Interpolation techniques in high-resolution residue antenna architectures

Abstract

A direction finding antenna based on residue number systems (RNSs) is presented. Special spacing requirements for the array elements are derived and processing of the array output for high speed direction of arrival (DOA) estimates is discussed. The RNS antenna processor encodes the interferometer phase response, which is a sawtooth folding waveform. By design, the phase response of each element pair folds with folding period equal to the chosen modulus. If DOA samples are generated by stepping the emitter direction between -90 and 90 degree in small increments, some samples will fall about the code transition points and result in encoding errors. The resulting DOA estimates from such a realizable system could contain large spikes or "glitches" at these points. These encoding errors in the resolved DOA can be reduced by interpolation. Three primary methods will be discussed to compare the capability of removing the glitches: LSB-Shift Method Random-LSB Method, and Shift Last Good-Sample Method. A comparison of the performance of the three methods is made on the basis of simulation data.