UBS Axcera 6U4AD Instruction manual

Instruction Manual

6X Series,

Liquid-Cooled

Transmitter

Axcera, LLC

103 Freedom Drive, P.O. Box 525 Lawrence, PA 15055-0525 USA

PHONE: [phone] • FAX [phone]

www.axcera.com • [e-mail]

RESTRICTIONS ON USE, DUPLICATION OR DISCLOSURE

This document contains information proprietary to Axcera, to its affiliates or to a third party to which Axcera
may have a legal obligation to protect such information from unauthorized disclosure, use or duplication. Any
disclosure, use or duplication of this document or any of the information herein for other than the specific
purpose for which it was disclosed by Axcera is expressly prohibited, except as Axcera may otherwise agree in
writing. Recipient by accepting this document agrees to the above stated conditional use of this document and
this information disclosed herein.

OF PROPRIETARY INFORMATION

Copyright © 2009, Axcera

6X Series Liquid-Cooled Transmitter Table of Contents

Table of Contents

Instruction Manual, Rev. 0 i October 14, 2009

6X Series Liquid-Cooled Transmitter Chapter 1, Introduction

CHAPTER 1 ........................................................................................................ 3

1.1 Manual Overview ..........................................................................................3

1.2 Assembly Designators ...................................................................................3

1.3 Safety .........................................................................................................3

1.4 Contact Information ......................................................................................4

1.5 Material Return Procedure..............................................................................5

1.6 Limited One-Year Warranty for Axcera Products................................................5

CHAPTER 2 ........................................................................................................ 1

2.1: Digital Modulator .........................................................................................1

2.2: Exciter, Upconverter, Driver Tray...................................................................3

2.3: Power Amplifiers..........................................................................................4

2.4: Combiners ..................................................................................................4

2.5: Liquid Cooling System ..................................................................................4

2.6: Protection Circuits........................................................................................5

2.7: GUI and Problem Identification System ..........................................................5

2.8: Local Control & Monitoring ............................................................................6

2.9: Remote Control & Monitoring ........................................................................6

CHAPTER 3 ........................................................................................................ 1

3.1: Unpacking and Installation of the Cabinets......................................................2

3.2: Unpacking and Installation of the RF System and Cooling System ......................2

3.2.1: Ethylene Glycol/Distilled Water Cooling System ..........................................4

3.2.1.1: Initial Filling the Water Cooled System ................................................4

3.3: Main AC Connections....................................................................................5

3.4: Main AC Power Up and Verification.................................................................5

3.5: Initial Turn-On Procedures ............................................................................6

3.6: Setup and Operation Procedures....................................................................6

3.6.1: Axciter Set Up Overview ..........................................................................6

3.6.2: Transmitter Set Up Procedures .................................................................7

3.6.2.1: Initial Test Set Up.............................................................................7

3.6.2.2: Setting Up the Output Power of the Transmitter ...................................7

3.6.2.3: Setting up of AGC 1 ..........................................................................7

3.6.2.4: Setting up of AGC 2 ..........................................................................8

3.6.2.5: Setting up of Overdrive Threshold ......................................................8

3.6.2.6: Axciter Pre and Post Filter Sample Values ............................................8

3.6.2.7: Exciter Driver Adjustment..................................................................8

3.7: Problem Identification ..................................................................................9

3.7.1: Pump Rack Cabinet Assembly...................................................................9

3.8: 6X PLC pump rack control software ..............................................................10

3.8.1: Functions.............................................................................................10

CHAPTER 4 ........................................................................................................ 1

4.1 Exciter, Upconverter, Driver Tray Boards .........................................................1

4.1.1 Frequency Agile Upconverter Board (1309695) ............................................1

4.1.2 Downconverter Board (1311103) ...............................................................1

4.1.3 Button Board (1311306) ...........................................................................2

4.1.4 Pre-Driver Amplifier Board, Exciter, 6X (1313190) .......................................2

4.2 Power Controller/AC Distribution Assembly, Boards ...........................................3

4.2.1 Button Board (1311306) ...........................................................................3

4.2.2 Power Supply Line Monitoring Board (1311312)...........................................3

4.2.3 Power Supply Control Board (1312059) ......................................................3

4.3: Power Amplifier Tray, Boards ........................................................................3

4.3.1 (A1) Fan Power Supply Board (1312004) ....................................................3

