A major change with this third edition is the availability of a new laboratory manual. The Lab Manual developed for the second edition will be retained for those of you who use it. This new Laboratory & Activities Manual provides more actual hands-on hardware experiments with modern circuits and components. While many circuits are still explored, the attempt is to push toward more systems-level experiments. Building a practical, affordable but meaningful lab is one of the more difficult parts of creating a college course in communications. This new manual provides practice in the principles by using the latest components and methods. Affordable and readily available components and equipment have been used to make it easy for professors to put together a communications lab that validates and complements the text.