May 1, 2000 12:00 PM,
CCTV has been around for a while, and the technology con tinues to growwith new and innovative products each year. All this innovation in CCTV didnot happen overnight; in fact, there was a time when surveillance meantsomeone would sit above the ceiling of a department store along a catwalkand watch people moving about below them. The only equipment they neededwas a pair of binoculars, a two-way radio, a bag of potato chips and asoda. I spent many an evening maneuvering these catwalks in various placesaround the country searching for broken wires and faulty splices andstumbling upon the attic trolls in their hideaway caves who would let mepass after I had paid the toll.
In the beginning, video surveillance consisted of one camera and one videomonitor. The monitor was located in a remote guard station, and the guardwas expected to look at nothing else but the never-changing picture on themonitor’s screen. Even with a setup this simple, there were obstacles. Thepower source to the camera may have been prone to brown outs and blackouts. The coaxial cable connecting the camera to the monitor had to be at aminimum length because of added noise interference resulting in displaysthat were poor in quality. The video monitor was quite large, and directsunlight was a real concern. A camera inadvertently positioned to look intodirect sunlight would quickly burn out. The ultraviolet rays would damagethe lens of the camera and the circuitry that processed the image. Lack ofsunlight or artificial light was another concern. If there are no lights,there is nothing to see but a black screen.
Ultimately, the industry realized the potential of CCTV and development ofmore sophisticated equipment began. The first big innovation was theintroduction of the multiplexer. This device had the ability to connectseveral cameras to one video monitor. Each camera would be home run to theguard station on individual coaxial cables, connecting individually to themultiplexer, which would sequence one camera image at a time to the videomonitor. The guard was able to control the speed at which the image wassequenced, and he even had the ability to skip certain cameras at hisdiscretion.
What if you needed to see more than one camera at a time? Well, you addedmore monitors. Monitors took up space and generated a lot of heat. Insteadof adding monitors, you could add a screen splitter, and one monitor coulddisplay up to four cameras at a time. The image was smaller (a quarter thesize of the video monitor), but if all you were doing was watching forunusual activity, it sufficed. In large businesses, it was not uncommon tohave a wall dedicated to video monitors and racks of multiplexers.
Another addition to the camera family was the pan-and-tilt camera. Thecamera would be mounted on a motorized bracket, and it would automaticallysweep an area from left to right and back again. If the guard saw somethingsuspicious, he could change the view of the camera. The guard would sit athis station and through the use of a video joystick, override the sweepingmotion and move the camera up or down and left or right to get a betterview of something. If you were really on top of things, you could zoom inor out to an object.
Around the same time that motorized cameras were becoming popular, videorecording was also coming into vogue. The video recorder relied ontime-lapse technology. The recorder would only record a few seconds offootage for every 20 seconds to 30 seconds of real time. This allowed thestore owner or guard to place a tape into the machine and let it run allnight without having to replace the tape every few hours. In the morning,you could watch the entire evening go by in less than an hour. Some 24-hourbusinesses would use this method to confirm that someone worked all night.After awhile, the employees would forget that the camera was there, and themorning video reviews could prove to be quite entertaining.
Banks were rapidly converting their older large black hold-up cameras tomore modern video surveillance systems. This was a blessing for them,because in the old days, a bank teller would have to press a hold-up buttonto activate the camera. The camera would then take photographs in rapidsuccession. The FBI would show up after a hold-up, remove the filmcartridge from the camera and take it to a film-processing lab. Hopefully,the security installer did his job well and had the camera correctly aimedand focused. If not, you had blurred images. If the hold-up button wasaccidentally pressed, which used to happen quite often, you needed to havethe film cartridge replaced as soon as possible. Now, you can immediatelyview the hold-up and get a description of the robber out to the streets inminutes instead of hours.
The video camera itself had evolved over the years from vacuum tube tosolid state. The solid-state camera would generate an image digitally. Theimage would then be converted into an analog signal and then converted to astandard composite video output. This style of camera still had itsdrawbacks. Too much light yielded a silhouetted picture. The quality ofcolor images was still limited to the lighting conditions. Cameramanufacturers developed the BLC (backlight compensation) feature to controlthe silhouettes. Unfortunately, activating the BLC introduced noise intothe video image. The solid-state camera (also known as CCD forcharge-coupled device) continues to evolve. Now, you can add date- andtime-stamp information to your video image. You can see video images in theslightest available light. Some cameras have night vision and IRcapabilities. Still, what was the next step of evolution?
