Multiplex Av Sig Fiberop Wp

1white paper

Extron Electronics - Multiplexing AV Signals in Fiber Optic Systems 01/26/2012 Revision 1.0

Table of Contents

Multiplexing Signals in Fiber Optic Systems ................2

Bidirectional Signaling ...............................................4

AV Signal Transmission Distance ................................4

Daisy-chaining ..........................................................5

Secure Systems ........................................................6

Switching and Distribution .........................................6

Summary .................................................................9

Abstract

A fiber optic AV system converts video,

audio, and control signals into one or

more serial digital streams of light pulses

for transmission along optical fiber.

Common multiplexing techniques include

time division multiplexing TDM and

wavelength division multiplexing WDM.

This paper examines both methods to

help designers and integrators make the

appropriate decisions when selecting

equipment for a fiber optic AV system.

Multiplexing AV Signals in Fiber Optic Systems

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1

23 2 1

3 2 1

3

1

2

3

Serializer

Deserializer

Serializer Deserializer

Transmitter Receiver

DVI - Clock

DVI - TMDS 2

DVI - TMDS 1

DVI - TMDS 0

RS-232 Send

AUDIO

DVI - Clock

DVI - TMDS 2

DVI - TMDS 1

DVI - TMDS 0

RS-232 Send

AUDIOA-to-D

ConverterD-to-A

Converter

E-to-OConverter

O-to-EConverter


Multiplexing Signals in Fiber Optic SystemsTime Division MultiplexingTDM combines multiple digital signals into a single serial digital bit stream. A specialized

circuit, called a serializer, allocates parallel input streams into time slots in the serial

output. In a fiber optic system, the serial bit stream is transmitted as a single wavelength

down a fiber optic cable. On the far end of the channel, a deserializer reconstructs the

original parallel signal from the serial bit stream as shown in Figure1. The serial data

rate must be sufficiently fast to ensure no data is lost. Fiber optic transmitters and

receivers for high resolution AV signals typically operate at a 4 to 6Gbps data rate.

TDM is used to transmit a wide variety of signals, including HDMI, DVI, multi-rate

SDI, RGB, HD and SD component video, S-video, composite, USB, audio, and RS-232

control. In modern fiber optic AV systems, analog video and audio are converted to

digital signals, avoiding nonlinear effects that plague direct optical conversion of analog

signals. Digital transmission ensures high-resolution video is transmitted pixel-for-pixel

along the fiber optic cable.

The transmitter in Figure2 accepts HDMI/DVI video, stereo audio, and RS-232 control

signals. The multiplexer combines the signals as a serial stream of digital pulses. An

electrical-to-optical E-to-O converter changes the digital pulses to light pulses at a

single wavelength for transmission down the fiber. The receiver on the far end converts

the signal from optical to electrical O-to-E before deserializing to restore the original

signal.

Figure 1: Serializer Deserializer

Figure 2: TDM Fiber Optic Transmitter and Receiver for HDMI/DVI, Audio, and Control

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WDMMultiplexer/

De-Multiplexer

WDMMultiplexer/

De-Multiplexer

DVI - Clock

DVI - TMDS 2

DVI - TMDS 1

DVI - TMDS 0

DVI - Clock

DVI - TMDS 2

DVI - TMDS 1

DVI - TMDS 0

RS-232 Send

RS-232 Return RS-232 Return

RS-232 Send

O-to-EConverter

E-to-OConverter

E-to-OConverter

E-to-OConverter

E-to-OConverter

E-to-OConverter

E-to-OConverter

O-to-EConverter

O-to-EConverter

O-to-EConverter

O-to-EConverter

O-to-EConverter

MultipleWavelengths

Over a Single Fiber



Wavelength Division MultiplexingWDM refers to transmitting two or more optical signals at different wavelengths along

a single fiber. Multiple wavelengths traveling down a fiber is similar to multiple radio

signals traveling through the air at different frequencies. Each wavelength can carry a

different signal that is independent of the other wavelengths. Additionally, the different

wavelengths can travel in the same or opposite directions, enabling bidirectional

optical communication over a single fiber as shown in Figure3. As long as the optical

converters have a sufficiently high bandwidth, WDM enables the original signal format

and data rate to be maintained in both the electrical and optical domains.

