Ensemble Designs BrightEye 25 User manual

This user guide provides detailed information for using the BrightEye™25
Analog Video/Audio to SDI Converter with TBC and Embedder.
The information is organized into the following sections:
• Product Overview
• Functional Description
• Applications
• Rear Connectors
• Operation
• Front Panel Controls and Indicators
• Using The BrightEye Control Application
• Warranty and Factory Service
• Specifications
• Glossary
BrightEye-1
Analog Video/Audio
to SDI Converter with
TBC and Embedder
User Guide
Revision 5.0 SW v1.0.4
ENSEMBLE
DESIGNS

BrightEye 25 A-D Converter with TBC/FS and Embedder
PRODUCT OVERVIEW
BrightEye™ 25 converts analog composite video to SDI with simultaneous conver-
sion of four channels of audio and embedding. A TBC/Frame Sync is a standard
feature and allows this BrightEye to work with any sort of video input.
BrightEye 25 is versatile enough to handle applications from broadcasting to
desktop video with sources such as VTRs and incoming satellite feeds.
Basic controls are accessed on the front panel. The BrightEye Control application
provides access to video proc functions, input/output and built-in audio mixer
controls not available from the front panel.
A glossary of commonly used video terms is provided at the end of this user guide.
FUNCTIONAL DESCRIPTION
As shown in the functional block diagram below, analog video is converted at
12 bits of resolution and digitally decoded to YCrCb components (601). The signal
is then time base corrected and frame synchronized to the reference input. Proc
amp adjustments are provided for the converted video.
The audio is converted to digital and then passes through the built-in four
channel mixer with shuffle and level control. One of the four audio groups is
selected for embedding into the SDI output.
The video and audio signals are joined in the embedder. This embedded signal
passes through a serializer to two timed SDI outputs on the rear of the unit.
BrightEye 25 is powered by a 12 volt DC universal power supply. This power
supply can accept an input voltage between 90 and 230 volts, at 50 or 60 Hertz.
It uses a standard IEC line cord and can be used anywhere in the world. It is
normal for the converter to be quite warm to the touch when operating.
BrightEye-2
SDI Outputs
Cpst In
Serializer
Embedder
Proc
Amp
TBC/
Frame Sync
12 bit
Video A-D
Converter
and
Decoder
Reference In
4 Channel
A to D
Analog Audio In
4 Channel
Mixer/Shuffler
BrightEye 25 Functional Block Diagram

APPLICATIONS
One useful application for the BrightEye 25 is for signal ingest from a satellite
receiver for feeding a video server requiring SDI video with embedded audio.
In this application shown below, analog video enters the BrightEye 25 and is
converted and decoded to digital video. The signal is time base corrected and
frame synchronized to the reference input.
The analog audio from the satellite feed enters the BrightEye 25 four channel
A-to-D converter. Adjustments for audio mixing, audio levels, and channel
shuffling can then be applied to the AES audio before it is embedded into the SDI
output signal feeding the video server.
BrightEye-3
BrightEye 25
SDI Out
Ref In
Ref In
Video Server
House Reference
Analog Audio In
Analog Video In
Microwave
Receiver
BrightEye 25 Signal Ingest Application

BrightEye 25 A-D Converter with TBC/FS and Embedder
BrightEye-4
REAR CONNECTORS
All connections to the BrightEye 25 converter are made on the rear of the unit.
Refer to the illustration below.
Power Connection
Connect a modular power supply to the 12 volt DC power input connection on the
far left of the unit. Use the locking ring to secure it.
USB Connector
The USB connector is used to provide more comprehensive control, diagnostics,
and upgrades to the unit from a PC or Mac. Use the BrightEye Control applica-
tion included on CD-ROM to make adjustments as described in the OPERATION
section of this user guide.
Input/Output BNCs
There are four rear BNC connectors used as inputs and outputs as follows:
Cpst In
This BNC input accepts an analog composite signal, 525 or 625 line standard.
The NTSC or PAL input standard is auto detected.
Ref In
For synchronizing (genlocking) the input signal to an external reference, connect
a composite video (PAL or NTSC with the same line rate as the input video) to
the Ref In BNC.
SDI Outputs
Two timed SDI outputs are provided with the selected embedded audio group.
Analog Audio In
A 15 pin D connector provides the input for four channels of analog audio
according to the pinouts given in the table and shown in the illustration below.
BrightEye 25 Rear Connectors
1
6
+
+
+
+
-
-
-
-
11
AUD 2 AUD 1
AUD 3
AUD 4
Analog Audio Pinouts
Signal Pins Input
Aud 1 +, –, G 1, 2, 7 Input 1
Aud 2 +, –, G 5, 4, 3 Input 2
Aud 3 +, –, G 11, 12, 6 Input 3
Aud 4 +, –, G 15, 14, 13 Input 4

