Bounds and algorithm for direction finding of phase modulated signals
Amir Leshem, Alle-Jan van der Veen · 2002
In many cases where direction finding is of interest, the signals impinging on an antenna array are known to be phase modulated, hence to have a constant modulus (CM). This is a strong property, by itself already sufficient for source separation, and can be used to construct improved direction finding algorithms. We first present the relevant Cramer-Rao bounds for arbitrary array configurations, and arbitrary numbers of signals and then specify uniform linear arrays with a single source. We then propose a simple suboptimal direction estimation algorithm, in which the signals are separated using the CM property only. Compared to the ESPRIT algorithm and to the Cramer-Rao bound for arbitrary signals, the algorithm shows good results.