Accuracy requirements in off-line array calibration

Practical sensor arrays are characterized by certain physical parameters, related to the array shape and its electrical properties. Accurate direction finding requires calibration of these parameters to a relatively high accuracy. Depending on the application, calibration may be performed either off-line or on-line. Off-line calibration is performed by transmitting signals from known locations and measuring the array response. The array parameters can then be estimated by maximum likelihood, least-squares, or some other algorithm. This work relates the parameter estimation accuracy achieved in off-line calibration to the direction-of-arrival (DOA) errors during on-line operation. It then proposes a criterion for choosing the off-line calibration points (number and location) so as to meet on-line accuracy requirements.