This book contains the essential information you need for actually installing, repairing and maintaining security systems, audo (sound) systems and video systems, such as formulas, tenhnical data and terms. In addition, I have included information on the technologies that these systems must now interact with, such as fiber optics. You will also find that I have covered the base technologies that security, sound and video systems are built upon - electronics and communications. In this book you will find not only the basic formulas and symbols for these technologies, but also the installation requirements for communication systems, which have been, over the years, extended to apply t securit, sound and video installations as well.