The short-wave technique has a very particular appeal: It can easily bridge long distances. By reflecting short-wave signals off the conductive layers of the ionosphere, they can be received in places beyond the horizon and therefore can reach anywhere on earth. Although technology is striving for ever higher frequencies, and radio is usually listened to on FM, DAB+, satellite or the Internet, modern means of transmission require extensive infrastructure and are extremely vulnerable. In the event of a global power outage, there is nothing more important than the short-wave. Amateur radio is not only a hobby, it's also an emergency radio system! Elektor's SDR-Shield (article no. 18515) is a versatile shortwave receiver up to 30MHz. Using an Arduino and the appropriate software, radio stations, morse signals, SSB stations, and digital signals can be received. In this book, successful author and enthusiastic radio amateur, Burkhard Kainka describes the modern practice of software defined radio using the Elektor SDR Shield. He not only imparts a theoretical background but also explains numerous open source software tools.