Angle and waveform estimation via RELAX

Describes how the RELAX algorithm, recently proposed for temporal spectral analysis, can be extended to the spatial problem of angle and waveform estimation for both narrowband and wideband plane waves arriving at a uniform linear array (ULA). Both numerical and experimental examples are used to demonstrate the performance of the RELAX algorithm and compare the performance of RELAX with that of other well-known algorithms including ESPRIT with forward/backward spatial smoothing, MODE/WSF, and AP/ANPA for narrowband signals, and CSM-ESPRIT for wideband signals.