Accession Number : ADA189434

Title :   Estimation of Azimuthal and Vertical Arrival Angles at a Rotatable Horizontal Line Array,

Corporate Author : DEFENCE RESEARCH ESTABLISHMENT ATLANTIC DARTMOUTH (NOVA SCOTIA)

Personal Author(s) : Trenholm, B A ; Theriault, James A

PDF Url : ADA189434

Report Date : Jul 1987

Pagination or Media Count : 52

Abstract : A Horizontal Line Array (HLA) receiver is a one-dimensional array of sensors lying in the horizontal plane. An HLA can be used to detect an underwater acoustic source, and to obtain an estimate of the direction of the arriving signal. Due to the one-dimensional nature of the HLA, the bearing estimates are subject to left-right ambiguity. HLA bearing estimates are also susceptible to bearing bias caused by non-zero vertical arrival angles. The true bearing angle and the vertical arrival angle may both be estimated if a second observation is made. This can be accomplished by rotating the HLA to a new orientation. The problem can be modelled as two nonlinear equations in two unknowns. A closed-form solution is presented for the case of stationary source and receiver. Error bounds on the estimates can be calculated as a function of observation errors, HLA rotation angle, and signal arrival geometry. For small observation errors, the resulting errors in the estimated angles can also be expressed in closed form. Keywords: Underwater acoustics; Beamforming; Antenna; Ambiguity; Signal processing.

Descriptors :   *ANGLE OF ARRIVAL, *SONAR ARRAYS, *BEAM FORMING, *PASSIVE SONAR, ANGLES, ARRAYS, BEARING(DIRECTION), BIAS, CANADA, DETECTORS, ERRORS, ESTIMATES, HORIZONTAL ORIENTATION, LINEAR ARRAYS, NONLINEAR ALGEBRAIC EQUATIONS, ONE DIMENSIONAL, SIGNAL PROCESSING, SOURCES, STATIONARY, UNDERWATER ACOUSTICS, VERTICAL ORIENTATION

Subject Categories : Acoustic Detection and Detectors

Distribution Statement : APPROVED FOR PUBLIC RELEASE