The interpolated ESPRIT algorithm

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. The approach allows for resolving D narrowband 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, this technique does not exhibit such weakness. While using two subarrays ESPRIT cannot resolve azimuth and elevation, even when the sensors are not collinear. The interpolated ESPRIT procedure resolves azimuth and elevation using only a single array. These advantages are obtained with a reasonable increase in computation load, thus preserving the basic and most outstanding advantage of ESPRIT.