MHR-2 Plenum Rated

Version Available
Two Conductor Mini High Resolution S-Video Cable

MHR-5/6 Plenum Rated

Five/Six Conductor Mini High Resolution Cable Version Available

MHR-2 Cable
MHRHF-5
MHR-5/6 Cable
Five Conductor Mini High Resolution Halogen-Free Cable
MHRHF-5 Cable

M59-3/5/6 M59-3/5/6 Cable

Three/Five/Six Conductor Mini 59 Flex Cable
RG59 Cable
RG59 Plenum Rated
Version Available RG59-3MHR-3 Cable
Single Conductor RG59 High Resolution Cable
RG6 Cable

MHR-5STP-2 Cable
RG59-3MHR-3
Three Conductor RG59 High Resolution and Three MHRVGA Cable
Conductor MHR Cable
CTL Cable

UTP23SF-4 Cable
Plenum Rated
MHR-5STP-2 Cable Version Available
Five Conductor MHR and Two 22 AWG Shielded STP Series Cable
Twisted Pairs Cable
STP24LC Cable
RG6 Plenum Rated
Version Available SPK Series Cable
Single Conductor RG6 Super High Resolution Cable
Cable Assemblies

Adapters
MHRVGA Plenum Rated
Version Available
Mini High Resolution Audio, Video, Control Cable Custom Cables

CTL Plenum Rated

Version Available
Comm-Link Control Systems Cable

Plenum Rated
UTP23SF-4 Version Available
Enhanced Skew-Free™ AV UTP Cable

Plenum Rated
STP Series Version Available
Serial Control/Audio Cable

STP24LC Plenum Rated

Version Available
Low Capacitance Serial Control/Digital Audio Cable

SPK Series Plenum Rated

Version Available
Speaker Cable
© 2005 Extron Electronics. All rights reserved.
All trademarks mentioned are the property of their respective owners. 05-05
68-554-01
REV. C
 STP20-2 N/A N/A 52

STP22-P 82761 25291 52

STP20-P N/A 25292 52

Extron Cables General Purpose Cable Cross-Reference STP22-2P

For your convenience in selecting the right cable for each application, we have prepared cross-reference tables for
STP20-2P N/A N/A 52
88723 N/A 52

Specifically Designed and Precision some of the most commonly used cables A/V professionals have come to rely on in integrating systems.

Engineered for the A/V Industry RG59 Cable

Extron Model Belden* West Penn* Page #
Low Capacitance Digital Audio Cable
Extron Model Belden* West Penn* Page #
RG59 1505A 819 40 STP24LC 1800B DA2401 54
One stop Cable Shopping Multiple Cable Warehouses
RG59P 1506A 25819 40 STP24LC-2 1802B DA2402 54
Extron Electronics offers a complete line of In order to provide timely and cost-effective
cable products specifically designed and delivery, we maintain a robust worldwide
engineered for the professional A/V industry. distribution network with warehouses in RG6 Cable Low Capacitance Serial Control Cable
Our cable product portfolio includes high California, North Carolina, The Netherlands, Extron Model Belden* West Penn* Page # Extron Model Belden* West Penn* Page #
quality bulk cables and cable assemblies, Singapore and Japan. Each of our cable
RG6 1694A 6350 44 STP24LC — D4851 54
problem-solving adapters, as well as Extron’s products is backed by a 24-hour Sales and 1419A
RG6P 1695A 256350 44 STP24LC-2 D4852 54
new Universal Crimp Tool and precision Technical Support Hotline, and range of 8162

machined BNC crimp connectors with Secure- support services that is second to none.
Lock pin positioning. Serial Control/Audio Cable Speaker Cable
Extron Model Belden* West Penn* Page # Extron Model Belden* West Penn* Page #
STP22 9451 (X)454 52 SPK18 8461 224 56
STP20 9464 N/A 52 SPK16 8471 225 56
Yukon
Nunavut
STP22-2 8723 77510/D510 52 SPK14 8473 226 56
Territory
Northwest
Territories
STP20-2 N/A N/A 52 SPK18P 82740 25224 56
STP22-P 82761 25291 52 SPK16P N/A 25225 56
Newfoundland

STP20-P N/A 25292 52 SPK14P N/A 25226 56

British STP22-2P 88723 N/A 52

Columbia
Alberta
STP20-2P N/A N/A 52

Manitoba
Saskatchewan Quebec
Ontario New
Brunswick Low Capacitance Digital Audio Cable
Nova
Washington
Scotia
Minnesota Maine
Extron Model Belden* West Penn* Page #
Montana North Dakota
New Hampshire
Oregon STP24LC 1800B DA2401 54
Crimp Connector to CableDA2402
Cross-Reference
Wisconsin Vermont
Idaho South Dakota Mass
New York STP24LC-2 1802B 54
The Extron BNC crimp connectors are designed to fit every Extron coaxial cable, as well as many other coaxial
Wyoming Michigan
Rhode Island
Iowa Connecticut
Nebraska Pennsylvania
Nevada
Utah Illinois Indiana
Ohio New Jersey
Delaware
cables used by A/V professionals. The chart below shows some of the many cables that are compatible with our
Colorado Maryland
Extron BNC crimp connectors.
Crimp Connector
Low Capacitance Serial
to Cable Compatibility
Control Cable
California West Virginia
Kansas Missouri Virginia
Kentucky
Extron
Anaheim North
Carolina Extron
Extron Model Belden* West Penn* Page #
Tennessee
Arizona Oklahoma Arkansas East Coast
Part # Description — Extron Belden Canare Liberty West Penn
South
New Mexico
Carolina Warehouse STP24LC D4851 54
Alabama
Georgia STP24LC-2
100-250-01 BNC male 1419A
MHR-2/5/6, D4852
MHRHF-5, 54 RGB5C-PVC
MHR, Qty. 50 8162
Hawaii Texas MHRVGA
Louisiana
Mississippi 100-250-02 BNC male MHR-2/5/6, MHRHF-5, RGB5C-PVC
Florida MHR, Qty. 500 MHRVGA
Alaska
Speaker Cable
Extron
100-253-01Model
BNC female Belden*
MHR-2/5/6, West Penn* Page #
MHRHF-5, RGB5C-PVC
MHR, Qty. 50 MHRVGA
Shipped from CA, Anaheim warehouse SPK18 8461 224 56
100-253-02 BNC female MHR-2/5/6, MHRHF-5, RGB5C-PVC
Shipped from NC, East coast warehouse SPK16 MHR, Qty. 500 MHRVGA
8471 225 56
SPK14 8473 226 56
100-263-01 BNC male M59 M59 -3/5/6
SPK18P Qty. 50 82740 25224 56
SPK16P
100-263-02 BNC male M59 N/A
M59 -3/5/6 25225 56
Qty. 500
SPK14P N/A 25226 56

100-257-01 BNC male RG59, RG59 1505A & 1506A V-4CFB & 20-CMR-VIDEO-color & 819 & 25819
Qty. 50 L-4CFB 20-CMP-VID-COAX
100-257-02 BNC male RG59, RG59 1505A & 1506A V-4CFB & 20-CMR-VIDEO-color & 819 & 25819
Qty. 500 L-4CFB 20-CMP-VID-COAX

100-260-01 BNC male RG6, RG6, RG6-5 1694A & 1695A 18-CMP-SD, 18-CMP- 6350, WP6354,
Qty. 50 VID-COAX, RGB5C WP6355, 256350
100-260-02 BNC male RG6, RG6, RG6-5 1505A & 1506A 18-CMP-SD, 18-CMP- 6350, WP6354,
Qty. 500 VID-COAX, RGB5C WP6355, 256350
 Introduction
Table of Extron Electronics has a complete line of quality audio, video, and
CONTENTS control cables specifically designed and engineered to meet the needs of
professional A/V environments - from large universities and businesses

EDUCATION to small residential installations. Whether you need to send digital video
signals down the hall or control communication signals across campus,
Understanding Cables in the A/V Industry............................... 2 Extron cables are available for every signal type with the bandwidth and
Introduction and explanation of the basic components and .
construction of all the major cable types used for voice, data, . performance for the most demanding applications. Integrator-oriented
audio, and video signals features include pre-terminated cable assemblies in cut lengths for shorter
Deciphering Cable Safety Ratings and Applications.............. 9
A description of cable safety ratings runs, and bulk cables with smooth SuperFlex jackets that are marked
Analog Versus Digital Video Signal Formats............................. 12 at one-foot intervals for convenient measurement and boxed in self-
A comparison of digital and analog signal formats
dispensing rolls.
Selecting the Right Cable........................................................ 18
An in-depth guide to help determine which cable is correct in different
applications Complementing the cables and cable assemblies are precision machined
problem-solving adapters and ergonomic, time-saving termination tools.
BULK CABLES In addition, Extron carries an extensive line of audio, video, and control
adapters and gender changers, including the most frequently used barrel,
Introduction to Extron Cable Products................................... 21
Cable Termination Tools right angle, t-type, and panel mount adapters that increase installation
Universal Crimp Termination System.............................................................. 22 options. Save time and money, and ensure quality with our universal crimp
BNC Termination Tools................................................................................... 22
Universal Compression System...................................................................... 27 termination system engineered for reliable and consistent impedance
Video Cables matched terminations. A universal compression termination system with
MHR-2 Cable................................................................................................ 30
MHR-5/6 Cable............................................................................................. 32
high quality BNC, F-type, and RCA connectors is available as well. Extron’s
MHR-5STP-2 Cable....................................................................................... 34 complete line of cables, cable assemblies, adapters, and connectors
MHRHF-5 Cable............................................................................................ 36
M59-3/5/6 Cable.......................................................................................... 38
are rigorously tested to ensure they meet published performance
RG59 Cable.................................................................................................. 40 specifications, as well as applicable safety ratings, which are clearly noted.
RG59-3MHR-3 Cable.................................................................................... 42
RG6 Cable.................................................................................................... 44 Inside this catalog you will find educational material that addresses:
MHRVGA Cable............................................................................................. 46
UTP Cables Understanding Cables in the A/V Industry, Deciphering Cable Safety
UTP23SF-4 Cable.......................................................................................... 48 Ratings and Applications, Analog Versus Digital Video Signal Formats,
Audio and Control Cables and Selecting the Right Cable. Throughout are detailed photographs
CTL Cable..................................................................................................... 50
STP Series Cable............................................................................................ 52 and product descriptions with performance specifications to help guide
STP24LC Cable.............................................................................................. 54 your selections. Whether you are relatively new to the A/V industry or a
SPK Series Cable........................................................................................... 56
seasoned systems integrator, this Product Catalog contains the essential
cable assemblies information you need to make well-informed product choices that provide
theCross
performance Cable
andCross
Cable Section you expect
Cable Cross Section
keep your customers satisfied.
Section
BNC to BNC Cable........................................................................................ 58
VGA to VGA Cables....................................................................................... 60
Video, S-Video & Audio Cables......................................................................
Six 26 AWG Coax Five6426 AWG Coax
VGA to BNC Cables (SY VGA)....................................................................... 66
Four 26 AWG Shielded Three 26 AWG Shielded
Twisted Pair Twisted Pair
Install Kits.................................................................................................... 68
17 Conductor 14 Conductor 14 Conductor Cable
Three 20 AWG Three
RS-232 Cables............................................................................................. 68
Conductors20 AWG Conductors
Installation CableInstallation Cable
DVI Cables................................................................................................... 69
Enhanced Skew-Free™ A/V UTP Cables.......................................................... 70

Adapters
Video Adapters............................................................................................. 71
Audio Adapters............................................................................................. 73
Miscellaneous Adapters................................................................................. 74
Computer and Control Adapters.................................................................... 75
Custom Cables
Custom Cables.............................................................................................. 76