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6X Series Liquid-Cooled Transmitter Chapter 1, Introduction

4.3.2 Front Panel Smart Button Board (1310349).................................................4

4.3.1 (A2) Phase/Gain Board (1312011) .............................................................4

4.3.2 (A8) Interface Board (1312562) ................................................................6

4.3.3 (A5) 4 Way Splitter Board, Top (1312033) ..................................................6

4.3.4 (A6) 4 Way Splitter Board, Bottom (1310448) .............................................6

4.3.5 (A7 & A9-A16) 878 Amplifier Pallets, Digital Bias (1310321) .........................7

4.3.6 (A17) 4 Way Combiner Board, Top (1310305) .............................................8

4.3.7 (A18) 4 Way Combiner Board, Bottom (1310308) ........................................8

4.3.8 (A19) Power Combiner (1312281)..............................................................9

CHAPTER 5: ....................................................................................................... 1

5.1: Maintenance ...............................................................................................1

5.1.1: Exciter/Amplifier Assembly ......................................................................1

5.1.2: Ethylene Glycol/Distilled Water Cooling System ..........................................1

5.1.2.1: Flushing and cleaning of the strainers .................................................1

5.1.2.2: Checking the glycol concentration level and PH value ............................2

5.1.2.3: Checking and cleaning the Heat Exchanger and back up Pump ...............3

5.2: 6X Transmitter Normal Inspection and Maintenance Schedule ...........................3

APPENDIX A ...................................................................................................... 6

6X DRAWINGS................................................................................................... 6

APPENDIX B ...................................................................................................... 6

TRANSMITTER SPECIFICATIONS ....................................................................... 6

Instruction Manual, Rev. 0 1-2

6X Series Liquid-Cooled Transmitter Chapter 1, Introduction

Chapter 1

Introduction

1.1 Manual Overview

This instruction manual is divided into five chapters and supporting appendices. Chapter
1, Introduction, contains information on safety, material return procedures, and

warranties. Chapter 2, System Description, contains the system and assembly
descriptions. Chapter 3, Installation and Set Up Procedures, describes the installation
procedure, set up procedure and the operation of the transmitter. Chapter 4, Circuit
Descriptions, contains the detailed circuit descriptions of the boards and subassemblies
that are contained in the transmitter. Chapter 5, Maintenance, describes the periodic
maintenance procedures for the transmitter. Appendix A contains the System,
Assemblies, Subassemblies and Boards drawings and parts lists.

1.2 Assembly Designators

Axcera has assigned assembly numbers, Ax designations, where x=1,2,3 etc, example A1,
to all assemblies, modules, and boards in the system. These designations are referenced
in the text of this manual and shown on the block diagrams and interconnect drawings
provided in the appendices. The Block Diagrams, Interconnects, Schematics, Assembly
Drawings and Parts Lists are arranged in increasing numerical order in the appendices.
Section titles in the text for assembly or module descriptions or alignment procedures
contain the associated part number(s) and the relevant appendix that contains the
drawings for that item.

The cables that connect between the boards within a tray or assembly and that connect
between the trays, racks and cabinets are labeled using markers. Figure 1-1 is an
example of a marked cable. There may be as few as two or as many as four Markers on
any one cable. These markers are read starting farthest from the connector. If there
are four Markers, the marker farthest from the connector is the system number such as
system 1 or translator 2. The next or the farthest Marker is the rack or cabinet “A”
number on an interconnect cable or the board “A” number when the cable is within a
tray. The next number on an interconnect cable is the Tray location or Board “A”
number. The marker closest to the connector is the jack or connector “J” number on an
interconnect cable or the jack or connector “J” number on the board when the cable is
within a tray.

4

3 2 1

Figure 1-1: Marker Identification

1.3 Safety

It is important that any user of this equipment read all of the instructions, especially the
safety information in this chapter, before operating the transmitter. Products
manufactured by Axcera are designed to be easy to use and repair while providing
protection from electrical and mechanical hazards. Listed throughout the manual are
notes, cautions, and warnings concerning possible safety hazards that may be
encountered while operating or servicing the product. Please review these warnings and

Instruction Manual, Rev. 0 1-3

6X Series Liquid-Cooled Transmitter Chapter 1, Introduction

familiarize yourself with the operation and servicing procedures before working on the
product.
Hazardous Accessibility – Axcera has made attempts to provide appropriate
connectors, wiring and shields to minimize hazardous accessibility.

