Ensemble Designs BrightEye 24 User manual

This user guide provides detailed information for using the BrightEye™24 SDI
to Analog Converter and Disembedder unit.
The information is organized into the following sections:
• Product Overview
• Functional Description
• Applications
• Rear Connectors
• Operation
• Front Panel Controls Indicators
• BrightEye PC
• Warranty and Factory Service
• Specifications
• Glossary
BrightEye-1
SDI to Analog Converter
and Disembedder
User Guide
Revision 3.0 SW v1.0.8
ENSEMBLE
DESIGNS
TM
BrightEye 24

PRODUCT OVERVIEW
BrightEye™ 24 is both a digital to analog video converter as well as an audio dis-
embedder. The incoming serial digital video signal is converted to an analog
composite signal, while digital audio signals embedded in the digital video signal
are extracted and converted to analog outputs.
Front panel controls select analog reference level, AES group for disembedding,
and provide gain adjustment. Input presence and output VU information are
indicated as well. The BrightEye PC Control application is provided to allow more
detailed control of the unit from a PC with USB support.
A glossary of commonly used video terms is provided at the end of this manual.
FUNCTIONAL DESCRIPTION
BrightEye 24 combines a video digital to analog converter with an audio dis-
embedder (demux) and audio digital to analog converter.
The input to the module is a standard definition 601 digital signal (SDI) at either
525 (NTSC) or 625 (PAL) line rate.
The SDI input is digitally encoded to composite video and then converted to
analog form for output on the Cpst Out BNC connector. The encoder will switch
automatically between NTSC and PAL to follow the line standard detected on the
SDI input. When operating in the NTSC standard, setup can be enabled/disabled
using the BrightEye PC interface.
In parallel to the video processing, one group (four channels) of embedded audio is
demultiplexed from the input SDI signal. The disembedder can be targeted at any
of the four possible embedded groups, both from the front panel as well as
through BrightEye PC. Audio levels for the four channels can be adjusted and the
assignment of input channels to output channels (channel swap and shuffle) con-
trolled from BrightEye PC. The audio processing chain also provides audio level
and peak indication. The reference level of the digital processing chain can be set
to either -18 or -20 dBFS.
After the digital audio processing, the four channels are converted to analog form
and output as low impedance, balanced signals. The analog reference level of the
outputs can be set to either -10dBu (pro-sumer) or +4dBu (professional).
Both the analog video and audio outputs will mute to no signal when the input
signal is lost or removed.
BrightEye-2
BrightEye 24 SDI to Analog Converter and Disembedder
Composite Output
Audio
Disembedder
SDI Input
Composite
Encoder
Mixer
Shuffler
Ch 1/2
Ch 3/4
DAC
D
A
C
Ch 1
Ch 3
Ch 2
Ch 4
Balanced
Audio
Outputs
BrightEye 24 Functional Block Diagram

APPLICATIONS
The BrightEye 24 is well suited to a range of signal conversion applications. It is
particularly useful in desktop, mobile and monitoring applications where the
unit’s small size makes it convenient.
Broadcast Application
BrightEye 24 is useful in broadcast facilities for taking embedded SDI signals
from a router or server and providing analog video and audio outputs for
monitors and VTRs. The diagram below illustrates one such application.
Desktop and Mobile Applications
BrightEye 24 can be used in post and desktop applications as well as in fly packs.
With BrightEye 24, and embedded SDI signal from a camera or workstation can
be converted to analog video and audio to feed a VTR.
BrightEye-3
TM
BrightEye 24
BrightEye 24
DAC &
Disembedder
SDI/Embed
Audio Amp
Router
Analog
Monitor
BrightEye 24
DAC &
Disembedder
SDI/Embed
Camera Analog VTR
Analog Audio
and Video
BrightEye 24 Broadcast Application
BrightEye 24 Desktop and Mobile Application