Glossary
Definitions of commonly used cable-related terms.......................................... 83


USA Europe Asia Japan www.extron.com
714.491.1500 / 800.633.9876 +31.33.453.4040 / +800.3987.6673 +65.6383.4400 / +800.7339.8766 +81.3.3511.7655 © 2005 Extron Electronics. All rights reserved.
714.491.1517 FAX +31.33.453.4050 FAX +65.6383.4664 FAX +81.3.3511.7656 FAX Pricing and specifications may change without notice.
 Understanding
xxx Cables in the A/V Industry

Cable Types
So many different models and types of cables exist that one could easily
Braid Shield
become intimidated by glancing through a cable catalog. But when you
EDUCATION

think about it, all of the various cable types really aren’t that different.
They are simply combined variations of basic cable configurations. When
you look at it this way, thi ngs become clearer. These different types of
Shielded Twisted Pair Cable
cables vary greatly in size, capabilities, quality, and performance within
their own groups, but most of the cables used in the A/V industry fall
within four main groups: individual conductor, twisted pair, coaxial, and Coaxial
fiber optic. Coaxial cable is a complex cable that consists of two conductors. The
center conductor carries the signal. The outer conductor (shield) provides
Individual Conductor a return path for the current to ground, and it provides protection against
This is the most basic of cables, commonly referred to as wire. It consists
outside interference. The two conductors are separated by a dielectric
of a center conductor that is wrapped in a plastic or rubberized outer
material (insulation) that establishes electrical characteristics and provides
jacket. This cable type is generally used to distribute low-frequency signals
physical protection for the center conductor.
such as speaker audio or computer ID-bit information. Larger variations of
this cable type are used to distribute power or for grounding. Outer Jacket Polyethylene Foam Insulator
Center Conductor

Foil Shield
.
Individual Conductor Cable Braid Shield

Twisted Pair Coaxial Cable

Twisted pair cable is available in two styles. Shielded and unshielded .
twisted pair (UTP) cables can be found in many types of environments, All of these components are jacketed to make one cable. In the A/V
ranging from telephony to professional audio. Twisted pair cable consists industry, coaxial cables generally have 75 ohm impedance and are used
of two individual conductors – generally running signal and return – that in video applications. They are also used with test equipment and RF
have been twisted together to form one pair. Usually found with 100 ohm distribution, and are found in many other environments. Due to the
impedance values in 20 to 24 American Wire Gauge (AWG) sizes, twisted complex design of coaxial cable, it is more expensive than twisted pair
pair cable is inexpensive and easy to work with. Because both conductors cable, but it provides excellent performance and shielding characteristics
have equal exposure to extraneous noise (which can be cancelled out at that make it very reliable. The frequency and resolution of your signal,
a receiver with a differential amplifier), twisted pair cabling, by design, and the distance of the cable, are very important determining factors in
provides an inexpensive form of protection from outside electromagnetic deciding which grade of coaxial cable should be used. Some have better
interference (EMI). signal loss characteristics than others. The crimp or compression style of
cable termination (connectorization) used with these cables makes them
Unshielded Twisted Pair (UTP) — Most commonly seen in very easy to terminate in field applications, and they offer very consistent
telecommunications and computer networking environments, UTP is and reliable connections.
categorized by its compatibility with the many different data transfer rates
associated with these types of equipment. For example, the most popular, Fiber Optic
Category 5/5e/6 cable, can accommodate transmission rates up to 100 Fiber optic cable is the best choice for hardwired signal transmission over
Mbps (megabits per second). long distances. This is due to the extremely low attenuation characteristics
(signal loss). Fiber optic cable accomplishes this by transmitting light
Outer Jacket (photons) instead of electricity (electrons). The way it works is simple:
Center Conductor
electrical energy from the source device is converted, via the transmitter,
into light energy. This light energy is then injected via a laser diode or high
performance LED into the fiber optic core. At this point, the light bounces
off the walls of the core in a very controlled manner and propagates
Unshielded Twisted Pair Cable
to the end of the cable, where it is detected by a wavelength-matched
photodiode and converted back to electrical energy at the receiver
Shielded Twisted Pair (STP) — Shielded Twisted Pair cable consists
location. The core is a strand of glass wrapped with a cladding material
of a regular twisted pair that is surrounded by a wire braid shield or a
to refract the light back into it. This makes fiber optic cable extremely
foil shield with a drain wire. Either shield provides additional protection
efficient, creating the near-perfect transmission medium. The core and
against RFI (radio frequency interference) and EMI (electromagnetic
cladding are covered by a protective coating that provides added strength.
interference), making it useful for sensitive signal distribution of audio
Finally, there is an outer jacket for additional strength and protection.
and computer sync information. A conductor called a drain wire is used to
Single mode and multimode cable types are available to provide multiple
provide a solid connection for the foil shield to each end of the cable.
signal distribution options.


USA Europe Asia Japan www.extron.com
714.491.1500 / 800.633.9876 +31.33.453.4040 / +800.3987.6673 +65.6383.4400 / +800.7339.8766 +81.3.3511.7655 © 2005 Extron Electronics. All rights reserved.
714.491.1517 FAX +31.33.453.4050 FAX +65.6383.4664 FAX +81.3.3511.7656 FAX Pricing and specifications may change without notice.
Understanding Cables in the A/V Industry (continued)

Fiber optic signal transmission is immune to many of the effects that which are capable of carrying electrical current. The most commonly used
reduce signal quality in traditional wired environments, and therefore, material is copper, due to its overall conductive properties, availability,
offers many advantages: cost, and workability. Other materials are available and are used in

EDUCATION
specific applications. Examples of other conductors that may be found
1. Complete immunity from EMI — Traditional wire and cable can include aluminum, silver, and gold. Solid and stranded center conductors
act like an antenna, picking up unintended stray signals. This poses are readily found in the construction of cable.
problems, particularly for display systems. Because fiber optic cable is
constructed of glass and the signal is light, it is not subject to outside Solid — A solid center conductor is one that is made of one single wire.
noise. The diameter, or AWG (American Wire Gauge), size may vary, but solid
conductor cables are generally easier to manufacture and are therefore
2. S mall size — Because most fiber optic cores are no larger than less expensive. These conductors are formable but not very flexible. For
human hair, these cables tend to be very small and lightweight. that reason, solid center conductor cables are generally used in permanent
3. L ow attenuation — Because fiber optic transmission is installations.
accomplished with light sent through glass, the normal resistance and Stranded — Stranded center conductors are comprised of multiple small
capacitance factors that introduce loss into traditional systems do not gauge wires that are twisted together to form a larger single conductor.
apply. This provides high bandwidth capabilities, and the ability to run The advantage of this type of conductor is the increased flexibility. These
long distances while protecting against outside interference. cables are easy to work with, and are found in more mobile applications.
4. H
 igh security — Transmission of light is not subject to electronic Gauge
eavesdropping, making fiber optic cable useful for secure Gauge is the diameter of a conductor with higher gauges being smaller
communications. and lower gauges being larger. For instance, an 18 gauge wire is very
Although fiber optics would appear to be the ultimate method of signal thin, while a 12 gauge wire is much thicker. It is generally preferable to
transmission, there are some drawbacks: use lower gauge wires whenever possible. The thicker wires allow a signal
to travel more freely over longer distances and generally allow greater
1. H
 igher price — Overall, a system that uses fiber optic runs will be quality. Wires with a thicker gauge have less resistance to current flow
more expensive. This is in part a result of the costs associated with fiber, (impedance) than thinner wires, making them preferable for connecting
transmitters, receivers, and labor. equipment, especially if the lengths of wire are fairly long. (See American
Wire Gauge chart on page 17).
2. D
 ifficult to use — Termination of fiber optic cable is crucial in
establishing a good transmission path. Fiber cable end termination Dielectric
is somewhat specialized, and it is not something that is quickly The dielectric, also known as cable insulation, serves an important dual
accomplished. This could contribute to a longer and more expensive role in coaxial cables. It is the material that separates the center conductor
installation. from the outer shield. This protects the center conductor. But, more
importantly, it establishes electrical characteristics, such as impedance and
3. P
 erformance — While fiber optic cable is the near-perfect
capacitance that greatly influence the overall cable performance. Some of
transmission medium, system limitations are introduced by the
the more common insulation materials include polyethylene for general
technical performance of the transmitting and receiving equipment.
purpose cable and fluoropolymers for plenum-rated cables.
In digital systems, fiber is very robust, particularly when based on
laser emitters. For most video systems, there are some very capable
fiber transmission systems, but virtually all are analog-based with
commensurate difficulty maintaining high speed performance and
linearity. The cost for transmitter/receiver combinations with high
performance graphics capability can be very costly compared to good
quality copper-based transmission lines.

Anatomy of a Cable
Most people view cable simply as something that is used to connect two
pieces of equipment together. Not much attention is given to what is
inside. The inner components of a cable and the materials used during
construction are absolutely critical in establishing how a given cable
will perform in an application. In this section, we will use coaxial cable
as an example because a coaxial cable consists of all of the following
components. In one form or another, all cables will use some, if not all, of
these components in their construction.

Conductors
The center conductor of a cable carries the signal from one point to
another. Center conductors are made of highly conductive materials,


USA Europe Asia Japan www.extron.com
714.491.1500 / 800.633.9876 +31.33.453.4040 / +800.3987.6673 +65.6383.4400 / +800.7339.8766 +81.3.3511.7655 © 2005 Extron Electronics. All rights reserved.
714.491.1517 FAX +31.33.453.4050 FAX +65.6383.4664 FAX +81.3.3511.7656 FAX Pricing and specifications may change without notice.
 Understanding Cables in the A/V Industry (continued)

Shielding Jacket
Shields also serve an important dual role. They work as a second Overall protection to the inner components is provided by the outer jacket.
conductor, which acts as a return path for the signal current to the system The outer jacket of a cable protects against weather, chemicals, liquids,
EDUCATION

ground. They also provide signal protection from outside interference. and sunlight. Cable must conform to any of a number of classifications
Several shielding methods are available to handle the different types of to be installed in specific environments. These standards are governed
interference that cables may encounter. Foil shields, braided shields, and by the NEC (National Electric Code) and have certain UL (Underwriters
combination foil/braid shields serve specific purposes. Laboratories) certifications.

Braid shield — This type of shield is made of many fine strands of Plenum — A typical projection system installation involves cable
wire woven together to form a braid that encompasses the internal distribution through walls and ceilings. If you climb a ladder and observe
conductor(s) and dielectric of the cable. A braid shield is typically lower the labyrinth that exists above ceiling panels, chances are you may see
impedance than a foil shield and offers better immunity from stray air conditioning ducts and other air movement systems. This type of area
electromagnetic fields or interference (EMI). Interference can take would be categorized as a plenum ceiling or plenum environment. It has
many forms, from low frequencies (such as rolling hum bars) to higher this designation because the air return system for a building is located in
frequencies (such as noise generated by appliances and switching power this area. Special consideration must be taken for all other equipment in
supplies). Braid shields may be used in combinations of multiple braids this environment. Therefore, cables that are used must be either plenum
or with copper or aluminum foils to offer higher percentages of shielding rated (CL2P/CMP) or run through electrical conduit. Local fire codes
coverage. dictate what equipment requirements are necessary. CL2P or CMP-rated
cables not only have special fire-resistant jackets, but they also use special
Foil shield — Foil shields provide 100% shielding effectiveness when compounds in the insulation material. This provides for low flame and
used in conjunction with a braid shield. Whereas copper braid shields may smoke output in the event that the cable is exposed to fire. Plenum cable
have more than 90% shielding effectiveness, realizing 100% with braid can be run through open air spaces, so the need for conduit is eliminated
usually requires two braid shields at higher cost, weight, and stiffness. A and installation costs can be reduced.
foil/braid combination accomplishes 100% shielding effectiveness much
more easily. Halogen-Free — Halogen-free cables utilize a low smoke and
fumes, zero halogen jacket material that meets European safety code
The foil shield is a foil-sided tape wrapped completely around the requirements (IEC 33203 flame test, IEC 61034 smoke test, and IEC 754-
insulation of the cable. In some cable designs, a small-gauge drain wire 1corrosivity test).
will accompany a foil shield. The drain wire facilitates shield connection
to a connector shell. The foil/drain wire approach provides only minimal Jacket materials go a long way in establishing the overall flexibility of the
shielding effectiveness, primarily at lower frequencies. cable. For example, because of the jacket material, a plenum-rated cable
will be more stiff, and therefore more difficult to maneuver and terminate.
Depending on the certification needs of the system, you would normally
want to use the most flexible cable that is available.

