While the futurists in our industry tout the improved benefits of IP networked CCTV surveillance and insist that all should switch immediately to it today, the realists know that such a drastic, immediate change is sometimes not possible for a host of reasons, including investments in present analog equipment that continue to work successfully.
As CCTV suppliers provide bridges between analog and digital equipment, providing most of the benefits of an IP system while using legacy analog equipment and forging a pathway to ultimate 100 percent IP, too often forgotten is the transmission system. It, too, must be created for later migration. Fortunately, there is a way to implement such a system, providing both a solution for today's system and laying the groundwork for an extremely easy switchover to IP in the future.
RJ45 connectors and hubs that provide power, video and data (PVD) in conjunction with UTP (Unshielded Twisted Pair) wiring create exactly what the great majority of today's CCTV systems should employ.
Straightening Out Today's Jumble of Wires and Cables
It's well accepted that coaxial cable is more difficult to install than UTP wire in most video transmission applications, resulting in higher labor charges and larger hardware costs. In addition, coax systems do not comply with structured standards-based protocols such as 568B, while UTP wire does. Contrary to coax, RJ45-connected, UTP video solutions also provide an ultimate migration pathway to an all-digital solution.
However, far too many integrators and their customers are unaware of this simple remedy. Too add confusion, different trades use different techniques.
For installing CCTV, RG-59 has been historically used by security industry personnel to transmit video signals from the cameras to the receivers. Meanwhile, the telecommunications and data communications industries developed quite different standards. For instance, Token Ring runs on 150 ohm shielded twisted pair, IBM System 3270 runs on RG-62 coax, and Ethernet runs on RG-58 coax. Telephone signals are transmitted on quad wire or unrated UTP wire.
Needless to say, this has created monumental problems for installers. When using RG-59, installers have had to provide a nearby outlet and/or power transformer. Additionally, most P/T/Z control required yet another shielded twisted-pair cable. Between RG-59, RG-58, RG-62 and 150 ohm shielded twisted pair, the industry created a mess. There was no common wiring, bulky coax seemed to exist everywhere, and there was no way to organize and manage all of it. As multiple systems came to market, the clutter grew larger and more out of control.
As a result, the datacom and telecom industries developed a standard that evolved to what is now known as the EIA/TIA-568B. This common cabling system standard accommodates all applications in datacom and telecom. But, for the most part, security systems installers continued using RG-59.
Power, Video and Data - All on One Small UTP Cable
Contrary to the above, unshielded Twisted Pair (UTP) will transmit all signals within one 4-pair cable. For leading integrators, this type of video transmission technology is now widely accepted as a transmission option along with coax and fiber. Installers can deliver a high quality picture over the same wire used by phone systems. In fact, most facilities already have UTP cable for their phones and datacom needs. However, that's only the beginning.
Today, there is a full range of passive video transmission hubs featuring RJ45 connectivity (the same used to plug in your phone or computer) that are specifically designed for installers specializing in implementing digital-ready structured cabling systems in accordance with structured cabling standard EIA/TIA 568B. These new RJ45 video-input passive hubs let end-users and installers employ new or existing unshielded twisted pair wire (UTP) to deliver a high quality picture while cutting costs and simplifying installation versus standard coaxial cable.
How It All Comes Together
To build this system, you'll need to employ video transceivers. The UTP CCTV power-video-data transceiver provides a direct video output connection from the camera. Plus, it adds power and data connections (the PTZ instructions) to and from the camera.
As a result, the interference rejection and low emissions of the RJ45 connector PVD let video signals co-exist in the same wire bundle as telephone, datacom or low-voltage power circuits. This allows the use of a shared or existing cable plant, reducing costs and time of installation.
With this new PVD, power, video and data are routed via UTP and RJ45 or 'press-fit' terminal block inputs/outputs. When used at the camera, the passive PVD has a 9-inch mini-coax pigtail lead for direct video output connection from the camera.
Alongside the coax lead are two sets of "press-fit" terminal blocks for quick pass-through connections for the camera's power and data. On the "house" or output side of the product, installers have the option of deploying convenient "press-fit" UTP connectors or the more efficient RJ45.
With this solution, installers can leverage the positive aspects of a structured cabling network architecture, their first step to an IP system. The RJ45 wiring pin-outs are compatible with the datacom and telecom industry standard EIA/TIA-568B, so termination mistakes are minimized and testing is standardized. Using the advantages of a structured cabling system and star-wired layout, power supplies can be centrally located.
How It Works
Power, video and data are converted at the camera by the transceiver, which uses a single 4-pair cable with RJ45 connectors to deliver each camera's signals to a "Cable Integrator" at the wiring or IDF closet. The cable integrator receives low-voltage camera power from any third-party Class 2 power supply and delivers it to the camera cables. Control room connections are achieved with 4-pair RJ45 cable(s) into a passive or active receiver hub. For single runs within the distance requirements, a second PVD may be employed at the receive end without the need for a Cable Integrator.
The schematics (above, right) further details the PVD system. Note that a backbone layout is used between the equipment closet containing the cable integrator and receive end control equipment.
Converting to an IP Solution
This is where the system really shines. Once the company is ready to go to a fully IP system, you simply disconnect the UTP connections. That's all there is to do...a win-for-today system becomes a win-for-tomorrow solution.
About the author: Guy Apple is vice president of Network Video Technologies (NVT) and a strong proponent of RJ45-based UTP connections. NVT offers a variety of video transceivers and hub systems for video transmissions. The company can be found online at www.nvt.com