WDM is suitable for any application where multiple signals are transmitted over fiber

optic cabling. The signals can be completely independent, such as for different channels

in a cable television environment, bidirectional USB or RS-232 signals, components of

a multi-lane HDMI or DVI signal, or a combination of these. Each signal is applied to

a different wavelength for independent transmission along the same fiber optic cable.

The WDM transmitter and receiver shown in Figure3 enable transmission of an HDMI/

DVI signal over fiber optic cable. The transmitter has five inputs and one output.

Each input has its own E-to-O converter with a laser diode that operates at a unique

wavelength. A special device called a WDM multiplexer/de-multiplexer combines the

various wavelengths for transmission down a fiber optic cable.

Figure 3: WDM Fiber Optic Transmitter and Receiver for HDMI/DVI

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t Skew

t Skew

Serializer Deserializer


DVI - Clock

DVI - TMDS 2

DVI - TMDS 1

DVI - TMDS 0

RS-232 Send RS-232 Send

AUDIO

DVI - Clock

DVI - TMDS 2

DVI - TMDS 1

DVI - TMDS 0

AUDIO

RS-232 ReturnRS-232 Return

A-to-DConverter

D-to-AConverter

E-to-OConverter

O-to-EConverter

E-to-OConverter

O-to-EConverter

Switch


The WDM multiplexer/demultiplexer also separates the optical signal used for the return

data, which operates at a wavelength different from the inputs. The return data optical

signal passes through an O-to-E converter to recover the original signal.

The WDM receiver shown in Figure 3 has one input and five outputs. The WDM

multiplexer/demultiplexer in the receiver separates the optical signals, sending each to

a separate O-to-E converter.

Bidirectional SignalingBidirectional signals, such as USB, RS-232, or Ethernet, are used in a wide variety of

AV applications. As shown previously in Figure3, a WDM system transmits bidirectional

signals over a single fiber using a unique wavelength for the return data. In a TDM

system, single wavelength transmission is inherently unidirectional, so bidirectional

signaling is accomplished by using a second fiber as shown in Figure5.

AV Signal Transmission DistanceIn a WDM system, the maximum transmission distance is affected by optical loss, fiber

bandwidth, and inter-channel skew. Optical loss equates to attenuation in the fiber,

connections, and splices. The loss budget, determined by transmitter output power and

receiver input sensitivity, is the maximum amount of allowable optical loss in the fiber

link between the transmitter and receiver. Fiber bandwidth is the maximum frequency

or data rate that can be transmitted along a given length of fiber optic cable. Skew

is caused by the various wavelengths propagating at different speeds along the fiber

as shown in Figure4. The result is similar to skew created by varying twist ratios in

Category cable within a twisted pair system.

Figure 4: Inter-Channel Skew in WDM Applications Limits Transmission Distance

Figure 5: Two-Fiber Bidirectional Signaling in a TDM System

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ScatteringWater Peaksin OS1 Fiber

OS2 Fiber

Absorption

ATTENUATION

WAVELENGTH

1300850 1550

HDMI/DVI Transmission Distance Over OM4 Multimode FiberHDMI/DVI Transmission Distance Over OM4 Multimode Fiber

TDM

WDM2

1. Based upon a pixel clock of 225 MHz and maximum inter-channel skew of 1.78 ns.2. Based upon a pixel clock of 165 MHz and maximum inter-channel skew of 2.42 ns.

WDM1 300 meters (984 feet)

400 meters (1,312 feet)

2,000 m (6,561 ft)


The amount of skew in a WDM system depends upon the range of wavelengths used

in the system. In multimode systems using wavelengths around 850nm, skew can be

the dominant effect limiting transmission distance. For example, an HDMI system with

a 225MHz pixel clock has a maximum allowable inter-channel cable skew of 1.78ns.