Shielding Effectiveness for Multiconductor Cables

The concept of a shield is simple. Think of it as an all-encompassing its exterior unwanted noise and shunts within its interior all locally
metal envelope surrounding that which is to be protected. Nothing generated noise. This can be accomplished in cables only when the outer
gets out. Nothing gets in. The concept is that it must be continuous and shield is terminated intimately at the connector body utilizing the full
unbroken; otherwise, energy may ingress or egress at the point where circumference of the shield itself.
the continuity is broken. This idea is the essence of the Faraday shield,
which shunts electromagnetic fields. Not having this quality shielding With VGA style terminations, shielding of the entire connector body is
means that a system is susceptible to outside noise and/or may radiate crucial in attaining EMI compliance. The shield is typically made of a
undesirable interference into other systems. solderable, soft, drawn metal. One end of the metal shield must contact
and be bonded (soldered) to the full circumference of the shield braid.
Carrying the Faraday shield idea forward, the metal enclosure The other end must conform to the shape of the connector body and be
surrounding a product can be a Faraday shield if constructed properly. bonded (soldered) to it as well. Only in this way is a complete Faraday
The outer shield of a cable, be it the shield of a single coax or the type shield created. Implementing quality shielding in cables and systems
shield of a complex group of wires, is a Faraday shield when terminated usually means more cost. Typically, better constructed cable assemblies
properly between the systems that it interconnects. Again, the idea cost more.
is a continuous, uninterrupted metallic surface that shunts around


USA Europe Asia Japan www.extron.com
714.491.1500 / 800.633.9876 +31.33.453.4040 / +800.3987.6673 +65.6383.4400 / +800.7339.8766 +81.3.3511.7655 © 2005 Extron Electronics. All rights reserved.
714.491.1517 FAX +31.33.453.4050 FAX +65.6383.4664 FAX +81.3.3511.7656 FAX Pricing and specifications may change without notice.
Understanding Cables in the A/V Industry (continued)

Cable Performance/Specifications matched as closely as possible in order to minimize skew time. In some
Performance Factors cases, electronic time delay circuitry may be employed to make up for
The way a cable performs in a system is largely determined by its physical cable variation leading to skew. As well, cables designed for minimum

EDUCATION
construction. While the following factors are somewhat related to the skew may be used.
physical cable, they have a large effect on the integrity of the signal at the
Cable Specifications
destination.
Cable specifications are the most important determining factor of how
Length — As cable length increases, signal loss increases as governed well a given cable will perform in a system. A cable can never be any
by the laws of physics. As the signal propagates along the cable, its better than the specifications allow it to be. For this reason, careful
performance is impeded by interactive factors associated with the attention should be paid to these important numbers before a cable
dielectric materials and its relationship to other conductors. Losses in purchasing decision is made. Many specifications for cables exist; some .
cable are calculated based on a unit length such as feet or meters. As of the most important ones are listed below.
transmission distance increases, loss of image brightness and detail
Impedance — Impedance is one of the most critical specifications.
gradually become apparent with analog signals. With digital signals,
It establishes the baseline for the flow of the signal. This flow must be
losses are not obvious until the receiving device can no longer recognize
maintained throughout the entire system for proper transfer of power.
the signal.
If there are impedance mismatches, the possibility that reflections will
Frequency — Consistent with cable length, increasing frequency is occur is very high. A reflection is essentially a faded, less powerful
another fundamental factor affecting signal transmission distance. As representation of an image that is being displayed. This reflected image
frequency increases, skin effect, dielectric quality, and cable construction will be noticed to the right of the original image. Reflections are caused .
determine how the cable will perform. For coaxial cables, the dielectric by impedance mismatches as well as improperly terminated connectors.
material must be a higher grade as frequency and distance requirements
Here is how reflections occur: Imagine water flowing through a large
rise. Since image detail is carried by the higher frequency components
diameter pipe. No problems exist as long as the pipe diameter remains
of a signal, image fuzziness is the first sign of poor high frequency
the same. If this pipe feeds into a smaller-diameter pipe, the water flow
performance.
is disrupted. As this bottleneck occurs, not all of the water will be able
Interference — Interference is any electromagnetic disturbance to flow through the smaller opening. This will cause some of the water
that interrupts, obstructs, or otherwise degrades or limits the effective to flow back into itself, and it will eventually be reintroduced into the
performance of electronics/electrical equipment. A cable may act as main water flow. A similar situation occurs with cable. The signal that is
a large antenna. Outside interference can pose significant problems reintroduced to the original signal is called a reflection. Most commonly
to signal integrity when the cable does not have adequate shielding used impedance for coax cable is 75 ohms.
properties.

Crosstalk — Crosstalk is a condition that occurs when signal

information on one conductor is electromagnetically induced into a nearby
conductor. This condition is usually thought of as degrading to system
performance and often occurs between conductors run in close proximity
without proper shielding or decoupling.

Temperature — A cable is an electronic component that is subject to

the same physical laws as other devices. All materials used within cable 1/2" Pipe 1" Pipe
construction are susceptible to performance variation due to heat-related Impedance mismatch
conditions. Because cables are typically installed in non-ventilated or
inadequately ventilated environs such as walls, ceilings, and equipment
racks, they tend to be exposed to higher-than-expected temperatures.
Therefore, it is important to select cables capable of consistent Attenuation — The next most important performance specification of
performance under those conditions. a cable is attenuation. Attenuation is a measurement of the amount of
Skew — Skew, in cabling terms, is used to describe the timing difference loss that will occur from one point to another. Attenuation is also referred
between two signals traveling over two separate conductors of differing to as insertion loss, and it is measured in dB (decibels). Typical cable
length (or other properties) and reaching their destinations at different specifications include a “loss table” which provides the dB loss value at
time intervals. Just as sound requires additional time to travel additional some selected frequencies for a standard length. For example, -2.2 dB/.
distance, so does an electrical signal propagating over a wire. As the 100 ft. @ 100 MHz would be a typical way of indicating a loss
wire length increases, the time required to travel the length of the wire specification. Cable loss is cumulative; so, at 200 MHz, the same 100-
increases proportionally. In multiconductor transmission systems, such as foot cable would have a different attenuation value. But, relative to
video over twisted pair cable, simultaneous arrival of the red, green, and one frequency (e.g. 100 MHz), the cumulative loss is additive as length
blue signals is essential for good video quality. Therefore, construction of increases. The same cable having 2.2 dB loss at 100 MHz at 100 feet will
cables for multi-channeled signal systems requires that cable lengths be have 4.4 dB loss at 100 MHz at 200 feet.


USA Europe Asia Japan www.extron.com
714.491.1500 / 800.633.9876 +31.33.453.4040 / +800.3987.6673 +65.6383.4400 / +800.7339.8766 +81.3.3511.7655 © 2005 Extron Electronics. All rights reserved.
714.491.1517 FAX +31.33.453.4050 FAX +65.6383.4664 FAX +81.3.3511.7656 FAX Pricing and specifications may change without notice.
 Understanding Cables in the A/V Industry (continued)

Extron Coax Cables Compared at 100'

0
EDUCATION

-1

-2

-3
Attenuation

-4

-5

-6

-7

-8

-9

-10
0 30 60 90 120 150 180 210 240 270 300
Frequency - MHz
Extron RG6/SHR - 18 AWG Extron RC - 24 AWG
Extron RG59/HR - 20 AWG Extron MHR - 26 AWG

Using The Cable Loss Table

Most coaxial cable specifications include loss values in dB for a range with that cable and not exceed -3 dB loss. If the loss factor exceeds our
of frequencies over a standard length, usually 100 feet or 100 meters. 3 dB budget, our choices would be to select a larger, lower-loss cable or
Depending on the most popular recommended application by the consider using interfaces or line drivers to compensate for the extra loss.
manufacturer, the list of frequencies will include “round number listings” Should the table not include the frequency of concern, you can interpolate
like 1, 5, 10, 20 MHz, etc. We use the loss at, or near, one of the specified a loss value between known values in the table or obtain a representative
frequencies to predict signal loss. This is a normal course at the beginning piece of the cable and have it measured specifically at the frequency of
of system design since most signal loss will occur in the cabling system interest. Cable losses are cumulative and are generally linear, which makes
over any significant distance between electronic components. Some tables interpolation of values fairly accurate.
will include loss values at very specific frequencies: 72, 135, 177, 270
MHz, etc. These frequencies relate to applications carrying serial digital Suppose your design calls for distribution of SDI signals. If you are
television signals. Serial digital interface (SDI) signals operate at specific distributing the most common rate from SMPTE 259M mode C, you will
speeds, or bit rates. System designers need to know the specific loss now look for the loss value corresponding to 135 MHz in the cable’s loss
values at these operating rates for SDI in order to better predict system table. For all SDI and HD-SDI loss calculations, the one-half clock rate
performance. Serial digital signals are unforgiving in that the signal will frequency is used. For 270 Mbps (270 MHz) component SDI, that would
not be recoverable if loss values exceed the receiver’s ability to read and be 135 MHz. Divide the dB loss value into 30 (SMPTE 259M allows a
decode the signal. maximum loss of -30 dB in which a Class A receiver should recover) and
the result will be the multiplier indicating how many multiples of 100-foot
Follow the cable’s specified insertion loss figure for 100 feet (or 100 lengths can be used. For example, if the loss at 135 MHz is -3 dB, we
meters) at the highest frequency of interest in your system design. For divide -30 by -3 to obtain a multiplier of 10. Now, with that specific cable,
example, if the highest frequency of interest in your design is 100 MHz, we can multiply 100 feet by 10 to obtain 1,000 feet. This would be the
then look for the loss value in dB at that frequency in the column having recommended length cable that could be run assuming a Class A receiver.
the units you use, either A class B receiver could reduce the run to -20/-3 = 6.67 for a run length
of 100 x 6.67 = 667 feet. Cables recommended for SDI or HD-SDI service
100 feet or 100 meters. Let’s say it is -2.5 dB for 100 feet. If your design
may include a 10% length reduction allowance to establish some margin
is distributing analog RGB signals, you will likely not want a loss more
against sudden signal loss, or the “cliff effect.” Usually, this will be noted
than -3 dB without taking other action (outlined below). So, if we take the
in the table. If not, decrease your run length by about 10% to obtain
ratio -3 dB/-2.5 dB, we obtain a value of 1.2. This 1.2 factor is now used
some margin. If any questions arise, consult with the cable manufacturer
as a multiplier against the 100 foot standard length cable used to build
before completing your calculations.
the loss table. Multiplying 100 by 1.2 equals 120 feet that we can run

USA Europe Asia Japan www.extron.com
714.491.1500 / 800.633.9876 +31.33.453.4040 / +800.3987.6673 +65.6383.4400 / +800.7339.8766 +81.3.3511.7655 © 2005 Extron Electronics. All rights reserved.
714.491.1517 FAX +31.33.453.4050 FAX +65.6383.4664 FAX +81.3.3511.7656 FAX Pricing and specifications may change without notice.
Understanding Cables in the A/V Industry (continued)

Electronic Compensation for Cable Loss Resistance — A definition of resistance is “that property of a substance
Although good cable loss planning is essential, there are times when no that impedes current and results in the dissipation of power in the form of
amount of cable planning will solve the real problem of high frequency heat.” Simply put, resistance is the characteristic of a conductor that slows

EDUCATION
loss in a system. In this situation, electronic compensation may be the only the flow of electrons. This specification is measured in ohms (W) and
reasonable solution. For this reason, all interfaces and line drivers, and represents the simple direct current, DC, loss in the conductor. In cable,
some distribution amplifiers and switcher/routers contain compensation resistance (DCR) is expressed as W/1,000 feet (ohms per one thousand
circuitry that provides for direct adjustment and compensation. Typically, feet). Resistance of a material is determined by material type, dimensions,
these components will have at least two controls, level (or gain) and and temperature.
peaking, which can make the difference between a usable or unusable
Resistance affects the voltage (amplitude) of a signal. Long cable runs
system. The best application for these compensation components is at the
or cable with high resistance values will make a displayed image appear
system head-end.
dim. For example, a piece of video equipment with an output of 0.7V p-p
is connected to a display via a 200-foot length of cable. The actual signal
level available at the display is only about 0.63 volt (loss of approximately
10%), for a mini high resolution cable with a DC resistance of 41W/1,000
feet. This is a result of the resistance of the center conductor reducing the
voltage level of the signal. Fortunately, there is equipment with features
specifically designed to compensate for these types of losses, such as the
level control on an Extron interface or line driver. The level control is used
to boost the signal voltage to compensate for resistive loss. The peaking
control is used to increase the voltage of the high frequency information.

