This user guide provides detailed information for using the BrightEye™ 30
Audio ADC and DAC, Bi-directional 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
BrightEye-1
Audio ADC and DAC,
Bi-directional Converter
User Guide
Revision 5.0 SW v1.0.2
ENSEMBLE
DESIGNS
TM
BrightEye 30
BrightEye 30 Audio ADC and DAC, Bi-directional
PRODUCT OVERVIEW
BrightEye 30 is a flexible audio converter that can function as a two channel
bi-directional ADC and DAC, or as a four channel ADC or DAC. With 24 bit processing, convenient front panel controls, a powerful PC-based configuration tool,
and a compact form-factor, the BrightEye 30 is perfect for desktop, post, and
broadcast applications.
BrightEye 30 can also be used as a sample rate converter.
Input presence, conversion mode, analog reference level, VU status, and gain
adjustments are all located on the front panel. More advanced adjustments are
available via the BrightEye Control application.
A glossary of commonly used video terms is provided at the end of this manual.
FUNCTIONAL DESCRIPTION
BrightEye 30 has four channels of digital audio I/O (two AES streams) and four
channels of balanced analog audio I/O. It also has a reference input that accepts
analog video reference, AES, and Word Clock.
BrightEye 30 has four different operating modes. In order to simplify the use of
the BrightEye 30’s resources, inputs and outputs are automatically configured for
the various modes.
1. Analog to Digital Converter Mode
In this mode BrightEye 30 is a four channel analog audio to digital (AES)
converter. All four analog audio I/O's are configured for input, and the two AES
connectors are both outputs. In this mode, there are four analog audio inputs and
two AES output streams.
The four analog inputs are digitized with a sample rate of 48 kHz at 24 bits of
resolution. The conversion process uses 256x oversampling which results in phenomenally low distortion, flat frequency response and large dynamic range. The
analog input stage can be configured to operate at either -10dBu (consumer) or
+4dBu (professional) analog reference levels.
BrightEye-2
BrightEye 30 Analog to Digital Converter Mode
AES, Word Clock,
or Video Ref In
Analog Input
4 Channels
Audio Clock
Generation
4 Channel
A to D
Formatter
AES
AES
Formatter
AES 1/2
Output
AES 3/4
Output
BrightEye 3
0
The converted signals pass through a four channel mixer/shuffler providing individual adjustment of gain and channel inversion (to address out of phase inputs).
The four output channels are each formed by summing any combination of
inputs. Each output can contain any of the input channels, allowing, for example,
stereo to mono mixdown, left/right channel swaps, and simultaneous stereo and
mono outputs.
Finally, these four processed signals are output in digital form through the two
AES connectors.
In order to access all of the features of the mixer/shuffler, configuration of
BrightEye 30 must be done using BrightEye PC or Mac and the unit's USB connection. The BrightEye Control application further provides selection between -18
dBFS and -20 dBFS for the digital reference level.
Front panel controls allow simple adjustment of gain in pairs of channels
(1&2, 3&4) and VU and peak signal indication.
The reference input is active in this mode. It will accept analog composite video
(NTSC or PAL), 48kHz AES, or 48 kHz wordclock. The reference circuitry will
automatically detect any of these four signals and lock BrightEye 30's internal
clocks to the reference signal. When locked to a reference, the AES outputs of
BrightEye 30 will be synchronous to that reference.
Successful genlock is indicated by a steady Green 'Ref' LED on the front of the
unit. The LED will light Red if some sort of genlock signal is present but
BrightEye 30 is not able to lock to it. BrightEye 30 operates internally at 48kHz
sample rate, and reference signals must be compatible with that rate.
The LED will be extinguished if no reference signal is detected. In this case, the
clocks are derived from an internal standard which exceeds AES specifications for
clock accuracy and jitter performance.
2. Digital to Analog Converter Mode
In this mode BrightEye 30 is a four channel digital (AES) to analog audio
converter. Both AES connectors are inputs and all four analog channels are
outputs. When configured as a DAC, BrightEye 30 will accept AES inputs with
sample rates from 44.1 to 96 kHz. These AES sources pass through a sample rate
converter to produce a standard sample rate of 48kHz.