A popular device used in multimode WDM HDMI and DVI extenders has a specified

maximum distance around 300meters (984feet) before the skew exceeds 1.78ns. The

same device can operate up to 400meters (1,312feet) for an HDMI or DVI signal with

a 165MHz pixel clock to allow a maximum skew of 2.42ns.

A TDM system transmits the fiber optic signal at a single wavelength, such that the entire

signal propagates at the same speed. With negligible skew, the maximum transmission

distance is limited only by the available loss budget and system bandwidth. A well-

managed loss budget and use of high-bandwidth, laser-optimized OM4 fiber enables

multimode TDM systems to achieve distances up to 2km (6,561 feet), as shown in

Figure6. As a result, TDM systems achieve much greater transmission distances than

WDM systems used for AV signal extension.

Singlemode systems use long wavelengths around 1310 nm or 1550 nm. At these

wavelengths, WDM systems experience less inter-channel skew to achieve longer

transmission distances. A typical WDM singlemode system for HDMI/DVI signals

transmits up to 12 km (7.5 miles), compared to 30 km (18.75 miles) for a TDM

singlemode system. However, not all WDM systems support OS1 fiber, which is the most

common type of installed singlemode fiber. WDM systems with wavelengths around

1390nm suffer high attenuation in OS1 fiber due to water peak absorption as shown

in Figure7.

Attenuation severely limits the transmission distance. Around the 1390nm wavelength,

OS1 fiber attenuation can 4dB/km or more due to water peak absorption. Assuming

a loss budget of 10 to 13dB, the maximum transmission distance is only 2 to 3km

at this wavelength. In order to achieve longer transmission distance, this type of WDM

system requires OS2 low water peak singlemode fiber. Alternatively, a singlemode TDM

system uses either a 1310nm or 1550nm wavelength, where OS1 fiber attenuation

is typically 1dB/km or less, so it operates at its full distance capability over both OS1

and OS2 fiber types.

Daisy-chainingDaisy-chaining allows a signal to be delivered to multiple destinations without the need

for routing or distribution equipment, or multiple transmitters as shown in Figure8. An

AV signal from a single transmitter, or from a single output on a matrix switcher, is sent Figure 8: Daisy-chain Configuration

Fiber Optic

Receiver

Fiber Optic

Receiver

Fiber Optic

Receiver

Figure 7: Attenuation in Optical Fiber

Figure 6: TDM Systems Experience Negligible Skew to Achieve Longer Transmission Distance

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Deserializer

Receiver

DVI - Clock

DVI - TMDS 2

DVI - TMDS 1

DVI - TMDS 0

RS-232 Send

AUDIO

RS-232 Return

TO NEXT RECEIVER IN DAISY CHAIN

D-to-AConverter

O-to-EConverter

E-to-OConverter

Switch

UnidirectionalFiber Optic Transmitter

Glass Fiber

UnidirectionalFiber Optic

Receiver

Public Black

AV Source

Secure Red

AV System


to a receiver with daisy-chain capability. The receiver provides a loop-out signal that is

sent to the next receiver in the daisy-chain. This configuration utilizes a single fiber from

the transmitter or matrix output to the first receiver in the chain. A single fiber connects

each consecutive receiver in the chain for efficient use of the fiber infrastructure. A

daisy-chain configuration is ideal for digital signage applications.

In a TDM system, the second fiber used for bidirectional communications is often

available as a loop out for creating a daisy-chain configuration as shown in Figure9.

Since there is a single bit stream, retransmission of the signal requires only a single

E-to-O converter. Alternatively, a WDM system is transmitting multiple bit streams,

requiring multiple optical converters and an additional WDM multiplexer/demultiplexer

to implement a loop-through. Therefore, a WDM receiver typically has only a single fiber

connection, and cannot be connected in a daisy-chain configuration.