Capacitance — Capacitance is defined as “the property of an electric

system that determines how much electrical charge will be stored in the
Level Control — The level control increases the overall signal level so as dielectric for a given potential difference between the conductors.” This
to overcome resistive losses in the cable. The resistive loss in a cable can can be interpreted as the ability of a component to charge, hold a charge,
easily amount to 5% or more. Against an analog signal of 0.7 volt, this and discharge. The unit of measurement for capacitance is the farad (F).
translates to a 35 mV signal decrease. This is significant in terms of driving In cable, capacitance is expressed as pF/ft. (picofarads per foot). A coaxial
displays to full light output. Resistive losses are linear with cable length cable is electrically nothing more than a large capacitor. How does this
and often can be much greater than 5%. affect the signal? Well, it affects the sharpness and detail of video signals.
This occurs due to the time it takes for a given cable to charge and
Peaking Control — The peaking control increases, or emphasizes,
discharge. Imagine a length of garden hose attached to a water faucet.
the high frequency content of the signal. Coaxial cable losses increase
When the faucet is turned on, it takes some period of time before a full
with frequency. So, in any system design, high frequency loss is of prime
flow is achieved. It first starts as a trickle and then gradually builds to the
concern since the high frequencies carry the fine detail in the image. The
full pressure. A similar situation occurs when the faucet is turned off; the
peaking control will boost system gain over a range of higher frequencies
water does not immediately stop flowing. It first slows, then gradually
to overcome the attenuation curve of the cable. Normally, the level
stops. The same concept holds true with the electron flow through cable.
control is set to return the low frequency signal amplitude to normal level
A video signal transition that is supposed to be black-to-white may,
(0.7 volt, for example) and the peaking control is adjusted to provide
due to this delay, appear as black-to-gray instead. Capacitance actually
the most recovery of the high frequencies without over compensating.
affects the rise and fall times of a signal; this translates to changes in
Over-compensating the high frequency loss may generate other noise
the sharpness or detail. Fortunately, there is equipment with features
and image artifacts considered more undesirable than a softer image.
specifically designed to compensate for these types of losses, such as the
During system calibration, both level and peaking setup can be interactive
peaking control on an Extron interface.
and should be aligned using test equipment or a display of known
performance. Cable Termination
Another critical element affecting the overall performance of an A/V
With some experience calculating real losses in cable, you will see that the
system is the connectors that link the cables to the display devices and
cable is the weakest link in any system design. While it is usually the last
other components within an A/V system. Extreme care must be taken
item considered in the system, it plays an extremely important role in your
when connecting cables within the system. One poorly constructed cable
realization of the expected system performance. Cabling is most often the
connection can erase all the care and attention to detail that went into
lowest cost area for ultimate realization of system performance, but often
the rest of the system. For example, an improperly crimped BNC connector
the first thing overlooked. Overcoming losses imposed by inappropriate
can result in signal reflections. A center conductor that has been damaged
cable selection is often more expensive than installing a larger, better
by poor installation stripping processes can have the same result.
quality cable in the beginning. Remember, -3 dB is the common reference
point for specification of analog bandwidth, but keep in mind that
cumulative cable loss and real system bandwidth will change as length is
increased or decreased.


USA Europe Asia Japan www.extron.com
714.491.1500 / 800.633.9876 +31.33.453.4040 / +800.3987.6673 +65.6383.4400 / +800.7339.8766 +81.3.3511.7655 © 2005 Extron Electronics. All rights reserved.
714.491.1517 FAX +31.33.453.4050 FAX +65.6383.4664 FAX +81.3.3511.7656 FAX Pricing and specifications may change without notice.
 Understanding Cables in the A/V Industry (continued)

Impedance Matching Figure 1. Step response

In video systems, proper impedance matching is the right thing to do. comparison of 50 ohm
versus 75 ohm BNC
For many years, the only cost-effective coaxial cable connector available
connector in a 75 ohm
EDUCATION

was the 50 ohm BNC. The 50 ohm version dominated because of the RF system
equipment industry. We connected our test signal generator (VTG 400)
through a 12-foot length of 75 ohm cable using, in one test, 75 ohm
BNC connectors and, in the second test, 50 ohm BNC connectors. The test
signal is a step response. The transient response at the leading edge tells
us if we will see any anomaly attributable directly to the mismatch. Any
serious perturbations here could translate into image artifacts that affect
high frequency details in an image. Compare the two waveforms of Figure
1. The yellow waveform illustrates the performance with a 75 ohm BNC
connector. The blue waveform represents the 50 ohm situation. You’ll see
that no difference is visible. This is our experience overall. Figure 2. TDR of
a 50 ohm BNC connector
The actual dimensions of BNC connectors are small enough that we will in a 75 ohm system
not see significant effects created by the connector in a system until we
approach 3,000 MHz where the connector’s physical length approximates A= Ferrule Interface
one-quarter wavelength of the frequency of interest. Therefore, the B= Ground Crimp
reason that BNC impedance mismatch effects are not prevalent in
systems we design is that the connector dimension is a miniscule part
of the transmission line length at frequencies for which we are primarily
interested. In the microwave industry, the connector dimension is
significant. Now, refer to Figure 2, which shows the TDR (time domain
reflectometry) presentation of a 50 ohm BNC. Compare this to the TDR
image of a 75 ohm BNC in Figure 3. These images represent time domain
measurements of an SDI signal carried on a 12-foot length of 75 ohm
cable. Perturbations seen for either connection impedance center primarily Figure 3. TDR of
on the connector crimp and contact interface. a 75 ohm BNC connector
in a 75 ohm system
Does this mean you can actually ignore coaxial cable impedance in
system design? NO. The electrical length of cables is significant at the A= Ferrule Interface
frequencies we encounter with graphics systems. This is why you see poor B= Ground Crimp
performance with some cables. They are not the correct impedance and,
therefore, reflect much of the transmitted energy back to the signal source.
Mismatched impedance levels can cause signal reflections (ghosting) and
attenuation, particularly with signals of 500 MHz or higher.


USA Europe Asia Japan www.extron.com
714.491.1500 / 800.633.9876 +31.33.453.4040 / +800.3987.6673 +65.6383.4400 / +800.7339.8766 +81.3.3511.7655 © 2005 Extron Electronics. All rights reserved.
714.491.1517 FAX +31.33.453.4050 FAX +65.6383.4664 FAX +81.3.3511.7656 FAX Pricing and specifications may change without notice.
Deciphering
xxx Cable Safety Ratings and Applications

Have you ever found yourself confused or unsure of the type of wire Cable Type Use
or cable to use in a project as it relates to local codes and safety
Cm Communications
requirements? What do the various cable safety ratings mean? What Class 2, Class 3 remote-control, signaling,
CL2, CL3

EDUCATION
materials and characteristics make one cable less flammable than and power-limited cables
FPL Power-limited fire protective signaling cables
another? What is meant by halogen-free cable? Is plenum cable cheaper
to run than cable in conduit? mP Multipurpose cable

PLTC Power-limited tray cable

The building authorities (usually county or city) in your locality adopt
standards and codes to which construction must conform for the overall
good and safety of the community. Remember that regardless of national
codes and standards, the local building authorities have the last word on for fire safety is shown in Table 1. Video, audio, and low voltage control
what is considered acceptable building and wiring practice in your area. cables fall into Class 2 typically due to the available power limits set in the
NEC. All computer network and telecommunications cabling falls into the
For both high voltage and low voltage electrical wiring, all building CM class. CM and CL2 categories of cabling are of primary concern in the
authorities in the United States adopt standards from the National A/V industry.
Electrical Code (NEC). The NEC is a collection of requirements for
electrical wiring and appliances that safeguard against electrical fire and Cable Marking Designations
electrocution. A committee under the supervision of the National Fire Table 2 is a handy applications table that will help you organize the cable
Protection Association, (NFPA), creates the NEC. The NEC is just one code marking designations mentally.
document among many created by the NFPA (visit www.nfpa.org for more Plenum-rated cables (suffix “P”) are at the top of the cable safety food
information). It’s important to note the difference between a standard and chain because they are constructed of materials having very low “fire
a code. A standard is a level of performance that may be adopted as an load.” Fire load is the term used to describe how much fuel a given
option, but a code is a mandate imposed by some authority. material provides a fire. A lower fire load rating means that the material
Cable Types is more fire resistant and produces less smoke. Smoke accounts for most
All signal cable used for computer networks, telephone, video, audio, fire-related deaths. Cables obtain the plenum rating upon successfully
and control applications of less than 50 volts is considered low voltage passing UL 910, Test for Flame-Propagation and Smoke-Density Values
cabling. Low voltage wiring is categorized into the following five basic for Electrical and Optical-Fiber Cables Used in Spaces Transporting
groups within the NEC: Environmental Air. Plenum is a commonly used term in the construction
and system installation industries because, in most cases, plenum-rated
Fire safety ratings under the NEC are conducted according to a common cables may be installed in air handling systems (air plenums) without
group of flame retardancy tests, which makes the cable markings similar expensive metallic conduit. Plenum cable can cut installation costs
across all of these designations. The NEC’s cable substitution hierarchy dramatically.

NEC Cable Substitution Hierarchy

Cable Permitted Substitution

Type
MPP
CMP
CL3P
CL2P
FPLP
MPR
CMR
CL3R
CL2R
FPLR
MPG
MP
CMG
CM
PLTC
CL3
CL2
FPL
CMX
CL3X
CL2X

Plenum Types
Riser Types
General Purpose Types
Dwelling Types


USA Europe Asia Japan www.extron.com
714.491.1500 / 800.633.9876 +31.33.453.4040 / +800.3987.6673 +65.6383.4400 / +800.7339.8766 +81.3.3511.7655 © 2005 Extron Electronics. All rights reserved.
714.491.1517 FAX +31.33.453.4050 FAX +65.6383.4664 FAX +81.3.3511.7656 FAX Pricing and specifications may change without notice.
 Deciphering Cable Safety Ratings and Applications (continued)

ethylene propylene). Teflon FEP is a registered trademark

of DuPont. But, Teflon FEP is much more expensive to
manufacture which explains the higher cost of plenum rated
EDUCATION

cables. The material is tougher and more difficult to extrude.

