passive sonar

technique

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July 1, 2026

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Passive sonar is a technique used to detect and determine the distance and direction of underwater objects by listening for sounds they produce. Unlike active sonar, which emits sound waves and analyzes the echoes, passive sonar systems simply use receiving sensors to pick up noise from targets like ships or submarines. These detected waveforms can then be analyzed to identify characteristics, direction, and distance.1

Passive sonar systems can be hull-mounted, deployed from sonobuoys, or towed behind a ship. Some are also placed on the seabed for continuous surveillance. While effective, sonar systems are limited by sound attenuation in water, bending caused by temperature differences, and extraneous noises.12

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sonar
Passive systems consist simply of receiving sensors that pick up the noise produced by the target (such as a ship, submarine, or torpedo). Waveforms thus detected may be analyzed for identifying characteristics as well as direction and distance. The third category of sonar devices is…
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Passive systems consist simply of receiving sensors that pick up the noise produced by the target (such as a ship, submarine, or torpedo). Waveforms thus detected may be analyzed for identifying characteristics as well as direction and distance. The third category of sonar devices is…
Read More

submarine
Silencing
…British navies began to investigate passive sonar, in which sensors detected noises emanating from the submarine itself. Early nuclear submarines were quite susceptible to such detection because their machinery was very noisy. In particular, the pumps required to circulate the coolant, which could not be turned off without melting the…
Read More
…British navies began to investigate passive sonar, in which sensors detected noises emanating from the submarine itself. Early nuclear submarines were quite susceptible to such detection because their machinery was very noisy. In particular, the pumps required to circulate the coolant, which could not be turned off without melting the…
Read More