IMPLEMENTATION OF ACQUISITION AND TRACKING SYSTEM FOR DIRECT SEQUENCE SPREAD SPECTRUM SYSTEM

Abstract

Spread sprectrum techniques, applied in recent years, have produced results in communications, navigation, and test systems that are not possible with standard signal formats. In many applications the advent of high-speed transistors and/or integrated circuits was the key to practical sized-and-powered equipment based on spread spectrum modulation. A number of techniques are available for spreading the spectrum of an information bearing signal. The direct-sequence spread-spectrum (DSSS) system has been particularly chosen for this dissertation because direct sequence systems are the best known and most widely used spread-spectrum systems. This is because of their relative simplicity from the stand point that they do not require a high-speed, fast-settling frequency synthesizer. The basic purpose of this dissertation is to review the techniques of acquisition and tracking of PN code and then consider hardware implementation of the DSSS system. The DSSS system has been implemented with ordinary components and TTL integrated circuits. An experimental direct-sequence spread-spectrum system, with a bandwidth expansion of 2000 times, to transmit 1 K bps signal over.a channel of 2 MHz has been designed. The receiver, comprising of a delay-lock loop tracking system and serial-search acquisition system has been built. Results of our investigation are reported in this dissertation.