Close Circuit Television
What is CCTV?
CCTV is the commonly used acronym for "Closed Circuit Television". It is "closed" in the sense that the images captured by the CCTV cameras go to a specific receiver for viewing. The term "CCTV" is used to distinguish this type of system from a broadcast television system which sends out a signal for the public at large to view when wished on their television sets.
A CCTV system consists of three components, cameras, digital video recorders, and monitors. Cameras capture the images, the digital video recorder, usually called a "DVR" records the images and the recorded images are viewed through a video monitor. Traditionally, CCTV systems have been used for security purposes in locations such as banks and airports, as well as retail stores, to enable security personnel to monitor events and to record images from a centralized location. The configuration of the CCTV system and the type of components used are dependent upon the areas being monitored and the use to be made of the images. As Provent is focused on our retail customers, this overview will focus on how CCTV systems are assembled and installed for the retail environment. What is a good CCTV system for a bank, need not constitute a good CCTV system for a retail store.
CCTV cameras are designed and built for specific uses. It is a myth to suggest that one size of camera fits all.
Indoor vs. Outdoor Cameras
Camera placement usually determines the type of CCTV camera required. For example, a camera placed in an outdoor location will require outdoor housing to ensure that it is able to withstand the elements. In colder climates, these camera housings are usually heated.
Field of View
The CCTV Camera must be placed in a position to permit it to capture the images wished to be captured. This is called the "field of view". If the field of view is in a confined space directly in front of the camera, a particular lens to capture these relative close images will be used. However, if the field of view extends a distance away from the camera such as in the length of a store aisle, to record images with sufficient resolution to utilize them properly, a CCTV camera with a lens to capture this field of view should be used.
As an image is the recording of reflective light images, the amount of ambient light in the field of view determines the quality of the image being captures. For example, if a CCTV camera is mounted to capture the images of people coming into a store and if the store entrance is to the outside and exposed to sunlight, without the proper camera lens, at the time of the day when the sun is shining into the store, the quality of the images captured will be very poor. Similarly, where there is a low light situation, unless a type of lens which uses Infrared technology and contains a wide angle view is installed, the images will be extremely poor. The use of vari-focal lens permits adjustments to the camera lens to increase or reduce the amount of light coming into the camera and to thereby improve the quality of the images recorded.
Camera Security Where concern exists for the security of the camera, it is placed in a vandal resistant housing.
Dome vs. Box
If the intention is that the person whose image is being taken does not know that his picture is being taken, a camera is placed inside a dome housing with the dome opaque so that from outside this dome the direction the camera is pointing cannot be detected. However, if the intention is to let a person know that his or her image is being recorded, a box camera is used.
Pan/Tilt/Zoom or PTZ cameras permit the manipulation of the camera to change the camera's field of view. This manipulation is done mechanically by using a control device called a "joy stick". By using the joy stick, the viewer can change the camera's field of view to track a person moving through the store. With the advent of digital camera technology, digital cameras are available which perform a similar function, but do so using software rather than mechanically manipulating the camera.
Analog vs. Digital Technology
Traditionally, CCTV cameras have captured an image and then sent it using an analog protocol over wires to the DVR. More recently, IP cameras have been developed with use the same technology as a computer network, so that the CCTV cameras become a component on the computer network.
Wireless vs. Wired
Cameras send the images they capture to a video recorder. The transmission of these images can either be by a cable running between the camera and the video recorder or by a wireless transmission. Although a camera will still need to be connected to a power source, many retailers are working to reduce the need to have a wire running from the camera to the video recorder, usually placed at the back of the store, by using wireless cameras. This reduces the necessity for unsightly wires, reduces installation costs, and gives greater flexibility to move cameras as the retailer's merchandising strategy is adjusted. Unfortunately, by its nature, wireless technology is subject to transmission failures. When this occurs, retailers will use a technology called "power over the ethernet" or "POE" whereby there is only one cable connecting the camera with the video recorder and this cable supplies power to the camera as well as transmitting images to the video recorder.
There are two types of video recorders, stand alone DVRs and network video recorders or "NVRs".
Stand Alone DVRs
Stand Alone DVRs are computers which are dedicated to capture and store images sent to them by CCTV cameras to which they are connected. Stand Alone DVRs are as their name implies not connected to a network. However, they are often connected to the internet so that an authorized person can view the images collected on the DVRs in real time over the internet. With such an internet connection, authorized personnel can, as well, locate and view images stored on the DVR.
NVRs are similar to Stand Alone DVRs, but they are part of a local area network and the images collected by them are viewed over this network. Where the local area network is attached to the internet, authorized personnel can view the images on the NVR over the internet.
Images captured by a CCTV Camera system in a store are viewed in the store over an LCD monitor. There are two general types of placement for these monitors recommended by Provent, Staff Awareness Monitors and Customer Awareness Monitors.
Staff Awareness Monitors
Where a retailer wishes staff to be able to view images captured in the store, a Staff Awareness Monitor is connected to the video recorder. The Staff Awareness Monitor is placed at the cash desk so that sales staff can monitor areas of the store not visible from the cash desk.
Customer Awareness Monitors
To make customers aware that there is a CCTV Camera system within a store, a Customer Awareness Monitor is hung from the ceiling at the store entrance. As customers enter the store, their images are captured by a camera pointing at the store entrance and displayed on the Customer Awareness Monitor.
Why use CCTV? Advances in CCTV technology are turning video surveillance into one of the most valuable loss prevention, safety/security and management tools available today. Retailers use CCTV to monitor for shoplifters and dishonest employees, compile recorded evidence against bogus accident claims, and keep an eye on stores that may be hundreds of miles away.