Pre-calibrated USBL positioning and communication system
Gaps in operation


Gaps is a high-performance Ultra Short Baseline (USBL) positioning and communication system dedicated to subsea assets localization. It combines an USBL antenna and a Fiber-Optic based Inertial Navigation System (INS) in the same housing. Gaps does not require on-the-field calibration.

Advanced acoustic techniques including wideband signals ensure maximum performance in the most challenging conditions. Its unique 3D acoustic array enables highly accurate tracking and communication from very shallow water, to the deep sea, and offers advanced performance at horizontal angles.


Main performances

% x slant range


  • Rapid deployment
  • Operational cost savings, pre-calibrated, easy to install & operate
  • Accurate positioning
  • Robust performance
  • Flexible deployment operations
  • Horizontal tracking
  • Tracking and communication with the same equipement


  • Compact, all-in-one INS and USBL solution
  • High-grade INS for ultimate performance
  • Provides absolute georeferenced position for the beacon
  • Compatible with all major navigation suites
  • Easy interface with subsea INS (iXblue and third-party)
  • DP mode : L/USBL/INS (PRS, MRU & Gyro in one equipment)
  • Over 500 available acoustic channels
  • Unified iXblue web interface
  • 3D display software included (Delph RoadMap)
  • 3D acoustic array geometry
  • Wideband modulation



Gaps Subsea applications

Oil & Gas

  • Structure placement, Dynamic Positioning (DP)
  • ROV navigation, AUV & glider operations, Towfish tracking
  • Cable/pipe laying
  • Diver tracking
  • Exploration, drilling, mining, seabed crawler, touch down monitoring, mattress lay, plough/trench positioning
  • Out Of Straightness, BSR positioning, seismic (streamer, nodes, OBC)


  • Diver & AUV tracking
  • Underhull inspection
  • Imagery
  • Mine counter-measure
Canopus in Operation

Earth Science

  • Geodetic fields monitoring and data collection
  • ROV, AUV, gliders and towfish tracking


  • Why is a Gaps calibration free?

    It is mandatory for USBL systems to be calibrated with an INS/AHRS on board of a vessel to give accurate position and attitude to the USBL system. Calibration is not necessary with Gaps because it contains an INS inside of the USBL head. The calibration is done during the manufacture process. In this case, no calibration is necessary by the end user and Gaps can be installed and be operational in less than an hour.

  • If Gaps is calibration free, why do I need to execute an alignment procedure?

    Gaps mixes USBL, INS and GPS technologies to give the most accurate USBL data in its category, it operates in deep or very shallow water and difficult environments where other systems are deficient. As Gaps has an integrated INS, this allows its use without a calibration. Where it is necessary to carefully calibrate all other USBL systems with the INS on board, It is not necessary to carry out this calibration for Gaps, as it is pre-calibrated at our factory with Phins inside. This will save a lot of time for users and GAPS can be operational in less than an hour. The important point to know is that it is necessary to align Gaps to obtain the best accuracy. This means that it is necessary that the vessel stay with a constant heading during 5 minutes for the coarse alignment, then it is necessary that it move in different directions for 25 minutes for the fine alignment. In only 30 minutes, Gaps will be ready to deliver you the specified accuracy.

  • How can I retrieve the IP address of my Gaps?

    By default the IP address is indicated on the Gaps BOX sticker and is, with XX being the last two numbers of the serial number. If the IP address has been changed and is not known, the following steps can be taken. If you have changed the address and lost it, you can retrieve this IP address as follows: Connect a hyperterminal on the PC to one of the RS232 sockets. Configure the terminal to the following settings: baudrate 115200 bds, data bits 8, parity: none, stop bits: 1. Reboot the unit by switching it off and on, the IP address will be broadcasted by Gaps on the hyperterminal.

  • How should I set the blanking time on my Gaps for the best performance?

    In order to get the best responses from your Beacons, you must always set a blanking time based on the recurrence you have set in the Gaps. The blanking time must always be -200ms from the recurrence of the interrogations from the system. For example, if the recurrence is set to 1s, then you must configure the blanking time to 0.8s. Refer to Gaps user manual for detailed tables for different examples.