact moment of a particular laser firing in

order to more closely associate it with time stamped data from an INS. By using the firing timing information given in

Figure

9-7 on the next page

you are able to compute the exact firing time for each data point.

Chapter 9 • Sensor Data 61

Main Page

Default Chapter2
- Limited Warranty2
- Revision History3
- 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
- Overview18
Chapter 2 • VLP-16 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
Chapter 4 • Unboxing & Verification22
- What's in the Box22
  - Variants22
- Verification Procedure22
Chapter 5 • Installation & Integration29
- Overview29
- Mounting29
- Encapsulation, Solar Hats, and Ventilation30
- Connections30
Chapter 6 • Key Features32
- Calibrated Reflectivity32
- Laser Return Modes32
- 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 Box (Sensor Power and Data Connections)40
- Ethernet Interface41
- GPS, Pulse Per Second (PPS) and NMEA GPRMC Message41
Chapter 8 • Sensor Operation49
- Firing Sequence49
- Throughput Calculations49
- Rotation Speed (RPM)50
Chapter 9 • Sensor Data52
- Sensor Origin and Frame of Reference52
- Calculating X,Y,Z Coordinates from Collected Spherical Data52
- Table 9-1 Vertical Angles (Ω) by Laser ID and Model53
- Figure 9-1 VLP-16 Sensor Coordinate System53
- Packet Types and Definitions54
- Discreet Point Timing Calculation61
- Figure 9-6 Wireshark Position Packet Trace61
- Figure 9-7 Firing Sequence Timing62
- Figure 9-8 Example Data Point Timing Calculation63
- Figure 9-9 Single Return Mode Timing Offsets (in Μs)64
- Precision Azimuth Calculation65
- Figure 9-10 Dual Return Mode Timing Offsets (in Μs)65
- Converting PCAP Files to Point Cloud Formats66
Chapter 10 • Sensor Communication68
- Web Interface68
- Sensor Control with Curl76
Chapter 11 • Troubleshooting87
- Troubleshooting Process87
  - Table 11-1 Common Problems and Resolutions87
  - Turned DHCP On, Lost Contact with Sensor88
- Service and Maintenance89
  - Fuse Replacement89
- Technical Support90
- Return Merchandise Authorization (RMA)90
Appendix A • Sensor Specifications91
Appendix B • Firmware Update92
- Firmware Update Procedure92
Appendix C • Mechanical Diagrams100
- Interface Box Mechanical Drawing101
- Figure C-1 Interface Box Mechanical Drawing 50-6001 Rev a101
- And Puck LITE Mechanical Drawing102
- Figure C-2 VLP-16 and Puck LITE Mechanical Drawing 86-0101 Rev B1102
- And Puck LITE Optical Drawing103
- Figure C-3 VLP-16 and Puck LITE Optical Drawing 86-0101 Rev B1103
- And Puck LITE Optical Keep out Zone104
- Figure C-4 VLP-16 and Puck LITE Optical Keep out Zone 86-0101 Rev B1104
- Puck Hi-Res Mechanical Drawing105
- Figure C-5 Puck Hi-Res Mechanical Drawing 86-0129 Rev a105
- Puck Hi-Res Optical Drawing106
- Figure C-6 Puck Hi-Res Optical Drawing 86-0129 Rev a106
- Puck Hi-Res Optical Keep out Zone107
- Figure C-7 Puck Hi-Res Optical Keep out Zone 86-0129 Rev a107
Appendix D • Wiring Diagrams108
- Interface Box Wiring Diagram109
- Figure D-1 Interface Box Wiring Diagram 86-0107A109
- Interface Box Schematic110
- Figure D-2 Interface Box Schematic 69-8230A110
Appendix E • Veloview111
- Features111
- Install Veloview112
- Visualize Streaming Sensor Data112
- Figure E-1 Veloview Open Sensor Stream112
- Figure E-2 Veloview Select Sensor Calibration113
- Figure E-3 Veloview Sensor Stream Display113
- Capture Streaming Sensor Data to PCAP File114
- Replay Captured Sensor Data from PCAP File114
- Figure E-4 Veloview Record Button114
- Figure E-5 Veloview Open Capture File115
- Figure E-6 Veloview Play Button115
- Figure E-7 Veloview Spreadsheet Tool116
- Figure E-8 Veloview Data Point Table116
- Figure E-9 Veloview Show Only Selected Elements117
- Figure E-10 Veloview Select All Points117
- Figure E-11 Veloview List Selected Points118
Appendix F • Laser Pulse119
- The Semiconductor Laser Diode119
- Figure F-1 Laser Diode Concept119
- Laser Patterns120
- Table F-1 VLP-16 Beam Divergence122
- Table F-2 Dimensions of VLP-16 Laser Spots at Distance122
Appendix G • Time Synchronization123
- Introduction123
- Background123
- Figure G-1 Web Interface PPS and GPS Qualifier Option Selections123
- PPS Qualifier124
- GPS Qualifier125
- Application125
- Logic Tables125
- Figure G-3 Sub-Second Counter Behavior125
- Figure G-4 Minutes and Seconds Counter Behavior126
Appendix H • Phase Lock127
- Phase Lock127
- Field of View130
- Figure H-5 Sensor Data Shadows130
Appendix I • Sensor Care131
- Cleaning the Sensor131
Appendix J • Network Configuration134
- Ethernet and Network Setup134
  - Defaults134
  - Establishing Communication Via Ethernet134
- Network Considerations135

Velodyne VLP-16 - Discreet Point Timing Calculation

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