This chapter is a description of the technology with which we can: capture an image, transform the image to the video signal format, transmit this signal to a remote location’s receiver, display the image on a monitor, and save the image and print it for preservation.
Top1. One-Camera Analog Video Security System
Video surveillance technology improved by leaps and bounds in the last half of the 1990s. Video components, including digital cameras, multiplexers, and DVRs developed rapidly. Also, security systems have become more prevalent; they have been integrated into wide area networks (WANs), computer-based local area networks LANs, wireless networks, intranets, and World Wide Web communications systems.
Today’s video surveillance system hardware is so advanced thanks to the great progress made on the following technologies: digital processing, wireless and wired signal transmission, microprocessor computing power, and solid-state and magnetic memory. Of course, the video system utilizes a lens, camera, means of transmission, monitor, recorder, and other basic equipment.
Video surveillance systems exist in order to assist security forces either centrally or remotely. The camera, lens, transmission method, and of course a light source and setting are the vital aspects of such a system. Secondary equipment often includes switchers, multiplexers, VMDs (video motion detectors), combiners and splitters, housings, and character generators. The following chapter is a description of the technology with which we can:
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Capture an image.
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Transform the image to the video signal format.
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Transmit this signal to a remote location’s receiver.
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Display the image on a monitor.
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Save the image and print it for preservation.
Figure 1 shows the simplest configuration; it calls for one video camera and one monitor.
Figure 1. The simplest configuration: one video camera and one monitor
The above one-camera configuration requires the following (Kruegle, 2007):
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Lens: The light source emits rays that reflect the image of the monitored area onto the camera’s sensor.
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Camera: After the lens captures the scene, the camera’s sensor transforms it into a transmittable electrical signal.
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Transmission Link: The electrical video signal is then transferred from the camera to the remote monitor via a transmission medium. These include (a) coaxial, (b) two-wire unshielded twisted-pair (UTP), (c) fiber-optic cable, (d) Local area network LAN, (e) Wide area network WAN, (f) intranet, and (g) Internet network. Wirelessly, one can transmit via (a) radio frequency (RF), (b) microwave, or (c) optical infrared (IR). Transmitted signals can be digital or analog.
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Monitor: In order to display the image, the monitor (which can be a liquid crystal display [LCD], plasma, or cathode ray tube [CRT]) converts the video signal back to a visible image format.
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Recorder: The scene can be recorded onto either a magnetic tape cassette using a VCR or onto a magnetic disk hard drive using a DVR.
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Printer: To produce a hard-copy printout of a scene, a video printer is necessary. It functions using a lens that collects light from the image and prints using printing technology like inkjet, laser, and thermal printing.
Top2. Multi-Camera Analog Video Security System
Block diagrams in Figures 2 and 3 depict a multi-camera analog video security system that uses the previously mentioned modules along with extra options and hardware to increase functionality and complexity. These additions can include: camera switchers, quads, multiplexers, environmental camera housings, camera pan/tilt mechanisms, image combiners and splitters, and scene annotators.
Figure 2. Multi-camera analog video security system