This is why plenum cables are not as flexible as PVC.

To obtain a plenum rating, the cable must pass the Steiner

Table 2. Cable Marking Designations for NEC Application Categories Tunnel Test within UL 910. The Steiner Tunnel is a specially
constructed fire chamber that positions a group of cables of
Riser (suffix “R”) describes cables having a lesser degree of flame the same type and about 24 feet in length into a horizontal frame within
retardancy than plenum, but may be used to convey signals vertically (i.e. an air handling plenum. Air rushes into one end of the plenum. Gas
floor to floor) in air shafts without requirement for metallic conduit. The burners supply a specific level flame under the cable bundle about 4.5 feet
compliant
Table 2 - Cablecable has Designations
Marking a flame propagation of less than 12
for NEC Application feet and has
Categories from the end near the air inlet. While the flame is applied for a specified
a temperature of 850 degrees Fahrenheit or less at a height of 12 feet period of time, the length of flame travel along the cable is monitored as
per UL 1666. General-purpose (no suffix) cables may be used in conduit, well as the amount of smoke produced. At the opposite end of the tunnel,
behind walls, or other enclosed locations where the cable is protected a vent shaft funnels the air and smoke past photoelectric sensors. Test
and not in an air plenum. Commercial installations, at a minimum, must criteria with which the cable must comply are:
use general-purpose cables (the typical CL2 designation for coaxial video
cables, for example). This type of cable must comply with UL 1581, the • Smoke Peak Optical Density: less than 0.50.
Vertical-Tray Flame Test. For CSA (Canadian Standards Association), the • Smoke Average Optical Density: less than 0.15.
vertical flame test differs in loading (more cable in bundles), burner angle, • Maximum Flame Propagation: less than 5.0 feet (1.524 m) from point
and failure criterion. of application

CL2X and CL3X are the lowest rated cable and must comply with UL VW- Halogen Used in Insulation
1 Vertical-Specimen Flame Test. The cable is not marked VW-1. This rating Most of the wire and cable insulation made in the US depends on the
may be used in residential dwellings. addition of halogens for fire retardancy. What are halogens? Halogens are
the elements in group VIIa on the periodic chart (yes, you will now use
PLTC (power-limited tray cable) complies with a 70,000 BTU/hour vertical- some of that obscure high school chemistry). The name is of Greek origin,
tray flame test. Cables of this type are marked PLTC with ink or marker meaning “salt-bearing.” The naturally occurring halogens are fluorine (F),
tape. chlorine (Cl), bromine (Br), and iodine (I). Halogens are nonmetallic and
closely resemble one another. They readily form bonds among themselves
Plenum Rating
and with most other elements.
The term “plenum” is used to describe the open space or environment
above ceiling panels that typically house air return systems for a building. While PVC contains chlorine, it is not fire resistant. PVC and polyolefin
In such environments cables must either be plenum-rated (meet certain products must have concoctions of other elements added in order to
low flame and smoke output requirements in the event of a fire) or run achieve any degree of flame resistance. Most fire resistant compounds
through conduit. Plenum-rated cables (designated by CL2P or CMP by contain fluorine or are said to be fluorinated, such as FEP (fluorinated
the National Electric Code) have special fire-resistant jackets and special ethylene propylene).
compounds in the insulation material.
Halogen-Free Cables
The most common insulation and jacketing material used on wire and European building authorities typically do not allow use of halogenated
cable is polyvinyl chloride i.e., PVC. PVC has many attributes that make cables. When halogen-based cables burn (at whatever level they will
it a great material for general-purpose wire. Unfortunately, PVC is very produce smoke), the smoke is corrosive and contains poisonous gases.
flammable. When PVC burns, a key byproduct is hydrochloric acid. The There is high concern about the true safety of halogen-based cables.
smoke and residues are very corrosive. While there are several versions (More information on the move away from halogens in cable insulation
of PVC with varying characteristics, basic PVC is not capable of passing may be obtained at: www.halogenfree.org.)
the plenum test. Only special formulations of PVC containing flame
and Smoke Suppressants are capable of attaining the plenum rating. While the European Union designs the safety tests for that region,
Some versions of PVC and another group of polymers from the family of there is great debate over the relevance of their position on cable flame
plastics called polyolefin may attain plenum capability when combined retardancy and safety versus that in the US. Halogen-free polymers require
with certain other polymers and fire resistant non-organic materials. other formulations of compounds in order to obtain low smoke cable
However, maintaining the safety margins against the plenum flame test is products.
sometimes difficult. Cable construction must be highly controlled in order
to maintain the necessary design margin for maintenance of the plenum
rating.

The best insulation for fire resistance to date is also one of the best MHRHF-5
dielectric materials for lower loss cables… Teflon® FEP (fluorinated Five Conductor Mini High Resolution Halogen-Free Cable

10
USA Europe Asia Japan www.extron.com
714.491.1500 / 800.633.9876 +31.33.453.4040 / +800.3987.6673 +65.6383.4400 / +800.7339.8766 +81.3.3511.7655 © 2005 Extron Electronics. All rights reserved.
714.491.1517 FAX +31.33.453.4050 FAX +65.6383.4664 FAX +81.3.3511.7656 FAX Pricing and specifications may change without notice.
Deciphering Cable Safety Ratings and Applications (continued)

Cable Ratings contractors have a responsibility (and a business opportunity) to work

The cable rating to use on a project is, first and foremost, dictated by with clients to not just install cabling systems, but manage them as well.
the local building authorities. Always check on your local codes before
Cost

EDUCATION
committing to the cabling design. In the United States, a general-purpose
Most systems installation companies find a significant cost advantage
cable, like CL2 or CM, is acceptable in enclosed raceways and protected
in using plenum-rated cable in commercial projects. The popularity of
regions not used as air plenums. Cable runs between floors in air spaces
plenum-rated cable pretty well tells the story. Of course, your costs will
must be riser-rated (CL2R or CMR) at a minimum or else installed within
vary due to local building codes and labor rates. If you have not used
an approved type of conduit. Cables installed within horizontal air plenum
plenum on a job, then talk with experienced contractors to obtain real
spaces must be plenum-rated (CL2P or CMP), or installed within approved
numbers for your area and situation. Although the incremental cost of
conduit.
plenum-rated cable is only a fraction of the cost of labor to run standard
In Europe, local cable ratings and requirements are much different. cable within metal conduit, new mandates by NFPA codes for the
Halogen-free cabling may be required in some countries. There may be management of abandoned cable adds a new dimension to both the
some instances where cable designs conforming to US standards may be contractor’s and the client’s concern for project cost in addition to the
useable. Again, always check with local authorities. need for education on changing code requirements.

Recognized Testing Laboratories Recycling

NRTL – Testing laboratories in the United States which intend to have their As cable management requirements become mandatory, recycling should
recognition mark affixed to an electric or electronic appliance must attain be considered among the resources that contractors make available to
NRTL, Nationally Recognized Testing Laboratory, status through the US their clients. Copious quantities of cabling removed from installation sites
Department of Labor Occupational Safety and Health Organization, OSHA. present a new threat to our environment if not disposed of appropriately.
A testing laboratory becomes “recognized” when capable of meeting the While technology brings us newer materials and products to solve
legal requirements for product safety testing in 29 CFR 1910.7. NRTLs technical problems each day, our ability to properly dispose of those
are private organizations or companies that operate businesses. There materials and products at the end of their useful life is now a serious
are several NRTLs throughout the United States, each with their own consideration.
registered trademark symbol.

The CE mark is unrelated to the requirements for product safety in the US.
It is a generic mark used in the European Union (EU) to indicate that a
manufacturer has declared that the product meets requirements in the EU
for product safety.

Underwriters Laboratories–UL – UL has become something of an icon

associated with US product safety. UL is a very successful not-for-profit
testing organization totally supported by fees charged to clients. UL is very
independent and, certainly, the most widely recognized mark in the US
and in more than 70 countries. But, UL is not the only recognized product
safety testing facility. There are many others with equal credibility.

ETL – Another well-known product safety listing mark is ETL. Intertek

Testing Services NA, Inc. (ITSNA) (formerly ETL Testing Laboratories, Inc.) is
an internationally recognized, fully independent testing company. The ETL
mark is widely recognized as equivalent to UL, since all test methods and
standards used by either organization must be recognized within the NRTL
system. Many are not familiar with ETL because they attained NRTL status
in 1989…relatively recent compared to UL.

Trends in Changing Standards

One may expect that codes and standards supporting fire safety will
continue their evolution. The NFPA 262 (UL910) test standard has
undergone change and update. Tougher regulations on plenum cable
requirements are anticipated. While NFPA 262 prescribes the testing
regimen for plenum-rated cable, the NFPA 90A code determines where
plenum-rated cables may be used. As of the release of the 2002 version
of the NEC, all accessible, abandoned communications cables in plenum
spaces must be removed unless inventoried and tagged for future use.
Network system growth has created a burgeoning quantity of potential
fire fuel (load) in most commercial applications. This means that

11
USA Europe Asia Japan www.extron.com
714.491.1500 / 800.633.9876 +31.33.453.4040 / +800.3987.6673 +65.6383.4400 / +800.7339.8766 +81.3.3511.7655 © 2005 Extron Electronics. All rights reserved.
714.491.1517 FAX +31.33.453.4050 FAX +65.6383.4664 FAX +81.3.3511.7656 FAX Pricing and specifications may change without notice.
 Analog Versus Digital Signal Formats

Consider the different sounds delivered by a piano and a violin. When With an all-digital connection between the display and computer, the
a pianist strikes the keys he plays first one tone, and then another; display tells the computer graphics card to only output a resolution that
however, when the violinist slides his fingers up the strings he can play exactly matches that of the display. This saves the display from needing to
EDUCATION

not only those same tones but all the tones in between. The piano can be do any scaling and preserves the integrity of the image. The direct digital
considered a digital device, delivering exactly the tones desired, while the standards also specify the transmission of a pixel clock signal; this gives
violin is analog, less exact but with infinite flexibility. the display an exact reference for the timing of the video signals and
removes the need for both the pixel phase and horizontal phase controls.
With analog video we have a variable signal that creates an image by
scanning information across a screen. With digital video, we have fixed As our industry evolves and the use of digital signals grows,
pixel locations, each of which requires specific image information at a understanding digital formats and the equipment that delivers them
specific time. When we convert analog video to digital video, we must becomes increasingly important to all A/V professionals. As with other
capture samples of a “moving” signal, translate the color and intensity A/V systems, the performance of systems utilizing digital formats is highly
of each sample, and then deliver it to a specific address on the digital dependent on the cables and connectors used. The following section will
display. We must also deal with probable losses in translation. A good introduce digital video signals by reviewing digital signals we are familiar
analogy would be this — a story translated from English to Japanese and with — control communications — and then we will explore how cabling
then back to English would not read the same as the original English- affects various digital video formats.
language story.
Control Communications
Currently, most desktop computers are all digital up to the point of the Control communications, or data communications, uses digital signals.
video card, which provides analog output. This means that the digital While analog and digital video signals require high-performance cabling,
display must convert that analog signal to digital (as illustrated in . control communications typically allows lower-performance cabling.
Figure 1). Data communications for control typically carries less information, hence
requiring less bandwidth. It is also more forgiving than digital video. In
high-speed data communications systems, there is significant overhead
added to handle error correction. And, if some data is lost, it can be
re-sent. With digital video, there is some error correction facility, but the
delivery is a one-way street. If you fail to receive all the data bits required
to make the system work, you lose picture information or lose the picture
completely.

Coax and SDI

Most professional broadcast formats (SDI, SDTI, SDTV, and HDTV) are
serial and use a single coaxial cable with BNC connectors. The first part of
this section will involve the cables used for serial digital formats. The next
section discusses parallel digital formats.