Digital signal processed (DSP) cameras do not convert from digital signalsto analog. Rather, they provide fully digital, complete video processing,which offers the primary advantage of improved video quality. Now, thevideo image can be enhanced during processing and output a truly impressivepicture. You can also control the leakage of undesired light in the imageand reduce those white vertical lines that appear when a bright objectenters the viewing area. Further, the camera’s sensitivity can be doubled.This opens the door to the use of colors in many applications. Colorcameras have been looked upon as inferior to their black-and-white cousinsbecause the quality of the image was not up to people’s standards. DSPcameras bring color applications closer to those standards, and it providesimproved iris control and increased S/N ratios.
Remember the BLC concerns mentioned earlier? With their ability to bettercontrol the gain and iris settings, DSP cameras greatly improve the image,even in the most difficult conditions. DSP cameras also allow remote setupsby way of an RS-232 or RS-485 signal, which will make many a securityinstaller happier because there is no longer the need to climb a 40 foot(12 m) ladder in the rain to adjust a camera’s lens or position. DSPcameras usually come in color models, but black and white models are alsoavailable. To learn more about DSP cameras and see specification forparticular models, feel free to contact the manufacturers.
The size and shape of security cameras has also changed with the evolutionof digital imaging. Because the vacuum tubes required a lot of space andgenerated heat, you needed an enclosure that could house and vent thecomponents. Cameras took on a shoebox appearance. Consequently, they werenot easy to conceal, and mounting them on the outside of a buildingrequired large, reinforced brackets with huge bolts to handle the weight.With the introduction of solid-state and digital cameras, you could greatlydecrease the size and hide them practically anywhere. Cameras can mount onthe wall or ceiling and enclosed in a dome-shaped cover. They can be assmall as a ping-pong ball with a hole the size of a dime on its side. Themounting bracket would be small and can be pivoted into any positionrequired.
Over the years, technology took off, and we began to see variations of thecamera-to-monitor configurations. Instead of a direct coaxial connectionfrom camera to monitor, the camera would connect to a modulator that wouldtake a baseband video image and assign it to its own television channel.You could take several cameras, assign them to unused channels and feed theimages into the cable system that fed the signals back to the television.If you had three or four televisions on the cable system, each televisioncould tune into any camera at any time.
What if you cannot run a coaxial cable from camera to monitor? Well, youcould invest in an RF video system. A video transmitter and receiver arerequired to get your image from one point to another. Some of the wirelessvideo devices that I have seen transmit at a frequency of 2.4 GHz or 5.8GHz. Other offerings on the market include the ability to work at your homePC and have a security camera’s image in the upper corner of your screen.This is accomplished by installing a video capture board into your home PCand connecting a security camera to it. Many video capture boards on themarket today offer this as a standard feature.
Modern intercom systems also offer video communication. Instead of taking achance that the voice at the other end of the phone is who he claims to be,your customer can visually verify the caller before granting access. It allcomes down to personal safety. Today, you do not technically need to be atthe premise to see what is going on. All you need to install is some formof intrusion detection device, motion sensors or door contacts thatinstruct the camera to take a still-shot picture. The image is storedelectronically and through a digital communicator, calls a securitymonitoring center. At the security monitoring center, there is a receiverthat accepts the call, takes the still-shot image and routes it to a videomonitor for display. The monitoring specialist can view the image anddetermine whether or not the police need to be notified. Earlier versionsof this offering proved to be slow, and the quality of the image displayedwas not always acceptable. Fiber optics !and the ever-expanding field ofdigital communications have greatly improved overall operation.
Let’s take this a step further. A security monitoring center is not evennecessary to accomplish remote image viewing. Products are available thatoffer remote viewing of single or multiple video cameras. Video may also berecorded onto a local hard drive or even printed as snapshots taken whileonline. To make this operation feasible, all that is required is a desktopPC equipped with a special video capture board, the appropriate software,and a modem (usually a minimum of 28.8 kbps) to communicate with the remotecamera location.
Remember, too, that regardless of the technology’s current state, therewill probably remain certain basic concerns that will need to be addressed.For example, all cameras, large or small, analog or digital, still need tobe sheltered from rain, direct sunlight and exceedingly hot or coldconditions, and many in the industry tout bulletproof specifications, whichensures the safety of the camera in the harshest environments.Additionally, every camera uses some sort of lens, the eyes through whichit sees the very area it is supposed to monitor. There are a wide varietyof lenses in many styles available for security cameras, the most common ofwhich are wide-angle, zoom or different angles of view. Some lenses canview angles of 80 degrees diameter; others drop down to 19 degreesdiameter. It all depends on the application.
Although it has evolved a great deal since its inception, CCTV technologyremains in a constant state of advancement. Keep your eyes open for newproducts and innovations at your local trade shows and in the pages of S&VC.