PURPOSE: To improve the accuracy of reading bearing while enabling the checking of the modulation and intensity of incoming radio waves by displaying a propeller image indicating the incoming direction of radio waves with a specified processing of a bearing pulse, multipulse or the like stabilized in the phase.

CONSTITUTION: According to radio waves received with an antenna 1 to be switched sequentially, a detection signal with the phase opposite to the direction of coming radio waves is generated from a detector 5 and a bearing signal, double and quadruple wave signals are formed stably at a high accuracy by removing noises and undesired components synchronizing the detection signal in the phase with a PLL7. These signals are processed with a gate circuit 8, an integration circuit 9 and the like to generate a triangular wave whose apex coincides with the coming direction of radio waves, which is combined with a received signal via an AM detector 6 to control a balance modulator 11 and a deflection circuit 14 with a combined wave whereby a propeller image indicating the incoming direction of radio waves is displayed on a CRT15. Such a construction not affected by noises or the like can improve the accuracy of reading bearing while enabling the checking of modulation and intensity of radio waves with a back image of the propeller image.