Passive-to-active UTP systems accommodate cable runs of up to 3,000 feet. Good-quality gain equalization compensates for cable loss, supporting high-resolution systems or digital head ends. Many amplified receivers also provide ground-loop isolation and surge protection. Although most amplified models don't support up-the-coax PTZ signals, most systems use RS-422 or RS-485, which can easily run on spare pairs within the same wire bundle as the video signals.
The active-to-active solution offers all the same features as the passive-to-active system, but at extended distances to 8,000 feet. Generally, there is no need for an amplified transmitter unless the cable runs are longer than 3,000 feet.
Most of the leading camera manufacturers are now offering cameras with UTP transmitters built in. This major trend provides a real benefit to the installer, both in price and ease of installation.
Getting Creative with UTP
To improve rack-space efficiency, many UTP manufacturers offer high-density, multi-channel solutions in which as many as 32 channels inhabit one rack space. Reduced installation labor and cable costs are achieved by using a shared cable. Multiple pairs in a single cable allow the sharing of video, PTZ control and 24VAC power. Video signals can even reside in the customer's existing telecom or datacom infrastructure without interference. This can be especially useful in multi-building environments.
Cable usage can often be maximized by employing a new, low-cost cable that contains two pairs of 24-gauge Cat 5 plus one pair of 16-2 or 18-2. Designed specifically for CCTV, this new cable enables the installer to run video, power and PTZ control within a single bundle, either zipped or composite. The cable is run from each camera to the local intermediate distribution frame wiring closet, which contains a multi-port power supply and cross-connect punch blocks. The pairs for power are terminated at the power supply, while the pairs for video and PTZ control get punched down and continue their path home in larger, multi-pair bundles. Vendors include Coleman, Genesis, West-Penn and Belden.
Transmission in Working Applications
The Aladdin Resort and Casino in Las Vegas has a state-of-the-art system that provided a testing ground for UTP video transmission. After the casino had operated for one full year on a UTP backbone, Mike Hollaway, lead surveillance technician at the Aladdin, commented, "There's no bad video here. All of our video is excellent. All cameras look the same whether they are at 10 or 3,000 feet. If I run across bad video, I know something happened recently to that camera due to camera failure, low voltage, input card or some other similar problem."
The system at the Aladdin is standardized for every camera. At the camera end, an NV-213A or equivalent adaptor that fits right into an Ultrak dome is used as a transmitter. All video and data runs back through the Cat 5 cable to the head-end termination wall, where the data is split out from the video. This termination wall is very important because it allows moves and changes to occur away from the head-end gear, requiring only that cross-connection wires be changed or added. The end result is a cleaner head end without the coax "rat's nest" so many large systems end up with after years of additions.
The video then goes to 16-channel amplified receivers handling more than 700 cameras via NV-1662R video receiver hubs. The only coax in the Aladdin's entire system runs between the hubs and the Ultrak multiplexers, then from the output of the multiplexers to the Max Pro video matrix.
In this passive-to-active configuration, video signals travel up to 3,000 feet without experiencing any loss and are protected from all types of noise, surges, lightning and ground loops. The resulting quality is more like fiber than coax, without the expense or hassle of either.
The Aladdin installed nearly three times the UTP cable necessary to begin with. Planning for expansion by pulling more cable than is initially needed can be a real time saver. Now, when the Alladin needs to add a camera, they rarely have to run new cable. This tactic can be a money saver as well, because a 25-pair bundle is about the same size and cost as three coax cables. In a given conduit space, you can pull 10 times more UTP cable than coax. This is especially important in cities like Las Vegas, where all low-voltage cable is required to be in conduit.