Performance assessments of a time-domain adaptive processor in a broadband environment

The paper is a study of a time-domain adaptive array processor operating in a broadband environment. The processor is a variant of that due to Widrow; in particular processing is carried out in octave bands and sensor data are not time shifted. The constraint system consists of four to seven linear point and gradient constraints, together with a soft norm constraint. Computations assume full adaptation, stationary data and sensor amplitude and phase errors. Calculations are made of array gain, array response and of the detectability of wanted-signal spectral lines in the output beam. Comparison is made between the performance of this processor and that of a conventional beamformer and of a frequency-domain adaptive processor. A wide variety of noise environments are selected, some fairly complex. Frequency bands are taken to cover a range of six octaves. The general conclusion is that the time-domain processor is both economical on processing time and has a reasonable level of robustness against sensor errors and time-varying environments. The performance loss due to suboptimal processing is normally not great, but for certain types of noise environments it can be significant.