BrightEye-3
BrightEye 30 Digital to Analog Converter Mode
TM
Internal Precision
Clock Source
AES 1/2
Input
Sample Rate
Converter
Sample Rate
Converter
AES 3/4
Input
AES
Rcvr
AES
Rcvr
4 Channel
Mix
Shuffle
Gain
4 Channel
D to A
Analog Output
4 Channels
BrightEye 30 Audio ADC and DAC, Bi-directional
The four incoming digital audio signals feed the four channel mixer/shuffler. As
with analog to digital mode, this provides individual adjustment of gain and
channel inversion (to address out of phase inputs). The four output channels are
each formed by summing any combination of inputs. Each output can contain any
of the input channels, allowing, for example, stereo to mono mixdown, left/right
channel swaps, and simultaneous stereo and mono outputs.
Digital to analog conversion is performed with 24 bits of precision at 48kHz with
256x oversampling.
The processed signals are output as balanced analog signals at either -10 dBm or
+4 dBm reference level.
In order to access all of the features of the mixer/shuffler, configuration of
BrightEye 30 must be done using BrightEye PC or Mac and the unit's USB connection. The BrightEye Control application further provides selection between
18 dBFS and -20 dBFS for the digital reference level.
Front panel controls allow simple adjustment of gain in pairs of channels
(1&2, 3&4) and VU and peak signal indication.
The reference input is not used in this mode. All clocks are derived from the
incoming digital signals. The Ref LED will be extinguished.
3. Bi-Directional Conversion
In Bi-Directional mode, BrightEye 30 is simultaneously a two channel digital to
analog converter and a two channel analog to digital converter. The channel 1/2
AES connector is an input (accepting sample rates from 44.1 to 96 kHz), while
the channel 3/4 AES connector is an output. Analog channels 1/2 are outputs, and
analog channels 3/4 are inputs.
The AES input presented to channel 1/2 is sample rate converted to 48kHz, synchronous to the reference if one if provided. The AES output on channel 3/4 will
also be at a 48kHz sample rate and will also be synchronous to the reference
input.
BrightEye-4
BrightEye 30 Bi-Directional Conversion Mode
AES, Word Clock,
or Video Ref In
AES 1/2
Input
AES
Rcvr
Audio Clock
Generation
Sample Rate
Converter
2 Channel
Mix
Shuffle
Gain
2 Channel
D to A
Analog Audio Output
Ch 1/2
2 Channel
A to D
Analog Audio Input
Ch 3/4
2 Channel
Mix
Shuffle
Gain
AES
Formatter
AES 3/4
Output
BrightEye 3
0
BrightEye-5
The four channel mixer/shuffler is sub-divided into two, two channel
mixer/shufflers. The digital to analog path is supported by channels 1 and 2. The
reverse path (analog to digital) uses channels 3 and 4. Channel assignments are
limited to only allow assignment of inputs 1 and 2 to outputs 1 and 2; and inputs
3 and 4 to outputs 3 and 4.
The channel 1/2 outputs of the mixer are presented on analog outputs 1/2; and
mixer's channel 3/4 outputs drive the 3/4 AES output connector.
Conversion to and from the analog domain is performed at 48kHz, oversampled
by 256x to 24 bits of precision.
The reference input is active in this mode. It will accept analog composite video
(NTSC or PAL), 48kHz AES, or 48 kHz wordclock. The reference circuitry will
automatically detect any of these four signals and lock BrightEye 30's internal
clocks to the reference signal. When locked to a reference, the channel 3/4 AES
output of BrightEye 30 will be synchronous to that reference.
Successful genlock is indicated by a steady Green 'Ref' LED on the front of the
unit. The LED will light Red if some sort of genlock signal is present but
BrightEye 30 is not able to lock to it. BrightEye 30 operates internally at 48kHz
sample rate, and reference signals must be compatible with that rate.
The LED will be extinguished if no reference signal is detected. In this case, the
clocks are derived from an internal standard which exceeds AES specifications for
clock accuracy and jitter performance.
