Underwater USBL Positioning Systems


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Positioning of offshore equipment

Highly accurate tracking of offshore equipment during installation to ensure accurate placement at predetermined coordinates

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Navigation of ROVs and AUVs

Track positions of multiple ROVs or AUVs and control their missions with instant commands

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Locate underwater features with geo-referenced coordinates when used together with GPS or differential GPS

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Diver tracking

Exchange information with several divers and track their positions during the mission

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Sensor tracking

Track positions of sensors and detectors to enhance measurement accuracy


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A typical USBL positioning system

A typical EvoLogics USBL (ultrashort baseline) positioning system is pictured above and operates as follows.

A USBL TRANSCEIVER is mounted on a Vessel and uses acoustic signals to determine the distances and bearings toward tracking targets - for example, to autonomous underwater vehicles (AUVs), remotely operated vehicles (ROVs), towfish etc.

A TRANSPONDER is attached to each target. Transponders reply to acoustic signals from the USBL transceiver with their own acoustic pulses, allowing the transceiver to calculate the targets' positions.

The USBL transceiver measures the time from transmission of its acoustic interrogation signal until an acoustic reply from the Transponder is detected and converts it to distance to the transponder. Containing several transducers separated by a short distance (the ultra-short baseline antenna), the transceiver calculates the angle to a transponder using the phase-difference method.

Optional third-party external instruments (an AHRS sensor and/or a GNSS receiver) provide information about the vessel's orientation and real-world coordinates.

The operator's NAVIGATION COMPUTER is interfaced with the USBL transceiver and the external instruments and is connected to the local computer network.

EvoLogics positioning software, the SiNAPS, is installed on the navigation computer. EvoLogics SiNAPS positioning software controls the positioning system and provides display features to monitor the mission in real-time.

USBL transceivers

EvoLogics S2C R USBL devices offer transceiver functionality combined with fully fledged acoustic modem performance: tracking targets and exchanging data with them at the same time does not require switching between modes of operation.

Models sorted by operating frequencies and depth ratings are listed below.

Target transponders

Each USBL transceiver is acoustically compatible with the corresponding type of EvoLogics underwater acoustic modems to be used as target transponders. They offer a wide range of designs and configuration options to match the target and the specific application scenario of the system. 




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S2C R USBL OEM devices

All EvoLogics S2C R USBL Communication and Positioning devices are available in OEM configurations, including versions with custom streamlined antenna covers.

SiNAPS Software

SiNAPS, the S2C intelligent Navigation and Positioning Software
from EvoLogics.

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The USBL buoy is a fully integrated solution. It comprises a USBL transceiver with a built-in battery, mounted to a floating unit with an on-board PC, GNSS receiver with dual antennas, and a Wi-Fi access point.