DVR (Digital Video Recorder) systems are used to connect analog CCTV cameras. A DVR system contains capture cards, which convert the analog video feeds into digital format for viewing and recording. Most systems will compress the video using standard video codecs. This compression reduces the amount of storage space required to record the same length of video. DVR systems have limited scalability, due to the amount of capture cards that can be placed in a PC, and the number of ports available on each card. Common DVR systems may have capture cards to accompany 4, 8, 16, or 32 cameras.
With a DVR system, an topology referred to as an octopus system must be used to connect the cameras. That means that each camera needs a dedicated coaxial cable running from the camera to the DVR. This usually equates to increases in both labor and material costs for the cabling. The cameras may be powered via siamese cable, which contains a coaxial cable for the video signal, plus 2 wires for transmitting power to the camera. Another option is to power the camera with a power adapter plugged into a nearby outlet.
When using analog cameras with CCTV signals transmitted over coaxial cable, the resolution is limited to 0.3 megapixels. These low resolution images do not provide the same detail as an NVR system utilizing IP megapixel cameras. The major advantage to DVR systems with analog cameras is the camera price. Analog cameras are generally cheaper than their IP counterparts.
NVR (Network Video Recorder) systems are used to connect IP cameras. IP cameras capture and transmit a digital image that is sent via standard networking protocols to the NVR. These systems are only limited in scale by the performance of the network and the NVR itself. An NVR should be built with sufficient processing power, memory, and storage to accompany the number of cameras being installed. Sometimes it is only a matter of adding more RAM or hard disk storage to accompany more cameras.
With NVR systems, the cameras may be wired with any of the various networking topologies. An independent “home run” cable from each camera back to the NVR is not necessary. Therefore, it is possible, with the use of switches, wireless access points, wireless bridges, routers, and other networking devices to daisy chain cameras, or use distributed star topologies. Combined with POE (Power-over-Ethernet) switches, this may lead to a reduction in the cost of both the cable itself, and the labor to run the cables. For example, a single Ethernet cable may be run to a second switch in a warehouse, from which an additional 8 cameras can be connected. Some businesses or residences may even choose to have the cameras connected to their existing network, utilizing existing cables. Northeast Remote Surveillance, LLC can determine if your existing network has the necessary bandwidth to support the IP cameras. You may request a completely air-gapped network for the surveillance system for security purposes.
When using IP megapixel cameras, you are not limited to the 0.3 megapixel resolution constraint found with analog cameras. A high resolution camera may be used to provide the same coverage area in greater detail, or to provide a greater coverage area with the same detail. A high resolution camera can sometimes cover the same area with greater detail than 3 or more low resolution analog cameras.
Hybrid (DVR/NVR) Systems:
Hybrid systems can be desired for several reasons. The most common reason is to utilize existing analog cameras, while providing new or replacement high resolution IP cameras. With a hybrid system, you may connect your existing installed cameras to the DVR portion of the surveillance device. This reduces the cost of your upgrade by utiziling existing components. Northeast Remote Surveillance, LLC has the experience necessary to give you the best value on a system upgrade. Our expertise in all realms of video surveillance prevents you from having to throw away good cameras that are functioning with your old DVR.
In other cases, a hybrid system may be used on new installations to provide the value of analog cameras, where high resolution images are not needed, and running independent coaxial cables to the DVR is sensible. High resolution IP cameras can then be used in areas where detailed images are needed, where making independent coaxial cable runs in not feasible, or where cameras need to be connected wirelessly.