How to Plan and Design a Digital CCTV System
Digital CCTV is offering integrators new and seemingly limitless design choices. Effective system planning means understanding your customer’s needs as well as the characteristics of the interlocking equipment. Asking the right questions and truly listening to your customers is essential.
Digital CCTV is here to stay. The introduction of the first digital signal processing (DSP) cameras and advancing digital technology has thrown the entire CCTV network into a major tailspin.
The basic theory, glossary of terms and many installation procedures have changed to meet this growing digital demand. However, the basic design of any CCTV system has remained the same. Digital technology may sound confusing, but understanding a few buzzwords will help in overcoming the fear of the digital revolution.
This article kicks off a special, six-part series on the world of digital CCTV by focusing on the planning and design stage – typically the most critical part of any project.
Understanding your customers’ needs as well as the characteristics of the interlocking equipment is essential. Ask questions, talk to your customers; try to completely understand their concerns and security needs. However, in the final stage, you are the expert and should make all recommendations concerning the system layout and connectivity.
Good Planning Is Based on Asking Good Questions
When planning any security system, a few important questions must be answered so the customer as well as the system integrator can discuss all available options. The questions may seem to be very simple or foolish in nature, however, they relate to the type of equipment required, or the type of special digital features that may enhance the security system.
To start, the word digital, when used in most CCTV cameras, only means that the camera incorporates digital enhancement for the video signal processing. These cameras offer improved image quality as well as added features (such as backlight compensation, CCD iris control, electronic zoom and electronic sensitivity) to overcome problems associated with certain applications.
However, remember one thing: the output from 95 percent of all surveillance cameras is still analog. The reason lies in the required maximum operating distance needed in surveillance systems. A truly digital output camera would have a very limited operating distance (usually less than 50 feet), which would not be very useful in CCTV. As we turn toward networked cameras and system networking equipment, this limitation will begin to change.
Degree of Protection Determines Equipment
The degree of protection will determine the use of fixed-positioned cameras, remote positioning equipment, or a combination of both. A camera location that uses a pan/tilt or scanning device offers a lower degree of protection. To improve the degree of protection, integration of different systems may be useful.
The overall application or purpose of the system will also determine the degree of protection required. As a rule, the greater the degree of protection, the greater the complexity of the system design, as well as the cost.
New System Applications Are Emerging All the Time
For many, understanding the application or needs of customers can be very difficult. The number of cameras required, the purpose of each camera, the type of switching system, the method selected to transmit the signals, how to display the information and the type of permanent storage devices can confuse even the best of us.
Applications can range from a single remote-view camera location to a 64- to 256-camera, multiplexed system with digital storage. Regardless of the system’s simplicity or complexity, incorporating digital features can enhance each design.
One of the major improvements in using digital signal processing (DSP) cameras is that of backlight compensation (BLC). BLC allows for cameras to be aimed at exits or entrances, loading-dock doors, ATMs or underground parking facilities without the effects of extreme shading or silhouetting.
Another advantage, which is often overlooked, is the reduction in equipment size when converting to digital.
Applications involving color have also increased with the development of digital video processing cameras. The need for additional lighting and increased image quality, which has plagued the CCTV industry, has been greatly improved.
With Camera Positioning, Location Is Everything
The last phase in the planning stage should be determining the location of the equipment. This area is not just limited to the camera site. It should also encompass the monitoring location.
With advanced digital camera features, once-forbidden areas of surveillance are now available. Locating camera equipment has become much easier. But let’s not forget that the age of digital equipment also brings some new areas of concern.
Outdoor Design Takes More Time Than Indoor
Systems are divided into two major sections: indoors or outdoors. For the most part, indoor applications require less design time than outdoors. Reasons for this settle around the need for environmental enclosures to protect the equipment and the requirement for auto-iris lens assemblies.
However, the incorporation of DSP can greatly enhance many indoor and outdoor applications, which were limited by older camera designs. The need for improved image quality by both the end user and today’s digital recording systems is essential for any successful surveillance system. Benchmarks in signal-to-noise ratios, improved BLC, and automatic gain features (AGC) are just a few of the improvements delivered by digital processed cameras.
One of the major concerns for any outdoor application is how well the camera equipment will perform during low or poor light applications. This is one area in which DSP camera assemblies excel.
Addressing the 3 Major Design Variables
When starting any system design, a number of questions should come to mind. This list of questions can quickly be reduced once the application is determined—reverting back to the planning stage of our system. The design stage is broken down into three major parts: camera equipment, communications and switching/display/storage.
Matching Cameras to Lighting Is Essential
We can compare CCTV to photography. In fact, CCTV is nothing more than electronic photography and follows basically the same rules.
Rule No. 1: The more light available, the less sensitive the camera has to be.
Rule No. 2: Matching lighting parameters with camera parameters can enhance image quality.
Rule No. 3: Cameras use reflected light to produce images.No matter how sophisticated the controlling system, transmission system or display and recording system, the total picture quality of any video surveillance system starts with the camera and lens. With this in mind, the first question for design should be, how much available light does the camera require to produce an acceptable video image?
What is electronic shuttering of cameras? In older CCD camera designs, an auto-iris lens was required to produce proper video output levels. The reason was the circuitry of those older chip camera imagers were always at full power or full sensitivity, which made the lens the controlling factor for the video output.
While most camera systems can produce satisfactory images with enough light, the selection of matching lighting characteristics can enhance many of today’s CCTV systems. The advantages of matching a camera to lighting characteristics can be easily recognized, especially when installing color cameras in outdoor applications.
Black-and-White Cameras Not Picky About Lighting
In a black-and-white (B/W) camera system, almost all forms of lighting can be used, even infrared (IR), which can be used to enhan
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