Using the City and Guilds/SITO Knowledge of Security and Emergency Alarm Systems syllabus (course 1851) as its basis, the chapters cover all aspects of CCTV theory and technology. The term "closed circuit" refers to the fact that the system is self-contained, with the signals being accessible only by equipment within the system. This contrasts with "broadcast television," in which the signals may be accessed by anyone with the appropriate receiving equipment. After tracing the development of the CCTV industry, a chapter on signal and power transmission addresses such subjects as CCTV signals, co-axial cable, ground loops, twisted pair cable, ribbon cable, fiber-optic cable, infrared beam, microwave link, CCTV via the telephone network, connectors, and power supplies. This is followed by a chapter on light and lenses, which discusses lens theory and parameters, electrical connections, lens mounts, filters, lens adjustment, and lens finding. A chapter on the technical aspects of the CCTV camera is followed by chapters on monitors, recording equipment, camera switching and multiplexing, telemetry control, and commissioning and maintenance. Extensive figures and a subject index