Digital transmissions are rapidly supplanting analog transmissions in both amateur and commercial radio communications. Digital radio transmissions offer many inherent advantages. Digital techniques allow virtually noise-free transmission of data, messages, control commands, sounds and images to be achieved. Digital transmissions allow information to flow from multiple sources to multiple destinations on the same radio channel in an organized and efficient way. Information is communicated in a form that is easy to store and access. And when needed, information security can be readily added to a digital transmission.

Amateur Radio can be proud of its pioneering contributions to digital radio communications techniques, and especially the TucsonAmateurPacket Radio Corporation (TAPR), which developed the first widely used terminal node controllers for amateur packet radio.

I believe one ofthe most important contributionsTAPR has made to digital radio communications recently is the publishing of this book. Tom McDermott, who has an extensive professional background in-digital telecommunications, covers the topic of digital radio transmissions in a remarkably lucid and accessible way. Tom has held the complex mathematics typically found in most books on this subject to a minimum. Instead, Tom uses an easy to understand graphical approach to explain digital communications concepts. Tom has also included a collection ofExcel" spreadsheets with this book that allows the reader to explore a number of digital communications principles.

Amateur radio enthusiasts, engineering students and radio communications professionals will find this book both an excellent introduction to the digital radio communications and a useful dayto-day reference.