By Robert Moskal
The application of CCTV security has not changed very much over the past years, but on the other hand, the tools and equipment have changed significantly. Surveillance cameras have become smaller, cheaper and better, but the major breakthrough has been in the recording equipment. Therefore many customers shopping for complete CCTV monitoring and recording systems are confused by such a veriaty of available products. The goal of this article is to guide buyers toward best possible and most economical type of CCTV equipment, based on intended implementation and requirements.
Selecting the Right Surveillance Cameras
In this article we will focus our attention on the most popular and widely used camera types in the CCTV "family". CCTV security cameras produce images using CMOS or CCD (Charge Couple Device) chips. Tiny, very low price CCTV cameras usually use CMOS technology, produce poor quality images and have very poor light sensitivity. Decent quality CCTV cameras use CCD technology. The size of the CCD chip is normally 1/4", 1/3" or 1/2". As a rule of thumb, the larger the size, the higher the quality of the image produced and the higher the price. However, higher density 1/4" and 1/3" CCD chips can now produce as good an image as many 1/3" or 1/2" chips.
The number of TV lines in the security camera image is a measure of picture resolution (sharpness). The larger the number of TV lines, the better the resolution and hence, overall picture quality. A standard resolution camera may have 350-380 lines, over 400 TV Lines is generally considered good resolution while over 500 TV lines is considered high resolution. B/W chip cameras produce greater resolution and better light sensitivity, therefore suitable for use in dark areas where light conditions are poor most of the time. On the other hand color cameras offer more realistic and natural pictures.
CCTV Camera Types
CCTV cameras are usually divided into different types based on the body of the camera used:
Professional grade cameras have a box type body with the ability to use different types and sizes of lenses. Exchangeable lenses enable this camera, to monitor objects from virtually any distance. Although intended for indoor use, they can be used for outdoors when combined with weatherproof housing. They are considered to be the most flexible and are widely used by professionals for commercial installations.
Bullet cameras are, as the name suggests, contained inside a bullet shaped housing. Most bullet cameras are weatherproof and sealed without the ability to use different lenses. A great advantage of bullet cameras is their small size and integrated design; some bullet cameras will even have an infrared LED feature built-in. Infrared technology is simply LED light in infrared spectrum (not visible to the human eye). This light will illuminate the viewing area, making monitoring possible in complete darkness. This is a great feature, but it only works up to a certain distance (usually between 10 and 50 ft. depending on the model. Being very simple to install and estheticly designed, bullet cameras are a great choice for residential and do-it-yourself (DIY) installations where monitoring objects are within about 25ft from the camera location (with standard 3.6mm lens).
Board Cameras are basically a fixed lens mounted on a circuit board. These cameras may be packaged in a small case (Mini Cameras) or dome (Mini Dome) or simply sold unpackaged, for mounting by the purchaser. Lenses in these cameras are either of a normal industry aperture or a "pinhole" lens of very small aperture. Pinhole lens cameras are often called "spy" cameras and may be mounted in a concealed way for covert surveillance purposes. The most popular examples of covert board cameras are smoke detector and motion detector cameras. Since the lenses in board cameras are pre-mounted, have a fixed iris and are usually of a short focal length (i.e. wide angle), their flexibility of usefulness is limited. However, this type of camera can provide a low cost solution in the right situation, particularly in a home environment. We have now briefly described the most popular types of cameras. Let us now discus, how and where they mighte be used.
Professional type cameras with C/CS mount lens attachments generally offer the best performance and many important features, like lens control output, Back Light Compensation and many more. The distance from the monitoring object to the camera is not an issue here, that is why the ability to select different lenses, based on camera location is so important. Installation is a bit complicated and professional installation is strongly recommended. We recommend this type of security cameras for commercial installations.
Most Bullet cameras, in comparison, do not offer high resolution and lens selection flexibility, but are likely to be weatherproof. Some will have an infrared light built-in and most of all they are relatively easy to implement. Bullet cameras usually come with 3.6mm lenses witch are considered to be suitable for most standard installations (good for covering small to medium size rooms or equivalent). For larger rooms or longer distances, cameras with 6mm or higher lenses may be required. They are a great choice for any do-it-yourself installation.
