Because this chapter uses a building block approach more than do previous chapters, it may seem to be a long succession of setting up straw men and demolishing them. To some extent, this imitates the development of radio and TV, which went on for most of the twentieth century. A large number of concepts were developed as the technology advanced, and each advance made new demands upon the hardware. At first, many of these advances were made by enthusiastic amateurs who had no fear of failure and viewed radio communication the way Hillary viewed Everest — something to be surmounted “because it was there.” Since about World War II, there have been increasing numbers of engineers who understood these principles and could propose problem solutions that might work the first or second time they were tried. The author fondly hopes this book will help develop a new cadre of problem solvers for the twenty-first century.