PURPOSE:To measure the incident angle of a radio wave and the distance to its transmission point by adding a function which measures the amplitude of a high-order signal and an arithmetic function to a stationary type Doppler system radio direction detecting device. CONSTITUTION:When a radio wave sent at a point S is received at a point R, there is a specific relation present among the elevation angle beta, ionospheric layer height (h), angle Y when the points S and R are viewed from the center O of the earth, and arc length Q. For the purpose, the radio wave is received while nondirectional antennas arranged on a circumference with a diameter D at equal intervals are switched and scanned in order to obtain a received signal and also obtain a component which varies in a SIN wave shape due to phase variation caused by the switching as an azimuth signal. Here, the amplitude (m) of the azimuth signal when the radio wave at an elevation angle of 0 deg., i.e. the radio wave of a ground surface wave is received is found and stored as a reference value and then the amplitude m' of the azimuth signal of a radio wave arriving at an elevation angle beta is measured to find the elevation angle beta. Then the distance Q is found from a trigonometric function of the elevation beta, earth radius (r), and ionospherical layer height (h).
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