Portable Diver Detection Sonar system (PDDS)
1. Product overview
PDDS is a portable sonar system capable of detecting potential underwater threats like divers and diver delivery vehicles in shallow waters. The system alerts the operator to confirm the type of threat so that effective countermeasures can be initiated in time. The system can be deployed either outboard a ship or at any location in a harbour, typically beside a wall, pier or at the sea bottom. The system consists of units under water and on shore, interconnected by water blocked cable carrying data and power supply lines. The wet-end unit is a sonar head consisting of transducer arrays, transmitter and front-end receiver electronics hardware. The shore units consist of an interface unit, a processing and display units and power supply. As an auto-alert system, PDDS performs detection, tracking and classification of divers or diver-like targets automatically and alerts the operator accordingly. The target information provided by the system includes (i) target position (range and bearing) and (ii) target dynamics (speed and course).
3. System Configuration
As shown in Fig. 2, the total system consists of a wet-end unit (sonar head) connected through a water-blocked cable to an interface unit, form where further data is transmitted to a 3 processing and display unit. A deployment structure is also provided, depending on the type of installation.
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3.1. Wet-end Unit
The wet-end unit of PDDS consists of the transducer arrays and the associated electronics for transmitter and receiver, all housed inside a watertight enclosure. The transmitter consists of a projector array and power amplifiers. The input signal to the power amplifier is generated by the processor and fed through a transmitting controller. The transmitter is designed to generate acoustic signals of specific strength, pulse shape and pulse width that can be controlled according to the water conditions prevailing at the location of operation. The receiver consists of a hydrophone array and front-end electronics. The hydrophone array picks up the incoming acoustic signals and transforms into electrical signals. The signal strength is very low of the order of a few microvolts. Therefore, the hydrophone output is amplified using preamplifiers, and then filtered, digitized and passed on to the signal processor.
3.2. Interface Unit
The data from the wet-end unit is transmitted through a watertight cable to an interface unit, which is installed on shore or on-board ship close to the point where the watertight cable comes out of the water. The data is received in the interface unit and further transmitted across to the processor and display unit. The power supply of 220V is fed to the interface unit, from where it is supplied to the wet-end unit.
3.3. Processor & Display Unit
The Processor & Display Unit is a high performance ruggedized computer (with integrated WLAN). It performs advanced acoustic signal processing algorithms, including, Beam former, Automatic Detection, Automatic Track and Automatic classification. The detector and track output are displayed in the display with map overlay.
4. System Features
High frequency sonar with extended detection range
Fully automated solution for underwater security
Detects and classifies underwater intruders with very low target strength
Automatic alarm on detection of threat
Capable of detecting multiple targets around 360° in the azimuthal plane
Useful for protection of waterside assets & installations with 24x7 surveillance
Very narrow beams for fine resolution in bearing of small targets
High probability of detection
Low probability false alarm
Very low maintenance requirements
Enables rapid deployment and movement between sites
Portable system with compact packaging
Flexible deployment schemes for fixed-site applications / on board vessels
Ruggedized system for operation in all-weather and water conditions
Modular design enables customization for site-specific geography
User friendly GUI scheme for quick and efficient operation
Provides sonar picture in desired formats
Provides tactical GUI with map overlay
https://www.drdo.gov.in/drdo/English/CAT-A_Portable_Diver_Detection_Sonar.pdf