Multiple target detection and estimation by exploiting the amplitude modulation induced by antenna scanning. Part II: detection

This work deals with the problem of detecting and estimating multiple radar targets present in the same range-azimuth resolution cell of a surveillance radar system with a mechanically rotating antenna. First, the target parameters are estimated assuming a maximum number of possible targets. To this purpose we use the asymptotic maximum likelihood (AML) RELAX estimator derived in the first part (for pt. 1 see ibid., p. 529-532 (2003)). Subsequently, these estimates are used in a sequential hypotheses test (SHT) procedure. The statistic of the test at each step of the SHT procedure is derived using an asymptotic expression of the generalized likelihood ratio test (GLRT) statistic. An upper bound of the false alarm probability is derived in closed form, whereas detection performance of the proposed SHT detector is investigated through Monte Carlo simulation.

1. INTRODUCTION

In most modern radar Systems, the target direction of arrival (DOA) is estimated by the monopulse technique [8]. When multiple targets are present in the range-azimuth resolution cell under test (CUT), the monopulse method provides an erroneous DOA measure [5]. This work describes a method to detect multiple targets present in the same CUT using only one receiving channel, exploiting knowledge of the antenna beam pattern and the amplitude modulation impressed on the received signal by mechanical scanning [1]. In the literature, the problem of estimating the number of components present in a multicomponent signal is termed the “detection problem” or “model order selection”. Many authors have investigated the model order selection problem by using information theoretic criteria (ITC) [9]–[11]. maximum a posteriori probability (MAP) methods [4], or sequential hypotheses testing (SHT) methods [7], [9].