Geo Acoustics Sidescan Sonar – Available for rental,hire and ex-rental purchase from Ashtead Technology.
The GeoAcoustics Dual Frequency Side Scan Sonar system is the ideal tool for seabed feature mapping, offering flexibility and high quality results in a simple and reliable package. The system offers high resolution, switch selectable, dual frequency operation (100/410 kHz), which when combined with multiplexed data transmission enables a low drag co-axial tow cable to be used. This also facilitates simple installation onto remotely operated vehicles (ROV's) and combined systems towfish. The versatility, ease of operation and cost effectiveness of the system has made it a popular choice with commercial survey companies.
Transceiver Model SS941 The transceiver unit allows the operator a simple means of controlling various Side Scan operating parameters. The unit includes standard controls such as: Gain, Time Varying Gain (TVG) and Automatic Gain Control (AGC), with duplicated controls for Port and Starboard channels. The operating frequency can also be switched from 110kHz to 410kHz directly from the Transceiver. The choice of frequencies means that long range scanning and short range high resolution investigations are both possible.
Multiplexer - Model SS942 The Multiplexer Unit (SS942) is the sub-sea processing section of the Side Scan Sonar system. The SS942 is mounted in the tail of the towfish, on the tail of a combined towfish or on a ROV, as required. The use of standard sub-sea connectors throughout allows easy installation in all situations. The SS942 includes all of the transmitter and multiplexing electronics, thereby ensuring that transmission power is not lost in the towcable and also reducing the risk of high voltage defects.
The multiplexed data transmission technique employed allows the system to be used with a wide selection of towcables, including twisted pair and co-axial cables. Data from the Dual Frequency Side Scan Sonar can be input to many sonar processing systems, including Coda or Octopus Digital Processors, or it can be displayed on a wide variety of industry standard graphic recorders.
The multiplexed data is analogue and so is not limited by analogue to digital converter resolution and conversion/speed trade-offs inherent in digital systems. This has resulted in a robust unit which is considerably more tolerant of cable leakage than digital systems, and yet offers a resolution equivalent to a 16 bit converter operating at 50k samples/sec per channel.
The standard system employs a lightweight towfish, which is easily deployed by one person and can operate to a depth of 1000 m with an option of 1800 m. There are separate controls for each channel, which makes the system very easy to operate.
The basic system includes the following: · Transceiver (model SS941) · Towfish (model 159D), which houses the Multiplexer (model SS942) and Two Dual Frequency Transducers (model 196D/Port and Starboard).
|Transceiver Model SS941 - Power Requirements||110/240 VAC switchable, 50-60Hz, 50W|
|Temperature||Storage: 20 to 75°C|
|Operating: 0 to 50°C|
|Humidity||10% to 95% RH, non-condensing|
|Mounting||The unit is suitable for either bench or rack mounting|
|Power output to tow vehicle||150 VDC ±3 VDC, 100mA average, 320mA peak|
|Key burst out||455kHz, pulse width selectable 16 Vpp, PRR determinded by key source|
|Key input||Positive CMOS to TTL, 10kW input impedance|
|Modulation frequency||Port 135kHz, Starboard 65kHz|
|Sensitivity||6mV rms input produces 800 mV rms output with a 20dB signal-to-noise ratio (all gain maximum)|
|Input Impedance||5k ohms|
|Output Impedance||600 ohms on all outputs|
|Dynamic Range||Gain: adjustable over 60dB range TVG: -20 to +20dB maximum AGC: -34dB maximum|
|Output||Selectable signal envelope or amplitutde modulated 12kHz|
|TVG delay||3.3ms minimum, 330ms maximum|
|Event Mark||5Vpp, 12kHz, front panel push button or BNC input requiring CMOS or TTL level pulse. Produces visual mark on recording media|
|Key out||0.6ms CMOS/TTL compatible|
|Modes||100kHz and 500 kHz operation|
|Raw signal and processed signal|
|Front Panel Connectors - BNC||Seven each for signals and keys|
|Amphenol||MS3102A-22-34S for deck cable|
|Towfish Model 159D - Tow Speed||1 to 12 knots|
|Frame||Cast aluminium with shear release carry handle/towpoint|
|Nose||Shock absorbing, abrasive resistant urethane. Cavity can carry small auxiliary transducer|
|Multiplexer Model SS942 - Frequency||110/410kHz ±1%|
|Power Output||1.2kW / 1kW pulse ±20%|
|Pulse length||167 µsec/88µsec ±1%|
|Pulse repetition rate||50 pulses per second maximum|
|Protection||Open and short circuit protected|
|Efficiency||Greater than 80%|
|Port Channel||110/410kHz, heterodyned to 135kHz|
|Starboard Channel||110/410kHz, heterodyned to 65kHz|
|TVG||Transmission loss curve compensated at both frequencies. Approximately + 40dB at 100m range|
|Keyburst Frequency||455kHz ±2%|
|Pulse Length||300µsec for 110kHz operation. 600µsec for 410kHz operation|
|Power Requirements||150 VDC at 100mA|
|Tranducers Model 196D - Source Level||223 ±3dB re 1µPa@ 1m|
|Beamwidth||50° by 1°/40° by 0.5°|
|Sensitivity||-190dB re 1V/µPa|
|Depression angle||10° ±1° down|
|Transceiver Model SS941 (W x D x H)||432 x 457 x 187mm||17 x 18" x 7.4""||16kg||35.3 lbs|
|Towfish Model 159D (D x L x 3 fins of tail)||114 x 1285 x 75mm||4.5 x 50.6" x 3""||16.3kg / 22.5kg / 38.6kg depending on ballast used||35.9lbs / 49.6lbs / 85.1lbs|
|Multiplexer Model SS942 (D x L)||102mm x 345mm||4.01 x 13.6""|
|Weight in air||3.2kg||7.05 lbs|
|Weight in water||0.45kg||1 lb|