Title :
The effects of IF bandpass mismatch errors on adaptive cancellation
Author_Institution :
US Naval Res. Lab., Washington, DC, USA
fDate :
5/1/1990 12:00:00 AM
Abstract :
The effects of IF bandpass mismatch errors on adaptive cancellers are investigated. Frequency mismatch errors occur because of errors in the synthesis process of the bandpass filters which are designed to be identical and are in each input channel. Tapped-delay line transversal filters can be used to compensate for these frequency mismatches and thus improve cancellation performance. A pole/zero error model of the filters is developed whereby closed-form solutions of the maximum achievable average cancellation are obtained. This cancellation is a function of the order of the ideally matched frequency filters, the number of time-delay taps in the compensating transversal filter, the bandwidth-tapped time-delay product, and the constraints on these parameters. A design procedure is outlined for optimizing the canceller with respect to these parameters and their constraints; specifically, results are presented for Butterworth-type input filters. It is shown that an arbitrarily low output noise residue cannot be achieved by arbitrarily increasing the number of time-delay taps
Keywords :
antenna phased arrays; band-pass filters; delay lines; error compensation; poles and zeros; Butterworth input filter; IF bandpass mismatch errors; adaptive arrays; adaptive cancellation; bandpass filters; bandwidth-tapped time-delay product; closed-form solutions; compensation; pole/zero error model; time-delay taps; Band pass filters; Closed-form solution; Constraint optimization; Design optimization; Filtering theory; Frequency synthesizers; Matched filters; Noise cancellation; Poles and zeros; Transversal filters;
Journal_Title :
Aerospace and Electronic Systems, IEEE Transactions on