Cables and SDI

Cable loss specifications for standard SDI, SDTI, and uncompressed SDTV
If the graphics card provides direct digital output, this eliminates both the are addressed in SMPTE 259M and
digital-to-analog (D/A) circuits in the host computer, and the analog-to-
digital (A/D) circuits in the digital display. (See Figure 2.) When analog ITU-R BT.601. In these standards, the maximum recommended cable
signals are sent through a cable to the display, they are susceptible to length equals 30 dB loss at one-half the clock frequency. Note that
interference and signal degradation. Digital signals are largely immune to this high loss value does not correlate with losses normally accepted
such effects, subject to distance limitations. If we use all-digital computer- for analog video and graphics signals. This serial digital loss level is
video interfacing, we no longer need A/D and D/A conversion circuits, so acceptable due to the serial digital receiver. Serial digital receivers have
we get a better video image at a lower cost. special signal recovery processing.

For HD-SDI running at 1.5 Gbps, SMPTE 292M governs cable loss
calculations. In that standard, maximum cable length equals 20 dB loss
at one-half the clock frequency. Due to the data coding scheme, the bit
rate is effectively the same as the clock frequency in MHz. Similarly, high
definition serial digital receivers have special signal recovery capability as
well. See Table 1 for some examples of cable length calculations.

Recommendations among cable manufacturers will certainly vary, but it

is good practice to limit your run lengths to no more than 90% of the
calculated value. This provides leeway for cable variations, connector loss,
patching equipment, etc. Table 1 includes this allowance. In all cases, your
system must operate solidly before the “cliff region” where sudden signal

12
USA Europe Asia Japan www.extron.com
714.491.1500 / 800.633.9876 +31.33.453.4040 / +800.3987.6673 +65.6383.4400 / +800.7339.8766 +81.3.3511.7655 © 2005 Extron Electronics. All rights reserved.
714.491.1517 FAX +31.33.453.4050 FAX +65.6383.4664 FAX +81.3.3511.7656 FAX Pricing and specifications may change without notice.
Analog Versus Digital Signal Formats (continued)

dropout occurs. Recall that digital systems do not perform linearly to cable
losses. Final performance rests with the cable and the type of receiver
used. The bottom line in these systems is maintaining low BER (bit error

EDUCATION
rate). SDI signals are nominally 800 millivolts… not much different in
level from analog video signals. Refer to Figure 3 for a standard-level SDI
signal that conforms to SMPTE specifications.

SMPTE 259 SMPTE 292

Level A Level B Level C Level D
Application NTSC 4fsc PAL 4fsc 525/625 525/625 HDTV
Composite Composite Component Component
Data Rate in Mbps (clock) 143 177 270 360 1485
1/2 Clock Rate in MHz 72 89 135 180 743

Extron Cable Product Feet Meters Feet Meters Feet Meters Feet Meters Feet Meters

MHR 26 AWG (22-020-xx) 583 178 531 162 428 130 365 111 94 29
M59, 24 AWG (22-127-xx) 813 248 736 224 600 183 519 158 150 46
RG59, 20 AWG (22-124-xx) 1034 315 944 288 801 244 687 209 188 57 Figure 3. Standard reference level SDI signal
RG6 18 AWG (22-098-xx) 1406 429 1274 388 1067 325 915 279 285 87 conforming to SMPTE 259M
Table 1. Recommended Serial Digital (SDI) Transmission Distances Through
Extron Coaxial Cable

Comparing Digital Formats

Standard Format Intended Use Connector Cable Transmission Sample Data Guiding
Serial/Parallel Style Type Distance [4] Rate Rate (Mbps) Document

D1 component parallel broadcast multi-pin D multi-pairs few meters 27 MHz 270 ITU-R BT.601-5
SDI serial broadcast one BNC coax [1] 100s of meters 27 MHz 270 SMPTE 259
SDTI serial data transport one BNC coax [1] 100s of meters variable 270 or 360 SMPTE 305
SDTV serial broadcast one BNC coax [1] 100s of meters 27 MHz 3 to 8 ATSC; A/53
HDTV serial broadcast one BNC coax [1] 100s of meters 74.25 MHz 19.4 ATSC; A/53
HD-SDI serial broadcast one BNC coax [1] 100s of meters 74.25 MHz 1500 SMPTE 292M
DV serial prof/consumer (see IEEE 1394) (see IEEE 1394) 4.5 meters 20.25 MHz 25 IEC 61834
IEEE 1394 serial prof/consumer 1394 6 conductors, 4.5 meters n/a 100,200,400 IEEE 1394.
(FireWire) 2-STPs/2 pwr Mbps
USB 1.1 serial consumer USB A & B 4 conductors, 5 meters n/a 12 USB 1.1 .
1-UTP & 2 pwr Promoter Group
USB 2.0 serial prof/consumer USB A & B 4 conductors, 5 meters n/a 480 USB 2.0.
1-UTP & 2 pwr Promoter Group
DVI serial/parallel consumer DVI (multi-pin D) Four STPs 10 meters to 165 MHz 1650 DDWG; DVI 1.0

[1] Also implemented over fiber systems

2 STP = Shielded Twisted Pair; UTP = Unshielded Twisted Pair
3 n/a = not applicable
[4] Transmission distances may vary widely depending on cabling and the specific equipment involved.

13
USA Europe Asia Japan www.extron.com
714.491.1500 / 800.633.9876 +31.33.453.4040 / +800.3987.6673 +65.6383.4400 / +800.7339.8766 +81.3.3511.7655 © 2005 Extron Electronics. All rights reserved.
714.491.1517 FAX +31.33.453.4050 FAX +65.6383.4664 FAX +81.3.3511.7656 FAX Pricing and specifications may change without notice.
 Analog Versus Digital Signal Formats (continued)

What is different Although the SDI

about SDI cable loss waveform is not
considerations? With . discernable, a good
EDUCATION

SDI signals, the receiver receiver will capture

is more complex in it. By using color
its ability to equalize enhancement modes
and recover the signal. on a time domain
Signal recovery is reflectometer (see
nonlinear. SMPTE 292M Figure 7), you can
describes the minimum see a pattern in the Figure 6. SDI signal after (700 feet / 213.4 m) of
Figure 4. SDI signal after (100 feet / 30.48 m) of
Extron SHR coax cable
capabilities of what it Extron Mini High Resolution coax cable data that is somewhat
calls a type A receiver recognizable.
(the better) and a type
B receiver. Like RF receivers, SDI receivers are adaptive in their ability to Table 2 provides the performance specifications mandated in SMPTE
amplify, equalize, and filter out the information. Selecting the best receiver 259M and SMPTE 292M. This is the benchmark in terms of rise/fall time
will make a tremendous difference in the final performance of a serial performance and jitter as it guides the design of equipment sourcing the
digital system. Figure 4 shows the loss . serial digital signal. Basically, if your system design provided this level
effect on an SDI signal after it runs through 100 feet of Extron MHR of performance after your longest cable run, then you would have a
cable. Although rise time is significantly affected, all quality receivers can benchmark design with little, if no, concern about the receiver’s ability to
recover this signal. In fact, for this particular cable a class “A” receiver decode the signal. Any SDI receiver of reasonable design could display the
can recover a solid image after 425 feet (see Table 1, page 13). Figure 5 image.
illustrates signal quality after it passes through 100 feet of Extron RG6 But we don’t live in
cable. Note that the improved signal waveform ensures that the signal can an ideal world. The
be conveyed much longer distances. For RG6 cable, standard SDI can be economy of distributing
transmitted over 1,000 feet. SDI and HD-SDI lies
Cable Versus in the ability of the
Receiver serial digital receiver
So, how much of your to recover a low-level
system performance signal much like TV
depends on the cable receivers recover a
Figure 7. Color enhancement shows essence of
and how much depends complex television
the data pattern in the image of Figure 4
on the receiver? It’s a image from a weak RF
good idea to know this signal. The extended
boundary as receiver capability of the serial digital receiver makes the run lengths in Table
Figure 5. SDI signal after 100 feet (30.48 m) of 1 (shown on page 13) possible with few exceptions. Just what is the
and cable specs vary. The Extron RG6 Super High Resolution coax cable
primary loss parameters receiver’s contribution? Well, comparing the SMPTE loss calculation to the
that affect serial digital –3 dB point used in regular video systems suggests an effect upwards of
losses are rise time/fall time degradation and signal jitter. This is why serial 10 times; i.e. 30 dB compared to 3 dB.
digital signals normally undergo reshaping and reclocking as they pass
through major network hubs like matrix routers. Interestingly, viewing
the SDI signal waveform on a scope will not really
tell you much once signal level drops to a certain
point. Only specific instrumentation made for testing
SDI signals will yield the ability to receive a proper
image transmission. Figure 6 shows a typical scope
presentation after 700 feet of Extron RG6 cable.

Table 2. SMPTE Serial Digital Performance Specifications

*SMPTE 292 guides the interface for multiple high definition standards; i.e., SMPTE 260M A/B, 295M C,
274M D-K, 296M 6/L.

14
USA Europe Asia Japan www.extron.com
714.491.1500 / 800.633.9876 +31.33.453.4040 / +800.3987.6673 +65.6383.4400 / +800.7339.8766 +81.3.3511.7655 © 2005 Extron Electronics. All rights reserved.
714.491.1517 FAX +31.33.453.4050 FAX +65.6383.4664 FAX +81.3.3511.7656 FAX Pricing and specifications may change without notice.
Analog Versus Digital Signal Formats (continued)

DVI, Firewire, and USB 2.0 pixel time, or 3.64 nanoseconds. These parameters are largely responsible
Cabling for DVI, Firewire, and USB 2.0 is paramount for each format for the short transmission distances for DVI.
in order to provide you with the performance specified. Recall that DVI
In addition to the above requirements, a cable for DVI should be

