Designed for Distance
The available technologies include traditional coaxial cable, combinations of video baluns with UTP Category cable, and fiber optics. It’s important to understand that each of these technologies can work flawlessly when properly planned and installed. Security system designers must consider the issues of maximum cable run distances, power requirements, and installation issues in order to select the video transmission method that will yield the needed functionality of the camera while minimizing installation costs and time.
Letâ€™s Go Old SchoolThe traditional method for CCTV signal transmission is that old standby – coaxial copper cable. The CCTV industry was built on coax transmission as is evident by the presence of a coax BNC connector on virtually every analog CCTV camera manufactured today.
The most common coax cable used in CCTV installations is RG-59U, which will provide an acceptable quality video path from a camera to the head end out to 750 feet.
Coax CCTV installations are very straightforward. Make sure that the cabling distance doesn’t exceed the maximum recommendation. As with any installation, smart security companies will always use high-quality cable and connectors combined with careful installation practices. Most dealers purchase RG-59U with a 95 percent braided copper shield, while three-piece BNC connectors reduce future service calls for faulty connections.
Based on the distance it may be necessary to provide local power to energize the camera. Many installation dealers use a Siamese cable, consisting of a single RG-59U wedded to an attached 18/2 cable to provide power and video connections to a remote camera, while effectively pulling a single cable. Long distances will increase voltage drop, and installers must calculate whether the selected power supply and cabling can deliver the necessary voltage over the distance(s) needed.
Changing TechnologiesWhile coax cabling is ubiquitous in CCTV installations, installers need other options when distances exceed coax capabilities. UTP (Unshielded Twisted Pair) cable, typically Cat5e, can provide long-distance video transmission, while the extra conductors of the typical four-pair cable can be used to provide power to the camera along with pan/tilt/zoom control signaling.
Putting analog CCTV signals onto UTP cable requires the conversion of the unbalanced BNC output of the camera into a balanced signal that can be carried on one pair of the UTP. When the signal reaches the head end/recorder, the signal must be reconverted so that it can be connected properly with a standard BNC-type connector.
The baluns, which perform the conversion of the coax output of the typical camera to a UTP-friendly signal, are available in passive and active versions. While passive baluns just convert the signal, active baluns provide an amplification method, which increases the potential distance of transmission.
The UTP/balun method of analog CCTV transmission is a fast-growing segment of our industry. Distances up to 12,000 feet to a camera can be achieved; UTP cabling is lighter and easier to install than RG-59U, with UTP cabling being less expensive to purchase than comparable lengths of RG-59U.
Paul Gulczynski, president of e.Norman Security Systems Inc. of Naperville, Ill., says, “There is no reason to use any coax on large (100-plus) camera jobs.” He estimates that his company installs 40 percent of its CCTV cameras with traditional coax, while 60 percent of his installations use either UTP/balun or fiber optic technology. The growth of UTP/balun usage is exemplified by the fact that some major CCTV camera manufacturers such as GE Security and Bosch Security are including built-in passive baluns on some of their cameras.
One of the primary advantages of UTP/balun technology is the ability to use existing UTP cabling that has been previously installed for common enterprise network use, such as backbone cables between telecom closets or horizontal cables that have been installed out to workstation areas. If these existing cables can be verified to be within industry standards for performance, UTP/balun technology can be utilized quickly to hook up a camera with little or no installation of new cabling.
While the basic technology of UTP/balun is pretty simple, dealers need to understand that proper choices must be made in balun selection, as there are a variety of ways to achieve the proper signaling between a remote analog CCTV camera and the head end. The different choices usually relate to whether passive or active baluns are used at the camera (transmission) end, at the receiving end, or both.
The distances detailed in the illustration on the previous page are based on the specifications from NVT and Nitek, two of the major manufacturers of UTP/balun technology for the electronic security industry. Dealers should check carefully with their supplier for the exact distances allowed by specific product sets.
To make UTP/balun technology even more attractive, the major vendors produce a wide variety of video signal concentrators, typically called hubs, along with single-camera receivers. The hub devices provide both active and passive balun ends in combinations of four, eight, and 16 camera connections, and modular rack-mount units allow dealers to assemble a receiving system to a specific size, mixing active and passive balun sets. Each camera input is connected to a traditional BNC/coax output, which then can be fed into the DVR or other head end equipment. The active baluns can be used for long-distance video feeds, while the less expensive passive baluns can be mated to either passive or active baluns at the camera end.
Because UTP/balun technology uses a single pair of a typically four-pair UTP cable to transmit the video, the remaining three pairs are available to potentially provide power and pan/tilt/zoom control signaling from the head end to a remote camera. Both Nitek and NVT provide camera powering and pan/tilt/zoom telemetry options that can be carried in the same four-pair UTP as the video signal.
When planning such an installation, cabling distance is a critical issue. For example, the specifications for the Nitek UTPLink camera-powering technology calls for strict adherence to the EIA/TIA 568 maximum of 100 meters from the head end to the camera.
