Introduction

The term Structured Cabling System is used to describe organised cable networks designed to facilitate a variety of internal and multi-building communications services, including integrated voice, video and data. Primarily installed by the data and telecommunications industries, these advanced cable networks have evolved rapidly in the last 10 years, switching from an early reliance on coax, to using other cable media, with the vast majority now using unshielded twisted pair (UTP) cable for the transmission of a variety of communications signals.

The explanation for this major change is simple; UTP offers a technically superior transmission media, it can be used within simple cable network configurations, is commonly available and is cost-effective when compared to coax. For these reasons, CCTV video transmission technology is able to exploit the intrinsic advantages of UTP cable, to offer an extremely effective choice of transmission media vs. coax and fibre-optic.

Structured cabling systems' standards of performance for use with data and telecommunications services are regulated by the International Standards Organisation (ISO) and its European counterpart the IEC. However, when considering their use for the application of stand-alone CCTV video networks, we need only apply their basic principles and methodology to the installation and design of UTP based video cable networks. In conjunction with high-performance video transmission technology, a myriad of benefits associated with the simpler and superior UTP based cable-networking topology can be exploited.

The evolution of UTP structured cable systems using CAT5e cable for data and telecoms offers designers and specifiers of camera surveillance systems, a major breakthrough in the way CCTV is installed. With the vast majority of cameras in Germany still being connected to the control room via coax, the associated problems are well known and documented, so why do we put up with them? UTP cable video networks can eradicate these problems, can provide us with a straightforward and unproblematic solution and dramatically reduce overall installation costs.

When designing a CCTV system, the installer will typically run a 25-pair UTP cable bundle video distribution CAT5e 'backbone' in the building or site, to conveniently placed central distribution points where they are terminated in a UTP patch block. From these points, much smaller multi-pair UTP cable bundles can be run to the cameras, carrying video, telemetry and low voltage power signals.

CCTV installers using UTP based structured cabling wiring principles will experience a number of benefits; these can be summed up in two distinct categories. For example, by running 25-pair UTP cables as a backbone to strategic distribution points in a building we can achieve:

1. Lower cable cost per metre than running multiple coaxes and associated telemetry control cables - i.e. one UTP cable carries all the signals.
2. Reduction in the cost of labour due to ease of installing single multi-pair UTP cables, rather than masses of separate coaxes.
3. Future proof expansion capability. By installing 25-pair UTP 'backbone' cables, additional capacity is catered for, so that at any time in the future, additional cameras / dome cameras can be installed by simply connecting a short UTP cable run to the nearest main distribution point.
4. All UTP cables are 'colour coded' which makes installation & maintenance easier and quicker.
5. UTP cables take up less containment space than is the case with coax. A 25-pair UTP is the size of just 2 coax cables.
6. Flexibility of cable runs. - Multiple signals can be transmitted down the same multiple UTP cable and between several buildings without any induced interference to the video signals.
7. Easier transportation to site of much lighter (than coax) UTP cables.

By wiring UTP cables in a 'star' configuration to individual cameras, other associated benefits include:

1. Only one cable is required from the main distribution point to any given camera - Instead of 2 to 3 as would be the case with coax. This dramatically reduces the amount of cable mass required, associated cost of materials and labour.
2. By sending video, telemetry (data) control and power down one UTP cable, costs can be cut to (typically) a quarter of that compared to using coax.
3. By running power from central distribution points, there is no need to install an un-switched fused spur for each camera. This saves money at each and every camera point.

Combining the benefits of using UTP with the features of high-performance video transmission equipment that includes features such as fully-adjustable brightness and sharpness adjustment, hum-bar protection, surge & lightening protection, cross-talk immunity and better noise and interference rejection, the resulting UTP video transmission solution is superior to that of traditional coax based systems.

With the advent of NVT's convenient, simple to use, high-quality UTP video transmission equipment, it is now fair to say, that virtually anywhere coax or fibre is used, UTP video transmission can now provide a viable and competitive solution.

Notes

NVT is the multi--winning manufacturer of CCTV products for the transmission of high-quality, real-time video & audio over unshielded twisted pair cable.

Camera video transmission over Unshielded Twisted Pair (UTP) cable is one of the fastest growth areas in the European CCTV industry. And now, products from the award-winning manufacturer Network Video Technologies (NVT) are available through CBC Gmbh.

Using NVT products, real-time, high-quality video transmission using low cost UTP cables can be achieved at a price and performance that is better than coax, and offers a viable alternative to fibre, for distances up to 1,6Km.

