| 摘要 |
PROBLEM TO BE SOLVED: To provide an azimuth measuring apparatus in which a phase detection of good linearlity is executed by processing a digital signal, in which an azimuth can be measured by a simpler calculation and in which a sinusoidal signal can be regenerated precisely. SOLUTION: An azimuth antenna 2 scans a plurality of antenna elements arranged at equal intervals on the circumference of a circle sequentially at a prescribed rotation frequency. An A/D converter 17 converts signals from the respective antenna elements into digital signals. An A/D converter 16 converts a reference signal from a receiving antenna 1 into a digital signal. A phase detector 18 multiplies the signals, from the respective antenna elements, to be output from the A/D converter 17 by the reference signal to be output from the A/D converter 16 so as to be phase-detected, and it obtains the rotating sinusoidal signal containing a rotation frequency. An FFT processing part 21 performs a fast Fourier transform processing operation while an azimuth reference signal is used as a frame starting point with reference to the rotating sinusoidal signal. An azimuth-angle calculation part 23 finds the arrival direction of received radio waves based on the azimuth angle of a frequency component vector corresponding to the rotation frequency within a spectrum in an FFT output. |