Circuit Breakers and Wiring – All circuit breakers and wire are UL and CE certified and
are rated for maximum operating conditions.

Single Point Breaker or Disconnect - The customer should provide a single point
breaker or disconnect at the breaker box for the main AC input connection to the
transmitter.

Transmitter Ratings - The transmitter ratings are provided in the text of this manual
along with voltage and current values for the equipment.

Protective Earthing Terminal – A main protective earthing terminal is provided for
equipment required to have protective earthing.

Read All Instructions – All of the operating and safety instructions should be read and
understood before operating this equipment.

Retain Manuals – The manuals for the equipment should be retained at the site in which
the equipment is operating for future reference. We provide two manuals for this purpose;
one manual can be left at the office while the other manual can be kept at the site.

Heed all Notes, Warnings, and Cautions – All of the notes, warnings, and cautions
listed in this safety section and throughout the manual must be followed.

Follow Instructions – All of the operating and use instructions for the product should be
followed.

Cleaning – Unplug or otherwise disconnect all power from the equipment before cleaning.
Do not use liquid or aerosol cleaners. Use a damp cloth for cleaning.

Ventilation – Openings in the cabinet and module front panels are provided for
ventilation. To ensure the reliable operation of the transmitter, and to protect the unit
from overheating, these openings must not be blocked.

Servicing – Do not attempt to service this product yourself until becoming familiar with
the equipment. If in doubt, refer all servicing questions to qualified Axcera service
personnel.

Replacement Parts – When replacement parts are needed, be sure that the parts have
the same functional and performance characteristics as the original part. Unauthorized
substitutions may result in fire, electric shock, or other hazards. Please contact the
Axcera Technical Service Department if you have any questions regarding service or
replacement parts.

1.4 Contact Information

The Axcera Field Service Department can be contacted by phone at 1-724-873-8100 or
by fax at 1-724-873-8105.

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6X Series Liquid-Cooled Transmitter Chapter 1, Introduction

Before calling Axcera, please be prepared to supply the Axcera technician with answers to
the following questions. This will save time and help insure the most direct resolution to
the problem.

1. What are the Customers’ Name and call letters?

2. What are the model number and type of transmitter?

3. Is the transmitter digital or analog?

4. How long has the transmitter been on the air? (Approximately, when was the
transmitter installed?)

5. What are the symptoms being exhibited by the transmitter? Include the current LCD
and/or touch screen readings. Also the status of LEDs on the front panels of the
trays or modules. If possible, include the LED, LCD and/or touch screen readings
before the problem occurred.

1.5 Material Return Procedure

To insure the efficient handling of equipment or components that have been returned for
repair, Axcera requests that each returned item be accompanied by a Return Material
Authorization Number (RMA#). The RMA# can be obtained from any Axcera Service
Engineer by contacting the Axcera Technical Service Department by Phone at 724-873­8100 or by Fax at 724-873-8105. This procedure applies to all items sent to the
Technical Service Department regardless of whether the item was originally
manufactured by Axcera.

When equipment is sent to the field on loan, the RMA# is included with the unit. The
RMA# is intended to be used when the unit is returned to Axcera. In addition, all shipping
material should be retained for the return of the unit to Axcera. Replacement assemblies
are also sent with the RMA# to allow for the proper routing of the exchanged hardware.
Failure to close out this type of RMA# will normally result in the customer being invoiced
for the value of the loaner item or the exchange assembly.

When shipping an item to Axcera, please include the RMA# on the packing list and on the
Axcera-provided shipping container. The packing slip should also include contact
information and a brief description of why the unit is being returned.

Please forward all RMA items to:

Axcera
Customer Service Department
103 Freedom Drive
P.O. Box 525
Lawrence, PA 15055-0525 USA

For more information, concerning this procedure, call the Axcera Customer Service
Department.

Axcera can also be contacted through e-mail at [e-mail] and on the Web at

www.axcera.com.

1.6 Limited One-Year Warranty for Axcera Products

Axcera warrants each new product that it has manufactured and sold against defects in
material and workmanship under normal use and service for a period of one (1) year
from the date of shipment from Axcera's plant, when operated in accordance with

Instruction Manual, Rev. 0 1-5

6X Series Liquid-Cooled Transmitter Chapter 1, Introduction

Axcera's operating instructions. This warranty shall not apply to tubes, fuses, batteries,
or bulbs.