Secure SystemsSecure environments include any system that deals with sensitive information, such as

government and military briefing rooms, emergency operations centers, or a corporate

presentation or planning room for proprietary technology. Many of these systems must

access information from both secure and public sources. Secure sources are referred to

as red signals, while public sources are referred to as black signals.

The detailed requirements for secure systems are often classified and not available to

the public, but general guidelines have been declassified. Secure systems with black

sources must take great care to ensure red information does not leak out through

the connection to the black source. Red and black systems must be electrically

isolated from each other. In a copper-based system, red and black signals must remain

physically separated. Since fiber optic cables are made of glass, a fiber optic system is

preferred as it provides near-perfect electrical isolation between black and red signals,

see Figure10.

Secure systems require that signals from public sources be unidirectional. Transmission

of any signal from a red secure system to a black unsecure system is not permitted.

Because of this, TDM fiber optic systems are preferred over WDM systems. Bidirectional

fiber optic devices that use WDM techniques are prohibited from use to connect a black

source to a red system.

Switching and Distribution

Active Switching and Distribution in AV SystemsSwitching systems used in fiber optic AV systems typically employ optical input-

electrical switching-optical output OEO technology. The optical signal is converted

to the electrical domain at the input of the router, switcher, or distribution amplifier.

Figure 9: TDM Receiver Configured for Daisy Chain

Figure 10: TDM is Preferred in Secure Fiber Optic AV Systems

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INPUT 1

INPUT 2

INPUT 3

INPUT 4

INPUT N

INPUT 1

INPUT 2

INPUT 3

INPUT 4

INPUT N

O-to-EConverter

O-to-EConverter

N x NMatrix Switcher

O-to-EConverter

O-to-EConverter

O-to-EConverter

E-to-OConverter

E-to-OConverter

E-to-OConverter

E-to-OConverter

E-to-OConverter

ANAHEIM, CA

RESETRS232/RS422

REMOTE LAN

ACT LINK

100-240V 50/60Hz

1.2A MAX.

100-240V 50/60Hz

1.2A MAX.

REDUNDANT

PRIMARY

PRIMARY POWER SUPPLYDISCONNECT BOTH POWERCORDS BEFORE SERVICING REDUNDANT POWER SUPPLY

FAN ASSIMBLY

FAN ASSIMBLY

1 - 1

617

- 32

33 -

4849

- 64

65 -

8081

- 96

97 -

112

113

- 128

129

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A B C D E F G H I J K L M N O P

