Digital Video: A Revolution in Recording

Digital video technology has, during the last five years, revolutionized television surveillance. This leading-edge technology is providing dramatic changes for facility designers and equipment installers and bringing important new benefits to users. The technology is a major advancement over previous technologies. Remember that for 20 years-from the mid 1960s to the mid 1980s-tubes were the biggest improvements in television surveillance. After that came the CCD camera followed in years 1985-1995 by the multiplexed monitoring video. And now we have digital video technology. Digital video has the ability to record, archive, playback, and process images in an operationally assignable fashion. The advantage of digital video is that it improves both facility operations and management.

Making the Most of Technology

Recording digitally is done in a number of fashions-on tape, hard digital memory, digital tape, hard disk, CD-read-write disks, and others. Almost all video is analog, but with digital video technology, the image is immediately digitized upon processing. And digital techniques allow various service features to be inserted or processed, including multiplexing, event alarming, alarm by overall picture light, alarm by pixel-sensitive segments, and sleep-writing. Sleep-writing (sleep-mode) involves the recording of images that are not written into permanent memory but instead continuously written over until an event occurs. This feature saves a tremendous amount of hard disk space and media processing while maintaining a high level of alarm, capture, and video evidence of historical events for management review. In effect, it “unreads” what is not important. System designs are based on critical needs and appropriate applications. Typically, most devices are tailored to specific tasks. If a user wants every available feature, however, the system will be very large, expensive, and probably unnecessary because full systems usually apply to highly specialized applications. These units are large PC-based systems that consume an entire console bay and come complete with CRT, processing computer, electronics, keyboard, mouse, and other typical PC widgets. However, more typical are smaller units-less than two inches high-that store 50 gigabits of video memory with 16 picture, multi-application processing.

Digital Value

When properly setup, digital video can reduce the physical size of security and monitoring equipment, ease maintenance, and increase facility efficiency. And when a “killer app” is specified, costs may triple, complexity may double, but it could be the envy of Q in a James Bond movie. For the next dozen or so years, not one outboard technology will have the in-your-face impact that video cameras and the digitization of this media will have on the corrections industry.

Jerry Forstater is CFO and chief engineer of Philadelphia-based security and communications consultants Professional Systems Engineering LLC. Mr. Forstater is frequently invited to speak about digital video at many industry events. He can be reached through the firm’s Web site,