Date of Award

12-1991

Document Type

Thesis

Degree Name

Master of Science

Department

Department of Electrical and Computer Engineering

First Advisor

Martin P. DeSimio

Abstract

This thesis presents a Time Dependent Adaptive Filter (TDAF) which exploits the cyclostationarity of digitally modulated communications signals and seeks to improve the Signal to Interference Ratio (SIR) and Signal to Noise Ratio (SNR) of such signals. The TDAF is embedded in a computer simulation of a simple communication system consisting of a data source, data formatter, pulse shaping filter, BPSK modulator, and demodulator. In the simulation the TDAF and a Time Independent Adaptive Filter (TIAF) attempt to extract the Signal of Interest (SOI) from noise or interference. the criteria of Mean Squared Error (MSE) is used as the primary means to compare the performance of the two adaptive filters. Plots of MSE improvement in interference, the improvement is measured as a function of the baud rate of the interference signal, and carrier frequency of the interference signal. It is shown that with respect to the TIAF, the TDAF provides up to 12 dB of improvement. Bit Error Rates (BER) for several simulations are presented. The data indicate that significant improvements in BER might be expected when a TDAF is used in lieu of a TIAF.

AFIT Designator

AFIT-GE-ENG-91D-19

DTIC Accession Number

ADA243800

Comments

The author's Vita page is omitted.

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