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Ethernet ROV Locator
Ethernet ROV Locator
  • ROV Locator
  • Overview
  • General Specifications
  • Quick Start for BlueROV
  • Fundamentals Useful to System Designers
    • Sound Reflection and Absorption
    • Multipath
    • Ping Length
    • What to Do About Multipath and Other Issues
    • Clock Drift Expectations
    • Accuracy Expectations
      • Accuracy Test: Topside GPS
      • Accuracy Test: 110 Meter Slant Range
      • Accuracy Test: 295 Meter Slant Range
    • Operation in a Pool
  • Configuring the ROVLe
    • Finding the Configuration Web Page
    • Example Configuration Web Page
    • Live Status Page
    • Setting Device Type
    • Setting the Static IP Address
    • Setting the Fallback IP Address
    • Setting the MAVLink REST Server Parameters
    • Setting the Secondary (GNSS) MAVLink Interface
    • GPS/GNSS Forwarding (Re-tweeting)
    • Magnetic Declination
    • CIMU Calibration Offsets
    • Speed of Sound
    • GNSS Antenna Mounting Rotation
    • Output Messages
    • Configure Simulation
  • System Variants
  • Autosync
    • Autosync Mission Scenarios and Mission Suitability
    • Autosync Availability
    • Autosync GPS/GNSS Output
    • ROVL Channels (Autosync only; Operating Multiple Units in Proximity)
  • Communicating With the ROVL
    • Serial Parameters
    • The Ethernet Interface
      • Tips on How to Find the IP Address Assigned to Your Ethernet Adapter
      • Blue Robotics Discovery Protocol (Ethernet Only)
    • Packet Format
    • Messages from ROVL to Host
      • $USRTH Receiver-Transmitter Relative Angles Message
      • $USTLC Target Location Message
      • $USINF/$USTXT Information Message
      • $USERR Error Message
      • $USNVM Non-Volatile Memory Message
    • Messages from Host to ROVL
      • NMEA-Format Messages to Receiver
      • Valid Commands from Host to ROVL, Serial and Ethernet
      • Valid Commands from Host to ROVL, Ethernet Only
        • Command: DHCP
        • Command: FALLBACK-ADDRESS
        • Command: IP-ADDRESS
        • Command: HOST-ADDRESS
        • Command: MAVLINK-ADDRESS
        • Command: MAVLINK-AUTO-ORIGIN
        • Command: MAVLINK-SYSID
        • Command: PAUSE
        • Command: RESUME
        • Command: RETWEET-GPS
        • Command: RETWEET-GPS-ADDRESS
        • Command: RETWEET-message
        • Command: SEND-ROV-POS-TO-MAP
        • Command: SEND-TOPSIDE-TO-MAP
        • Command: SEND-USRTH
        • Command: SEND-USTLC
        • Command: UNICAST-TO-ME
  • Cerulean Inertial Measurement Unit (CIMU)
    • CIMU Calibration Background
      • CIMU Magnetometer Calibration
      • CIMU Accelerometer Calibration
      • CIMU Gyro Calibration
  • Operating and Accuracy Considerations
  • Multi-Unit Operation (Swarms)
    • Multi-Unit 1:1
    • Multi-Unit 1:2
    • Multi-Unit 2x1:1
  • ROVL Mounting
    • ROV/Deepside Mounting
    • Topside Mounting
    • Simple Topside Deployment Fixture
  • ROVL Wiring
    • Standard Cabling Options
    • ROVL-e PC Board Internal Connections
      • JST-GH Connector Pin 1 Identification
      • Ethernet/Power Connections
      • Serial Connection
      • USB Connection
      • GNSS Compass Main (4-pin) RS-232 Connection
      • GNSS Compass RTK (2-pin) RS-422 Connection
    • Electrical Noise
  • Connecting and Powering Your ROVLe Ethernet Receiver or Transceiver
    • Example Power Injectors
    • Data Connection
    • Example Power/Wi-Fi Setup for Remote Usage
    • Battery
  • Mounting Dimensions
    • Mk II Receiver with Omnitrack Top
    • Transmitter/Transceiver/Receiver with Standard Top
    • Mk III Transcceiver
    • ROVLe Omnitrack Top
    • ROVLe Standard Top
    • Example Mounting Scheme with 3D-Printed Bracket
  • ROVL Coordinate Systems and Angles
    • Definitions
    • NED or "Compass" vs. ENU or "Math" Angles
    • Math to Compass Frame Conversions
    • Transducer Down Orientation
    • Transducer Up Orientation
    • Receiver/Transceiver Orientation Frames
    • Best Operating Envelope
  • Appendix: Math for Computing Remote Latitude/Longitude
    • Receiver & GPS at Topside and Transmitter Deepside
    • Transmitter & GPS Topside and Receiver Deepside
  • Appendix: Factory Usage Command Set
  • Troubleshooting
    • How to Tell if Your Mk II Receiver is Working
    • How to tell if your Mk II Transmitter is working
    • What to do when you find an unresolvable problem when troubleshooting
  • Copyright
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  1. Communicating With the ROVL
  2. Messages from ROVL to Host

