AV over CAT5 – Introduction

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Since the early datacom years (circa 1984), baluns (BALanced-Unbalanced) have played a key role in the migration from coax-based cabling systems to structured twisted pair cabling systems (SCS).   In fact, the largest adopter of unshielded twisted pair (UTP) technology today is the Ethernet LAN industry.   Prior to 10/100BaseT becoming a standard, companies such as MuxLab were developing baluns to adapt earlier Ethernet cabling standards (10Base5 and 10Base2) to unshielded twisted pair.

A balun is basic cabling device that interfaces with a structured cabling system, providing the essential link between traditional coax-based equipment and copper twisted pair cable.   Its importance lies in its relative simplicity and its ability to passively or actively connect a wide range of data/video equipment to a pre-existing copper twisted pair cabling infrastructure, thereby overcoming the inherent limitations of UTP and preserving the investment in the cabling system.   Over the past ten (10) years balun technology has started to make inroads into the traditional audio-video arena.  Today balun technology is having a major impact on the way audio-video (AV) equipment is installed.

Figure 1: Typical Video Balun

Figure 1: Typical Video Balun

With recent improvements in copper twisted pair cabling and balun technology, the performance of audio-video over copper twisted pair has improved considerably.   Today, there are many balun models supporting a wide range of audio-video formats over Cat5.  Some of these environments include composite video, S-Video, RGB, component video, digital audio, analog audio, RF/CATV, DVI, and HDMI.   As basic building blocks, these baluns support point-to-point connections over Cat5 and may be used in a wide range of applications including; security video, digital signage, classroom training, boardroom systems and video kiosks.

Originally viewed as a luxury item to support Cat5 cable, today, the balun has become a key element in preserving the investment in a structured cabling system (SCS) and as balun prices decrease, Cat5 is becoming a more attractive alternative to coaxial cable even at short cable lengths under 200ft.  This has spurred development of new technology that optimizes analog and digital AV signal transmission over copper twisted pair cable.

As balun technology becomes more accepted in the audio-video environment, the market is moving from a product-centric to a solution-centric industry.  More and more products are expected to be introduced that streamline audio-video cabling using copper twisted pair technology.  Audio-video equipment that is twisted pair ready will probably be introduced by more vendors on a proprietary basis to capitalize on the advantage of using Cat5 for AV connections.  This will precipitate a need for second tier products that support AV transmission over twisted pair.  Products such as distance extenders, switchers and distribution amplifiers will probably surface over the next few years to support the many vertical market applications that exist. 

MuxLab has been fortunate to be involved in a wide range of applications where balun technology has been applied.   As the industry progresses, the key will be whether vendors can successfully build on the basic building block technology and migrate to the next generation products that provide a more complete Cat5 cabling solution.  Some of the key areas of activity are described below.

AV over CAT5 – Classroom Training

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Figure 2: Typical VGA and Keyboard/Mouse Balun Application

Figure 2: Typical VGA and Keyboard/Mouse Balun Application

Classroom multimedia systems have been dramatically streamlined.  By allowing standard Cat5 cabling to be used, balun technology has enabled schools to deploy classroom projector systems more efficiently.  Typically a VGA projector is connected to a teacher’s PC.  By using balun technology, valuable conduit space is saved and bulky VGA cable is replaced by Cat5.

AV over CAT5 – Digital Signage

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The proliferation of dazzling new display technologies has led to the development of new applications.  Digital signage is one such application.  Typically, a server receives digital video content over a network and then outputs the information through a VGA port on the server.  A distribution amplifier (DA) may distribute the video content to multiple screens within the premises.  Retail stores, airports, hotels and restaurant chains are some of the key users.  Balun technology enables these multiple displays to be connected to the video server via Cat5 instead of coaxial AV cable yielding considerable cost savings and preserving the investment in pre-existing cable.

Figure 3: Typical Digital Signage Application

Figure 3: Typical Digital Signage Application

Active, or powered video baluns that amplify and equalize the video signal are capable of supporting extended cable lengths over Cat5 at image resolutions up to 1920 x 1440 pixels, thus placing new applications within distance reach.  For example multi-screen video kiosks may be deployed in large stores or public areas more easily where pre-installed Cat5 cable is available.

