High-resolution phase sampled interferometry using symmetrical number systems

This paper identifies a new phase sampling interferometer approach that can be easily incorporated into the established techniques to provide a high r esolution, small-baseline array with fewer number of phase sampling compara tors. The approach is based on preprocessing the received signal using symm etrical number systems (SNS). Antennas based on both an optimum symmetrical number system (OSNS) and a robust symmetrical number system (RSNS) are inv estigated. The SNS preprocessing is used to decompose the spatial filtering operation into a number of parallel suboperations (moduli) that are of sma ller computational complexity. A much higher direction finding (DF) spatial resolution is achieved after the N different moduli are used and the resul ts of these low precision suboperations are recombined. By incorporating th e OSNS or RSNS preprocessing concept, the field of view of a specific confi guration of interferometers and phase sampling comparator arrangements can be analyzed exactly. The OSNS gives the maximum dynamic range or number of spatial resolution bins while the RSNS reduces considerably the number of p ossible encoding errors. Experimental results for both a 5-bit OSNS and a 6 -bit RSNS array are compared. The errors in the encoding of the direction o f arrival are quantified for both architectures.