Apparatus for the Detection of Angles-of-Arrival of Radio Frequency Signals.
DEPARTMENT OF THE ARMY WASHINGTON DC
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Incoming radio frequency signals from one or more remote transmitters, that may be changing or hopping in frequency, are received at two closely spaced antennas. A pair of Chirp-Z transform processors are respectively coupled to said antennas. The transform processors are operated in synchronism and produce a pair of sampled comb filter output responses, each of which comprises a multiple of frequency bins distributed over a given spectrum. The bins are read out of the Chirp-Z processors in a synchronous sequential order, and each bin is represented by a pair of signals in phase quadrature. The phase quadrature signals of corresponding bins are multiplied in a predetermined manner and the products there of are selectively added and subtracted to provide a predetermined function tan psi of the phase difference psi between the signals incident on the pair of antennas. This predetermined function is coupled to a processor that calculates a trigonometric function are sine thereof which is indicative of the angle-of-arrival of the incident waves.
- Direction Finding
- Radiofrequency Wave Propagation