EDUCATION
(Digital Visual Interface) is penetrating the computer-monitor interface
evaluated on its insertion loss for a given length. The DVI transmitter
market as flat panel LCD monitors become affordable.
output eye pattern is specified into a nominal cable impedance of 100
Firewire, or IEEE-1394, is that tiny, square-like connector tucked away on ohms. A normal signal swings +780mV to –780mV. The minimum positive
the side of your digital camcorder that allows you to upload DV format signal swing is +200mV and the minimum negative swing is –200mV
signals to your computer, among other things. USB has received a major (total swing of 400mV). When the signals are combined in the differential
overhaul... analogous to jacking up your radiator cap and driving in a receiver, the resulting signal level is two times the swing value. But, for the
new car underneath it. Yes, USB 2.0 brings us hot swappable, hosted cable situation, we must assume minimum performance on the transmitter
peripherals now capable of talking at 480 Mbps instead of just 12 Mbps. side and best sensitivity on the receiver end. The receiver must operate on
signals as low as +75mV to -75mV, or a total swing of 150mV. This means
Getting from Here to There with DVI that under worst-case conditions, the cable attenuation can be no more
The DVI connection between local monitors and computers presents than 8.5 dB at 1.65 GHz (10 bits/pixel times 165 MHz clock). As you can
an interesting interfacing environment. It is a combination serial digital imagine, maintaining this type of performance on twisted pair wires is
interface and a parallel interface format, somewhat like combining the relatively difficult.
broadcast serial digital and parallel digital interfaces.
DV and Firewire – Serial Digital for the Rest of Us
Transmission of the TMDS (transition minimized differential signaling) The DV, or digital video, recording standard now driving most consumer
format combines four differential, high-speed serial connections (in camcorder purchases is a serial digital format of 25 Mbps, sometimes
its base configuration) transmitted in a parallel bundle. When the DVI called DV25. The Firewire (IEEE 1394) interface conveniently handles the
specification is extended to the dual mode operation, greater data data rate of DV, and then some. The DV format is the first application
rates for higher display resolutions are possible, but now there are making tremendous use of the IEEE 1394 capability. IEEE 1394 is much
seven parallel, differential, high-speed pairs. Cabling and connection bigger than DV in terms of data handling. This specification supports
become extremely important. In this way, DVI is similar to the original up to 400 Mbps currently and extensions to the standard are under
D1 parallel interface which requires eight or 10 differentially driven serial consideration. Its key strengths are its “just-in-time” data delivery
lines capable of handling a full byte on each clock cycle. If you have the and peer-to-peer relationship… meaning that Firewire appliances can
opportunity, take a look at available D1 cables, and you will find them communicate without need for a host controller.
limited in usable lengths — very much like DVI.
So, when we talk DV, we are really talking about using 1394 and a portion
The nominal DVI cable length limit using low cost patch cables is of its capability. The connection scheme and cabling for this interface are
4.6 meters (about 15 feet). Using specialized high performance DVI specific as well. The 1394 system uses two shielded twisted pairs and two
cables, signals can be transmitted up to 75 feet. Electrical performance single wires. The twisted pairs handle differential data and strobe (assists
requirements are similar to serial digital. Signal rise time (0.330 in clock regeneration) while the separate wires provide the power and
nanoseconds), cable impedance (100 ohms), far end crosstalk (FEXT) of ground for remote devices needing power support. Signal level is 265mV
no more than 5%, and signal rise time degradation (160 picoseconds differential into 110 ohms.
maximum) are the key parameters highlighted in the DVI specification
regarding the physical connection. Cable for DVI is application specific The 1394 specification limits cable length to 4.5 meters in order to satisfy
because maintaining these specifications is no easy feat since the actual the round trip time maximum required by the arbitration protocol. Some
bit rate per channel is 1.65 Gbps. And we’re talking twisted pair cable applications may run longer lengths when the data rate is lowered to the
here. 100 Mbps level. The typical cable has 28 gauge copper twisted pairs and
22 gauge wires for power and ground. A Firewire connected appliance
With digital video interfaces, if any vital data is missing, you lose may or may not need power from its host, but must be capable of
picture information or even the entire picture. So, the DVI cable and its providing limited power for downstream devices.
termination is very important. The physical parameters of the twisted pairs
must be highly controlled. Specifications for the cable and the receiver The 1394 specification provides electrical performance requirements
are given in fractions of bit transmission time. Therefore, the requirements that leave open the actual parameters of the cable design. As with all
depend on the clock rate or signal resolution being used. Transferring the differential signaling systems, pair-to-pair data skew is critical… ≤ 0.40
maximum rate (1600 x 1200 at 60 Hz) for a single link system means that nanoseconds. Crosstalk must be maintained below -26 dB from 1 to 500
one bit time (10 bits per pixel) is 0.1(1/165 MHz), which is only 0.606 MHz. The only requirement on the size of wire used is that velocity of
nanoseconds. Ten bit times describe one pixel in this system. propagation must not exceed 5.05 ns/meter. Refer to Table 3 for other
critical details of the physical interface system for 1394. Figure 8 shows
The DVI receiver specification allows only 0.40 x bit time, or about 0.242 the cable internal conductor arrangement.
nanoseconds intra-pair skew (within the twisted pair). Remember, this is
differential transmission. The “eye” pattern seen at the receiver end must
be as symmetrical as possible. Further, the inter-pair skew, which governs
how bits will line up in time at the receiving decoder, may only be 0.6 x

15
USA Europe Asia Japan www.extron.com
714.491.1500 / 800.633.9876 +31.33.453.4040 / +800.3987.6673 +65.6383.4400 / +800.7339.8766 +81.3.3511.7655 © 2005 Extron Electronics. All rights reserved.
714.491.1517 FAX +31.33.453.4050 FAX +65.6383.4664 FAX +81.3.3511.7656 FAX Pricing and specifications may change without notice.
 Analog Versus Digital Signal Formats (continued)

USB 2.0 – Fire in Another Wire

The USB, universal serial bus, simplifies connection of computer
peripherals. USB 1.1 is limited to a communications rate of 12 Mbps,
EDUCATION

which is plenty fast for most items like printers, audio devices, keyboards,
scanners, etc. During 1999 the USB Implementers Forum began work
to upgrade USB capability by more than 40 times. The new USB 2.0
interface supports up to 480 Mbps communication. It is anticipated that
USB 2.0 will replace higher cost SCSI interfaces for some peripherals. The
Implementers Forum says that fully compliant USB 1.1 cables will perform
at USB 2.0 speeds. In-depth information is available at www.usb.org. Table 3. Critical IEEE 1394 Timing Parameters
The USB cable consists of one twisted pair for data and two untwisted
wires for powering downstream appliances. Specifically, a full-speed
cable contains a 28-gauge twisted pair, an untwisted pair of 28 to 20
gauge power conductors, an aluminized polyester shield, a drain wire,
and an overall 65% (minimum) copper braid. Nominal impedance for the
data pair is 90 ohms. The maximum cable length for USB is a function of
Signal Lines A
signal propagation delay. The cable may have no more than 26 ns delay Shielded Twisted Pair
from connector A to connector B. An additional allowance of 4 ns is split Power Supply
between the sending device connection and the receiver connection/ (8 to 40V Max. DC Current: 1.5 A)
response function, making the entire one-way delay 30 ns maximum. In Signal Lines B
addition, the cable may not have a velocity of propagation greater than Shielded Twisted Pair
5.2 ns per meter. The length and twist of the data pair must be matched
Signal Line Shield
well enough so that no more than 0.10 ns time skew exists between bit
polarities. The nominal differential signal level is 800mV. Figure 8. IEEE 1394 Cable

The digital video and data world is exciting, but, as you can see,
assembling high-speed data cables is not going to be a trivial or casual
task.

16
USA Europe Asia Japan www.extron.com
714.491.1500 / 800.633.9876 +31.33.453.4040 / +800.3987.6673 +65.6383.4400 / +800.7339.8766 +81.3.3511.7655 © 2005 Extron Electronics. All rights reserved.
714.491.1517 FAX +31.33.453.4050 FAX +65.6383.4664 FAX +81.3.3511.7656 FAX Pricing and specifications may change without notice.
 Understanding Audio Cable

Properly conveying audio signals embodies many of the same Most speakers have very low operating impedance. It is important that
considerations applied to the transmission of video signals. Since the selected wire have a DC resistance much lower than the impedance
the audio range resides at much lower frequencies, certain electrical provided by the speaker. Good practice recommends keeping speaker wire

EDUCATION
parameters are now more important than others. At the outset, it’s resistance lower than 5% of the speaker impedance so as to ensure that
important for audio cable to maintain fairly low elements of inductance, most audio power is transferred to the speaker where it is needed. In any
capacitance, resistance, and impedance. To minimize these elements and case, a speaker wire resistance of 10% (loss of 0.5 dB) of the speaker
ensure optimum performance, the cable’s conductors should be made of impedance should not be exceeded. Commercial audio distribution
high conductivity electronic-grade copper. This means the purity of the systems utilizing 70/100 volt audio drive may utilize smaller gauge wiring,
copper ranges from 99.95% to 99.99% pure. In addition, the proper type relative to low impedance speakers. In these applications DC resistance
of insulation is important. Depending on the application, shielding is a key is important and should be kept low compared to the system’s operating
consideration. Audio cable may be divided into two basic categories: line power, but since the operating voltage is higher, the insulation rating of
level group and speaker group. the speaker cable is now more important.

Line Level Group When selecting speaker wire, it is important to know that the lower
Cable for audio and control applications falls within the line level group the gauge number, the thicker the wire. An 18 gauge wire is thinner, or
and is usually constructed of one or more pairs of stranded wires, or smaller diameter, than a 14 gauge wire, for example. To maximize the
stranded twisted pairs. Shielded, twisted pairs are commonly used for line potential of your audio signal, it is generally preferable to use lower gauge
level audio and control applications. The twisted pair, as we have already wires whenever possible.
learned in this guide, provides a balanced signal path that minimizes
susceptibility to outside interference. Combining a shield with the twisted
pair improves unwanted signal rejection significantly. For line level audio Actual Size
and control applications, balanced line (twisted pair) construction and
shielding are the most important features. American Wire Gauge (AWG)
Size Reference Stranded Wire
The small values of cable capacitance encountered with shielded twisted
pair cable have little impact on audio performance since the equivalent
impedance offered by the typical shunt capacitance represents much
larger impedance than the typical audio circuit impedances; thus it can
be largely neglected. For control applications involving communications 10 12 14 16 18 20 22 24 26 28
.116" .095" .073" .059" .048" .036" .03" .024" .02" .015"
protocols operating at relatively high speeds compared to audio, the shunt 2.95mm 2.41mm 1.85mm 1.5mm 1.22mm .91mm .76mm .61mm .51mm .38mm

capacitance values are more important. Lower cable capacitance values

mean less impact on control code transmission speeds.

Wire gauge size for line level audio and control applications is a lesser
consideration and is usually dictated, to some degree, by transmission For any A/V application, cable length should be kept to the minimum
distance and by termination hardware. Larger gauge wire has less DC required. When driving speakers, the wire lengths should be equal for
resistance per unit length; hence, less signal loss over long distance paths. both left and right channels to ensure balanced transfer of power from
the amplifier. Long runs of 50 feet or more should use thicker gauges
Speaker Group (14 or larger) to ensure that enough power is transferred to the speaker.
Speaker cables fall within the speaker group and require the delivery of Defaulting toward heavier gauges of wire is also a good idea in the event
significant levels of current necessary to drive speakers directly. In those that a system design is upgraded to higher power output in the future.
special instances where powered speakers are specified, the amplifier Installing new wire will cost more in the long run.
driving the speaker’s current demand is local to the speaker. Therefore, the
cable required to drive this type of system falls within the line level group
previously discussed.

Wire gauge or diameter is the key attribute distinguishing cables in the

speaker group. The conveyance of high currents directly to speakers
requires wires of the appropriate cross-sectional area. Choosing the
proper gauge size for your A/V system is determined by the length of the
cable runs compared to the load (speaker) impedance and the power to
be delivered. As power delivery or current demand increases, the cable
diameter must increase as well. Thicker gauge wires have less resistance
to the flow of electric current than thinner wires. It’s a good idea to err
on the side of heavier, or thicker, gauge wires for speaker connections
rather than install thinner gauge wire which limits performance and could
overheat. While heavier gauge wire may cost a little more, the return on
investment in terms of time and performance are usually worthwhile.