4. Sample Rate Conversion (and two channel Digital to Analog Conversion)
When configured as a digital sample rate converter, BrightEye 30 is a two
channel device, processing the channel 1/2 AES input connector and outputting to
the channel 3/4 AES output connector. The same signals are also output in analog
form on channels 3/4.
BrightEye 30 Sample Rate Conversion Mode
TM
AES or Video Ref In
AES 1/2
AES
Rcvr
Audio Clock
Generation
Sample Rate
Converter
2 Channel
Mix
Shuffle
Gain
AES
Formatter
AES 3/4
Output
2 Channel
D to A
Analog Audio Output
Ch 3/4
BrightEye 30 Audio ADC and DAC, Bi-directional
BrightEye-6
The channel 1/2 AES input will accept signals with sample rates from 44.1 to 96
kHz. The signal is digitally sample rate converted to 48kHz. The new sample rate
can be locked to an external reference (see below) in order to generate a digital
output which is synchronous to the reference.
After sample rate conversion, the two audio channels feed the Channel 1/2 inputs
of the mixer/shuffler. By default, channel 1 is routed to output 3 and channel 2 is
routed to channel 4. Inputs 1/2 can be routed to any combination of outputs 3/4.
Finally, the channel 3/4 outputs of the mixer/shuffler feed the AES 3/4 output and
analog audio channels 3/4.
Digital to analog conversion is performed with 24 bits of precision at 48kHz with
256x oversampling.
The reference input is active in this mode. It will accept analog composite video
(NTSC or PAL), 48kHz AES, or 48 kHz wordclock. The reference circuitry will
automatically detect any of these four signals and lock BrightEye 30's internal
clocks to the reference signal. When locked to a reference, the Channel 3/4 AES
output of BrightEye 30 will be synchronous to that reference.
Successful genlock is indicated by a steady green 'Ref' LED on the front of the
unit. The LED will light red if some sort of genlock signal is present but
BrightEye 30 is not able to lock to it. BrightEye 30 operates internally at 48kHz
sample rate, and reference signals must be compatible with that rate.
The LED will be extinguished if no reference signal is detected. In this case, the
clocks are derived from an internal standard which exceeds AES specifications for
clock accuracy and jitter performance.
0
BrightEye-7
APPLICATIONS
The BrightEye 30 can be used for four channel analog to digital or digital to
analog conversion, as well as two channel bi-directional conversion. Additionally,
the BrightEye 30 can provide two channel sample rate conversion with two
channel digital to analog conversion. These preset modes can be further adjusted
to fit particular applications (with channel mixing and other features.) Some of
the many possible applications are explained and illustrated below.
Analog to Digital Conversion
In this application, the BrightEye 30 is configured to convert four channels of
analog audio into two streams of AES audio. Note the use of the BrightEye 54 for
AES and composite reference. In most video applications, it is essential that AES
sample clocks be locked to a video reference.
Digital to Analog Conversion
In this application, the BrightEye 30 is configured to convert four channels of
analog audio into two streams of AES digital audio. Note the use of the BrightEye
54 for AES (or composite reference.) In most video applications, it is essential
that AES sample clocks be locked to a video reference.
BrightEye 3
TM
Analog VTR
BrightEye 54
Sync Generator
Composite Ref
AES Reference
AES In Ch 1/2
Four Channel Audio
Analog Audio Outputs
Ch 1
Ch 2
BrightEye 30
ADC Mode
AES Out Ch 1/2
AES Out Ch 3/4
Audio Tape
Recorder
AES In Ch 3/4
BrightEye 54
Ref
SPG/TSG
BrightEye 30
DAC Mode
Ch 3
Ch 4
Audio Tape
Recorder
BrightEye 30 Audio ADC and DAC, Bi-directional
BrightEye-8
Bi-Directional Conversion Mode
Use BrightEye 30 in Bi-Directional mode to simultaneously convert analog
signals to digital for input to a digital media capture card in a desktop video
system AND convert the digital audio output back to analog for monitoring.
Sample Rate Conversion Mode
Use BrightEye 30 to convert AES content at 44.1 kHz sampling rate to 48kHz
synchronous to a video or digital audio reference. CD or DAT audio playback can
then be used in a professional video environment.
