TRUE BEARING DETECTOR

PURPOSE:To obtain a stable true bearing against the fluctuation of tidal current, etc., by providing a ship motion measuring means to measure the travel direction and speed of the ship based on the transmission/reception of an ultrasonic wave, a drift angle calculation means, a true bearing calculation means, and an automatic true bearing switching means. CONSTITUTION:A CPU 40 supervises the control of whole tidal current. A program to be executed by the CPU 40 is written on a ROM 41 in advance, and the passage data of each layer, the travel direction and speed of its own ship, etc., are stored in a RAM 42, and display data is stored in a VRAM 43, and a display control circuit 46 performs the readout control of the VRAM 43. An interface(I/F) circuit 47 performs interface with a compass 48, and the CPU 40 reads a bow bearing via the circuit 47. An I/F circuit 49 performs the interface with a tidal current control circuit 30, and the CPU 40 finds the tidal current and the travel direction and the speed of the ship from the Doppler shift quantity of a reflected wave and that of submarine reflection from each layer via the circuit 49. An I/F circuit 50 performs the interface which supplies the true bearing and the leading, etc., to a ship locus display device 51 and a scanning sonar 52.