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Extracting tactical information from acoustic signals

Smart acoustic sensor systems can be deployed for the automatic detection, localization, classification and tracking of military activities, which are inherently noisy. Acoustic sensors are appealing because they are passive, affordable, robust. and compact. Also, the propagation of sound energy is not limited by obstacles, which block or obscure the clear line of sight that is required for the effective operation of electromagnetic systems. Methods, with examples, for extracting tactical information from acoustic signals emitted by moving sources (air and ground vehicles) are provided for both single sensor and multiple sensor configurations. The methods are based on processing either the narrowband or broadband spectral components of the source's acoustic signature. For example, the tactical information extracted by narrowband processing of single sensor data for a moving source is the source speed, slant range and time at the closest point of approach, as well as the source (or rest) frequency of the narrowband signal. For an array of sensors, the tactical information consists of estimates of a complete set of target motion parameters, which indicate the speed and trajectory of the source. Weapon firings generate acoustic impulses and supersonic projectiles generate acoustic shocks, which can be localized and classified using spatially distributed acoustic sensors. The methods developed for land-based acoustic surveillance using microphone data are also applied to hydrophone data for passive acoustic surveillance of the underwater environment.