Optimized Algebraic Algorithm for Ambiguity Resolution and DOA Computation in Baseline Interferometer

Abstract

Background: Interferometer is the most preferred technique for high accuracy direction finding. For broadband direction finding (DF) applications, multiple antennas forming a number of baselines are used to achieve better accuracy in measuring the direction of arrival (DOA). Ambiguity resolution in multi-element interferometers is a crucial algorithm for the computation of DOA. Objective: This paper introduces a fast, algebraic Common Minimum Modulo Search (CMMS) algo-rithm for ambiguity resolution and DOA computation. LabVIEW-based tool for Monte Carlo simula-tion of the algorithm over various parameters is described. Method: The CMMS is a computationally efficient algorithm, where the longest baseline phase difference is used for accuracy, and the phase difference data from all other baselines are used for resolving the ambiguities in the longest baseline. A hybrid approach using correlation and minimum algebraic search is used to determine the best fit set of ambiguities to the measured phase difference data. Results: Case studies have been presented in the literature and the performance of the CMMS algo-rithm was validated against established algorithms. This paper discusses the FPGA implementation as well as its simulation results. Analysis is performed on the 6-18 GHz frequency band. Moreover, the sources of errors and resulting limitations regarding the applicability of the algorithm are also discussed. Conclusion: Simulation results establish the algorithm's effectiveness in ambiguity resolution and applicability to diverse array configurations. The short nine-clock cycle processing latency in FPGA is demonstrated by the simulation results.