OUT IN OUT IN OUT IN OUT IN OUT IN OUT IN OUT IN OUT IN OUT IN OUT IN OUT IN OUT IN OUT IN OUT IN OUT IN OUT IN

















12V 0.3A MAX

FOX 3G HD-SDI

HD/SDI IN

POWER

BUFFERED OUTPUTS

MODEOPTICAL

RxTx

1 21 2

ON

12V 0.3A MAX

FOX 3G HD-SDI

HD/SDI IN

POWER

BUFFERED OUTPUTS

MODEOPTICAL

RxTx

1 21 2

ON

S

M

M

S

M

S

S

M

S

FOX AV Rx

Y/VID

OUTPUTS

RS-232OVER FIBER

RS-232REMOTE

Tx Rx Tx Rx

AUDIO

L R

RxTx

ALARM

1 2R-Y

B-Y/C

S-VID

OPTICAL

POWER12V 0.8A MAX

FOX 500 TX100-240V 0.3A

50/60 Hz

AUDIO INPUTS

RGB INPUT

R G B

H/HV V

ORL R

RS-232PASS THRU

TX Rx NA

RS-232CONTROL ALARM

* OPTIONAL FORRETURN DATA

TX Rx 1 2

INPUT LOOP THRU

RGB

OPTICAL1 2*

LIN

K

LIN

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FOX AV Tx

Y/VID

INPUTS

RS-232OVER FIBER

RS-232REMOTE

Tx Rx Tx Rx

AUDIO

L R ALARM

1 2R-Y

B-Y/C

S-VID

OPTICAL

POWER12V 0.8A MAX

RxTx

FOXBOX Tx VGA

RGB

AUDI

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OPTICAL

RxTx

LIN

K

LIN

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FOXBOX Rx DVI Plus

DVI

AUDI

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OPTICAL

RxTx

LIN

K

LIN

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FOX 500 Rx100-240V 0.3A

50/60 Hz

AUDIO OUTPUTS

RGB OUTPUT

R G B

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RS-232PASS THRU

TX Rx NA

RS-232CONTROL ALARM

* OPTIONAL FORRETURN DATA

TX Rx 1 2S

RGB

OPTICAL2* 1

LIN

K

LIN

K

FOX AV TransmitterMultimode

FOX AV ReceiverMultimode

FOX Matrix 14400Modular Fiber Optic Matrix Switcher

FOXBOX DVI Plus ReceiverSinglemode

FOXBOX VGA TransmitterSinglemode

FOX 500 RGB ReceiverSinglemode

FOX 3G HD-SDI TransceiverSinglemode

FOX 500 RGB TransmitterMultimode

FOX 3G HD-SDI TransceiverMultimode

Singlemode HD-SDIMultimode

FOXBOX Tx HDMITransmitter Multimode

FOXBOX SR HDMIScaling Receiver Multimode

MUTI-RATE SDI INPUTS

HGA D E FCB

MUTI-RATE SDI OUTPUTS

HGA D E FCB

MUTI-RATE SDI INPUTS

HGA D E FCB

MUTI-RATE SDI OUTPUTS

HGA D E FCB


OUT IN OUT IN OUT IN OUT IN OUT IN OUT IN OUT IN OUT IN OUT IN OUT IN OUT IN OUT IN OUT IN OUT IN OUT IN OUT IN 3G P BNC


OUT IN OUT IN OUT IN OUT IN OUT IN OUT IN OUT IN OUT IN OUT IN OUT IN OUT IN OUT IN OUT IN OUT IN OUT IN OUT IN 3G P BNC

FOXBOX Tx HDMI

OPTICALHDMI INPUT AUDIO INPUT

RS-232OVER FIBER ALARM

Tx Rx 1 2

POWER12V 1.0 A MAX

LIN

K

LIN

K

RxTx

AUD

IO

HD

CP

HD

MI

CONFIG

HDMI LOOP THRUEDID MINDER 50Hz

AUDIO

DIGITAL

ANALOG60Hz

1 2

FOXBOX Tx HDMI FOXBOX SR HDMI

LIN

K

LIN

K

OPTICAL

RxTx

HDMI

AUDIO

OUTPUTS

REMOTERS-232

Tx Rx

RS-232OVER FIBER ALARM

Tx Rx 1 2

POWER12V 1.0 A MAX L R

OFF

ONHDMI AUDIO

POWER

PHONES

INPUT

MIXING

EXT 1-4

IMX

5-8REC

REC

CH1 5 CH2 6

UNITY VARIABLE

CH3 7 CH4 8 CUE

CUE

L

R MONITOR

PREVIEW AUTO EDIT

DMC EDIT DELETE

REVIEW

LIST GOOD SHOT MARK TRIM

CH1 5 CH2 6 CH3 7 CH4 8

PB

REC

PB

REMOTE EJECT1(9P) 2(50P) RS-232C

MPEG IMX Digital BETACAM HDCAM HDCAM High DefinitionVideo System

MEMORY

REC/ERASE AUDIO

ENTRY

PREROLL

REW

REC

PLAY

EDIT

F FWD

STANDBY

STOP

IN

IN

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OUT

REC INHI

REVER

SE FORWARD

JOG

SHUTTL

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F1 F2 F3 F4 F5 F6

JOG

HOME

SHUTTLE/VAR

DISPLAYFULL/FINE

CHANNELCONDITION

ASSEMBLE INSERT

VIDEO CH1 CH2 CH3 CH3 CUE

RESET

TC

00:00:00:00KEY INHIALARM

PUSH/SHIFT

MULTICONTROL

PLAYER

RECORDER

HD SDI HD SDI HD SDI HD SDI

db db db db0

10

20

30

40

50

0

10

20

30

40

50

0

10

20

30

40

50

0

10

20

30

40

50

db0

10

20

30

40

50

H

COMMUN

ICATION

Tx

COMMUN

ICATION

Tx


It is then processed in the electrical domain, and restored to an optical signal at the

