Accession Number : ADP006173

Title :   Design of a Compensation Filter for a Quadratic Phase Communication Channel,

Corporate Author : ILLINOIS UNIV AT URBANA

Personal Author(s) : Yeh, K. C. ; Mickelson, R. L.

Report Date : SEP 1989

Pagination or Media Count : 14

Abstract : There has always been great interest in understanding and describing the dispersive effects that occur in many types of communication channels. In this paper an analysis of a general dispersive channel is performed by assuming a known transfer function. It is shown that, for bandlimited signals, the channel can be simulated by a set of weighted delay lines. This model clearly illustrates that mitigation of dispersive effects can be achieved via an inverse filtering procedure. Specifically, a compensation filter is designed using a conjugate delay line. Ideally, complete compensation can be achieved and a replica of the transmitted signal can be restored. In practical implementation and application, these idealized conditions can never be met. Nevertheless, this channel simulator and compensation filter are implemented for a quadratic phase transfer function. The system is tested for three basic signals: Gaussian pulse, rectangular pulse, and sudden phase-switched signal. In addition, the case of transmitting multiple pulses is considered. The simulation yields good results for moderate dispersion. As dispersiveness increases, the number of taps in the compensation filter must be increased in order to restore the received signal to a reasonable approximation of its original shape.

Descriptors :   *ELECTROMAGNETIC WAVE FILTERS, COMPENSATION, TRANSFER FUNCTIONS, DELAY LINES.

Subject Categories : Electrical and Electronic Equipment

Distribution Statement : APPROVED FOR PUBLIC RELEASE