BrightEye-5
OPERATION
Control and operation of the BrightEye 25 unit is performed from the front panel
or remotely from a networked PC with the BrightEye Control application.
Some control settings are only available with BrightEye PC or Mac. These parameters
cannot be monitored or controlled from the front panel.
Front Panel Controls and Indicators
The front panel of the converter, shown in the figure below, provides status and
control indicators for the module.
Status Indicators
The following status indicators are provided on the front panel:
In
Illuminates green when a valid analog video input is detected on the Cpst
In BNC connector.
Ref (Reference)
Illuminates green when a valid NTSC or PAL reference is detected on the
Ref In BNC connector.
Pwr (Power)
Illuminates green when power is applied to the converter and the internal
voltage regulator is functioning correctly.
Group
The audio group (1, 2, 3, or 4) currently selected for embedding into the SDI
output is illuminated green.
Ch 1/2 and Ch 3/4
VU output level and the status of the Gain adjustment for each of these
channel pairs is indicated by the state the VU and Gain indicators. The VU
indicator illuminates red when the audio level exceeds the headroom level
set by the user (with the Peak Indicator control in BrightEye PC or Mac.)
NOTE:
BrightEye 25 Front Panel

BrightEye 25 A-D Converter with TBC/FS and Embedder
BrightEye-6
Additionally, the VU indicator illuminates orange when the output is above
0 VU, illuminates green when the output is above -20 VU, and doesn’t illu-
minate when the output is below -20 VU.
The Gain indicator illuminates red when the gain level has been adjusted
off from unity by the user. The 0 VU point corresponds in the digital domain
to the digital reference level (-18 or -20 dBFS) and in the analog domain to
the analog reference level (-10 or +4 dBu).
ADJUSTING PARAMETERS FROM THE FRONT PANEL
Use the Mode, Right Arrow, and Left Arrow buttons to select and adjust
parameters from the front panel.
Pressing the Mode button activates the front panel for editing and tabs between
each section of editable parameters.
Pressing the Right Arrow or Left Arrow advances the selection within a given
section of parameters, or increases (Right Arrow) or decreases (Left Arrow) the
value of a selected parameter.
The LED of an edited parameter will blink for 15 seconds, after which time its value is
stored in memory.If power is interrupted before this 15 second timeout period has
elapsed, the edited state will not be not saved.
The controls and their indicators are described below:
TBC/FS
This control enables the Frame Sync genlock function when an external reference
is present on the Ref In BNC.
Vid Gain
This control adjusts the gain of the analog video signals in the Digital-to-Analog
converter and encoder circuitry of the converter. The right arrow will increase the
gain, the left arrow will decrease it. The Vid Gain indicator will illuminate green
when the gain is set to its nominal or unity setting.
This is the setting which will produce correct analog output levels from a digital
input source which itself is at proper level. The Vid Gain indicator will illumi-
nate red whenever the control is adjusted either higher or lower than the nominal
setting. The gain can be reset to nominal (green) by pressing both arrows simulta-
neously.
NOTE:

BrightEye-7
USING THE BRIGHTEYE CONTROL APPLICATION
The BrightEye PC and BrightEye Mac applications included on CD-ROM are
designed to allow you to configure and control the BrightEye 25 from a personal
computer. Installation and instructions for using this software application are
given in the PDF manual on disk.
If the BrightEye 25 is connected to a computer running this software, the
following menus are available for controlling and monitoring the unit.
Refer to the menu illustrations and explanations below.
Input Menu
• Input Pres – gives read-only status indication of input video presence
(None, 525 Lock, or 625 Lock).
• Ref Pres – gives read-only status indication of reference video presence
(No Ref or Ref Present).
• Comb Mode – set the type of comb filtering from 3 Line or 5 Line.
• Analog Setup – set to On if setup is present on the analog input or Off if
no setup is present.

