Method of detection and determining an angular location of frequency agile emitters

Abstract

The present invention uses feedback,from RF carrier frequency measurements,to disassociate the emitter angle-of-arrival component,in the ambiguous phase measurement,from the initially unknown phase measurement integer ambiguities,; to then process,resolve the ambiguities; and finally to process,to obtain the correct emitter AOA. The present invention does this by converting the actual interferometer baselines,on which the unassociated pulse,phase measurements,were made at different emitter frequencies to a baseline set,for a single-frequency equivalent interferometer array. This conceptual array has the following property: the phase measurement,that would be made on it at the fixed frequency for a signal at the same direction-of-arrival,are identical to the actual phase measurements made on the physical array. Because of this equivalency the conceptual array is called the E(equivalent)-array. But, whereas the physical array has antenna spacings,that are invariant, the E-array “antenna” spacings,change as a function of the RF carrier frequency measurement feedback,which depends on the particular residual pulses being tested. Thus there is a different E-array, even for the same frequency agile emitter, depending on the particular residual pulse set,used.