POSITION DETECTOR

PURPOSE:To simplify structure and to improve durability and reliability by utilizing the directivity of an acoustic wave receiver and calculating the direction of a received signal from its amplitude. CONSTITUTION:Once a computer 71 sends out a start signal for acoustic wave transmission, an oscillating circuit 72 and a transmitter 73 transmit an acoustic wave. At the same time, a time 74 starts measuring time. Signals of reflected waves receives by two receivers 75 and 76 are detected by detectors 77 and 78 and if either signal exceeds a preset threshold value, a comparator 79 generates a trigger signal. By this signal, the timer 74 stops counting and its value at that time is inputted to the computer 71. Signals detected by peak detectors 80 and 81, on the other hand, are supplied to a divider 82 for division and its output is inputted to the computer 71. The computer 71 finds the azimuth from a sensitivity ratioazimuth curve stored previously and also calculates the distance from time dealy.