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Source: World Naval Weapons Systems.

Signaal's (a Dutch company) Submarine Integrated Attack-and-Surveillance Sonar System employs a 96-stave passive cylindrical bow array (four transducers/stave: 96 preformed beams), a cylindrical active transmitting array, triple (25-transducer, arranged 5 x 5: total 32 preformed beams on each side) passive ranging arrays (using wavefront curvature) on each flank, and a four-element HF acoustic-intercept array (the big bow array is used for LF intercepts). They are probably essentially CSU 3-4 and PRS 3-15 arrays (Signaal always bought its wet ends from outside suppliers).

There are 28 broad-band tracking channels: four each for the cylindrical and flank arrays (on eight preselected frequencies), four for the active sonar, and 16 for the HF and LF intercept sonars.  Normally the passive-ranging sonar is slaved to the main bow cylindrical array: range is calculated automatically once a broad-band contact enters the ranging sector.  In at least some cases, tracking is based on the automatic association of inputs from different sensors operating in different frequency ranges.  Active modes are single-ping directional) and single- or multiple-ping ODT. Each sonar has an electronic classification library of up to 300 specific platforms (100 ship classes, 100 sonar types). The system as a whole can store up to 35 tracks, carrying out TMA on up to 20 of them.

Each of the 160 preformed beams is subject to simultaneous complex FFT analysis (LOFAR), the system computer holding 15 min of history on each (total 2 Mbytes). Targets can therefore be detected (and tracked) by ALI: different targets can be tracked simultaneously in wide- and narrow-band.  There are also enhanced classification channels, Zoom-LOFAR (high-resolution vernier analysis) and DEMON (blade and shaft rates).

The HF intercept sonar operates up to 100 kHz, and uses an FFT processor to detect, classify, and correlate contacts.  It incorporates a threat library and can generate automatic warnings.

Work on SIASS began in 1978, and production models were completed in 1982/83.

The system in installed on the Taiwanese (Dutch-built) Chien Lung/Hai Lung class. Reports of installation on board Dutch submarines are incorrect; this sonar was devised because the French government refused to release to Taiwan the Octopus used on board Walrus (2) class submarines.  The associated CDS is Spectrum, which is related to the SEWACO VII of the Walrus (2) class.

Source: World Naval Weapons Systems.

 

 

 

 

 

 

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