The interpolated ESPRIT algorithm for direction finding

The technique of interpolated arrays is applied to ESPRIT- type direction finding methods. The resulting method uses sensor arrays with arbitrary configuration, thus eliminating the basic restrictive requirement of ESPRIT for two (or more) identical arrays. Our approach allows for resolving D narrow-band signals if the number of sensors is, at least, D + 1, while the original ESPRIT method requires, at least, 2D sensors. Moreover, it is shown that while ESPRIT performs poorly for signals propagating in parallel (or close to parallel) with the array displacement vector, the advocated technique does not exhibit such weakness. Finally, using two subarrays ESPRIT cannot resolve azimuth and elevation even when the sensors are not collinear. However, the interpolated ESPRIT procedure resolves azimuth and elevation using only a single array. All the above mentioned advantages are obtained with a reasonable increase of computation load, thus preserving the basic and most outstanding advantage of ESPRIT. We also discuss, and illustrate numerically, the performance of the original ESPRIT when the sensor locations are perturbed. It is shown that the application of interpolation, in this case, can significantly improve the original ESPRIT performance. Our approach relies on the full knowledge of the array manifold like most basic array processing techniques and in contrast with the original ESPRIT.