Ensemble Designs Brighteye 10 User manual

This user guide provides detailed information for using the BrightEye™10
Optical and SDI to Analog and SDI Converter unit.
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
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TM
BrightEye 10
Optical/SDI to
Analog/SDI Converter
User Guide
Revision 3.0 SW v1.0.2
ENSEMBLE
DESIGNS

BrightEye 10 Optical/SDI to Analog/SDI Converter
PRODUCT OVERVIEW
The BrightEye™ 10 is a digital to analog video converter with both SDI (electri-
cal) and fiber optic inputs. Output formats include Beta and SMPTE component,
RGB, and composite (with simultaneous S-Video Y/C). Video processing, encoding,
and analog conversion are performed digitally at 12 bits of resolution with 8 times
sampling.
Front panel controls select between the optical and SDI input, choose the analog
output format, and adjust gain. The BrightEyeControl application is provided to
allow remote control of the unit from a personal computer with USB support.
The reclocked SDI output follows the input selector, thus providing optical to elec-
trical conversion when the optical input is selected. BrightEye 10 combines fiber
to SDI conversion and QC monitoring in one compact unit.
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, serial digital video is fed to the
converter on a single BNC connector. Or, an optical input can be connected to the
standard SC connector provided. Selection of the input type is made with the
front panel controls.
The SDI input is routed directly to the SDI Out BNC and the reclocking and dese-
rializing circuitry before entering the D to A converter. The optical input, if
selected, also passes through the reclocker and deserializer before being converted
to analog video.
The converted analog signal is then encoded to the desired output format as
chosen on the front panel or with the BrightEye Control application. During this
stage, gain can be adjusted for the correct output levels.
BrightEye 10 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.
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Reclocker Deserializer
SDI Out
Optical In
SDI In
C, Pr, R Out
Cpst, Y, G Out
Y, Pb, B Out
Front Panel Controls
Input
Gain Adjust
12-bit
D to A
Converter
and
Video
Encoder
BrightEye 10 Functional Block Diagram

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BrightEye 10
APPLICATIONS
The versatility of BrightEye 10 can be utilized in a number of different applica-
tions where conversion of SDI or optical video to analog is required. Some
examples of using BrightEye 10 are given below.
Optical to Electrical Conversion with Analog Monitoring
This application, shown in the illustration below, utilizes the full functionality of
BrightEye 10 by using the converted SDI output from an optical input to feed a
destination such as a video router while monitoring the signal on an RGB
monitor at the same time.
Analog Monitoring of an SDI Signal
This application performs conversion of an SDI signal from a production switcher
to the Composite/S-Video format for feeding an S-VHS tape machine with the Y/C
outputs while monitoring the signal on a composite analog monitor as shown
below.
BrightEye-3
BrightEye 10
Router
SDI
Out
Optical In
R
G
B
R
G
B
Monitor
BrightEye 10
Production
Switcher
Cmpst
Out
SDI In
Y
C
Y
C
Composite
Monitor
S-VHS
Optical to Electrical Conversion with Analog Monitoring Illustration
Analog Monitoring of an SDI Signal Illustration

BrightEye 10 Optical/SDI to Analog/SDI Converter
Driving an RGB Projector
The ability of BrightEye 10 to accept optical inputs makes it an ideal choice for
converting sources located a great distance away. One example of this would be to
drive an RGB projector whose video source is located in a distant location similar
to the example shown below.
Optical or SDI Input to Component VTR
BrightEye 10 can provide a converted video output from an SDI or optical input
to feed any type of component VTR format as shown in the example below.
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BrightEye 10 RGB
Projector
Optical
In
R
G
B
Application for Driving an RGB Projector
BrightEye 10
SDI or
Optical In
Y
Pr
Pb
Y
Pr
Pb
Beta Tape Deck
Optical or SDI Input to Component VTR Application

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BrightEye 10
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REAR CONNECTORS
All connections to the BrightEye 10 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.
Optical In
The optical input connector carries the same ITU-R 601 component digital televi-
sion signal as a directly modulated optical carrier in accordance with SMPTE
297M. The output wavelength is 1310 nm (nanometers), with a nominal output
power of -7 dBm. This is an SC type connector which is capable of driving both
single mode (SM) and multi-mode (MM) fibers.
As multi-mode fiber has a larger diameter than single mode fiber, multi-mode
ingests more light and this can result in overload of the optical receiver. When
using multi-mode fiber it is usually necessary to put a short single mode patch
cable ahead of the multi-mode fiber at the transmit end to reduce the signal to a
normal level.
A suitable arrangement can be a S3YYSFISA one meter, single mode patch cord
and a F1-8310 coupler. These items are inexpensive and available from Fiber
Instrument Sales (www.fiberinstrumentsales.com).
The patch cord has SC connectors and is used at the BrightEye optical transmit-
ter output. The SC-to-SC coupler then connects this single mode patch cord to the
input of the multi-mode fiber link.
BrightEye 10 Rear Connectors

BrightEye 10 Optical/SDI to Analog/SDI Converter
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Input/Output BNCS
There are five rear BNC connectors used as inputs and outputs as follows:
SDI In
This BNC input accepts a SMPTE 259M serial digital component signal, 525 or
625 line standard.
SDI Out
The Serial Digital Component signal from the reclocking circuitry is presented on
this connector. This output conforms to the ITU-R 601 standard for serial digital
video, with SMPTE 259M serialization at 270 Mb/s.
C, Pr, R Out
The function of this connector varies according to the selected output format as
follows:
•C– S-Video C output (use Y /C S-Video adapter) NTSC or PAL
•Pr– SMPTE/Beta analog component color difference R-Y channel output
•R– RGB Red output
Y, Pb, B Out
The function of this connector varies according to the selected output format as
follows:
•Y– S-Video Y output (use Y /C S-Video adapter) NTSC or PAL
•Pb– SMPTE/Beta analog component color difference B-Y channel output
•B– RGB Blue output
Cpst, Y, G Out
The function of this connector varies according to the selected output format as
follows:
• Cpst – NTSC or PAL composite output
•Y– SMPTE/Beta analog component Y (luminance) output
•G– RGB G output

