EPA - Water Security - Security Product Guide - Visual Surveillance Monitoring

Visual surveillance is used to detect threats through continuous observation of important or vulnerable areas of an asset. The observations can also be recorded for later review or use (for example, in court proceedings). Visual surveillance systems can be used to monitor various parts of collection, distribution, or treatment systems, including the perimeter of a facility, outlying pumping stations, or entry or access points into specific buildings. These systems are also useful in recording individuals who enter or leave a facility, thereby helping to identify unauthorized access. Images can be transmitted live to a monitoring station, where they can be monitored in real time, or they can be recorded and reviewed later. Many facilities have found that a combination of electronic surveillance and security guards provides an effective means of facility security.

Visual surveillance is provided through a closed circuit television (CCTV) system, in which the capture, transmission, and reception of an image is localized within a closed "circuit." This is different than other broadcast images, such as over-the-air television, which is broadcast over the air to any receiver within range.

At a minimum, a CCTV system consists of:

Specific attributes and features of these components are presented in the tables that follow.

Cameras capture the image for transmission to the monitor. They consist of a lens, which focuses light into the camera, and a system to convert that captured light into an electronic signal which can be transmitted to the monitor. The characteristics of the lens and the camera affect their ability to capture sharp images from a specific field of view under variable light conditions. Cameras and lenses can be purchased separately, which allows users to design a system that is tailored to their needs. Important attributes of camera systems, lenses, and lighting systems are provided in Tables 1-3 below.

Another important consideration when choosing cameras is whether they will be used indoors or outdoors. Camera location will determine the types of lighting available, as well as the types of cameras and lenses that are applicable. Cameras mounted outdoors may require climate-specific weatherproof housing, heaters for snow/ice blockage or reduction, blowers to reduce fogging, etc. These additional features will add to the cost and flexibility of the system.

Transmission Systems

Systems may be hardwired (physically connected by cables) or wireless. While hardwiring (such as through coaxial or fiber optic cables) is the traditional method for transmitting video signals in a CCTV system, new wireless applications, such as microwave links, optical systems, and radio frequencies, are becoming more prevalent.

Hardwired systems require a direct physical connection between the transmitter and the receiver. Because the signal is transmitted directly to the receiver and not over the air, hardwired systems may be more secure than wireless systems. However, it may be difficult to hardwire remote locations. In addition, video signals transmitted over cables suffer from interference with the signal. Specific factors affecting hardwired cable connections include:

Wireless transmission systems do not require that the transmitter and the receiver be physically connected to each other. This may make wireless more attractive for remote locations. However, wireless systems require a direct line of sight between transmitter and receivers and may require re-transmitters (also known as repeaters and amplifiers) for remote operations. In addition, wireless systems may be susceptible to interception or interference.

Monitors are used to view images transmitted by cameras. Factors to be considered when choosing the appropriate monitor for a specific application include:

In many cases, images generated by camera systems may be stored for later viewing. While the detection of certain images may require real-time, immediate action (such as when intruders are detected), the ability to store and view images at a later time may be important for forensic purposes (i.e., to determine what or how an event occurred at a site) or for legal actions to be taken at a later date. Options for image storage include:

DVR is rapidly replacing video cassette recording VCR as the medium of choice for recording and storing images. DVR devices record and store images digitally on a computer hard drive (i.e., a PC, handheld computer, or dedicated DVR system) vs. devices such as VCRs, which store images on videotapes using analog technology. Costs for DVR systems have declined in recent years while the technology has improved. Other advantages of DVRs vs. VCRs include:

However, some digital storage systems using PC hard drives require that the entire PC be dedicated to this system. This may not be practical for some utilities.

One of the important features when setting up a DVR system is determining how many frames per second (fps) will be recorded. The more fps that are recorded, the clearer the image will be, and it will be easier to view still pictures from the camera. However, the more fps that are stored, the more storage space will be required on the hard drive. Many DVRs also have a motion sensor mode that can be set to trigger an action (such as recording or an alarm) when the camera detects motion in its field of vision.

Table 4 provides a discussion of several optional features which enhance the management of a CCTV system.

Components for a CCTV/visual surveillance system can be sold separately, or packaged systems may be purchased. For example, a typical lower-end package consisting of a 4 camera CCTV system consisting of cameras/lenses, cables, power supplies, and a monitor can cost as little as $550. This is a capital cost only and does not include maintenance or installation costs, which are facility dependent.

Costs for individual components depend on their specifications. Several example costs and factors affecting costs are provided in Table 5 below.

Disclaimer: The information provided in this guide does not constitute an endorsement by the Environmental Protection Agency of any non-Federal entity, its products or its services. In addition, EPA does not endorse the vendors and products listed on this site. EPA is publishing lists of vendors on this site in an effort to further public awareness of vendors identified as possible contacts for further information and possible purchase of the different types of security equipment. The Agency has selected the listed vendors on that basis. The list of vendors is not a complete list, and EPA does not endorse the products or services of these vendors.