REAR CONNECTORS
All connections to the BrightEye 24 converter are made on the rear of the unit.
Refer to the illustration below.
Power Connection
A modular power supply is supplied with the product. Connect it to the 12 volt
DC power input connection on the far left. Use the locking ring to secure it.
USB Connector
The USB connector is used to provide more comprehensive control, diagnostics,
and upgrades from a PC. Use the BrightEye PC application included on CD-ROM
with every unit to make adjustments as described in the OPERATION section of
this user guide.
Composite Out
The Composite Out is a BNC connector that presents either NTSC or PAL
composite output. NTSC or PAL output is determined automatically based upon
the standard presented on the SDI Input.
Analog Audio Out
The Analog Audio Out is a HD15 connector that outputs 4 channels of analog
audio. Analog reference level and the AES to be disembedded can be set from the
front panel. Channel mixing, and other settings can be made from the BrightEye
PC application. An audio connector kit is provided with the unit. See the diagram
below for pinout information.
SDI In
The SDI In is a BNC connector that requires a serial digital component input,
which can also contain embedded digital audio signals. This input must conform
to the ITU-R 601 standard for serial digital video, with SMPTE 259M serializa-
tion at 270 Mb/s.
More technical details about these connections can be found in the SPECIFICATIONS
section of this manual.
BrightEye-4
BrightEye 24 SDI to Analog Converter and Disembedder
BrightEye 24 Rear Connectors
1
6
+
+
+
+
-
-
-
-
11
AUD 2 AUD 1
AUD 3
AUD 4
Analog Audio Pinouts
Signal Pins Output
Aud 1 +, –, G 1, 2, 7 Output 1
Aud 2 +, –, G 5, 4, 3 Output 2
Aud 3 +, –, G 11, 12, 6 Output 3
Aud 4 +, –, G 15, 14, 13 Output 4
NOTE:

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OPERATION
Control and operation of the BrightEye 24 is performed from the front panel or
with the BrightEye PC Control application.
Some control settings are only available with BrightEye PC. These parameters cannot
be monitored or controlled with the front panel.
Front Panel Controls and Indicators
The front panel, as shown in the figure below, provides status indicators and
control over video and audio output.
Status Indicators
The following status indicators are provided on the front panel:
In
This indicator illuminates green when a valid SDI signal is detected.
Analog Reference Level
The currently selected analog reference level (-10 dBu or +4 dBu) illuminates
green.
Group
The AES group (1, 2, 3, or 4) currently selected for disembedding and digital to
analog conversion illuminates green when the selected group contains audio, and
illuminates red when the selected group does not contain audio.
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 illu-
minates red when the audio level exceeds the headroom level set by the user
(with the Peak Indicator control in BrightEye PC.) 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. 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.)
Pwr (Power)
Illuminates green when power is applied to the converter and the internal voltage
regulator is functioning correctly.
TM
BrightEye 24
BrightEye 24 Front Panel
NOTE:

BrightEye-6
Controls
Adjustable parameters are controlled from the front panel using the three push-
buttons on the right hand side of the control panel.
The control system has the following modes:
Idle – all indicators apart from the VU meters are steady-state (no
blinking)
Analog Ref Level Select – currently selected analog reference output level
blinks
Group select – currently selected AES group blinks
Ch 1/2 or 3/4 Gain – blinks quickly when gain adjustments are made,
slowly when selected for adjustment but still at default
The normal state of the control panel is Idle. The panel state is changed by
pressing the Mode button. Each press will advance to the next state. If no button
presses are detected for 15 seconds, the state will automatically switch to Idle.
When one of the adjustable controls is blinking, its value can be changed by
pressing the Right or Left arrow button.
Adjustments made to the controls are stored in non-volatile memory, so the
converter will “wake up” in the correct state when power is interrupted and then
restored.
The control values are not saved until the 15 second time out has occurred. If power is
removed before the time out period, the new state will not be saved.
The controls and their indicators are described below:
Analog Reference Level
This control selects the output level of the analog output with these choices:
-10 dB – Analog reference level of -10 decibels
+4 dB – Analog reference level of +4 decibels
Group Select
This control selects the AES group for disembedding with the following choices:
1– AES Group 1
2 – AES Group 2
3 – AES Group 3
4 – AES Group 4
Ch 1/2 and Ch 3/4 VU Indicators
These indicators provide information about the level of the analog outputs on
these channels. More detailed indicators are available through the BrightEye PC
application.
Ch 1/2 and Ch 3/4 Gain Adjustment Indicators
These controls allow for quick adjustment of Gain level for these two channel
pairs. For independent channel adjustment, and other controls, use
BrightEye PC.
BrightEye 24 SDI to Analog Converter and Disembedder
NOTE:

