For some time now, it has been possible to build 100-percent digital, network-based systems for security, surveillance and remote monitoring. Nonetheless, there are still a few concerns regarding this move toward digital technology—what are its advantages over analog closed-circuit television (CCTV), how difficult is it to install and maintain and how can companies cost-effectively migrate from analog to digital technology?
Several technologies spurred the growth and adoption of digital video and related applications during the early years. As PCs came into use, companies began focusing security and surveillance applications around a central PC and started developing “frame grabbers,” computer cards and software that convert analog video into digital images.
When Ethernet standards were developed for the network and TCP/IP standards were developed for the Internet, network-based applications began to rapidly expand. As digital video gained acceptance due to improved technology and more affordable systems, an increasing number of companies were able to capitalize on the advantages of digital video in security and surveillance applications.
Today, there are many products for networked-based video that utilize Ethernet and TCP/IP standards. Most of these products still employ a PC at the heart of the system, and several cameras and video servers can be connected directly to the network. The main difference between this configuration and analog is that the video digitalization is being performed at the camera level, and the computer network is being used to transfer the picture back to a PC-based server for storage. This is beneficial because computer networks are generally readily available, and utilizing the Internet allows video to be remotely stored and monitored.
Getting Started
Digital video starts with the network camera. A network camera serves many of the same purposes as the standard analog CCTV camera, but it provides users with much more functionality at greater cost savings. Because network cameras plug directly into the existing data network via an Ethernet port, companies can save thousands of dollars by not having to wire their facilities with coaxial cabling as required for analog cameras. Because they also have integrated Web servers, image compressors and operating systems, network cameras operate independent of PCs, and images can be viewed from standard Web browsers.However, if a data network does not exist in the facility, and a wiring project is needed, Ethernet computer networks are much more efficient to install than analog systems. Because Ethernet networks run over small, inexpensive twisted pair wiring such as Category 5, they are much cheaper and easier to install than analog networks that transmit signals over thick coaxial cabling. In addition, several cameras can share a line of Ethernet cabling, requiring less cabling to be installed.
Network cameras also save companies money by reducing the amount of dedicated equipment needed to manage the security system because they can be monitored from any PC in the world. Analog CCTV systems require dedicated monitors and security personnel who are readily available to view the images.
To get started, all users have to do is connect the camera to the network. Software capable of pinpointing the camera’s location on the network can be installed on any network-connected PC. Once the camera is located, a fixed IP address can be set, or a dynamic (e.g. set by DHCP) IP address can be managed. Users are now able to transmit and record images digitally over the network as well as view images from a Web browser anywhere in the world. Video recording can be done locally, or thousands of miles away, if required out of convenience or for security purposes.
Sending Images Over the Network
Once the system is in place, users can start transmitting images over the network via a number of imaging standards such as motion JPEG, H.323 and MPEG. While both JPEG and MPEG standards transmit high-quality video, the H.323 standard, normally used in video conferencing, does not generate clear images of fast-moving objects.
Regardless of whether a whole image or a reference image is transferred, a fundamental factor in all network video applications is the amount of available capacity in the computer network, known as the available bandwidth. If bandwidth is limited, you must reduce the amount of information being sent over the network by choosing between longer update intervals or lower image quality.
Migrating to a Networked-Video System
For companies that have already made large investments in analog CCTV systems, it is possible to cost-effectively upgrade existing analog systems with digital video technology.Video servers are the key to transforming analog video into digital video, making it possible to migrate toward a digital system without having to discard functional analog equipment. Video servers convert images from existing analog CCTV cameras into digital video for network transmission, bringing new functionality to analog equipment and eliminating the need for dedicated equipment such as coaxial cabling and monitors.
Video servers typically have between one and four analog ports for CCTV cameras to plug in to as well as an Ethernet port for connectivity to the network. Like the cameras, they contain built-in Web servers, compression chips and operating systems so that incoming analog feeds can be transformed to digital video and transmitted over the computer network for easier accessibility and viewing.
Versatile Security Solutions
Migrating to a digital solution through the use of network cameras and video servers also increases a company’s opportunity to use images in support of other applications such as keycard access or entry control. For example, network cameras can take images when someone swipes a keycard for access to a secure area. This indicates that someone has entered the premises and verifies whether that person was indeed the authorized cardholder. When verifying an alarm, network cameras can send images to the arriving emergency personnel so that they know what conditions to expect on the scene.Today, companies can transmit video signals to PCs as well as to wireless devices such as mobile phones and personal digital assistants. This means that future security, surveillance and remote monitoring systems can be made even more personalized, accessible, cost-effective and flexible—no matter where in the world network administrators and security personnel are located.