The commercial and residential markets have recently turned toward balun technology to resolve many cabling issues associated with custom AV.  Multi-room systems, production and sound systems, rental and staging are a few markets that are starting to reap the benefits of pre-existing Cat5.   The following diagram illustrates the use of MuxLab’s component video baluns to connect a number of high-resolution cameras back to a mobile video production facility.

Figure 4: Typical Video Production Application

Figure 4: Typical Video Production Application

Until recently component video could only be transmitted at low resolution over Cat5.  Today there are Cat5 balun solutions that support HDTV (780p, 1080i) resolution over Cat5 and this is opening new doors in the custom AV market.  HDTV is now as easy to connect over Cat5 as Ethernet.

AV over CAT5 – Security Video

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Security video has rapidly adopted Cat5 as a preferred method for cabling.  A longstanding coaxial cable user, the CCTV industry has slowly shifted a significant portion of its cabling over to copper twisted pair.  One of the key drawing cards is the higher capacity of Cat5 versus coax.  A single Cat5 can support four (4) cameras versus one with coax.  Furthermore video, power and PTZ control can co-exist under the same Cat5 and therefore up to three cables may be replaced by one Cat5 cable in many installations as shown in the following diagram.

Figure 5: Typical Security Video Application

Figure 5: Typical Security Video Application

Recent innovations in balun technology have resulted in improved cabling techniques resulting in major improvements in cabling efficiency.  One of which is the introduction of auto-gain compensation into extended distance CCTV connections.  Prior to auto-gain, manual adjustments needed to be made on every camera port in order to ensure the correct signal levels.  Auto-gain technology has solved this problem and helped save installation time and eliminate unnecessary on-site maintenance calls.   Another recent balun technology innovation is the combination of video, power and PTZ camera control over one Cat5 cable.  Prior to these specialized baluns, power, video and control required three (3) separate cables.  Due to the excellent crosstalk immunity of video baluns and Cat5, these three (3) key camera signals may be combined over one cable, thereby eliminating extra cables and installation time.

AV over CAT5 – CATV

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The limits of balun technology become more apparent as RF video is transmitted over Cat5.  MuxLab has been involved in this market and CATV over Cat5 has been a problem solver for some RF video users.    However, even baluns and UTP have their limits.  The signal attenuation above 600 MHz is quite high and above 900 MHz it is virtually impossible to push an RF video signal through even with amplification.  This precludes any application for satellite RF over Cat5.   However, apartments, hotels, condominiums have been quick to use RF video baluns to solve sticky problems where coaxial cable is not available.

Figure 6: Typical CATV and Cable Modem Application

Figure 6: Typical CATV and Cable Modem Application

Among the latest developments in CATV balun technology is the support for terrestrial channel frequencies up to 900 MHz, enabling applications such as broadband Internet and HDTV channels.  At higher channel frequencies, superior quality twisted pair cable is needed and sometimes RF amplifiers must be used to compensate for the high signal losses over UTP.  Category 6/7 cable has been found to provide some improvement over Cat5 cable at frequencies above 550 MHz..  Siemon specifies its Category 7 cable for use with RF baluns in order to support RF video transmission over copper twisted pair.�
(http://www.siemon.com/e-catalog/ECAT_GI_page.aspx?GI_ID=mpc_tera-video-balun-cord).   Despite the fact that RF is an efficient distribution method for video and Internet,  there are relatively few UTP cabling solutions on the market.  This may also be due in part to the significant technical challenges and limitations in transmitting RF video/data over Cat5.  Some vendors have taken up the challenge.  For example, BH Electronics, Z-Band, Commscope (Systimax) and MuxLab are a few companies that offer proprietary solutions for RF-over-Cat5 which include RF video baluns and distribution hubs.

AV over CAT5 – Conclusion

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Today, Cat5 balun technology is being integrated into virtually every industry; from mass transportation and consumer video displays to submersible video systems.   In the commercial and residential markets, the proliferation of Cat5 audio-video cabling solutions is continuing to help to preserve the investment in structured cabling systems and facilitate cabling in more advanced AV systems.

MilesTek offers several AV Over CAT5 solutions including HDMI, VGA, USB, CCTV, CATV, Component Video and more.  For more information, visit:  http://www.milestek.com/lp_over_utp_baluns_wall_plates.asp