Azimuth and elevation determn. in multichannel direction-finder - involves fast fourier transform in sepd. processing blocks of sequential samples averaged with allowance for scattering

摘要

The method involves converting input signals in east/west, north/south and all-round channels by a complex digital filter (21-26) into equivalent baseband signals. The signals are distributed among processing blocks of N successive samples weighted (3) with a suitable windowing function, that influences resolution. A block-wise discrete Fourier transform (4) follows and an angle-of-arrival processor (5) feeds an averager (61) for each channel sepd. over M angles (66). The result is suppressed (63) if scattering (62) is interpreted as excessive. The spectral power distribution is also averaged (64,65). ADVANTAGE - Direction of arrival is determined with max. accuracy by simple circuit.