$USRTH Receiver-Transmitter Relative Angles Message

The USRTH message provides the basic information needed to find the ROV relative to the location of an ROVL receiver. It is the message typically sent by baseline (non-Omniscan) ROVLs.

Note: From time to time, Cerulean adds features to the ROVL as requested by users, some of which require changes to this message. Cerulean undertakes to maintain backward compatibly on this message, so once a field is defined and published, we try not to not move it or change its behavior. We may add new fields to the end of the message, so we recommend you allow for extra fields that you can ignore if writing a parser for this message, rather than requiring a specific field count.

Example $USRTH message:

$USRTH,0.0,-0.0,0.0,100.0,45.0,45.0,-0.1,-0.4,-0.4,45.0,45.0,76,T,F,153,CIMU,A,-2,-2,*11

Format: $USRTH,ab,ac,ae,sr,tb,cb,te,er,ep,ey,ch,db,ah,ag,ls,im,oc,idx,idq*hh

ab: apparent bearing (azimuth) to transmitter in Math degrees (ENU) [Note 1, 4]

ac: apparent bearing to transmitter in Compass degrees (NED) [Note 1, 4]

ae: apparent elevation to transmitter in degrees [Note 1]

sr: slant range to transmitter in meters [Note 1]

tb: true bearing (azimuth) to transmitter in Math degrees (ENU) [Note 2, 4]

cb: true bearing to transmitter in Compass degrees (NED) [Notes 1, 4]

te: true elevation to transmitter in degrees [Note 2]

er: Euler roll angle of sensor frame, in Math degrees (ENU) [Note 3]

ep: Euler pitch angle of sensor frame, in Math degrees (ENU) [Note 3]

ey: Euler yaw (heading) angle of sensor frame, in Math degrees (ENU) [Note 3, 4]

ch: compass heading in Compass degrees (NED) [Notes 3, 4]

db: Analog AGC gain, in decibels (range 16 – 82)

ah: CPU hardware supports autosync (also needs GNSS hardware) [Note 5]

ag: GNSS hardware support autosync is present [Note 5]

ls: Seconds since last autosync or distance sync command [Note 5]

im: IMU status string (four digits 0..3) [Note 5]

oc: Operating channel: “B” if Mk II hardware AND autosync installed AND set to channel B; else “A” [Note 6]

idx: Transmitter/Transponder ID decoded [Note 7, 8]

idq: Transmitter/Transponder ID queried [Note 7, 9]

hh: NMEA-style hex checksum, always the last field and following the asterisk

Note 1: this field will be empty if receiver is not locked on transmitter

Note 2: this field will be empty if receiver is not locked on transmitter or IMU data is not valid

Note 3: this field will be empty if IMU data is not valid

Note 4: See section on “Compass” vs. “Math” angles

Note 5: These fields appended March 2021; not present in earlier firmware releases

Note 6: [IDs are a deprecated feature as of 1/1/25] Field appended August 2021; not present in earlier firmware releases

Note 7: [IDs are a deprecated feature as of 1/1/25] Field appended December 2022; not present in earlier firmware releases

Note 8: [IDs are a deprecated feature as of 1/1/25] if -2, no ID was detected to be appended to the transmitter/transponder's ping. If -1, an ID was detected to be appended to the transmitter/transponder's ping but it was an invalid pattern. Otherwise, if 0..15 an ID was decoded. This is primarily a Mk III feature, but Mk III transmitters are also capable of appending an ID to their pings.

Note 9: [IDs are a deprecated feature as of 1/1/25] If -2, the receiver is not a Mk III unit (and thus does not send query pings), or the transceiver is a Mk III and no ID was appended to the query ping. Otherwise, if 0..15 that ID was appended to the interrogation ping.

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Last updated 1 month ago