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The JLR-31/JLR-21 GPS compass continues the success of its predecessor, reaching a new level of performance and stability with many new features and enhancements. This system is also known as a 3D Dynamic Sensor™, which besides giving heading information, is designed to provide highly accurate information of the ships movement in all axis.


Heave compensation

The JLR-31/JLR-21 has heave functionality built-in as standard. In rough ocean conditions (with high waves), the GPS compass can correct up and down (attitude), movement. This is especially useful for fish finders and sonars on fishing vessels where high waves are compensated for with 20cm rms accuracy, providing better potential for a profitable catch.


High speed update

The JLR-31/JLR-21 supports Speed Over Ground (SOG) and Course Over Ground (COG). The position, SOG and COG are updated every 200 milliseconds (which is 5 times faster than previous model JLR-30/JLR-20), delivering high accuracy.


JLR-31/JLR-21 and IMO recommendations

Traditionally, the means used to measure the heading of a ship has been a mechanical gyrocompass and/or a traditional magnetic compass. With the adoption of the new installation requirements in SOLAS-V, all passenger ships and all ships from 300 to 500 GT travelling international routes can now install a new technology directional sensor, the Transmitting Heading Device (THD).
JRC’s new JLR-31/JLR-21, IMO type-approved as both Transmitting Heading Device (THD) and as Satellite Navigator (GPS), suits for the vessels as SOLAS-V required primary heading sensor or primary GPS.
IMO performance standard Gross Tonnage
Transmitting Heading Device (THD) From 300GT to less than 500GT
Satellite Navigator (GPS) 20GT or more


Display modes

The JLR-31/JLR-21 incorporates many display modes readily available on a highly visible 5.7 inch LCD display. The display is fully dimmable and the keys are also backlit, making it easy to operate in low-light settings on the bridge.

Simple operation

The compact design of the JLR-31/JLR-21 incorporates an intuitive interface, providing enhanced ergonomics and user friendliness. The logic of the controls and excellent on-screen menus will greatly shorten most users’ learning period.


Measuring tool

The GPS compass allows calculation of distance and bearing between any two points, supporting Rhumb Lines (RL) for the short legs and Great Circle (GC) for long distance legs. Also, a trip log function comes standard for distance and heading.


CCRP and Anchor watch

The JLR-31/JLR-21 has CCRP¹ function incorporated, allowing the transfer of CCRP sentences to other onboard equipment and anchor watch alerts the watch officer of possible anchor dragging situations.1. Consistent Common Reference Point


Trend graph

The new trend graph display mode shows a history of roll, pitch and heave and SOG as an easy-to-read graphical view. Selections can be made to show maximum or average results.


The processor is built into the antenna. Eliminating alignment between antenna and processor found in separate systems, therefore contributing to an easy setup with less error and significantly reduced installation time. This concept also reduces the installation costs as only a single cable is used between antenna and display unit.

The outer shell of JRC’s new antenna system has a smooth surface. This slippery exterior makes it almost impossible for birds to perch on the domes or for the antennas to be completely covered in snow.

Should something interfere with the coverage, JRC’s proven antenna design incorporates a layer of air that reduces possible blind spots, allowing for a more precise heading than conventional systems.


High speed tracking

The GPS compass has its origins as a direction sensing system, but the JLR-31/JLR-21 goes far beyond that. The JLR-31/JLR-21 provides an impressive heading accuracy of 0.25° rms (JLR-31)/0.50° rms (JLR-21). Heave accuracy is 20cm rms and roll and pitch for both models is 0.5° rms. The tracking Rate of Turn (ROT) is 45° per second.

On the right a comparison between previous GPS compass model (JLR-30/JLR-20) and the new model (JLR-31/JLR-21).



The new GPS compass integrates 5 independent working NMEA output ports, which allows for connection to a wide range of onboard navigation equipment, such as radar, plotter, autopilot, sonar or other navigation devices.

Installation and maintenance

The JLR-31/JLR-21 display is compactly designed and can be mounted virtually anywhere. The three-antenna system is exclusively designed by JRC, making it far more reliable than conventional antenna systems. The system has a short start-up time (less than 2 minutes). Maintenance is not required, making it less expensive to maintain than a standard gyro system.


