Kongsberg EM 712 Multibeam Echosounder

Description

The Kongsberg EM 712 is a multibeam echosounder for high to very high resolution seabed mapping. The EM 712 minimum acquisition depth is less than 3 m below its transducers, and the maximum depth is 3600 m, dependent on array size. Across-track coverage (swath width) is up to 5.5 times water depth, with a maximum of up to 4400 m.

The EM 712 operates in the 40 to 100 kHz frequency range at a maximum ping rate of 30 Hz, with a swath coverage sector of up to 140°. The EM 712 transmit fan is divided into three sectors, transmitted sequentially within each ping on distinct frequencies or waveforms, to maximise range capability and suppress interference from multiples of strong bottom echoes. Beam focusing is applied to transmit and receive beams, with dynamic focusing on all receive beams, and roll (±15°), pitch (±10°) and yaw (±10°) stabilisation is applied in real time.

The datasheet describes three versions: the full performance EM 712, which supports FM sweep pulses, and the EM 712S and EM 712 RD, which use CW pulses. Maximum depth is 3600 m for the EM 712 0.25° × 0.5°, 3200 m for the EM 712 0.5° × 1°, 1800 m for the EM 712S 1° × 2° and 600 m for the EM 712 RD. Transducer arrays range from 0.25° × 0.5° (TX length 3880 mm, RX length 1940 mm) to 2° × 2° (TX and RX length 490 mm), with up to 1600 beams per ping in dual swath mode.

The EM 712 Transmitter Unit measures 600 × 380 × 600 mm (W × H × D) and weighs 67.5 kg, and the Receiver Unit measures 250 × 350 × 260 mm (W × H × D) and weighs 11 kg. An EM 712 USV Subsea Transceiver Unit measures 600 × 227 × 650 mm (W × H × D) and weighs 150 kg. Listed features include dual swath, modular design, water column display, water column logging, extra detections, FM chirp and seabed image.

Technical Specification

Frequency range

40 to 100 kHz

Max ping rate

30 Hz

Swath coverage sector

Up to 140°

Swath width

Up to 5.5 × water depth, max up to 4400 m

Beam patterns

Equiangular and equidistant

Roll stabilised beams

±15°

Pitch stabilised beams

±10°

Yaw stabilised beams

±10°

Transmit sectors

3, transmitted sequentially within each ping

Max depth (EM 712 0.25° × 0.5° / EM 712 0.5° × 1° / EM 712S 1° × 2° / EM 712 RD)

3600 m / 3200 m / 1800 m / 600 m

Min depth (all versions)

3 m

CW transmit pulses

0.2 to 2 ms (EM 712 and EM 712S); 0.2 ms (EM 712 RD)

FM sweep pulse

Yes (EM 712); no (EM 712S, EM 712 RD)

EM 712 max coverage, summer

4400 m (0.25° × 0.5°), 4200 m (0.5° × 0.5°), 3950 m (0.5° × 1°), 3700 m (1° × 1°), 3550 m (1° × 2°), 3350 m (2° × 2°)

EM 712 max depth, summer

3600 m (0.25° × 0.5°), 3400 m (0.5° × 0.5°), 3200 m (0.5° × 1°), 3100 m (1° × 1°), 2900 m (1° × 2°), 2800 m (2° × 2°)

Depth and coverage conditions

BS = −20 dB, NL = 35 dB, f = 40 kHz

TX length

3880 mm (0.25° × 0.5°), 1940 mm (0.5° × 0.5°), 1940 mm (0.5° × 1°), 970 mm (1° × 1°), 970 mm (1° × 2°), 490 mm (2° × 2°)

RX length

1940 mm (0.25° × 0.5°), 1940 mm (0.5° × 0.5°), 970 mm (0.5° × 1°), 970 mm (1° × 1°), 490 mm (1° × 2°), 490 mm (2° × 2°)

Transducer width × depth (all arrays)

224 mm × 118 mm

Max no. of beams per ping (dual swath mode)

1600 (0.25° × 0.5°), 1600 (0.5° × 0.5°), 800 (0.5° × 1°), 800 (1° × 1°), 400 (1° × 2°), 400 (2° × 2°)

EM 712 RD availability

Only with the 2° receiver array configurations

Transmitter Unit

600 × 380 × 600 mm (W × H × D) / 67.5 kg

Receiver Unit

250 × 350 × 260 mm (W × H × D) / 11 kg

EM 712 USV Subsea Transceiver Unit

600 × 227 × 650 mm (W × H × D) / 150 kg

Features

Very high resolution, wide frequency range, FM chirp, roll, pitch and yaw stabilisation, transmit and receive nearfield focusing, seabed image, dual swath, modular design, water column display, water column logging, extra detections

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