Warranties are valid only when and if (a) Axcera receives prompt written notice of
breach within the period of warranty, (b) the defective product is properly packed and
returned by the buyer (transportation and insurance prepaid), and (c) Axcera
determines, in its sole judgment, that the product is defective and not subject to any
misuse, neglect, improper installation, negligence, accident, or (unless authorized in
writing by Axcera) repair or alteration. Axcera's exclusive liability for any personal
and/or property damage (including direct, consequential, or incidental) caused by the
breach of any or all warranties, shall be limited to the following: (a) repairing or
replacing (in Axcera's sole discretion) any defective parts free of charge (F.O.B. Axcera’s
plant) and/or (b) crediting (in Axcera's sole discretion) all or a portion of the purchase
price to the buyer.

Equipment furnished by Axcera, but not bearing its trade name, shall bear no warranties
other than the special hours-of-use or other warranties extended by or enforceable
against the manufacturer at the time of delivery to the buyer.

NO WARRANTIES, WHETHER STATUTORY, EXPRESSED, OR IMPLIED, AND NO
WARRANTIES OF MERCHANTABILITY, FITNESS FOR ANY PARTICULAR
PURPOSE, OR FREEDOM FROM INFRINGEMENT, OR THE LIKE, OTHER THAN AS
SPECIFIED IN PATENT LIABILITY ARTICLES, AND IN THIS ARTICLE, SHALL
APPLY TO THE EQUIPMENT FURNISHED HEREUNDER.

Instruction Manual, Rev. 0 1-6

6X Series Liquid-Cooled Transmitter Chapter 1, Introduction



 WARNING!!!



 HIGH VOLTAGE 

DO NOT ATTEMPT TO REPAIR OR TROUBLESHOOT THIS EQUIPMENT UNLESS
YOU ARE FAMILIAR WITH ITS OPERATION AND EXPERIENCED IN
SERVICING HIGH VOLTAGE EQUIPMENT. LETHAL VOLTAGES ARE PRESENT
WHEN POWER IS APPLIED TO THIS SYSTEM. IF POSSIBLE, TURN OFF
POWER BEFORE MAKING ADJUSTMENTS TO THE SYSTEM.

 RADIO FREQUENCY RADIATION HAZARD 

MICROWAVE, RF AMPLIFIERS AND TUBES GENERATE HAZARDOUS RF
RADIATION THAT CAN CAUSE SEVERE INJURY INCLUDING CATARACTS,
WHICH CAN RESULT IN BLINDNESS. SOME CARDIAC PACEMAKERS MAY BE
AFFECTED BY THE RF ENERGY EMITTED BY RF AND MICROWAVE
AMPLIFIERS. NEVER OPERATE THE TRANSMITTER SYSTEM WITHOUT A
PROPERLY MATCHED RF ENERGY ABSORBING LOAD ATTACHED. KEEP
PERSONNEL AWAY FROM OPEN WAVEGUIDES AND ANTENNAS. NEVER
LOOK INTO AN OPEN WAVEGUIDE OR ANTENNA. MONITOR ALL PARTS OF
THE RF SYSTEM FOR RADIATION LEAKAGE AT REGULAR INTERVALS.

Instruction Manual, Rev. 0 1-7

6X Series Liquid-Cooled Transmitter Chapter 1, Introduction

EMERGENCY FIRST AID INSTRUCTIONS

Personnel engaged in the installation, operation, or maintenance of this equipment are urged to become
familiar with the following rules both in theory and practice. It is the duty of all operating personnel to be
prepared to give adequate Emergency First Aid and thereby prevent avoidable loss of life.

RESCUE BREATHING

1. Find out if the person is

breathing.

You must find out if the person
has stopped breathing. If you
think he is not breathing, place
him flat on his back. Put your ear
close to his mouth and look at his
chest. If he is breathing you can
feel the air on your cheek. You
can see his chest move up and
down. If you do not feel the air
or see the chest move, he is not
breathing.

2. If he is not breathing, open
the airway by tilting his head
backwards.

Lift up his neck with one hand
and push down on his forehead
with the other. This opens the
airway. Sometimes doing this will
let the person breathe again by
himself.

BURNS

SKIN REDDENED: Apply ice cold water to burned

area to prevent burn from going deeper into skin
tissue. Cover area with a clean sheet or cloth to
keep away air. Consult a physician.

