Abstract: A marine radar interrogator-transponder navigation and collision avoidance system provides facilities for early detection of, identification of, and communication with cooperating marine vessels. For these purposes, a general coded call may be transmitted by own ship to all other ships in radio range, the reply then being returned from each answering ship with the coded identification of that ship. In this manner, the other ships may be identified. Own ship may call a specific second ship or a shore based transponder, the called transponder returning only the coded message it received. Own ship may call a specific second ship causing an alarm to call the ship's operator to a radio telephone, the identical coded message being reradiated.

Abstract: An electronic docking system utilizing a multiplicity of sensing subsystems to derive and display docking parameters during the docking operation is disclosed. The parameters displayed include bow and stern velocities ship's velocity perpendicular and parallel to the jetty and ship's orientation to the jetty during the docking maneuver. Parameters are derived from data gathered by sensors that include a receive only monopulse and a receive only doppler system which determine the angular position of a selected reference location aboard the ship and a signal with a frequency representative of the ship's velocity from a signal radiated from a beacon antenna aboard the ship. Range measurements are accomplished by utilizing baseband pulse radar systems capable of determining range to accuracies in the order of one foot.

Abstract: A navigation system in which a transmitter-antenna combination radiates two independent signals with a known frequency separation there between. These signals are radiated to an antenna on a navigation marker whereby they are received and directed to a non-linear device in which signals at the fundamental frequencies and frequencies that are linear combinations of the two fundamental frequencies are generated. These generated signals are then guided to the antenna and retro-directively re-radiated. The re-radiated signals are received by an antenna at the transmitting location and directed to a receiver wherein the fundamental frequencies and the desired linear combination thereof are detected and processed to provide the locations and identification of the navigation markers.

Abstract: The invention is a radar harbor surveillance sensor, computer, and display system for providing a graphic display of vessels negotiating confined navigation channels and permitting rapid and accurate assessment of the degree of hazard or safety in the movements of the monitored vessels.