US Patent 7952520 DVOR monitor device, and DVOR monitor method

A monitor antenna receives radio waves transmitted from a Doppler very high frequency omnidirectional radio range (DVOR) device and includes a carrier signal and a subcarrier signal, orthogonal detectors shift a phase of a signal of each subcarrier component by a phase difference equivalent to a prescribed distance away from the DVOR apparatus relative to a signal of a carrier component, and a combiner combines signals of the carrier component and the subcarrier component to output the combined signal to a DVOR demodulator.