BrightEye 25 A-D Converter with TBC/FS and Embedder
Proc Menu
The Proc menu provide the following video adjustments:
• Gain – adjust the overall gain of the signal from 50 to 150%.
• Chroma – adjust the chroma gain of the signal from 50 to 150%.
• Pedestal – adjust the pedestal level of the signal +/- 5 IRE.
•Hue– adjust the hue of the signal +/- 180 degrees.
BrightEye-8

Audio Mixer Menu
• Outputs 1-4 – provide peak/VU status, with the same methodology as
the front panel VU indicators, but on a per channel basis, rather than per
channel pair. Peak/VU indicators illuminate red when the audio level on
that channel exceeds the headroom level set by the user with the Peak
Indicator control. Additionally, the VU indicator illuminates orange when
the output is above 0 VU, illuminates green when the output is above -20
VU, and doesn’t illuminate when the output is below -20 VU.
•Input Ch 1 – assign Input Channel 1 to the desired output bus or tie to
Channel 2. Set the input level using the slider control or by entering a
number in the window and pressing the Enter key on your PC.
•Input Ch 2 – assign Input Channel 2 to the desired output bus or tie to
Channel 1. Set the input level using the slider control or by entering a
number in the window and pressing the Enter key on your PC.
•Input Ch 3 – assign Input Channel 3 to the desired output bus or tie to
Channel 4. Set the input level using the slider control or by entering a
number in the window and pressing the Enter key on your PC.
•Input Ch 4 – assign Input Channel 4 to the desired output bus or tie to
Channel 3. Set the input level using the slider control or by entering a
number in the window and pressing the Enter key on your PC.
Selecting the Tie button in Input Ch 1 or Input Ch 2 will tie the two controls
together. Selecting the Tie button in Input Ch 3 or Input Ch 4 will tie the
controls for these channels together.
Select the Default button to return to the default value (0 dB).
Select the Invert button to invert the phase of the audio content.
BrightEye-9

BrightEye 25 A-D Converter with TBC/FS and Embedder
Timing Menu
The timing function operates in one of three modes:
1. When the Frame Sync control is turned On and a proper reference signal is
connected to the Ref In BNC, the video output of the unit will be syn-
chronous and locked to the external reference. The output may be timed
with respect to the Ref In using the timing controls. In this case, the unit
will accept asynchronous video and time base errors will be corrected.
2. When the Frame Sync control is turned On and no reference signal is
connected, the unit will act as a time base corrector only. The output will
not be synchronous to any reference, including the input. This mode allows
a noisy input signal to be time base corrected for a clean stable output.
3. When the Frame Sync control is turned Off, any reference signal to the Ref
In BNC is ignored. The video input is synchronous to the video output when
a nearly perfect, clean video input signal is present (no time base correction
required).
The following timing controls are available when the Frame Sync function is On:
• Ver Time – adjust the vertical timing of the signal in lines with reference to
the Frame Sync input.
• Hor Time – .adjust the horizontal timing of the signal in clocks with
reference to the Frame Sync input.
Use the following control to enable the Frame Sync function:
• Frame Sync – set the Frame Sync function On to genlock to the external
reference input to the module or Off for no Frame Sync.
BrightEye-10

