JPS5735772A - Radio direction finder - Google Patents

Abstract

PURPOSE:To enable correct detection of direction without interference of noise by scanning successively the output of plural antennas arranged circularly, and measuring the direction and S/N and utilizing only effective signals during scanning. CONSTITUTION:Plural antennas #1-#n are arranged circularly on the same plane. Receiving signals are inputted to a receiver 3 and a direction detector 4 from an antenna switching unit 2 through control of a switching signal generator 5, and a part of the output is inputted to a direction measuring unit 6 through an S/N measuring circuit and a signal presence detector 9, and the other part is inputted to a direction measuring unit 6 througn a delay circuit 10 simultaneously. When the signals continue and S/N is large, the direction measuring unit 6 detects direction. In the case of noise only or when S/N is small even if there are signals, the signal presence detector 9 sends stop instruction to the direction measuring unit 6. When the direction signal is lacking during the rotation period from the switching signal generator 5, a direction masuring selector 11 controls a gate 12 to stop measruing. By this way, direction measurement is made only when S/N is larger than a fixed value, and thus occurrence of errors can be prevented.