Adaptive Canceller Limitations due to Frequency Mismatch Errors.
Abstract
The effects of frequency mismatch errors on adaptive cancellers are investigated. Frequency mismatch errors occur because of errors in the synthesis process of the bandpass filters designed to be identical which are in each input channel. These frequency mismatches among the channels result in cancellation degradation. 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 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 when the input filters are the Butterworth type. It is shown that an arbitrarily low output noise residue cannot be achieved by arbitrarily increasing the number of time delay taps. Keywords include: Adaptive filter, Radar, and Adaptive cancellation.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 02, 1986
- Accession Number
- ADA163122
Entities
People
- Karl R. Gerlach
Organizations
- United States Naval Research Laboratory