METHOD FOR RADIO MONITORING Russian patent published in 2000 - IPC

FIELD: radio engineering. SUBSTANCE: method may be used for secret detection of characteristics (frequency, azimuth, angle of elevation, distance and target type) of multiple intermittent-operation transmitters, which simultaneously enter into current reception band. The method involves coherent reception and synchronous detection of multiple- frequency signals for all bases, produced by reference antenna and all antennas in array, for bandwidth, which is significantly greater than spectral width of single signal of transmitter using Fourier transform. Then, method involves reproduction of complex temporal spectra of signals of each antenna and power spectrum of reference antenna signal. Power spectrum of reference antenna signal is compared to threshold value for selection of frequencies for which complex amplitude of detected signals are calculated by means of convolution of complex conjugate spectra of reference antenna and array antennas. Complex amplitudes of each detected signal using set of three-dimensional Fourier transforms, which differ by phase shift with respect to angle of elevation provide possibility to reproduce two-dimensional complex angular spectrum, which absolute value is used for calculation of azimuthal and elevation directions. Compare of elevation directions β against threshold value provides possibility to distinguish ground and aerial transmitters and detect the slant range D towards aerial transmitters using the following equation D = H|sinβ, where H is known height of target flight. In special case, method involves selective reproduction of two-dimensional angular spectrum with respect to time and frequency using signal of additional reference antenna as time-and- frequency reference mark. EFFECT: increased efficiency and speed of monitoring. 1 dwg