Overview

Triangulation is the appellation applied to estimating a PF by calculating the most likely point for the target, given the intersection of two or more LOBs from sensors at known locations. It is widely used in this role, and there are several techniques available for measuring the azimuth angles of arrival of signals. Noise, measurement errors, and multipath reflections typically limit the PF accuracy.

Triangulation can be implemented on all varieties of platforms, including aircraft, ships, and ground vehicles. If signal phase is used as the parameter for computing the LOBs, then triangulation requires an array of antennas, with a baseline shorter than half a wavelength to avoid ambiguities in phase angle measurement. Parameters other than phase, such as relative amplitude, can also be used as the angle indicator. Most methods, however, require the antenna array.

This chapter starts with a simple illustration of triangulation to introduce the fundamental concepts. Several of the available algorithms for optimum PF calculation are based on the least-squared error (LSE) estimation technique. Therefore, a generalized introduction to the LSE method is presented next. An extension to the LSE method is the total least-squared error (TLSE) technique, which is somewhat more general and is presented next. PF algorithms based on the method of least-squared distance error are presented. This is followed by a discussion of optimum PF estimation based on the method of minimum mean-square error. A technique based on dividing up the area of interest (AOI) into discrete intervals,...