Output Menu
Use the Output menu to set the following output conditions for the module:
• V Blanking – set the vertical blanking to Narrow (NTSC: lines 1-9,
PAL: lines 1-6) or Wide (NTSC: lines 1-20, PAL: lines 1-22).
• Test Pattern – select a test pattern at the module output from Black or
Color Bars or turn to Off for normal operation.
• Signal Mute – select the condition on which to mute the output signal from
No Muting, Mute On Noise, or Freeze on Noise.
Aud Config Menu
Use the Aud Config menu to set the following output conditions for each audio
group:
• Group Sel – Select the audio group to embed into the SDI output from
Group 1-4.
• Dig Ref Level – selects the digital reference output level. This pulldown
lets you choose between: -20 dBFS or -18 dBFS.
• Anlg Ref Level – selects the analog audio input level for embedding. This
pulldown lets you select between: -10 dBu Analog and +4 dBu Analog.
• Peak Indicator – selects the amount of headroom to use in determining
peak indications. This pulldown lets you chose between: Clipping,2 dB
Headroom,4 dB Headroom,6 dB Headroom, 8 dB Headroom, or 10
dB Headroom.
BrightEye-11

BrightEye 25 A-D Converter with TBC/FS and Embedder
WARRANTY AND FACTORY SERVICE
Warranty
Ensemble Designs, Inc. warrants this product to be free from defect in material
and workmanship for a period of five years from the date of delivery. During this
two year warranty period, Ensemble Designs, Inc. will repair any defective units
at Ensemble’s expense if the unit should be determined to be defective after con-
sultation with a factory technician.
This warranty is not transferable. Any implied warranties expire at the expira-
tion date of this warranty.
This warranty does not cover a defect that has resulted from improper or unrea-
sonable use or maintenance as determined by us. This warranty is void if there is
any attempt to disassemble or adjust factory set presets without factory autho-
rization.
Factory Service
If you require service (under warranty or not), please contact Ensemble Designs
and ask for Customer Service before you return the unit. This will allow the
service technician to provide any other suggestions for identifying the problem
and recommend possible solutions.
You may also refer to the technical support section of the Ensemble web site for
the latest information on your equipment at the URL below:
http://www.ensembledesigns.com/support
If you return equipment for repair, please get a Return Material Authorization
Number (RMA) from the factory first.
Ship the product and a written description of the problem to:
Ensemble Designs, Inc.
Attention: Customer Service RMA #####
870 Gold Flat Rd.
Nevada City, CA 95959 USA
[phone]
Fax: [phone]
[email protected]
http://www.ensembledesigns.com
Be sure to put your RMA number on the outside of the box.
BrightEye-12

SPECIFICATIONS
Analog Video Input:
Number: One
Signal Type: NTSC, PAL Composite
Impedance: 75 Ω
Return Loss: > 40 dB, DC to 5.5 MHz
Input DC: +/- 1 volt DC
Input Hum: < 100 mV
Reference Input:
Number: One
Signal Type: 1 V p-p Composite Video, PAL or NTSC
Impedance: 75 Ω
Return Loss: > 40 dB
Serial Digital Output:
Number: Two
Type: 270Mb/s Serial Digital
SMPTE 259M
Impedance: 75 Ω
Return Loss: > 15 dB
Output DC: None (AC coupled)
Analog Video to SDI Performance:
Bit Resolution: 12 bit input quantization,
4X oversampling
Decoding: Adaptive Comb Filter,
3 or 5 line selectable
Signal to Noise: > 62 dB, weighted
Freq Response: ± 0.1 dB, 0 to 5.5 MHz
Analog Audio Inputs:
Number: Four
Type: Balanced
Impedance: > 15 k Ω
Maximum Input
Level: 24 DBu
CMRR: > 60 dB, 20 Hz to 10 kHz
Quantization: 24 bits, 128x oversampled
Sample Rate: 48 kHz
Reference Level: -10 dBu or + 4 dBu
Frequency Response: ± 0.1 dB, 20 Hz to 20 kHz
Crosstalk: < 106 dB
Dynamic Range: > 106 dB
BrightEye-13

