Analog CCTV systems for security and surveillance applications gained popularity back in the 1970s. As security challenges increased and technological innovation grew apace, analog systems proved ineffective and inefficient for all but the smallest security environments. Digital video recorder technology emerged in the mid '90s to provide end users a high-performance, cost-effective alternative to the VCR. The DVR offered a number of compelling benefits over analog recording, including image superiority, increased storage space, near-instant access to key information, reduced maintenance time and costs, and flexible recording control.
The DVR at Its Apex
The 2003 J. P. Freeman Co. Inc. CCTV report estimated that DVRs comprised 75 percent of all new installations last year. There are now hundreds of manufacturers with proprietary DVR architectures. In the last few years, end users with analog CCTV systems hastened their migration to DVR technology because of its many improvements over analog. However, DVR technology is actually a hybrid?part digital, part analog. The DVR is a PC and hard drive-based VCR replacement; thus, it requires analog coaxial cables. The signal is converted from digital to analog in the camera, then transmitted over a coax cable, then converted back to digital at the DVR. This conversion process slows down performance, and the cable increases system costs.
DVR technology also presents some challenges for end users in the market for a multi-site, multi-building enterprise solution, because many DVRs have a limited number of control inputs and outputs for interfacing and integrating to various systems and devices. Most have no matrix switching functionalities for security communication and surveillance control centers. The DVR industry, as yet, has no clear software standard for digitization and compression, and most manufacturers use closed source codes that limit third-party application development and high-level integration with other systems.
A newer technology has recently stepped onto the security video field that shares some of the DVR's benefits while addressing many of its limitations. This next technological evolutionary step is the network video recording system.
Enter the NVRS
Video surveillance over Internet protocol (IP) uses private and public networking to allow access to real-time video, anywhere there is a network connection. A network video recorder (NVR) offers all the features of legacy DVRs, including recording of video and audio, fast image retrieval time, encryption of all digital information, wireless viewing from cell phone or PDA, system control via a map or a camera list, and automatic, event-driven pop-up screens and audio clips. It also offers complete matrix functionality, a software-only solution, virtual redundancy using the network, and the ability to add a single camera simply by adding a software license.
Uses the existing network. Connect an NVRS system in two ways?through an existing Ethernet network or by leveraging the existing telephone infrastructure?to create a dedicated security network. Either way you eliminate the need to pull wires, trench fiber, or run additional coax cabling.
The diagram shows a typical, high-end NVRS that uses the existing network infrastructure, computer hardware, analog cameras and matrix keyboards to create a digital system that replaces a DVR, matrix switch, and multiplexer.
Matrix capability. Because the NVRS camera and/or video source is all digital, the network becomes a true virtual matrix switcher, complete with all the capabilities of an analog matrix switch. As part of the network, the recording system can share information and resources. Scalability. Adding cameras to an NVRS is as easy as ordering licenses?no major expense, no technician, and no downtime. It does not require the purchase of a new unit, as it often does with DVR-based systems.