output. OEO systems restore full transmission power level on the output to preserve

the optical loss budget. The use of OEO technology avoids the losses that occur in

optical input-optical switching-optical output OOO systems that use passive splitters

to distribute optical signals to multiple destinations, which is particularly important when

multicasting a fiber optic AV signal to several displays.

Switching and Routing Fiber Optic TDM AV SignalsTDM switching systems process a single serial bit stream for each signal to produce an

efficient, compact design. The single wavelength/single fiber switching system performs

a single E-to-O conversion for each input and a single O-to-E conversion on each output

as shown in Figure11. High-speed digital switching ensures pixel-for-pixel performance

for high resolution video signals. The matrix switcher also maintains the serial format of

the signal to simplify switching and maintain proper timing.

Maintaining the serial digital bit stream enables switching to be independent of the

underlying video format as shown in Figure 12. This allows the distribution system

to support a wide variety of digital signals, including HDMI/DVI, multi-rate SDI, USB,

RS-232, and other digital signals. Signal types are defined by the endpoints the

transmitter and receiver. Serial digital signals, such as multi-rate SDI, are supported in

their native format, enabling local inputs and outputs.

Bidirectional signals are easily handled by using two fibers, an input and output that

are switched together. However, multi-lane signals such as HDMI, DVI, and RGB require

external transmitters and receivers to provide local inputs and outputs. The ability to

support a wide variety of signals simplifies upgrading of sources and displays with

minimal impact on the switching and routing system.

Figure 11: Matrix Switcher for TDM Systems

Figure 12: TDM Fiber Optic Signal Routing Easily Handles Multiple Video Formats

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WDMMultiplexer/

De-Multiplexer

WDMMultiplexer/

De-MultiplexerTMDS Clock

N x N Matrix Switcher

TMDS 2N x N

Matrix Switcher

TMDS 1N x N

Matrix Switcher

TMDS 0N x N

Matrix Switcher

DATAN x N

Matrix Switcher

RETURN DATAN x N

Matrix Switcher

INPUT 1

O-to-EConverter

E-to-OConverter

E-to-OConverter

E-to-OConverter

E-to-OConverter

E-to-OConverter

E-to-OConverter

O-to-EConverter

O-to-EConverter

O-to-EConverter

O-to-EConverter

O-to-EConverter

OUTPUT 1

WDMMultiplexer/

De-Multiplexer

WDMMultiplexer/

De-Multiplexer

INPUT N

O-to-EConverter

E-to-OConverter

E-to-OConverter

E-to-OConverter

E-to-OConverter

E-to-OConverter

E-to-OConverter

O-to-EConverter

O-to-EConverter

O-to-EConverter

O-to-EConverter

O-to-EConverter

OUTPUT N


The efficient design of a TDM matrix switcher enables a large number of inputs

and outputs in a compact space with moderate power requirements. The Extron

FOXMatrix14400 shown in Figure12 provides a full 144x144 non-blocking fiber optic

matrix switcher in an 8U frame.

Switching and Routing Fiber Optic WDM AV SignalsA matrix switcher for WDM signals is larger and more complex than that used for a

TDM signal as shown in Figure13. Each fiber optic input includes the complete WDM

receiver circuit to convert the optical signal to an HDMI/DVI format. The core switching

system supports the multi-lane format of an HDMI/DVI signal, which requires multiple,

parallel internal switching components. Each fiber optic output includes the complete

WDM transmitter circuit to convert the HDMI/DVI signal back into an optical signal. The

additional switching resources and I/O circuitry causes WDM matrix switchers to be

large, high powered, and require additional cooling. Since the core switching system

supports HDMI/DVI signals in their native format, local inputs and outputs are easily

added to the matrix. Supporting other signal types, such as multi-rate SDI, requires

external converters to change the original signal into a DVI/HDMI signal. WDM matrix

switchers do not typically support local multi-rate SDI signals.