UTP/balun technology is increasingly the primary choice for medium to large analog CCTV installations. The vendors of the hardware build very reliable products in a variety of configurations to fit any possible scenario an installation company might encounter.
Fabulous FiberProviding EMI/RFI immunity, robust cabling distances and huge bandwidth capability, fiber optics is the high-performance standard for all types of cable-based communications including enterprise networking and both analog and IP CCTV.
What makes fiber so fabulous? Cut into a typical fiber optic cable and you’ll find an aramid-yarn (Kevlar) inner wrap, a 900-micron inner plastic jacket wrapped around the fiber strand itself. With its own “bulletproof vest” installed, fiber cables usually have a minimum of 100 pounds of pull-strength capacity. And because there’s no metal in the cable, it cannot carry lightning pulses or transient voltages from an outdoor-mounted camera into a building, possibly damaging expensive head end equipment. EMI and RFI cannot affect a fiber signal, as there’s typically no metal in the cable to attract interference and the signals within the fiber core are a blinking LED or laser which cannot be disturbed by electrical anomalies.
There are two common types of fiber strands, called multimode and singlemode. Multimode cable can reliably transmit signals out to three miles, while singlemode can go 60 miles before the signal needs to be amplified or regenerated. So we’ve got plenty of distance capability with fiber optics. The bandwidth capacity of a single strand of standard multimode fiber is more than 45 times that of a Cat5e UTP cable, while the maximum bandwidth capacity of singlemode fiber has yet to be reached by scientists.
What makes fiber optics attractive for CCTV use is the fact that there are millions of unused (often termed “dark”) fibers pre-installed in buildings and campuses around the world. When a fiber optic cable for general networking use is being installed between buildings or telecom closets, usually the cable will include a number of spare fibers. Because fiber optic cable and connectors have been standardized since the mid-1980s, security dealers can have confidence that an existing fiber link may be perfectly usable for CCTV transmission purposes.
A simple light test with any size visible flashlight can determine quickly whether a fiber link is likely usable. If the light is visible at the other end, the fiber is not broken. If the light is not visible, the most likely problem is that one (or both) of the connector ends is defective. In this case it’s probably best to replace both connector ends. Dealers planning to use fibers for high-bandwidth applications should test the target fibers more thoroughly using either a fiber optic power meter/light source two-ended tester or an Optical Time Domain Reflectometer (OTDR). Such tests should be performed at the same frequencies at which the planned video transmission transmitters/receivers will operate.
Once we know a fiber is functional, what are the typical applications? The capabilities of CCTV video transmission and pan/tilt/zoom telemetry controls are almost unlimited. Reliable industry manufacturers such as American Fibertek, GE’s IFS, ComNet, Optelecom-NKF, and others produce an array of fiber optic transmitters, receivers and transceivers that can provide multiplexed video, audio and pan/tilt/zoom signaling from the head end to various analog or IP CCTV subsystems, tying them all to a central point.
It’s important to know that a single fiber strand can provide bi-directional signaling, so one fiber between two buildings can provide multiple streams of video signals in one direction while the pan/tilt/zoom control signals can be traveling in the opposite direction simultaneously on the same fiber strand.
Installation companies should work smart with fiber optics. Always use factory-made fiber jumpers for short connections to equipment and patch panels. If available, the ability to weld factory-made connectors onto fiber optic strands using a fusion splicer will provide low-loss connectors and minimize present and future problems.
Making Smart DecisionsWith the proven technologies of coax, UTP/balun and fiber optics all available, security dealers must carefully weigh the benefits and costs of each when considering an analog CCTV installation. Two factors are of primary importance. First, what are the maximum distances from the head end to the planned camera locations? Second, is there available pre-installed UTP and/or fiber that can be exploited to reduce installation time and cost, which will effectively lower the cost of the system for the client?
In today’s challenging economy, security dealers must use every avenue available to present the customer with a quality installation proposal at a highly competitive price. Smart dealers will know their options in cabling and use the right mix of cables and connectivity devices to achieve this goal.
Tech TipsHere are some tips to make your UTP/balun system installations worry-free:
• Use non-blue colored UTP cabling for your camera runs; typical enterprise network cabling is usually blue, so yellow, red or green UTP will differentiate the CCTV cabling.
• Equipment racks should be of the type where opening a door or swinging the rack out does not flex the UTP cable or connections. Typical UTP has solid copper conductors, and excessive flexing will create cracks and breaks in the conductors under the jacket.
• Purchase and use factory-made UTP and BNC/coax jumpers for connections to patch panels and DVRs; homemade jumper cables are often the cause of problems.
• Unless you are using one of the power-hub options, cameras will need a separate power supply connection to provide the electrical current necessary for operation.
• As with any cabling installation, using high-quality UTP and RJ45 connectors, properly installed, is the only way to go.