The book provides diagrams of devices for protecting information, describes the principles of operation, and provides recommendations for manufacturing and configuration.

The book is intended for trained radio amateurs who want to apply their knowledge in the field of protecting information and objects.

Contents: Radio transmitters for warning and alarm systems. Telephone repeaters. Acoustic microphones and transducers. Receivers for warning and alarm systems. Technical means of information security. Radio emission detectors. Protection of telephone sets and communication lines.