NVT's technology allows cables to be run in high noise environments and alongside other cable bundles carrying video, telemetry, telecom, datacom and low voltage power. The ability to run multiple camera video, telemetry & power through one multi-pair UTP cable also takes up less ducting space - leading to faster, less complex installations.

Available through CBC Gmbh, NVT's range includes miniature single and rack mountable multi-channel UTP video transmitters and receivers that can bring substantial cost and performance benefits to your CCTV installations.

Frequently Asked Questions (FAQ)

Q: What kind of cable should I use with UTP devices? A: Use Unshielded Twisted Pair, such as CAT5e or telephone cable; part CW1308. 24AWG or thicker, stranded or solid versions.

Q: Can shielded twisted pair cable be used? A: Some customers have successfully used shielded cable up to a few hundred feet. However NVT does not recommend it as the transmission distance will be reduced. Using a multi-pair cable (ten, or more pairs) with an overall shield is OK.

Q: Can the cable runs have splices? A: Yes. NVT recommends designing CCTV systems in much the same way as telephone/data systems. You can splice the cable, by using a range of 4 to 100 pair Krone boxes to make connections. Video has been sent through a dozen of these connections without significant degradation.

Q: Can Category 6 cable be used? A: Yes. Unshielded Twisted Pair cable, Category 2, telephone or better, can be used with NVT equipment.

Q: Can un-twisted cable be used? A: Some installers have successfully used untwisted cable. NVT does not recommend it due to its interference susceptibility.

Q: Can cables be installed near RF antennas, fluorescent lights, motors, generators, or high voltage? A: Yes. The NVT signal is highly immune to interference.

Q: How can I send video from one camera to more than one monitor using NVT? A: There are a couple ways to accomplish this. One is to connect the video source to a distribution amplifier. This provides multiple video outputs for each input. Connect a transmitter and receiver to each cable run leading back to each monitor. The alternate method is to send the video signal to the first monitor using a pair of transceivers. Then loop out of that monitor and use another pair of transceivers to continue on to the next monitor.

General

Q: Will RF interfere with the video when using NVT devices? A: No. The NVT signal is highly immune to interference. NVT signals are sent differentially. That is, the equipment is only concerned with the voltage difference between the two conductors. RF or other fields will still couple into the conductors, but will do so in each conductor equally. This Common-Mode signal is ignored by the NVT equipment, which has a 60 dB Common-Mode Rejection Ratio (CMRR).

Q: What is the warranty on NVT products? A: All NVT products, including active receivers, carry a full "Lifetime Warranty" - demonstrating NVT's confidence in equipment performance and long-term reliability.

Q: Can NVT help me with my design? A: Yes. NVT offer a comprehensive system design service. This facility offers system drawings and specification documentation free of charge, available by contacting the NVT Technical Support team.

Q: What if I need field support, can NVT help me? A: Yes. NVT will support "on-site" design and surveys, and also helps with any technical issues whenever necessary.

Supported Signals

Q: Do NVT transceivers support "up the coax" pan/tilt/zoom controls? A: Yes. When using passive transceivers to transmit and receive, "up the coax" control signals can be sent with the video up to 300 metres.

Q: Can NVT devices transmit VGA? A: Yes. The NTSC or PAL output of a VGA or SVGA scan converter can be transmitted using NVT.

Q: Can more than one video signal be transmitted in a single multi-pair cable? A: Yes. One of the benefits of using NVT transceivers is interference rejection. NVT video signals can reside in the same cable bundle as multiple video signals, Ethernet, 24VAC, RS-422, RS-485, etc.

Q: Can video signals be sent in opposite directions within the same cable? A: Yes, however, due to near end crosstalk, there are distance limitations. When using telephone cable, do not send video in opposite directions within the same cable more than 300 metres. With CAT5e, do not send bi-directional video more than 600 metres.

Q: Do NVT transceivers support broadband RF/VHF/UHF? A: No. Use demodulators and modulators to convert to baseband composite video.

Q: Can satellite or cable TV be transmitted using NVT transceivers? A: No. NVT transceivers do not support the wide bandwidth cable TV signal. However, a single channel can be sent if a demodulator and modulator are used.

Q: Can I transmit a multiplexed signal on unshielded twisted pair? A: Yes, in the same way as you would use a coax cable, with NVT allow for a pair of transceivers per output.

Q: Can NVT transmit RS-422 or RS-485 signals? A: RS-422 or RS-485 signals are hard-cabled between the P/T/Z equipment and are not transmitted or received by NVT transceivers. The data signal may be sent on a spare pair within the same cable as the video signal.