BrightEye 25 A-D Converter with TBC/FS and Embedder
General Specifications:
Size: 5.625” W x 0.8 “ H x 5.5” D
(143 mm x 20 mm x 140 mm)
including connectors
Power: 12 volts, 7 watts
Temperature Range: 0 to 40 degrees C ambient
Relative Humidity: 0 to 95% noncondensing
Due to ongoing product development, all specificationsare subject to change.
BrightEye-14

BrightEye-15
BRIGHTEYE POWER SUPPLY INFORMATION
Below is a list of power supplies and optional items that may have come with
your BrightEye:
BEPS
BrightEye Individual Power Supply.
BEPS6
Spider Power Supply. This powers 6 single high BrightEyes or 3 double high
BrightEyes (BrightEye 90 family).
BEPS6-RP
Redundant Power Supply for Spider.
BERKMT
BrightEye Rack Mount. This holds 6 single high BrightEyes or 3 double high
BrightEyes (BrightEye 90 family) or a combination.
BEBP
BrightEye Blank Panel. Single high, for empty slots in Rack Mount.
BEAC
Analog Audio Breakout Cable.

BrightEye 25 A-D Converter with TBC/FS and Embedder
GLOSSARY
This is a brief glossary of commonly used terms associated with this product.
AES/EBU
The digital audio standard defined as a joint effort of the Audio Engineering
Society and the European Broadcast Union. AES/EBU or AES3 describes a serial
bitstream that carries two audio channels, thus an AES stream is a stereo pair.
The AES/EBU standard covers a wide range of sample rates and quantizations
(bit depths.) In television systems, these will generally be 48 kHz and either 20 or
24 bits.
Bandwidth
Strictly speaking, this refers to the range of frequencies (i.e. the width of the
band of frequency) used by a signal, or carried by a transmission channel.
Generally, wider bandwidth will carry and reproduce a signal with greater
fidelity and accuracy.
Beta
Sony Beta SP video tape machines use an analog component format that is
similar to SMPTE, but differs in the amplitude of the color difference signals. It
may also carry setup on the luminance channel.
Blanking
The Horizontal and Vertical blanking intervals of a television signal refer to the
time periods between lines and between fields. No picture information is trans-
mitted during these times, which are required in CRT displays to allow the
electron beam to be repositioned for the start of the next line or field. They are
also used to carry synchronizing pulses which are used in transmission and
recovery of the image. Although some of these needs are disappearing, the
intervals themselves are retained for compatibility purposes. They have turned
out to be very useful for the transmission of additional content, such as teletext
and embedded audio.
CAV
Component Analog Video. This is a convenient shorthand form, but it is subject to
confusion. It is sometimes used to mean ONLY color difference component
formats (SMPTE or Beta), and other times to include RGB format. In any case, a
CAV signal will always require 3 connectors – either Y/R-Y/B-Y, or R/G/B.
Checkfield
A Checkfield signal is a special test signal that stresses particular aspects of
serial digital transmission. The performance of the Phase Locked-Loops (PLLs) in
an SDI receiver must be able to tolerate long runs of 0’s and 1’s. Under normal
conditions, only very short runs of these are produced due to a scrambling
algorithm that is used. The Checkfield, also referred to as the Pathological test
signal, will “undo” the scrambling and cause extremely long runs to occur. This
test signal is very useful for testing transmission paths.
BrightEye-16

