A direct sequence baseband communications system using programmable logic devices

Abstract

As digital systems grow rapidly in complexity and sophistication, the educational process must provide future developers with experience that incorporates advanced development tools and modem design techniques. However, this cannot be achieved at the expense of relevant theory and traditional design methods on which modem methods are based. Hence, the learning experience must efficiently combine emphasis on classical design principles with an exposure to state-of-the-art tools and techniques. This student project demonstrates the use of hardware description language design with programmable logic devices to develop a digital system of significant complexity, while introducing the basic principles of spread spectrum communications. After 20 years, this latter technology still remains a modern digital approach to reliable communications, and provides a practical and challenging educational application. This paper summarizes the design and full system hardware implementation of a baseband digital direct sequence spread spectrum communication system for classroom demonstration. The system configuration includes a serial transmitter with pseudorandom spreading routine, a receiver with despreader, and other diagnostic equipment.