Figure 13: WDM Matrix Switcher

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FOXMatrix14400

144x144

System (A)TDM

Design

Rack Height

System (B)WDM w/

BidirectionalSignal

System (C)WDM w/

UnidirectionalSignal

Third-partyWDMMatrix

Switcher80x80

Third-partyWDMMatrix

Switcher144x144

16U15U

8U


Relative Matrix Sizes of TDM and WDM Matrix SwitchersA high speed digital matrix switcher in a TDM system operates efficiently, typically

using less power than a WDM matrix switcher. The efficient design also enables a

TDM matrix switcher to occupy less rack space. For example, System A in Figure14

is the Extron FOX Matrix 14400 144x144 fiber optic matrix switcher that occupies

eight rack units. It is compatible with the complete family of FOX Series transmitters

and receivers to supports HDCP-compliant HDMI, DVI, multi-rate SDI, RGB,

HD/SD component, S-video, composite video, USB, stereo audio, and RS-232 control

signals. A matrix board is also available to provide local multi-rate SDI signals.

SystemB in Figure 14 is an 80x80 WDM matrix switcher that is almost twice the size

at 15rack units, and supports HDCP-compliant HDMI and DVI signals. It lacks support

for multi-rate SDI signals, standard definition video, audio, USB, and control, but does

provide local HDMI and DVI inputs and outputs. SystemC in Figure14 is a 144x144

WDM matrix switcher that consumes 16rack units, but only supports non-HDCP DVI,

VGA, HD component video, audio, and one-way RS-232 control. It lacks support for

multi-rate SDI signals, standard definition video, and bidirectional RS-232. As a WDM

matrix switcher, it does support local DVI or VGA inputs and outputs, but not HDCP-

compliant HDMI. The TDM system is the most compact design with complete support

for AV signal types. Support for local multi-rate SDI signals can be provided within the

modular matrix frame. Local inputs and outputs for other signal types are provided with

the compact transmitters and receivers. WDM systems require significantly more rack

space for the matrix switcher and support fewer signal types. For example, SystemB in

Figure14 would consume 30rack space units in order to provide the same switching

resources as in the FOXMatrix14400. The FOXMatrix consumes significantly less rack

space, even with the addition of a few transmitters and receivers for local HDMI inputs

and outputs.

SummaryBoth TDM and WDM are common technologies implemented in fiber optic AV systems.

Each has its own unique advantages and challenges. The table below compares and

contrasts the two technologies:

Figure 14: Relative Size of Matrix Switchers

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Extron Electronics, headquartered in Anaheim, CA, is a leading manufacturer of professional AV system integration products. Extron products are used to integrate video and audio into presentation systems in a wide variety of locations, including classrooms and auditoriums in schools and colleges, corporate boardrooms, houses of worship, command-and-control centers, sports stadiums, airports, broadcast studios, restaurants, malls, and museums.

www.extron.com 2012 All rights reserved.

TDM WDM

Up to 2 km on multimode fiber 300 to 400 m typicalUp to 30 km on singlemode fiber Up to 12 km on OS2 fiber. OS1 depends on wavelengthsBidirectional signaling Extend HDMI / DVI Signals Extend RGB Signals Extend multi-rate SDI signals Requires ConversionHDCP Support USB Extension Daisy Chain Capability w/ loop-through Not typically supported

Preferred for secure systems Low power matrix switcher High I/O density matrix switcher HDMI / DVI Local I/O w/ external converters RGB Local I/O w/ external converters Digital-to-analog conversion

Multi-Rate SDI Local I/O

Comparison of TDM and WDM Technologies

Multiplex Av Sig Fiberop Wp

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