OVERVIEW: The SCAD‑102 (Submarine Countermeasure Acoustic Device) is an internal, self-contained torpedo-decoy round used by Royal Navy submarines. It functions by emitting programmed acoustic signals to misdirect incoming torpedoes.

DETAILS: SCAD‑102 is fitted to internal signal launchers aboard British SSBN and SSN classes, including Vanguard and Astute submarines. The decoy is mission-programmed before deployment and, once ejected, hovers at a selected depth (10-300 m), broadcasting spoof sonar signals including active and passive decoy patterns tailored to counter threats like Mk 48 ADCAP torpedoes. It autonomously adjusts its acoustic profile to mimic the submarine’s Doppler signature and remains operational until its battery depletes or the mission profile concludes.

FONCTION:
Launched from a submarine’s internal signal-launcher system.
Hovers at depth while emitting pre-programmed acoustic decoy patterns.
Seduces or jams incoming homing torpedoes through tailored acoustic signature reproduction.

SOURCE:
The Shadowy World Of Submarine And Ship‑Launched Torpedo Countermeasures – explainer page; International Defense Security & Technology article on SCAD‑102; Escuela Superior de Guerra Naval (SCAD descriptions) PDF