Low-Frequency Active Towed Sonar (LFATS)

 

Photo Credit: L3HARRIS

Overview

  • Full-feature, long-range, low-frequency variable depth sonar
  • Designed for active sonar operation against modern diesel-electric submarines
  • Demonstrates consistent detection in shallow and deep water
  • Provides passive mode with a full suite of tools

Compact & Configurable

  • Small, lightweight, air-transportable, ruggedized system
  • Easy installation on small vessels
  • Operates stand-alone or integrated into ship’s combat system

Tactical Capabilities

  • Bistatic and multistatic interoperability with HELRAS helicopter dipping sonar
  • Compatible with key sonobuoys

Maneuverability & Handling

  • Own-ship noise reduction algorithms with compact twin line receivers
  • Enables short-scope towing, efficient maneuvering, fast deployment, shallow-water operation
  • Ultrastable winch and handling system for safe operation in heavy seas
  • Manual or console-controlled deployment, retrieval, and depth-keeping

Coverage & Transmission

  • Full 360° coverage with dual parallel array configuration
  • Advanced signal processing for unambiguous left/right target discrimination
  • Omnidirectional, large aperture acoustic performance in compact tow-body
  • Directional transmission (forward, aft, port, starboard) reduces reverberation near shorelines

Mission Planning

  • Built-in sonar performance prediction based on modeled or measured environmental data

Key Features

  • Wide-area search
  • Target detection, localization, and classification
  • Tracking and attack capability
  • Embedded training

Sonar Processing

Active

  • Band: 1,200–1,000 Hz
  • Processing: CW, FM, wavetrain, multi-pulse matched filtering
  • Pulse lengths: 0.039–10 sec (range-dependent)
  • FM bandwidth: 50, 100, 300 Hz
  • Tracking: 20 auto and operator-initiated
  • Displays: PPI, bearing range, Doppler range, FM A-scan, geographic overlay
  • Range scales: 5, 10, 20, 40, 80 kyd

Passive

  • Band: Continuous 100–2,000 Hz
  • Processing: Broadband, narrowband, ALI, DEMON, tracking
  • Displays: BTR, BFI, NALI, DEMON, LOFAR
  • Tracking: 20 auto and operator-initiated

Common

  • Own-ship noise reduction
  • Doppler nullification
  • Directional audio

Playback & Testing

  • Playback mode integrated into passive and active operation
  • Enables post-analysis of mission data for training
  • Built-in test modes: power-up, continuous background, operator-initiated

Displays & Interfaces

  • Workstation-based operator interface with trackball, menus, parameter selection
  • Multifunction OpenGL displays for search, classification, geographic formats
  • Ground-stabilized, high-resolution color monitors
  • Operator aids: recommended settings, automated range-of-day estimation, data history recall
  • Modular, expandable open architecture with COTS hardware

Ship Electronics

  • Towed subsystem
  • Winch and handling system
  • Transmit power amplifier
  • Sonar operator console

Specifications

  • Operating Modes: Active, passive, test, playback, multi-static
  • Source Level: 219 dB omnidirectional, 222 dB sector steered
  • Projector Elements: 16 in 4 staves
  • Transmission: Omnidirectional or sector
  • Operating Depth: 15–300 m
  • Survival Speed: 30 knots

Size

  • Winch & Handling: 180 × 138 × 84 in (4.5 × 3.5 × 2.2 m)
  • Console: 60 × 26 × 68 in (1.52 × 0.66 × 1.73 m)
  • Amplifier: 42 × 28 × 68 in (1.07 × 0.71 × 1.73 m)

Weight

  • Winch & Handling: 3,954 kg (8,717 lb)
  • Towed Subsystem: 678 kg (1,495 lb)
  • Ship Electronics: 928 kg (2,045 lb)

Platforms

  • Frigates, corvettes, small patrol boats

Receive Array

  • Configuration: Twin-line
  • Channels: 48 per line
  • Length: 26.5 m (86.9 ft)
  • Directivity: >18 dB @ 1,380 Hz


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