OVERVIEW: The AN/SLQ-61 is a lightweight towed torpedo countermeasure system designed to provide surface ships with active and passive defense against incoming torpedo threats. It is part of the Surface Ship Torpedo Defense (SSTD) suite, specifically configured as the Torpedo Defense Mission Module (TDMM) for modular platforms such as the Littoral Combat Ship (LCS).

DETAILS: The AN/SLQ-61 TDMM consists of a towed acoustic countermeasure array designed to detect, classify, and decoy incoming torpedoes. It uses a combination of passive acoustic sensors and onboard processing to track threats, while deploying countermeasure signals to divert or confuse torpedo guidance. It is housed in a Mission Package container and deployed via the Surface Tow Module (STM) on LCS variants. The system was developed for rapid modular integration, with minimal impact on platform structure or propulsion.

The “AN/SLQ” designation refers to a shipboard electronic warfare or decoy system. The SLQ-61 is specific to the Lightweight Tow (LWT) role and represents a shift to containerized torpedo defense systems under the Littoral Combat Ship Mission Module architecture. The TDMM variant adds modular deployment capability and integration with other Mission Package components such as the ASW Mission Package.

FUNCTION: Once deployed, the AN/SLQ-61 tows an acoustic array behind the ship to detect torpedo signatures. Upon confirmation of a threat, it transmits jamming or false target signals to confuse torpedo homing sensors, thereby seducing the weapon away from the ship.

NOTE:
IOC: 2014 (SLQ-61 baseline), 2016 (SLQ-61 TDMM, LCS deployment)
Operators: United States
Platforms: Independence-class LCS, Freedom-class LCS

SOURCE:
U.S. Navy Program Executive Office LCS: https://www.navy.mil/Resources/Fact-Files/Display-FactFiles/Article/2222824/littoral-combat-ship-lcs/ ; U.S. Department of Defense Budget Justification Books FY2016–FY2018 ; Naval Sea Systems Command (NAVSEA) Publications ; Jane’s Underwater Warfare Systems ; Congressional Research Service Reports on LCS Mission Packages