BrightEye-7
BrightEye PC Control
The BrightEye PC application is included on CD-ROM with every BrightEye unit.
Installation and instructions for using BrightEye PC are given in the data pack
that accompanies the application.
If the unit is connected to a computer running the BrightEye PC application, the
following menus are available for controlling and monitoring the
BrightEye 24 unit.
Config Menu
• Input Pres – indicates the presence of an SDI input. Shows: None, 525
Lock, or 625 Lock.
• Setup – enable or disable setup on output by selecting On or Off. Only
available on 525 NTSC output.
• DeMux Status – indicates the status of the AES group selected for disem-
bedding. Shows group number and if there is valid audio in that group.
• Group Sel – selects the AES group for disembedding. This pulldown lets
you chose between: Group 1, Group 2, Group 3, or Group 4.
• Peak Indicator – selects the amount of headroom to use in determining
peak levels. This pulldown lets you chose between: Clipping,2 dB
Headroom,4 dB Headroom,6 dB Headroom, 8 dB Headroom, or 10
dB Headroom.
• Dig Ref Level – selects the expected reference level for the embedded
audio. This pulldown lets you choose between: -20 dBFS or -18 dBFS.
• Anlg Out Level – selects analog output reference level. This pulldown lets
you chose between: -10 dBu or +4 dBu.
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BrightEye 24

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Mixer Menu
• Outputs 1-4 – provides 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.
• Inputs Ch 1-4 – these controls provide mixing and output level control for
AES channels 1 to 4 of the selected AES group. The text field at the top of
the control indicates the amount of gain applied to the channel in dB. The
gain level can be adjusted by moving the vertical slider control, or entering
a desired level directly in the field (from -70 dB to +12 dB.) On the right-
hand side of the control are Output Bus Assignment buttons. These
buttons control which analog output channel the AES channels are mapped
to. It is possible to map an Input channel to anywhere from zero to four
output channels.
The Tie function is used for stereo operation where gain of a pair of
channels is usually desired to be the same.
The Default button resets the gain to unity (0 dB).
The Invert button allows inversion of a channel to permit phase correction.
BrightEye 24 SDI to Analog Converter and Disembedder

WARRANTY AND FACTORY SERVICE
Warranty
Ensemble Designs, Inc. warrants this product to be free from defect in material
and workmanship for a period of two 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-9
TM
BrightEye 24

BrightEye 24 SDI to Analog Converter and Disembedder
SPECIFICATIONS
Video Input:
Type: 270 Mb/s Serial Digital
(SMPTE 259M)
Impedance: 75 Ω
Return Loss: > 15 dB to 270 MHz
Cable Length: 300 meters
Video Output:
Number: One
Type: NTSC or PAL composite
Standard follows input
Impedance: 75 Ω
Return Loss: > 40 dB to 5.5 MHz
Output DC: ± 50 mV
SDI to Analog Performance:
Bit Resolution: 10 bit output reconstruction
2 X oversampling
Signal to noise: > 65 dB
Frequency Response: -0.1 dB, 0 to 5.5 MHz
K Factors: < 1.0%
Differential Phase: < 1.0 degree
Differential Gain: < 1%
Analog Audio Outputs:
Number: Four
Type: Balanced, transformerless
Impedance: 30 Ω
Max Output Level: 24 dBu
Resolution: 24 bits, 128x oversampled
Reference Level: -10 or +4 dBu, selectable
Frequency Response: ± 0.1 dB, 20 Hz to 20 kHz
Crosstalk: < 106 dB
Dynamic Range: > 106 dB
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: 12-24 volts, 7 watts
(100-230 VAC modular
power supply provided)
Temperature Range: 0 to 40 degrees C ambient
Relative Humidity: 0 to 95% noncondensing
Due to ongoing product development, all specifications are subject to change.
BrightEye-10

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 quantization
(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.
Chroma
The color or chroma content of a signal, consisting of the hue and saturation of
the image. See also Color Difference.
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BrightEye 24

BrightEye 24 SDI to Analog Converter and Disembedder
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 ever 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.
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.
BrightEye-12

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 transmission.
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 gen-locked 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.
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.
BrightEye-13
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BrightEye 24

BrightEye 24 SDI to Analog Converter and Disembedder
Interlace
Human vision can be fooled to see motion by present 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 accomplished 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.
Multi-mode
Multi-mode fibers have a larger diameter core than single mode fibers (either 50
or 62.5 microns compared to 9 microns), and a correspondingly larger aperture. It
is much easier to couple light energy into a multi-mode fiber, but internal reflec-
tions 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.
BrightEye-14