Chroma
The color or chroma content of a signal, consisting of the hue and saturation of
the image. See also Color Difference.
Component
In a component video system, the totality of the image is carried by three
separate but related components. This method provides the best image fidelity
with the fewest artifacts, but it requires three independent transmission paths
(cables). The commonly used component formats are Luminance and Color
Difference (Y/Pr/Pb), and RGB. It was far too unwieldy in the early days of color
television to even consider component transmission.
Composite
Composite television dates back to the early days of color transmission. This
scheme encodes the color difference information onto a color subcarrier. The
instantaneous phase of the subcarrier is the color’s hue, and the amplitude is the
color’s saturation or intensity. This subcarrier is then added onto the existing
luminance video signal. This trick works because the subcarrier is set at a high
enough frequency to leave spectrum for the luminance information. But it is not a
seamless matter to pull the signal apart again at the destination in order to
display it or process it. The resultant artifacts of dot crawl (also referred to as
chroma crawl) are only the most obvious result. Composite television is the most
commonly used format throughout the world, either as PAL or NTSC. It is also
referred to as Encoded video.
Color Difference
Color Difference systems take advantage of the details of human vision. We have
more acuity in our black and white vision than we do in color. This means that we
need only the luminance information to be carried at full bandwidth, we can
scrimp on the color channels. In order to do this, RGB information is converted to
carry all of the luminance (Y is the black and white of the scene) in a single
channel. The other two channels are used to carry the “color difference”. Noted as
B-Y and R-Y, these two signals describe how a particular pixel “differs” from
being purely black and white. These channels typically have only half the
bandwidth of the luminance.
Decibel (dB)
The decibel is a unit of measure used to express the ratio in the amplitude or
power of two signals. A difference of 20 dB corresponds to a 10:1 ratio between
two signals, 6 dB is approximately a 2:1 ration. Decibels add while the ratios
multiply, so 26 dB is a 20:1 ratio, and 14 dB is a 5:1 ratio. There are several
special cases of the dB scale, where the reference is implied. Thus, dBm refers to
power relative to 1 milliwatt, and dBu refers to voltage relative to .775V RMS.
The original unit of measure was the Bel (10 times bigger), named after
Alexander Graham Bell.
BrightEye-17

BrightEye 25 A-D Converter with TBC/FS and Embedder
dBFS
In Digital Audio systems, the largest numerical value that can be represented is
referred to as Full Scale. No values or audio levels greater than FS can be repro-
duced because they would be clipped. The nominal operating point (roughly corre-
sponding to 0 VU) must be set below FS in order to have headroom for audio
peaks. This operating point is described relative to FS, so a digital reference level
of -20 dBFS has 20 dB of headroom before hitting the FS clipping point.
EDH
Error Detection and Handling is a method to verify proper reception of an SDI or
HD-SDI signal at the destination. The originating device inserts a data packet in
the vertical interval of the SDI signal and every line of the HD signal which
contains a checksum of the entire video frame. This checksum is formed by
adding up the numerical values of all of the samples in the frame, using a
complex formula. At the destination this same formula is applied to the incoming
video and the resulting value is compared to the one included in the transmis-
sion. If they match, then the content has all arrived with no errors. If they don’t,
then an error has occurred.
Embedded Audio
Digital Audio can be carried along in the same bitstream as an SDI or HD-SDI
signal by taking advantage of the gaps in the transmission which correspond to
the horizontal and vertical intervals of the television waveform. This technique
an be very cost effective in transmission and routing, but can also add complexity
to signal handling issues because the audio content can no longer be treated inde-
pendently of the video.
Frame Sync
A Frame Synchronizer is used to synchronize the timing of a video signal to
coincide with a timing reference (usually a color black signal that is distributed
throughout a facility). The synchronizer accomplishes this by writing the
incoming video into a frame buffer memory under the timing direction of the sync
information contained in that video. Simultaneously the memory is being read
back by a timing system that is genlocked to a house reference. As a result, the
timing or alignment of the video frame can be adjusted so that the scan of the
upper left corner of the image is happening simultaneously on all sources. This is
a requirement for both analog and digital systems in order to perform video
effects or switch glitch-free in a router. Frame synchronization can only be
performed within a single television line standard. A synchronizer will not
convert an NTSC signal to a PAL signal, it takes a standards converter to do that.
Frequency Response
A measurement of the accuracy of a system to carry or reproduce a range of
signal frequencies. Similar to Bandwidth.
BrightEye-18