17
USA Europe Asia Japan www.extron.com
714.491.1500 / 800.633.9876 +31.33.453.4040 / +800.3987.6673 +65.6383.4400 / +800.7339.8766 +81.3.3511.7655 © 2005 Extron Electronics. All rights reserved.
714.491.1517 FAX +31.33.453.4050 FAX +65.6383.4664 FAX +81.3.3511.7656 FAX Pricing and specifications may change without notice.
 Selecting The Right Cable

Deciding on the correct cable for an application in system designs today Harmonic Considerations
is, in many cases, augmented by the devices to be interconnected. For Analog video signal distribution requires that the designer consider cable
example, the connection of network components typically dictates the distance, the source signal characteristics, allowable raceway space,
EDUCATION

use of Category 5 (or better) type cable. Digital appliances have specific application environment, the cable’s technical specifications, and the need
requirements that are generally straight forward. In the area of analog for upgrade. Often, we are asked how far a particular cable may be run
video signal distribution, cable selection is more challenging. for a specific signal type. Giving a simple answer is difficult because video
signals are complex and made up of many frequency components, called
Analog video signals degrade at a generally predictable rate during
harmonics. A harmonic is an integer multiple (i.e. 1st, 2nd, 3rd, 4th, etc.)
distribution; so the designer is faced with balancing tradeoffs involving
of a fundamental frequency component which is not a sine wave, or non-
cable type, image quality, and economics. Do not underestimate the
sinusoidal. Harmonics respond differently to cable loss depending on the
importance of the cabling decision. Cabling is an infrastructure investment
type of cable and the run length within the application. An array of pixels
that should yield long term benefits for upgrading the system; not just
make up the video graphics image and a single pixel represents what we
satisfy the current need. While the cost of cable is relatively low compared
call the fundamental frequency component within the image. As pixels
to many components0dband devices connecting to it, its total cost after
Waveform
are bunched together along a horizontal line to create line structure, sub-
installation is significant. In most cases, the cabling infrastructure will
harmonics exist which approach the horizontal line rate frequency. As lines
outlast those components, like displays, that connect to it. The effect of
are created on the screen to scan the image, sub-harmonics exist near the
signal loss in a system is cumulative and, once performance is sacrificed,
vertical refresh frequency. A video image is rich in harmonic content and it
recovery is difficult to impossible.
is this content that contributes to image sharpness and clarity.

Visible effect of signal roll off

T

0db Waveform

Original (Fundamental) Signal

Waveform
T

6db Waveform

-3 dB Loss*

9db Waveform

-6 dB Loss*

T
Original Level
Smear Region

Slower Rise Time

-9 dB Loss*
* Loss measured at 3rd harmonic of fundamental

18
USA Europe Asia Japan www.extron.com
714.491.1500 / 800.633.9876 +31.33.453.4040 / +800.3987.6673 +65.6383.4400 / +800.7339.8766 +81.3.3511.7655 © 2005 Extron Electronics. All rights reserved.
714.491.1517 FAX +31.33.453.4050 FAX +65.6383.4664 FAX +81.3.3511.7656 FAX Pricing and specifications may change without notice.
Selecting the Right Cable (continued)

A spectrum analysis of a video signal will show that harmonics exist The third harmonic will be attenuated in a cable sooner than the second
above and below some fundamental repetition frequency used to create harmonic. The second harmonic will be attenuated sooner than the
the image. In other words, the clock frequency of the graphics system is fundamental. Harmonic content in a signal exists at a lower amplitude

EDUCATION
the basis for timing and graphic image creation. Ironically, when a full relationship to the fundamental frequency on a somewhat nonlinear scale.
screen of white pixels are clocked into the display, we see a full white In other words, the harmonics of the fundamental are decreasing as their
screen and while the system worked hard to accomplish that, the result frequency increases. So, each successive harmonic provides less energy
represents very low frequency content to the display device. If we wish to toward the creation of fast, square-looking pixels used to create an image.
fully challenge the display, we send it alternating pixels that appear as a
screen full of vertical stripes. In this instance, the display must work harder Since this harmonic energy is lost more or less in a linear fashion as cable
to transition between full black and full white at maximum rate. This is length increases, one should pay attention to the cable’s loss performance
why we halve the pixel count or take one-half the clock rate in bandwidth in the third harmonic frequency region when designing distribution
calculations. This is a worst-case image. systems. The appearance of the image will degrade as harmonic energy
is lost. You must be the judge of the importance of maintaining full
Now, back to harmonics. Once we have a single pixel event on the screen, image content, or harmonic content. This is where our ability to provide
we are witnessing the fundamental frequency component of the image. In the answer to the original question of signal run distance is not easy
order for it to look very crisp, the sides of the pixel must have a very fast, to provide. One of the more effective ways to understand the effect of
or sharp looking, rise time (transition to white). Likewise, it must have a cable loss is through actual images. To that end, we are providing images
very fast, or sharp, fall time (return to black). A mathematical concept, showing how the loss will manifest under those conditions. Ultimately,
called Fourier Analysis, describes the makeup of any non-sinusoidal you and/or the client must decide if image quality is adequate based on
waveform, such as a pulse or pixel, by showing that it is made up of a the tradeoffs of a given application.
fundamental frequency and an infinite number of harmonics. The addition
of those harmonics add up, one by one, to create the fast rise and fall Example: The design calls for transmission of RGBHV graphics at a
edges of the pixel. Further, an analysis of that addition process shows resolution of 1024 x 768 at 60 Hz refresh. The graphics card clock rate
that about 80% of the harmonic energy needed to reasonably recreate a will be about 65 MHz for this resolution. Now, we take one half the clock
pixel event extends from near DC through the third harmonic. Beyond the rate since this represents the highest viewable resolution, which yields
third harmonic, the gain in rise time or sharpness is negligible in visual 32.5 MHz. About 80% of the energy required to create sharp edge detail
terms. This is why we concentrate on maintaining the third harmonic in the image rests with all frequency components from near DC to the
performance of the video signal in system design. Even digital signals third harmonic frequency: 3 x 32.5 = 97.5 MHz. Use this 97.5 MHz value
contain these harmonics, which provide the fast transitions required for to peruse the loss tables of various coax types to determine the distance
digital systems to perform properly. So, this concept extends beyond any at which losses will mount to a noticeable level. Look at the loss table
discussion of analog signals. for Cable Type A (refer to table on following page) and note that the
loss will be -5.4 dB at 100 MHz for 100 feet of this type cable. This loss

Maximum Recommended RGB Video Transmission Distance

(Without Using an Interface or Line Driver)
Resolution VGA – 640x480 SVGA – 800x600 XGA – 1024x768 SXGA – 1280x1024 UXGA – 1600x1200
Image Refresh Rate 60Hz 75Hz 85Hz 60Hz 75Hz 85Hz 60Hz 75Hz 85Hz 60Hz 75Hz 85Hz 60Hz 75Hz 85Hz
Horizontal Scan Rate 31.5KHz 39KHz 45KHz 38KHz 50KHz 54KHz 48KHz 60KHz 68KHz 64KHz 80KHz 91KHz 75KHz 94KHz 107KHz

Extron Cable Type recommended Distance (in feet) Based on 3rd harmonic at -3 dB
MHR (26 Gauge) 85 69 59 56 44 37 33 26 23 20 15 13 13 10 9
M59 (24 Gauge) 152 123 106 100 78 67 59 46 40 35 27 24 24 18 16
RG59 (20 Gauge) 309 249 215 204 158 136 121 94 82 71 56 49 48 38 33
-3 dB
RG6 (18 Gauge) 560 452 389 368 286 246 219 171 149 128 101 88 87 68 60

Extron Cable Type recommended Distance (in feet) Based on 3rd harmonic at -6 dB
MHR (26 Gauge) 328 265 228 216 167 144 128 100 87 75 59 52 51 40 35
M59 (24 Gauge) 613 495 426 404 313 269 240 187 163 141 110 96 95 74 65
RG59 (20 Gauge) 1120 903 778 737 571 491 438 341 298 257 201 176 174 136 119
-6dB
RG6 (18 Gauge) 1800 1452 1250 1184 918 789 703 549 479 413 324 283 280 218 191
Based on resolution and refresh rate

19
USA Europe Asia Japan www.extron.com
714.491.1500 / 800.633.9876 +31.33.453.4040 / +800.3987.6673 +65.6383.4400 / +800.7339.8766 +81.3.3511.7655 © 2005 Extron Electronics. All rights reserved.
714.491.1517 FAX +31.33.453.4050 FAX +65.6383.4664 FAX +81.3.3511.7656 FAX Pricing and specifications may change without notice.
 Selecting the Right Cable (continued)

Cable Type A Cable Type B The solution to the loss problem is to specify a cable which, at its -3 dB
MHz
dB/ dB/
100 ft. 100 m
MHz
dB/ dB/
100 ft. 100 m
point for the highest frequency of interest, will yield an image no worse
1 -0.5 -1.7 1 -0.3 -1.0 than the -3 dB shown on the previous page 18. Should you not be able to
EDUCATION

5 -1.2 -3.9 5 -0.6 -2.0 attain a loss budget of -3 dB or less for a given cable type and distance,
10 -1.7 -5.5 10 -0.9 -3.0
20 -2.4 -7.8 20 -1.2 -3.9 then select a lower loss cable type.
50 -3.8 -12.3 50 -1.3 -4.3
71 -4.5 -14.8 71 -2.1 -6.9
T
100 -5.4 -17.6 100 -2.3 -7.5
Smear Region
135 -6.3 -20.6 135 -2.7 -8.9
180 -7.3 -23.9 180 -3.0 -9.8
200 -7.7 -25.4 200 -3.2 -10.5 Amplitude Loss
270 -9.1 -29.9 270 -3.8 -12.5
400 -11.5 -37.3 400 -4.7 -15.4
750 -16.4 -53.8 750 -6.5 -21.3
1000 -19.5 -64.0 1000 -7.8 -25.6
3000 -43.6 -143.0 3000 -17.6 -57.7
Fixed pixel
displays tend
to mask
edges

is approaching the -6 dB value for a distance of 100 feet. Scale the loss
downward linearly if your design requirement is for a shorter distance
(see frequency/loss chart on page 6 for loss curves). For any type cable, Lower level pixels create soft edges
-12db Waveform.eps
we can see from the accompanying photos taken from an actual graphics
Figure 1: Pulse and Bar may be partially “repaired”
monitor the typical image degradation encountered with increasing loss of by fixed pixel boundary effects, but amplitude is not
the third harmonic energy. Included are actual oscilloscope measurements restored.
showing the loss of the high frequency information (narrow pulse height) .
compared to low frequency information (wider, flat step function next If other factors such as cost or cable size become an issue, the other
to it). In addition, the flatness of the lower frequency step function is alternative is the use of an interface or other type of cable driver amplifier
rounded from the leading edge and takes a comparatively longer time capable of adding level and pre-emphasis (peaking) to overcome some
to settle to its normal amplitude. This effect will be seen as the dark or all of the loss. The interface or line driver would best be applied at the
streaking that occurs to the right of the text or other detail transitions head-end of the cable run. By increasing the level and peaking controls,
from dark to light. Compare the likely performance of Cable Type A with the head-end can be pre-emphasized to overcome some, or all, of the
the -6 dB images shown. cable loss characteristic.
Note that as cable losses rise, the intensity of the image, or brightness, is A typical amount of high frequency peaking available in most cable
affected to some degree. The brightness loss is in addition to the loss of drivers of this type will be at least +3 dB and may extend to as much as
high frequency information. Images appear fuzzy or smeared on analog +12 dB or more. Refer to -9 dB Loss diagram. If you are considering a
(CRT) displays or on digital displays like LCD projectors, lower brightness design situation with a potential loss of 6 dB, the cable interface/driver
on some pixels. See Figure 1. Now, look at losses for Cable Type B. Note can potentially overcome a significant portion or all of the cable loss. At
that, at 100 MHz, the loss is less than -3 dB. This cable would provide a a minimum, you can see that the goal should be no more loss than -3 dB
better result if our run distance is 100 feet. Again, you can scale the loss for best results. Adjusting the12db Waveform.eps
level control provides the necessary gain to
value against the distance to interpolate closely to the performance you restore overall image brightness lost in the cable DC resistance, as shown
might expect. in the -12 dB Loss diagram below.

T T

RGB 201 Rxi Interface

-12 dB Loss Signal recovery using
RGB 201 Rxi
Actual Screen Images

-12 dB Loss After level and peaking

20
USA Europe Asia Japan www.extron.com
714.491.1500 / 800.633.9876 +31.33.453.4040 / +800.3987.6673 +65.6383.4400 / +800.7339.8766 +81.3.3511.7655 © 2005 Extron Electronics. All rights reserved.
714.491.1517 FAX +31.33.453.4050 FAX +65.6383.4664 FAX +81.3.3511.7656 FAX Pricing and specifications may change without notice.