On fundamental performance limitation of direction finding of multiple narrow-band sources under sensor position and pattern perturbations

The authors study the effects of sensor-pattern and sensor-position perturbations on the angle-estimation performance bound for multiple narrowband sources. The Cramer-Rao lower bound is used with a probabilistic modeling of the perturbations. For a uniformly spaced sensor array the position perturbations are found to be a more serious problem than the pattern perturbation, in the sense that raising SNR offers very limited help in compensating the performance degradation caused by the position perturbation