IEC
The International Electrotechnical Commission provides a wide range of
worldwide standards. They have provided standardization of the AC power con-
nection to products by means of an IEC line cord. The connection point uses three
flat contact blades in a triangular arrangement, set in a rectangular connector.
The IEC specification does not dictate line voltage or frequency. Therefore, the
user must take care to verify that a device either has a universal input (capable
of 90 to 230 volts, either 50 or 60 Hz), or that a line voltage switch, if present, is
set correctly.
Interlace
Human vision can be fooled to see motion by presenting a series of images, each
with a small change relative to the previous image. In order to eliminate the
flicker, our eyes need to see more than 30 images per second. This is accom-
plished in television systems by dividing the lines that make up each video frame
(which run at 25 or 30 frames per second) into two fields. All of the odd-numbered
lines are transmitted in the first field, the even-numbered lines are in the second
field. In this way, the repetition rate is 50 or 60 Hz, without using more
bandwidth. This trick has worked well for years, bit it introduces other temporal
artifacts. Motion pictures use a slightly different technique to raise the repetition
rate from the original 24 frames that make up each second of film—they just
project each one twice.
IRE
Video level is measured on the IRE scale, where 0 IRE is black, and 100 IRE is
full white. The actual voltages that these levels correspond to can vary between
formats.
ITU-R 601
This is the principal standard for standard definition component digital video. It
defines the luminance and color difference coding system that is also referred to
as 4:2:2. The standard applies to both PAL and NTSC derived signals. They both
will result in an image that contains 720 pixels horizontally, with 486 vertical
pixels in NTSC, and 576 vertically in PAL. Both systems use a sample clock rate
of 27 Mhz, and are serialized at 270 Mb/s.
Jitter
Serial digital signals (either video or audio) are subject to the effects of jitter. This
refers to the instantaneous error that can occur from one bit to the next in the
exact position each digital transition. Although the signal may be at the correct
frequency on average, in the interim it varies. Some bits come slightly early, other
come slightly late. The measurement of this jitter is given either as the amount of
time uncertainty or as the fraction of a bit width. For 270 Mb/s video, the
allowable jitter is 740 picoseconds, or 0.2 UI (Unit Interval – one bit width).
Luminance
The “black & white” content of the image. Human vision had more acuity in
luminance, so television systems generally devote more bandwidth to the
luminance content. In component systems, the luminance is referred to as Y.
BrightEye-19

BrightEye 25 A-D Converter with TBC/FS and Embedder
Multi-mode
Multi-mode fibers have a larger diameter core (either 50 or 62.5 microns), and a
correspondingly larger aperture. It is much easier to couple light energy into a
multi-mode fiber, but internal reflections will cause multiple “modes” of the signal
to propagate down the fiber. This will degrade the ability of the fiber to be used
over long distances.
See also Single-mode.
NTSC
The color television encoding system used in North America was originally
defined by the National Television Standards Committee. This American
standard has also been adopted by Canada, Mexico, Japan, Korea, and Taiwan.
(This standard is referred to disparagingly as Never Twice Same Color.)
Optical
An optical interface between two devices carries data by modulating a light
source. This light source is typically a laser or laser diode (similar to an LED)
which is turned on and off at the bitrate of the datastream. The light is carried
from one device to another through a glass fiber. The fiber’s core acts as a
waveguide or lightpipe to carry the light energy from one end to another. Optical
transmission has two very significant advantages over metallic copper cables.
Firstly, it does not require that the two endpoint devices have any electrical con-
nection to each other. This can be very advantageous in large facilities where
problems with ground loops appear. And secondly, and most importantly, an
optical interface can carry a signal for many kilometers or miles without any
degradation or loss in the recovered signal. Copper is barely useful at distances of
just 1000 feet.
Oversampling
A technique to perform digital sampling at a multiple of the required sample rate.
This has the advantage of raising the Nyquist Rate (the maximum frequency
which can be reproduced by a given sample rate) much higher than the desired
passband. this allows more easily realized anti-aliasing filters.
PAL
During the early days of color television in North America, European broadcast-
ers developed a competing system called Phase Alternation by Line. This slightly
more complex system is better able to withstand the differential gain and phase
errors that appear in amplifiers and transmission systems. Engineers at the BBC
claim that it stands for Perfection At Last.
Progressive
An image scanning technique which progresses through all of the lines in a frame
in a single pass. Computer monitors all use progressive displays. This contrasts
to the interlace technique common to television systems.
BrightEye-20