Summary
International Symposium on Antennas and Propagation
2012
Session Number:POS2
Session:
Number:POS2-31
Monopulse Angle Estimation for Unresolved Targets with a Fourth Order Cumulant
Ryuhei Takahashi, Rokuzo Hara, Teruyuki Hara, Atsushi Okamura,
pp.-
Publication Date:2012/10/29
Online ISSN:2188-5079
Summary:
Monopulse angle estimation with the sum and difference antenna beam has been widely used in current radar and navigation systems. Direction-of-arrival (DOA) is obtained from the monopulse ratio, the ratio of the difference beam to the sum beam output, by referring to the monopulse error curve. Monopulse angle accuracy is generally very close to Cramer-Rao lower bound. However when multiple target signals are arriving at the mainbeam, the monopulse ratios for every single target signal cannot be calculated. As a result, the performance of angle estimation is dramatically degraded. Applying the superresolution angle estimation method such as MUSIC is one of the solutions for this problem only if more than three receiver channels are available. Moreover, the array manifold data must be measured and stored. Generally the array responses are required to be measured at finer angle step than required angle accuracy, resulting in high expense and exhausting measurement. Our goal in this paper is to develop an affordable method that can estimate DOAs of the unresolved multiple targets in mainbeam with monopulse-based method so that no additional receiver channel and no effort for obtaining array manifold are required. To this end, the monopulse method with the virtual ESPRIT algorithm (VESPA) is proposed in this paper. Original VESPA by Dogan and Mendel is a novel cumulant-based DOA estimation algorithm and require a pair of 'guiding sensor' with known identical phase characteristics and relative distance vector. In the proposed method, a derivative VESPA with the sum and difference channel as guiding sensors is used for calculating multiple monopulse ratios of received targets. By introducing the derivative VESPA, the array's degree-of-freedom of monopulse beamformer is increased to four from two. Consequently DOAs for up-to three targets can be estimated via monopulse error curve with the monopulse ratios obtained by the derivative VESPA.