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USBL Positioning and Tracking Systems

EvoLogics S2C R USBL modems combine powerful USBL transceiver functionality with full benefits of an S2C technology communication link.   S2C R modems with a built-in USBL antenna enable accurate tracking and full-duplex digital communication, delivering an excellent all-round performance.  Switching between positioning and communication modes is not necessary: positioning data is calculated simultaneously with acoustic transmissions. Both features complement each other in a fully integrated positioning and communication system.

S2CR USBL devices implement advanced data delivery algorithms, support addressing and networking and are easy to control with a comprehensive set of commands and software-configurable settings.

The S2C R USBL series offers a selection of short- mid- and long-range devices for shallow or deep water applications. Each product is available in a variety of configurations to offer the best-fit solution for a particular scenario.


EvoLogics'  underwater acoustic positioning software, SiNAPS, provides easy-to-use display features for real-time tracking of multiple targets, supports interfacing with external instruments and offers advanced data management tools.

Applications for USBL

Positioning of offshore equipment

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

Navigation of ROVs and AUVs

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


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

Diver tracking

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

Sensor tracking

Track positions of sensors and detectors to enhance measurement accuracy


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

EvoLogics S2C R 1527 USBL Acoutic Modem


Depth-rated devices for long-range vertical or slant transfers

Frequency: 15 - 27 kHz

Acoustic Connection: up to 9.2 kbit/s

Operating Range: 6000 m

Directivity: wide-angle (120 degrees)

EvoLogics S2C R 1224 USBL Acoustic Modem


Depth-rated devices for long-range vertical or slant transfers

Frequency: 13 - 24 kHz

Acoustic Connection: up to 9.2 kbit/s

Operating Range: 6000 m

Directivity: conical (70 degrees)


S2C R 42/65 USBL

High-speed devices for mid-range vertical and slant transmissions

Frequency: 42 - 65 kHz

Acoustic Connection: up to 31.2 kbit/s

Operating Range: 1000 m

Directivity: wide-angle (100 degrees)


S2C R 48/78 USBL

High-speed devices for  mid-range horizontal transmissions

Frequency: 48 - 78 kHz

Acoustic Connection: up to 31.2 kbit/s

Operating Range: 1000 m

Directivity: horizontally omnidirectional


S2CR USBL ROV Tracking System for VideoRay ROV

EvoLogics S2C VideoRay ROV USBL Tracking System

This USBL solution offers high accuracy positioning to VideoRay owners by simply swapping the floating block of the VideoRay. The EvoLogics floating block is self-contained and self-powered, so that even in the case of a broken tether, it still is possible to track the position of the ROV.

EvoLogics S2C R 717 USBL modem


Depth-rated devices for long-range horizontal, vertical or slant transfers

Frequency: 7 - 17 kHz

Acoustic Connection: up to 6.9 kbit/s
Operating Range: 8000 m
Directivity: Several available



Depth-rated devices for long-range horizontal, vertical or slant transfers

Frequency: 7 - 17 kHz

Acoustic Connection: up to 6.9 kbit/s

Operating Range: 10000 m

Directivity: Directional 80 degrees


For a same-day quote, please use our email form.  

Or give us a call at 855-SUBSEA1  (855-782-7321)

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SC2 R 18/34 USBL

High-speed device for short-range applications in shallow waters.

Frequency: 18 - 34 kHz

Acoustic Connection: up to 13.9 kbit/s

Operating Range: 3500 m

Directivity: Horizontally omnidirectional


S2C R 18/34H USBL

High-speed devices for short range transmissions in shallow water

Frequency: 18-34 kHz

Acoustic Connection: up to 13.9 kbit/s

Operating Range: 3500 m

Directivity: hemishperical

EvoLogics USBL Modem OEM Version

OEM Version

For vehicle/platform integration 

All EvoLogics S2C Underwater Acoustic Modems and Positioning Systems are available in OEM configuration without housing, ideal in cases where minimal size and weight are critical.

OEM devices feature standard S2C electronics and a cable-mounted transducer, carefully matched to the analog front end unit for best performance.


These systems are ideal for integration into your own products and equipment, such as:

  • AUVs and ROVs

  • Integrated sensors

  • Surface buoys


OEM devices can be configured with most of options and modules available with standard S2C devices.

SiNAPS USBL tracking software by EvoLogics

SiNAPS Tracking Software

S2C intelligent Navigation and Positioning Software

  • Web-based user interface - use the software on any device

  • in the local computer network.

  • Real-time multiple target tracking.

  • Extensive system configuration options.

  • Increased positioning accuracy when interfaced with an internal or external AHRS (Attitude and Heading Reference System) sensor and an external

  • GPS receiver.

  • Useful display tools, distance measurement tool, settings management tools.

  • Advanced data management options: internal database, real-time NMEA data output, customizable data export.

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