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Sentinel sonar head

Intruder detection sonar

Engineered for: Diver

Used a part of a Sentinel underwater security installation, a Sentinel sonar head provides wide-area coverage detection, tracking and classification of underwater threats.

At a glance

Man-portable, easy and quick to deploy

Up to 900 metre diver detection range; up to 1,200 m UUV detection range

Choice of housing materials to suit deployment scenarios and environmental conditions

Environmentally friendly low 206 dB re 1 µPa @ 1 m source level

360 degree coverage; segmentable into 45 degree sectors e.g for deployment against a harbour wall

Integrated attitude and heading reference sensor to compensate for movement

360 degree, long range detection

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Developed by our sister company Wavefront Systems and manufactured and commericalised by Sonardyne, a Sentinel sonar head has a wide bandwidth transmission capability, centred by default on 70 kHz with a bandwidth in excess of 20 kHz.

Source level for the default transmission is 206 dB re 1 µPa @ 1 m. 8 separate 45° transmit sectors are used, which are individually addressable, allowing any segment to be disabled to reduced nuisance acoustic returns from close in objects such as harbour walls or jetties.

The transmitters themselves are fully programmable and supplied with a number of frequency modulated Doppler tolerant pulses that can be selected via the Sentinel system configuration file.

The compact 1:3 piezo-composite transducer array has 128 separately wired elements, which are used to form 256 equally spaced, receive beams – each with a 1.4° (3.5m) horizontal beam width. Software further interpolates these beams to provide highly accurate bearing estimation for the target.

The sonar head also contains the electronics to digitise, baseband, multiplex and transfer the signals received by the transducer, along with control and monitoring software that performs constant built-in-testing to verify the health of the transducer elements and front-end electronics.

Efficient electronics and transducer arrays result in a total power budget of less than 70 W.

Data is transferred to the surface via either 65 m copper or 300 m or greater fibre-optic cable.

An attitude and heading reference sensor is included in the sonar to compensate for orientation and motion of the sensor. This also allows the sonar to be mounted either way up.

Sentinel sonar heads are available in both a lightweight aluminium housing, suitable for expeditionary use, and in an super duplex housing for permanent installations.


Feature Type 8160-000-01 Expeditionary Model Type 8160-000-02 Long Immersion Model
Depth Rating 50 m 50 m
Operational Frequency 70 kHz 70 kHz
Bandwidth 20 kHz 20 kHz
Source Level (dB re 1 µPa @ 1 m) 206 dB 206 dB
Pulse Length 40 ms 40 ms
Receive Beams 256 256
Detection Range (Scuba Diver) Radius 1000 m Radius 1000 m
Acoustic Cover 360° 360°
Target Bearing Accuracy Down to 0.35° Down to 0.35°
Target Position Accuracy <1 m at 150 m range <1 m at 150 m range
Voltage 55–0–55 V ac 55–0–55 V ac
Power Maximum 70 W Maximum 70 W
Communication Cat6 Ethernet Cat6 Ethernet
Mechanical Construction Aluminium alloy, PVC and PU Super duplex, PVC and PU
Dimensions (Length x Diameter) 432 x 330 mm (17 x 12”) 432 x 330 mm (17 x 12”)
Weight in Air/Water 35/6 kg (77/13.5 lb) 45.5/18 kg (100/40 lb)

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360 degree, long range detection