Analog Input
CH 1
CH 2
BrightEye 30
BiDir Mode
Digital Output
CH 2
CH 2
Analog Monitor feed
of Digital Output
CH 3
CH 4
Desktop Video
System
CD or DAT
Player
AES Digital Audio
@ 44.1 to 96 kHz
House or Local Ref
AES Digital Audio
@ 48 kHz, synchronous to video
BrightEye 30
SRC Mode
Analog Monitor Output
0
REAR CONNECTORS
All connections to the BrightEye 30 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 application included on CD-ROM to make adjustments as described in the OPERATION
section of this user guide.
AES 1/2 and AES 3/4 (ADC and DAC modes)
AES 1/2 and AES 3/4 are BNC connectors that can function as either digital
audio inputs (ADC mode) or outputs (DAC mode.) Each connector can input or
output an AES stream (each containing two channels.)
AES In and AES Out (BiDir and SRC modes)
AES In and AES Out are BNC connectors that provide AES input and AES
output, respectively.
Analog Audio I/O
The Analog Audio Out is a HD15 connector that provides analog audio inputs
and outputs. In ADC mode it functions as an input, in DAC mode it functions as
an output, in BiDir mode it provides both inputs and outputs, and in SRC mode it
provides two channels of analog output as shown in the table and diagram below..
AES Ref In
The AES Ref In is a BNC connector that accepts an AES refence signal, audio
word-clock signal, or composite reference signal.
BrightEye-9
BrightEye 30 Rear Connectors
Analog Audio Pinouts
Signal Pins Input Output Bi Dir SRC
Aud 1 +, –, G 1, 2, 7 Input 1 Output 1
Analog output
from AES 1/2 In
Output 1
Aud 2 +, –, G 5, 4, 3 Input 2 Output 2
Output 2
Aud 3 +, –, G 11, 12, 6 Input 3 Output 3
Analog input to
AES 3/4 Out
Output 3
Aud 4 +, –, G 15, 14, 8 Input 4 Output 4
Output 4
BrightEye 3
TM
AUD 2 AUD 1
---
+
+
AUD 4
-
AUD 3
+
1
6
11
+
BrightEye 30 Audio ADC and DAC, Bi-directional
OPERATION
Control and operation of the BrightEye 30 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 indicators and control over video input and output selection, and gain.
Status Indicators
The following status indicators are provided on the front panel:
Ref (Reference)
Illuminate green when a valid reference is present on the AES Ref In connector.
Illuminates red when an invalid reference is present, and does not illuminate
when there is no signal present. A valid reference is AES, Word Clock, or
Composite Video.
Mode
The currently selected conversion Mode (A –> D, D –> A, BiDir, or SRC) is illu-
minated green.
Analog Ref Level
The currently selected analog reference level for input and output (-10 dB or +4
dB) 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.) 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.)
BrightEye-10
BrightEye 30 Front Panel
NOTE:
0
Pwr (Power)
Illuminates green when power is applied to the converter and the internal voltage
regulator is functioning correctly.
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:
Mode
This control selects the conversion mode with the following choices:
A –> D – Convert analog to digital audio
D –> A – Convert digital to analog audio
BiDir – Convert two channels of analog to digital and simultaneously
convert two channels of digital to analog
SRC – Convert the sample rate of the AES In and output the reclocked
audio on AES Out, with simultaneous analog monitoring
Analog Ref Level
This control selects analog reference levels for input and output, with the
following choices:
-10 dB – Accept -10 dB inputs, and provide -10 dB outputs
+4 dB – Accept +4 dB inputs, and provide +4 dB outputs
BrightEye-11
NOTE:
BrightEye 3
TM
BrightEye 30 Audio ADC and DAC, Bi-directional
BrightEye-12
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
Control 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 the BrightEye
Control application.
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 30 from a personal
computer. Installation and instructions for using this software application are
given in the PDF manual on disk.
If the BrightEye 30 is connected to a computer running this software, the
following menus are available for controlling and monitoring the unit.
Config
• Mode – select device conversion mode. This pulldown lets you choose
between: Analog to Digital, Digital to Analog, Bi-Directional, and
Sample Rate Convert.