Board cameras in contrast are widely used in covert camera installations, sometimes called Spy Cameras. Many wireless cameras are basically board cameras with built-in transmitters. We are not going to go into wireless cameras right now, as this would be enough material for s completely new article. Board cameras are sold as plain circuit boards, for integrating into hidden camera devices. They are also available in dome housing, as a very popular Dome Camera or integrated with Smoke Detector, Motion Detector, Exit Sign and so on. Most board cameras also come with 3.6mm lenses, although some will allow lenses to be replaced. Over time, the most practical design has been the Dome Camera; with its esthetic appearance it blends well into most surroundings, especially with drop down sealings. It is great for use in stores, lobbies, gas stations and other public places. Practical solutions for covert installation also include Motion and Smoke Detector cameras, although they are absolutely not a substitute for your security alarm or fire protection. Cameras should always be selected based on the location of the camera (inside/outside), distance from the monitoring object, light conditions and budget. When shopping for security cameras, customers are faced with the fact that they will need to select one or another recording device. The days of the well-known CCTV time-lapse VCR recorder are almost over. Although some customers still prefer this old fashioned recording solution, it is well worth it to invest some extra money toward purchasing a good quality digital video recorder (DVR).
Digital recorders transfer an analog camera video feed into digital format, and store it on to a hard drive. There are two major types of digital recorders on the market right now.
PC Based CCTV Systems
A special board and software installed on the computer will allow camera inputs and store video on the hard drive. Many people are under the misconception that a personal computer with additional hardware installed, will do the job. This explains the hundreds of companies that have hung up a sign, taken out some ads and begun working out of a basements or garages, presenting themselves to be DVR manufacturers and security specialists. The main problem with this type of CCTV recorder lies in the main component of it... Yes, it is a computer, designed to do unlimited tasks, but not very well. The truth is that any computer based digital video recorder is, and will always be vulnerable to software crashes, hang-ups, system instability, virus related problems etc...
Very similar in appearance and control functions to a standard VCR recorders, these are truely remarkable devices. Most of the video processing is done by hardware, therefore eliminating system crashes, video is also stored on hard drive in digital format. The basic operating system, usually Linux, is permanently stored on a special processor, witch is impossible to overwrite or corrupt. Designed and manufactured with a single application in mind, it is by far better in performance and reliability than its PC based rival. Some DVR systems will even have remote monitoring capability, useful when monitoring is required in different locations through the Internet or network. One of the most important futures to look for when selecting the right DVR recorder are motion detection and frame speed. The higher the frame speed the more fluent the video recording. Motion detection will allow video recording from each camera only when motion is detected. This is great for extending video recording time.
Video from Security recorder could be displayed on a regular TV monitor. It is OK to do it this way, for baby monitoring or residential application, when quality of the picture is not that important. However, for professional installation, security monitors are as important as cameras. They offer extended life to a picture tube (necessary with any static picture, that can cause picture burnout) and much better resolution.
Cables and Wiring
Any camera installation will require proper wiring. Good quality cables will prevent video degradation over long distance runs. It is recommended to use RG59 or RG6 coaxial cables as they are fully shielded and will prevent video loss up to 400 ft. Coaxial cables will require BNC connectors and proper installation by experienced technicians. In short runs plug and play non-coaxial cables with factory installed BNC connectors may be used (up to 150 ft.). The plug and play cables are easy enough to install by non-experienced users. Cables for CCTV cameras consist of two cables bundled in one jacket. One cable for video and one for power delivery.
Every CCTV system is as good and reliable as its weakest component. With this in mind, investing in the highest quality and performance cameras and purchasing low performance recorders, from an economical and practical standpoint, just does not make sense. For example, why use cameras with 500 TV lines of resolution with a monitor that offers only 380 or less. All the benefit of a high-resolution camera is affectively sacrificed by limited capability of the monitor. Asking questions is important before purchasing video security systems, and your vendor will probably be able to give more details and recommend equipment for specific needs and requirements.
Robert Moskal is Technical Department Manager at V2Comp, Inc., a major distributor of surveillance cameras and CCTV Systems located in Chicago area. More information about new products can be accessed here or here