DOA Estimation Algorithmsfor Noncircular Signals Based On Instrumental Sensor Method

DOA(direction of arrival) estimation plays an important role in array signal processing, and a lot of research has been done on it, some algorithms have been proposed based on the natural characteristics of the signals, which have showed great advantage in the accuracy of DOA estimation in engineering usage. Noncircular signal, one kind of these signals, is widely used in modern communication for its non rotating invariance, and attracts attention of many scholars.The existing DOA estimation algorithms for noncircular signals often require a large number of complex matrix operations, which along with the inevitable influence of noise and array errors makes it hard for these algorithms to reach their theoretical accuracy. In this thesis some research work is done to overcome the above problems, and some algorithms are proposed based on ISM(instrumental sensor method). Here are the details of the main research work and contributions of this paper:1. An analysis is given about the MUSIC(Multiple signal classification) and MUSIC-like algorithms for noncircular signals based on an ideal array signal model for DOA estimation, and then a summarization for general process of direction finding is presented. After that direction- attaching array error model is introduced, an analysis on ISM and the influence on DOA estimation for array error is also presented.2. An improved DOA estimation algorithm for noncircular source was proposed, which is based on ISM combined with the characters of noncircular signal. This algorithm used the real-value extension output mode of noncircular signals, which transform the computing in real mode, at the same time ISM sampled the time-domain characteristics of noncircular source, thus improved DOA estimation accuracy while reducing the computational complexity. The spatial spectrum form is given and a simplification of computing is made followed.3. Some model errors caused by perturbs, mechanical vibration and attitude est. are still exiting in instrumental sensors, which not only reduce the accuracy of angle estimation greatly, but also affect the sensor error correction. A theoretical analysis is made about the influence of unexpected errors on the algorithms proposed above, derived the expression for DOA estimation error, providing a theoretical basis for the algorithm inpractical engineering application.4. Programs are designed for the simulations of the algorithms presented, the simulations are in some certain conditions, then a numerical analysis is made about the simulations results, which show the advantages of ISM algorithm for noncircular signals in DOA estimation on accuracy and resolution. The simulation for the real value algorithm above is also proposed, which displays its simplified calculation ability.