Remote Maintenance System (RMS)

system_fig03 JRC has the ability to cost-eff ectively monitor performance and functionality of the JLR-31/JLR-21 while at sea, significantly reducing downtime and maintenance costs. More about RMS, Click HERE.


Name GPS Compass/GPS Navigator
Model JLR-21 JLR-31
IMO approved (THD)
IMO approved (GPS)
Model NNN-21 NNN-31
Receiver Type Multi channel all-in-view (12ch + 1ch SBAS)
Frequency 1575.42MHz ± 1MHz(C/A code)
Direction accuracy 0.5° rms 0.25° rms
Rolling accuracy 0.5° rms
Pitching accuracy 0.5° rms
Heaving accuracy 20cm rms
Display resolution 0.1°
Resolution output 0.1° or 0.01° (selectable)
Tracking Rate of Turn 45° / sec
Tracking acceleration 1G
Start-up time less than 2 minutes (warm start fix, typically 30 seconds)
DGPS input RTCM SC-104 Ver.2.0 Type 1, 2, 9, 16
SBAS receiver Built-in(MSAS/WAAS/EGNOS)
RAIM function Built-in
Position accuracy GPS : 12m 2drms (C/A code, HDOP≦4, SA OFF)
SBAS : 6m 2drms when SBAS corrected
DGPS : 4m 2drms when DGPS corrected (when connected to beacon receiver)
GPS : 12m 2drms (C/A code, HDOP≦4, SA OFF)
SBAS : 5m 2drms when SBAS corrected
DGPS : 3m 2drms when DGPS corrected (when connected to beacon receiver)
Protection IPX6
Ambient conditions -25 to +55°C (operational)
-25 to +70°C (storage)
Model NWZ-4701
Display 5.7-inch LCD, 320 by 240 pixels
Display modes Compass rose, bow heading, navigation, rate of turn (ROT), water/ground speed, trend graph, calculation, GPS status
Direction & nav. data output1 IEC61162/NSK(shared) 5 ports (AD-10 output availuable: 2 of 5 ports)
Current data input 1 port(CUR, VBW)
Alarm contact signal 2 ports (alarm output)
1 port (ACK input)
LOG pulse 1 port (off , 200p/NM, 400p/NM)
Protection IPX4
Ambient conditions -15 to +55°C (operational)
-25 to +70°C (strage)
Power 12 to 24V DC (-10% to +30%)
Power consumption 12W (including sensor), 6W (excluding sensor)
Vibration/EMC IEC60945 ed4
Rectifier NBG-320
Data cable (for serial data) CFQ-5374 (3m), CFQ-5374-15 (15m)
Data cable (for contact signal) CFQ-5404 (3m), CFQ-5404-15 (15m)
Extention cable (sensor-display) CFQ-7249 (20m), CFQ-7249-10 (10m)
Junction box NQE-7720
Data cable (for sub display) CFQ-7251 (1.5m Y-cable)
Data cable (for JRC Radar) 2 CFQ-5469 (10m)
Data cable (for beacon receiver) CFQ-7250
Mount base (for NNN-21) MPBX44117
1 Selectable sentences depend on versions (NMEA 1.5, 2.1, 2.3) Some combinations of output sentence, bit rate, and output intervals may not be possible
ATT and HVE sentence can be set from output cycles of 25ms, 50ms,100ms, 200ms, 1s, 2s only
2 Accepted for JMA-3300/5100/5200/5200MK2/5300/5300MK2 series



Antenna (JLR-31)


Antenna (JLR-21)






Standard in the box

Cables Cables
Installation parts •Power cable display 2 m
Spare parts · •Serial data cable 3 m
Manual •Display to antenna* 10 m

*The cable length may vary depending on sales region.


Serial data cable CFQ-5374 (3 m)
Sensor extension cable CFQ-7249 (20 m)
Flush mount kit · MPBC43664
AC power rectifier · NBG-320
DGPS receiver JLR-4341

All specifications are subject to change without notification.