CCTV system involved the use of analog cameras that were connected to a VCR for recording video. The system was completely analog. The VCR used the same type of cassettes as those sold for a home VCR. Each camera needed its own coax cable to run from the camera all the way to the VCR. The video was not compressed, and when recording at full frame rate, one tape lasted a maximum of eight hours. Eventually, a so-called time lapse mode was incorporated into the VCRs to make the tape last longer. The time lapse mode enabled the recording of every second, fourth, eighth, or sixteenth image. That was how the video surveillance industry came up with such specifications as 15 fps (frames per second), 7.5 fps, 3.75 fps, and 1.875 fps, because these were the only recording frame rates possible in analog systems that used time lapse recording. If several cameras were used, quads became another important system component. A quad simply took inputs from four cameras and created one video signal output to show four different images on one screen; hence, the name “quad.” This invention made the system a bit more scalable but at the expense of lower resolution.
In even larger systems, multiplexers became commonplace. A multiplexer combined the video signals from several cameras into a multiplexed video signal. This made it possible to record even more cameras, often 16 on one device. The multiplexer also made it possible to map selected cameras to specific viewing monitors in a control room. Still, all equipment and all signals were analog. To monitor the video, analog monitors connected to a VCR, quad, or multiplexer.
Although analog systems functioned well, the drawbacks included limitations in scalability and the need to maintain VCRs and manually change tapes. In addition, the quality of the recordings deteriorated over time. The cameras, for a long time, were also black and white. Today, most analog cameras are in color.
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