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Acoustic underwater positioning and navigation systems HiPAP and HPR

We presently offer two different lines of Acoustic underwater positioning and navigation systems. For more information on each system use the links on the left side:

  • HiPAP family - High Precision Acoustic Positioning
  • HPR 400P - Portable Hydroacoustic Position Reference

Our family of underwater positioning and navigation systems uses three different principles for measurements and calculations (SSBL, LBL and MULBL). Any combination of the three principles secures flexibility as well as a high degree of redundancy and accuracy.

SSBL - Super Short Base Line - click to enlarge picture

SSBL - Super Short Base Line

The calculation of positioning is based on range and on vertical and horizontal angle measurements, from a single multi element transducer. The system provides three-dimensional transponder positions relative to the vessel. The HPR (Hydroacoustic Positioning Reference) and HiPAP (High Precision Acoustic Positioning) systems are both leaders within these principles.

SBL - Short Base Line - Click to enlarge picture

SBL - Short Base Line

The calculation of position is based on range, and vertical and horizontal angle measurements from a minimum of three hull mounted transducers. The baselines are between transducers on the vessel. A transponder is positioned relative to the vessel. Accuracy is < 0.5% of slant range. The system provides three-dimensional transponder positions relative to the vessel.

LBL - Long Base Line - Click to enlarge picture

LBL - Long Base Line

The calculation of position is based on range measurements only. The ROV, a subsea module and the vessel are positioned relative to a calibrated array of transponders.

MULBL - Multi-User Long Base Line system - Click to enlarge picture

MULBL - Multi-User Long Base Line system

Multi-User Long Base Line (MULBL) hydroacoustic positioning system. Several individual vessels and Remotely Operated Vehicles (ROV) units can now position themselves using the same seabed transponder array.

Acoustic Positioning Operating Station (APOS) - Click to enlarge picture

Acoustic Positioning Operating Station (APOS)

The HiPAP and the HPR systems are operated from the very operator friendly and well proven APOS which is a Windows based software. The system can be operated from one single APOS station or from a wide number of APOS operator stations connected on a network.

Cymbal acoustic protocol

Cymbal – the new acoustic protocol

Second generation HiPAP systems, models 501/451/351/101 which are fitted with the new transceiver unit may be upgraded to the new Cymbal acoustic protocol. This protocol utilizes wideband Direct Sequence Spread Spectrum (DSSS) signals. The Cymbal protocol transmits more energy into the water and thus has longer range, and together with uniqueness coding makes a number of new HiPAP features available.

Hydroacoustic positioning principles

A hydroacoustic positioning system consists of both a transmitter (transducer) and a receiver (transponder). A signal (pulse) is sent from the transducer, and is aimed towards the seabed transponder. This pulse activates the transponder, which responds immediately to the vessel transducer. The transducer, with corresponding electronics, calculates an accurate position of the transponder relative to the vessel.

Wide range of applications

HiPAP is a hydroacoustic Super Short Base Line - SSBL or USBL, underwater positioning system, able to operate in shallow and deepwater areas to proven ranges to about 4000 metres (MF) and 10000 metres (HiPAP101 - LF). It is a multi-purpose system used for a wide range of applications including towfish & towed platform tracking, seabed reference Dynamic Positioning of a vessel, high accuracy subsea metrology and positioning and telemetry and scientific research. Optional enhanced operation is available with Hydroacoustic Aided Inertial Navigation, HAIN, system which increases the HiPAP SSBL positioning accuracy by a factor of up to 300%.

Key HiPAP features

  • Unique spherical transducer design with up to 241 individual elements
  • Extraneous noise suppression techniques
  • Extremely narrow, ±5 degree listening beams
  • Extreme tracking range capabilities
  • True Multi-User LBL function
  • Comprehensive transponder range to support positioning operations
  • Reference output to dynamic positioning system

Technical specifications for the HiPAP family

Model HiPAP 501 HiPAP 451 HiPAP 351 HiPAP 351P HiPAP 101
Operating range1 – 4000 m 1 – 3000 m 1 – 3000 m1 – 3000 m 1 – 10000 m
Position accuracy in % of range1) 0,2 %0,3 % 0,3 %0,3 % 0,2 %
Angle accuracy 1)0 dB S/N: 0,30º
10 dB S/N: 0,18º
20 dB S/N: 0,12º
0 dB S/N: 0,40º
10 dB S/N: 0,23º
20 dB S/N: 0,18º
0 dB S/N: 0,40º
10 dB S/N: 0,23º
20 dB S/N: 0,18º
0 dB S/N: 0,40º
10 dB S/N: 0,23º
20 dB S/N: 0,18º

20 dB S/N: 0,14º
Accuracy dual mode option, Two-TD system1) 20 dB S/N: 0,09º 20 dB S/N: 0,13º20 dB S/N: 0,13º 20 dB S/N: 0,13º 20 dB S/N: 0,09º
Angle accuracies with use of Cymbal will be improved with up to 30 % for all systems
Range detection accuracy1) is 0,1m for all systems
Range detection accuracy with use of Cymbal is 0,02m for all systems
Operating beam (max.)200º 160º 160º160º 120º
Minimum gate valve size required 20 inches/500 mm20 inches/500 mm 14 inches/350 mm14 inches/350 mm 20 inches/500 mm
Transducer diameter400 mm 400 mm 320 mm345 mm 460 mm
Number of active elements241 46 4646 31
Narrow pointing receiving beam10º 15º 15º15º 20º
Hull unit for automatic transducer deployment through hull Available AvailableAvailable Available Available
Number of HPR 400/Cymbal channels 56/5056/50 56/5056/50 30/20
Receive frequency band27,0 – 30,5 kHz 27,0 – 30,5 kHz 27,0 – 30,5 kHz27,0 – 30,5 kHz 13,0 - 15.5 kHz
Telemetry frequency band24,5 – 27,0 kHz 24,5 – 27,0 kHz 24,5 – 27,0 kHz24,5 – 27,0 kHz 12,0 - 13,0 kHz
Transmit frequency band21,0 – 24,5 kHz 21,0 – 24,5 kHz 21,0 – 24,5 kHz21,0 – 24,5 kHz 10,0 - 12.5 kHz


It is very important to use transponders with strong enough output source level to obtain highest S/N ratio and thereby also the best SSBL accuracy.

All HiPAP351P models includes attitude sensors with different accuracies. HiPAP 351P includes MRU-H, HiPAP 351P-5 includes MRU-5 and HiPAP 351P-I includes an IMU and provides also Heading relative North.

1) The Operating range and the SSBL accuracy specifications are based on; free line of sight from transducer to transponder, no influence from ray-bending, Signal to Noise (S/N) ratio in water in the 250 Hz receiver band, and no error from heading and roll/pitch sensors. The angular figures are errors in both axis, elevation and orthogonal.

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