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 that
can be reproduced by a given sample rate) much higher than the desired
passband. This allows more easily realized anti-alias 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 imaging scanning technique that progresses through all of the lines of a frame
in a single pass. Computer monitors all use progressive displays. This contrasts to
the Interlace technique common to television systems.
Return Loss
An idealized input or output circuit will exactly match its desired impedance
(generally 75 ohms) as a purely resistive element, with no reactive (capacitive or
inductive) elements. In the real world, we can only approach the ideal. So, our
real inputs and outputs will have some capacitance and inductance. This will
create impedance matching errors, especially at higher frequencies. The Return
Loss of an input or output measures how much energy is returned (reflected back
due to the impedance mismatch.) For digital circuits, a return loss of 15 dB is
typical. This means that the energy returned is 15 dB less than the original
signal. In analog circuits, a 40 dB figure is expected.
BrightEye-15
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BrightEye 24

RGB
RGB systems carry the totality of the picture information as independent Red,
Green, and Blue signals. Television is an additive color system, where all three
components add to produce white. Because the luminance (or detail) information
is carried partially in each of the RGB channels, all three must be carried at full
bandwidth in order to faithfully reproduce an image.
ScH Phase
Used in composite systems, ScH Phase measures the relative phase between the
leading edge of sync on line 1 of field 1 and a continuous subcarrier sinewave.
Due to the arithmetic details of both PAL and NTSC, this relationship is not the
same at the beginning of each frame. In PAL, the pattern repeats every 4 frames
(8 fields) which is also known as the Bruch Blanking sequence. In NTSC, the
repeat is every 2 frames (4 fields.) This creates enormous headaches in editing
systems and the system timing of analog composite facilities.
SDI
Serial Digital Interface. This term refers to inputs and outputs of devices that
support serial digital component video. This generally means standard definition
at 270 Mb/s. The use of “HD-SDI” is beginning to appear to indicate High
Definition Serial Digital Video at 1.485 Gb/s.
SMPTE
The Society of Motion Picture and Television Engineers is a professional organi-
zation which has done tremendous work in setting standards for both the film
and television industries. The term “SMPTE’” is also shorthand for one particular
component video format - luminance and color difference.
Single mode
A Single mode (or monomode) optical fiber carries an optical signal on a very
small diameter (9 micron) core surrounded with cladding. The small diameter
means that no internally reflected lightwaves will be propagated. Thus only the
original “mode” of the signal passes down the fiber. A single mode fiber used in an
optical SDI system can carry a signal for up to 20 kilometers. Single mode fibers
require particular care in their installation due to the extremely small optical
aperture that they present at splice and connection points.
See also Multi-mode.
TBC
A Time Base Corrector is a system to reduce the Time Base Error in a signal to
acceptable levels. It accomplishes this by using a FIFO (First In, First Out)
memory. The incoming video is written into the memory using its own jittery
timing. This operation is closely associated with the actual digitization of the
analog signal because the varying position of the sync timing must be mimicked
by the sampling function of the analog to digital converter. A second timing
system, gen-locked to a stable reference, is used to read the video back out of the
memory. The memory acts as a dynamically adjusting delay to smooth out the
imperfections in the original signal’s timing. Very often a TBC will also function
as a Frame Synchronizer.
See also: Frame Sync.
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Time Base Error
Time base error is present when there is excessive jitter or uncertainty in the line
to line output timing of a video signal. This is commonly associated with playback
from video tape recorders, and is particularly severe with consumer type hetero-
dyne systems like VHS. Time base error will render a signal unusable for
broadcast or editing purposes.
Tri-Level Sync
An analog sync reference signal that is used in High Definition systems. Tri Level
Sync is constructed with three signal levels, the sync pulses extend above and
below a mid-level average voltage (the blanking level). Unlike conventional
analog sync which is bi-level, the proper 50% pickoff point is already identified in
Tri Level Sync. This contributes to lower jitter in digital systems.
YUV
Strictly speaking, YUV does not apply to component video. The letters refer to the
Luminance (Y), and the U and V encoding axes using in the PAL composite
system. Since the U axis is very close to the B-Y axis, and the V axis is very close
to the R-Y axis, YUV is often used as a sort of shorthand for the more long-
winded “Y/R-Y/B-Y”.
Y/Cr/Cb
In digital component video, the luminance component is Y, and the two color dif-
ference signals are Cr (R-Y) and Cb (B-Y).
Y/Pr/Pb
In analog component video, the image is carried in three components. The
luminance is Y, the R-Y color difference signal is Pr, and the B-Y color difference
signal is Pb.
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