High-resolution phase sampled interferometry using symmetrical number systems

This paper identifies a new phase sampling interferometer approach that can he easily incorporated into the established techniques to provide a high resolution, small-baseline array with a fewer number of phase sampling comparators. The approach is based on preprocessing the received signal using symmetrical number systems (SNS). Antennas based on both an optimum symmetrical number system (OSNS) and a robust symmetrical number system (RSNS) are investigated. The SNS preprocessing is used to decompose the spatial filtering operation into a number of parallel suboperations (moduli) that are of smaller computational complexity. A much higher direction finding (DF) spatial resolution is achieved after the N different moduli are used and the results of these low precision suboperations are recombined. By incorporating the OSNS or RSNS preprocessing concept, the field of view of a specific configuration 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 possible 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 of arrival are quantified for both architectures.