JLN 550

JRC’s well-thought out designed speed log is world renowned, easy to install and maintain. With accurate speed measurements you do not need any other device again.

The JLN-550 Doppler Sonar is designed to provide ship speed information with higher stability in the dual frequency modes; one using a lower ultrasonic frequency that is adequate to measure the ship’s speed against the ground up to larger depths and the other using a higher ultrasonic frequency that allows the ship’s speed against the water to be measured even in water with tiny bubbles.

The transducer is designed for dual-frequency transmission, but its size is smaller than the conventional models.

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  • IMO Type Approved


The JLN-550 Doppler sonar is designed to provide stable speed information with high stability in dual frequency mode. The lower ultrasonic frequency measures the ground speed (up to large depths) and the higher ultrasonic frequency calculates the ship’s speed against water with a minimized effect of aeration, allowing for stable and accurate operation.

Error free

An ultrasonic beam is transmitted in fore and aft directions. At the same time, the hull motions such as rolling and pitching are detected and removed by simply measuring the difference of the Doppler shift reception signal, ensuring accurate and stable speed data, even in the roughest conditions.

Compact transducer

The transducer allows for dual frequency transmission, but the size is still smaller than conventional models, enabled to install on the bow, a suitable location that has the slightest amount of influence to bubbles, which allows for stable and accurate operation.

GPS connectivity

By connecting a GPS receiver, the JLN-550 Doppler sonar displays comprehensive speed information received from satellites, ensuring a highly reliable and accurate positioning.

Online maintenance

The (optional) online maintenance is a unique function, capable of remotely monitoring and analyzing the Doppler sonar, allowing for prompt action and service for any faults that may occurs during navigation.

Easy interfacing

This Doppler sonar incorporates a highly reliable interfacing field. You can easily connect a wide range of navigational equipment to optimize your operability.