Automated Situational Awareness Technology for Collision Avoidance

The primary sensor used by a submerged submarine for target detection, tracking and collision avoidance is passive SONAR. Modern SONARS have evolved to a point where contacts can be detected and tracked with a high degree of accuracy. There are situations however, when contacts are not detected or trackers become unstable due to acoustic conditions or relative position of the contact to the submarine. This can result in a close encounter or even more disastrous, a collision. All vessels emanate horizontal electric dipole (HED) and extremely low frequency electromagnetic signals (ELFE) caused by permanent galvanic corrosion currents on the hull of the vessel, which leak into the surrounding conducting seawater. These signals have been detected at ranges to 2000 meters. E-field sensors have specific advantages over acoustic sensors because they are not affected by acoustic conditions and are most effective inside SONAR near field ranges. An array of E-Field sensors on the submarine hull can provide enhanced short-range localization. Acoustic and E-Field signal detections can be fused to provide an alert to the submarine Commander of contacts "close aboard" therefore improving situational awareness and avoid disastrous consequences such as a collision at sea.