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Sonar Performance Prediction Systems SPPS

The SPPS is desiged for:

• Performance Evaluation of Sonar Systems
• Evaluation of Naval Warfare Scenarios
• Detection and classification aid in sonar systems
• Sonar System Design
• Oceanographic Studies

It handles active and passive sonar detection problems, broadband and narrowband signals. All types of sonar antennas are included like

• Towed array (nested)
• Bottom moored line array (nested)
• Flank array (line and planar)
• Conformal array
• Hull - mounted arrays (active, passive)
• Passive ranging arrays
• Variable depth arrays
• Active towed arrays
• Vertical arrays
• Bistatical transmitting / receiving arrays
• ROV - arrays

The directivity patterns of the antennas are variable (including side lobe level, horizontal beamwidth, horizontal direction, vertical beamwidth and tilt angle).

Coherent and non-coherent signal processing algorithms. Threshold system. Examination of environmental effects on the sonar system and the naval warfare scenario.

Integrated Ocean-Accoustic Propagation Model

The objective of this hybrid model system is to provide accurate, valid and userfriendly 2D, N x 2D and 3D model capable of realistically predicting the propagation of sound in the sea. The frequency ranges of the hybrid model system cover the ranges from 10 Hz to 1 MHz. The hybrid model system will be able to incorporate:

• shallow water propagation
• compressional and shear waves
• coupling between wave types at interfaces and boundaries
• depth dependence in the elastic properties
• wide propagation angles

Environmental Data Base (EDB)

An EDB is a system for storage, display, management and analysis of spatial data. This data base will store in files shallow water acoustic measurements in terms of the measurement position in latitude and longitude and the measurement time in year, month and hour (useful for checking diurnal effects).

In an EDB each piece of spatial information has an associated co-ordinate that explicitly specifies where it is located. For example, when storing sea temperature and/or salinity data, there are x,y,z co-ordinates that specify the location and depth of each particular measurement.

An EDB, therefore, consists of different layers and coverages of information that are interrelated through the coordinate system. Because of these interrelationships, data on different layers (i.e. temperature, salinity etc.) can be analysed and potential relationships explored.

Finally, a very important characteristic of an EDB is that it permits visualisation of spatial data.

An EDB system that stores data related to the sea could include layers related to:

• bathymetry
• hydrographic measurements (e.g. CTD, XBT data)
• bottom stratification

and could be “tied” to interpolation routines that estimate temperature, salinity etc. between measurement points and display thematic maps.

PC Based Generic Sonar Simulator

Characteristics

Targets

• Number of targets: 16
• Active characteristics: Target Strength and highlights (as a function of aspect angle)
• Passive characteristics:
• BB and NB spectrum of each noise source on board target (as a function of aspect angle and speed)
• Several noise sources may be defined
• DEMON (as a function of RPM, # of blades, # of shafts)
• Transients
• On board Active sonar
• Dynamics:
• Platforms: straight line with piloting by Instructor
• Torpedo: typical dynamics (search and homing phase)

Own Ship

• Self noise due to BB, NB, DEMON sources
• Flow Noise (as a function of speed and dome parameters)

Environment and sea acoustic parameters

SVP, wind speed, bottom depth and material, sub-bottom parameters, reverberation parameters, shipping density, rain, ice, biologic, seismic Transmission Loss calculation is based on

• Ray model for frequency above 1 kHz
• Normal mode model for frequency below 1 kHz

Sonar Model

• Transmitter: frequency, pulse length, source level, modulation, transmission mode (Omni, Directional, RDT, etc.), PRI
• Active Search Receivers: Energy detector, Coherent Processor, Split Beam Correlator and more
• Passive BB Receivers: Energy detector, Split Beam Correlator and more
• Passive NB Receiver
• Active Classification: A-Scope
• Passive Classification: DEMON, LOFAR
• Active and Passive Tracking

Video

GSS generates sonar video for all typical display formats: B-Scope, A-Scope, PPI, Passive amplitude/bearing, Passive waterfall (BT), DEMON, LOFAR, NB frequency/bearing (BFI), Active bearing track (SSI), Active Doppler track (TDI), Passive bearing track (BDI), and more.