Techniques and benefits of shaping the pulses of binary sequences with application to spread spectrum radio communications.

Abstract

This research is concerned with binary sequences. Such two-level voltage waveforms are used in some types of spread spectrum systems. Of interest in this work is the effect of shaping the normally rectangular pulses of the binary sequence. An objective is to find and tabulate particular sequences and specific shapes having desirable autocorrelation functions and power spectra. A direct and versatile method of shaping binary sequences is presented. Photographs of sequences having triangular, raised sine and ramp shapes are included in the report. Photographs of the autocorrelation function and spectra of selected shaped sequences are presented. The computer programs used to search for sequences of interest and used to calculate the autocorrelation function and spectra of particular shaped sequences are described. Shaped sequences having interesting spectra were discovered. For example, some spectra have very small side lobe levels; others have no discernible nulls in the spectra; some spectra have nulls which are not simply related to the sequence clock frequency (pulse rate).