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
.jpg)