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BrightEye 10
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OPERATION
Control and operation of the BrightEye 10 converter is performed from the front
panel or with the BrightEye Control application.
Some control settings are only available with BrightEye PC or Mac. These parameters
cannot be monitored or controlled with the front panel.
Front Panel Controls and Indicators
The front panel of the converter, shown in the figure below, provides status indi-
cators and control over video input and output selection, and gain.
Status Indicators
The following status indicators are provided on the front panel:
In
Illuminates green when an input for the currently selected video format is
detected on the input connector.
Input
The currently selected input type (SDI or Optical) will illuminate green.
Output
The currently selected output format (Cpst {S-Video}, Beta,SMPTE,or RGB)
will illuminate green.
Gain
Illuminates green when output gain is set to its nominal or unity value.
Illuminates red when gain is set higher or lower than nominal setting.
Pwr (Power)
Illuminates green when power is applied to the converter and the internal
voltage regulator is functioning correctly.
BrightEye 10 Front Panel
NOTE:

BrightEye 10 Optical/SDI to Analog/SDI Converter
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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:
Input
This control selects the video input format with the following choices:
Optical – Fiber optic video
SDI – Serial digital component video
Output
This control selects the video output with the following choices:
Beta – Component Video in Beta format
SMPTE – Component Video in SMPTE format
RGB – Component Video in RGB format
Cpst – NTSC or PAL Analog Composite Video with simultaneous Y/C (use a
standard S-Video Y/C adapter on the two inputs)
The selected output will be indicated by a green indicator.
NOTE:

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BrightEye 10
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 Gain indicator will light green when the
gain is set to its nominal or unity setting.
This is the setting which will produce correct analog output levels from an digital
or optical input source which itself is at proper level. The Gain indicator will light
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 simul-
taneously.
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 10 from a personal
computer. Installation and instructions for using this software application are
given in the PDF manual on disk.
If the BrightEye 10 is connected to a computer running this software, the
following menus are available for controlling and monitoring the unit.
Input Menu
• Input – Select the type of input signal to the unit from the Input pulldown
as Optical or SDI.
The Input Pres status window will report the presence of a video input.
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BrightEye 10 Optical/SDI to Analog/SDI Converter
Output Menu
• Output – select the type of output signal from the unit from the Output
pulldown as Composite,Beta, SMPTE,or RGB.
• Gain – adjusts the gain of the analog video signals in the Digital-to-Analog
converter and encoder circuitry of the converter. The front panel indicator
will light green when the gain is set to its nominal or unity setting.
This is the setting which will produce correct analog output levels from an
digital or optical input source which itself is at proper level. The indicator
will light red whenever the control is adjusted either higher or lower than
the nominal setting. The gain can be reset to nominal by selecting the
Default button.
•Chroma – adjust the amount of chroma on the output signal in percent as
required. This control is only available on BrightEye PC or Mac. There is no
front panel control or indication of this setting.
•Setup – check the box to add setup to the output signal (525 mode). Leave
the box unchecked for no setup. This control is only available on BrightEye
PC or Mac. There is no front panel control or indication of this setting.
Setup will be grayed out when a SMPTE, RGB, or 625 input signal is
present.
•Vert Blanking – select the blanking width with this pulldown from Wide
(PAL Lines 1-22, NTSC Lines 1-20) or Narrow (PAL Lines 1-6, NTSC Lines
1-9). This control is only available on BrightEye PC or Mac. There is no
front panel control or indication of this setting.
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BrightEye 10
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.
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BrightEye 10 Optical/SDI to Analog/SDI Converter
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SPECIFICATIONS
Serial Digital Input:
Number: One
Signal Type: 270 Mb/s SD Serial digital (SMPTE 259M)
Impedance: 75 Ω
Return Loss: > 15 dB
Max Cable Length 300 meters
Optical Input:
Number: One
Type: SD
(SMPTE 297M Optical equivalent of 259M)
Wavelength: 1310 nm
Sensitivity: –18 dBm
Maximum Length: 20 km
Fiber Type: Single Mode
Multi-mode compatible with 8 dB atttenuation at transmit end
Connectro: SC
Analog Output:
Number: One
Type: Beta/SMPTE, Y, Pr, Pb,
RGB
NTSC. PAL Composite
NTSC, PAL S-Video
Return Loss: > 40 dB
Output DC: None (AC coupled)
Serial Digital Output:
Number: One
Type: 270 Mb/s SD Serial Digital
(SMPTE 259M)
Impedance: 75 Ω BNC
Return Loss: > 15 dB
Output DC: < 50 mV
SDI to Analog Performance:
Bit Resolution: 12 bit output reconstruction
8 X oversampling
Signal to Noise: > 65 dB
Frequency Response: ± 0.1 dB , 0 to 5.5 MHz
K Factors: < 1%
ScH Phase Error: < ± 2 degrees
Differential Phase: < 1 degree
Differential Gain: < 1%

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BrightEye 10
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 specifications are subject to change.
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BrightEye 10 Optical/SDI to Analog/SDI Converter
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.
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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 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.
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BrightEye 10 Optical/SDI to Analog/SDI Converter
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.
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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 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 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.
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BrightEye 10 Optical/SDI to Analog/SDI Converter
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.
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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.
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BrightEye 10 Optical/SDI to Analog/SDI Converter
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.
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 ever 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 mono-mode) 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.
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