• AES 1/2 and AES 3/4 Status – these controls indicate the status/behavior
of the AES I/O connections. They show: No Input, Audio Present, Data
Present, Input Mode, or Output Mode.
• Analog Ref Level– selects analog output reference level for input and
output. This pulldown lets you chose between: -10 dBu or +4 dBu.
• Dig Ref Level – selects the digital reference level. This pulldown lets you
choose between: -20 dBFS or -18 dBFS.
• Peak Indicator – selects the amount of headroom to use in determining
peak levels. This pulldown lets you chose between: Clipping, 2 dB
BrightEye 3
0
BrightEye-13
Headroom, 4 dB Headroom, 6 dB Headroom, 8 dB Headroom, or 10
dB Headroom.
• Ref Pres – indicates the status of the reference input. This indicator shows:
None, 525 Unlocked, 625 Unlocked, AES Unlocked, WClk Unlocked,
525 Lock, 625 Lock, AES Lock, or WClk Lock.
Mixer
• 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 righthand side of the control are Output Bus Assign 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.
TM
BrightEye 30 Audio ADC and DAC, Bi-directional
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 consultation with a factory technician.
This warranty is not transferable. Any implied warranties expire at the expiration date of this warranty.
This warranty does not cover a defect that has resulted from improper or unreasonable 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 authorization.
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
(530) 478-1830
Fax: (530) 478-1832
service@ensembledesigns.com
http://www.ensembledesigns.com
Be sure to put your RMA number on the outside of the box.
BrightEye-14
BrightEye 3
0
SPECIFICATIONS
AES/EBU Digital Inputs:
Number: Two (total of four channels, selectable as inputs or outputs)
Type: AES3id
Connectorization: Coaxial, 75 Ω
Bit Depth: 20 and 24 bit
Sample Rate: 30 kHz to 100 kHz (Sample Rate Converted internally to 48kHz)
Reference Level: -18 or -10 dBFS (selectable)
AC-3, Dolby-E: Supported when inputs are synchronous
AES/EBU Digital Outputs:
Number: Two (total of four channels)
(selectable as inputs or outputs)
Type: AES3id
Connectorization: Coaxial, 75 Ω
Bit Depth: 20 and 24 bit
Sample Rate: 48KHz (Synchronous to video output)
Reference Level: -18 or -10 dBFS (selectable)
Analog Audio Inputs:
Number: Four (selectable as inputs or outputs)
Type: Balanced
Impedance: >15k Ω
Max. Input Level: 24 dBu
CMRR: >60 dB, 20 Hz to 10 kHz
Quantization: 24 bits, 128x Oversampling
Sample Rate: 48 kHz
Reference Level: -10 dBu or +4 dBu
Frequency Response: ±0.1 dB, 20 Hz to 20 kHz
Crosstalk: <102 dB
Dynamic Range: >106 dB
Analog Audio Outputs:
Number: Four (selectable as inputs or outputs)
Type: Balanced, transformerless
Impedance: 30 Ω
Max. Output Level: 24 dBu
Resolution: 24 bits, 128x Oversampled
Reference Level: -10 dBu or +4 dBu
Frequency Response: ±0.1 dB, 20 Hz to 20 kHz
Crosstalk: <102 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
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-15
TM
BrightEye 30 Audio ADC and DAC, Bi-directional
BrightEye-16
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.
0
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 transmitted 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.
BrightEye-17
BrightEye 3
TM
BrightEye 30 Audio ADC and DAC, Bi-directional
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 reproduced because they would be clipped. The nominal operating point (roughly corresponding 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.Frame
BrightEye-18
BrightEye 3
0
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 independently 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 connection 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-19
TM
BrightEye 30 Audio ADC and DAC, Bi-directional
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 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.
BrightEye-20
BrightEye 3
0
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 connection 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 broadcasters 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-21
TM
BrightEye 30 Audio ADC and DAC, Bi-directional
BrightEye-22
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 organization 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.
BrightEye 3
0
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 longwinded “Y/R-Y/B-Y”.
Y/Cr/Cb
In digital component video, the luminance component is Y, and the two color difference 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.
BrightEye-23
TM
Loading...