Mixed signal processor for a robust symmetrical number system direction finding antenna

Abstract

This applied research project has designed, simulated, constructed and tested the performance of a processing system for a prototype direction finding antenna. A mixed signal architecture to derive the direction of arrival from a Robust Symmetrical Number System (RSNS) encoded direction finding array is based on a new phase sampling interferometer approach that can be easily incorporated into established techniques to provide a high resolution, small-baseline array with few number of phase sampling comparators. The approach is based on preprocessing the received signal using the RSNS. The 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 spatial resolution is achieved after the N different moduli are used and the results of the low precision suboperations are recombined, in addition to the reduction of the number of possible encoding errors due to the RSNS' inherent Gray-coding properties. This has resulted in a four inch antenna array being able to attain an angular resolution of less than 1.8 degrees with a continuous field of view of 120 degrees. The accompanying electronics occupy two 6 inch by 8 inch printed circuit boards, making this system ideal for platforms with limited space and volume.