SKIN BLISTERED OR FLESH CHARRED: Apply
ice cold water to burned area to prevent burn from
going deeper into skin tissue.

3. If he is still not breathing,
begin rescue breathing.

-Keep his head tilted backward.
Pinch nose shut.

-Put your mouth tightly over his
mouth.

-Blow into his mouth once every
five seconds

-DO NOT STOP rescue breathing
until help arrives.

LOOSEN CLOTHING - KEEP
WARM

Do this when the victim is
breathing by himself or help is
available. Keep him as quiet as
possible and from becoming
chilled. Otherwise treat him for
shock.

Cover area with clean sheet or cloth to keep away
air. Treat victim for shock and take to hospital.

EXTENSIVE BURN - SKIN BROKEN: Cover area
with clean sheet or cloth to keep away air. Treat
victim for shock and take to hospital.

Instruction Manual, Rev. 0 1-8

6X Series Liquid-Cooled Transmitter Chapter 1, Introduction

dBm, dBw, dBmV, dBµµµµV, & VOLTAGE

EXPRESSED IN WATTS

50 Ohm System

WATTS PREFIX dBm dBw dBmV dBµV VOLTAGE
1,000,000,000,000 1 TERAWATT +150 +120
100,000,000,000 100 GIGAWATTS +140 +110
10,000,000,000 10 GIGAWATTS +130 +100
1,000,000,000 1 GIGAWATT +120 + 99
100,000,000 100 MEGAWATTS +110 + 80
10,000,000 10 MEGAWATTS +100 + 70
1,000,000 1 MEGAWATT + 90 + 60
100,000 100 KILOWATTS + 80 + 50
10,000 10 KILOWATTS + 70 + 40
1,000 1 KILOWATT + 60 + 30
100 1 HECTROWATT + 50 + 20
50 + 47 + 17
20 + 43 + 13
10 1 DECAWATT + 40 + 10
1 1 WATT + 30 0 + 77 +137 7.07V

0.1 1 DECIWATT + 20 - 10 + 67 +127 2.24V

0.01 1 CENTIWATT + 10 - 20 + 57 +117 0.707V

0.001 1 MILLIWATT 0 - 30 + 47 +107 224mV

0.0001 100 MICROWATTS - 10 - 40

0.00001 10 MICROWATTS - 20 - 50

0.000001 1 MICROWATT - 30 - 60

0.0000001 100 NANOWATTS - 40 - 70

0.00000001 10 NANOWATTS - 50 - 80

0.000000001 1 NANOWATT - 60 - 90

0.0000000001 100 PICOWATTS - 70 -100

0.00000000001 10 PICOWATTS - 80 -110

0.000000000001 1 PICOWATT - 90 -120

TEMPERATURE CONVERSION

°°°°F = 32 + [(9/5) °°°°C]

°°°°C = [(5/9) (°°°°F - 32)]

Instruction Manual, Rev. 0 1-9

6X Series Liquid-Cooled Transmitter Chapter 1, Introduction

USEFUL CONVERSION FACTORS

To Convert From To Multiply By

mile (US statute) kilometer (km) 1.609347
inch (in) millimeter (mm) 25.4
inch (in) centimeter (cm) 2.54
inch (in) meter (m) 0.0254
foot (ft) meter (m) 0.3048
yard (yd) meter (m) 0.9144
mile per hour (mph) kilometer per hour(km/hr) 1.60934
mile per hour (mph) meter per second (m/s) 0.44704
pound (lb) kilogram (kg) 0.4535924
gallon (gal) liter 3.7854118
U.S. liquid
(One U.S. gallon equals 0.8327 Canadian gallon)
fluid ounce (fl oz) milliliters (ml) 29.57353
British Thermal Unit watt (W) 0.2930711
per hour (Btu/hr)
horsepower (hp) watt (W) 746

NOMENCLATURE OF FREQUENCY BANDS

Frequency Range Designation

30 to 300 kHz LF - Low Frequency
300 to 3000 kHz MF - Medium Frequency
3 to 30 MHz HF - High Frequency
30 to 300 MHz VHF - Very High Frequency
300 to 3000 MHz UHF - Ultra High Frequency
3 to 30 GHz SHF - Super High Frequency
30 to 300 GHz EHF - Extremely High Frequency

3 to 30 kHz VLF - Very Low Frequency

LETTER DESIGNATIONS FOR UPPER FREQUENCY BANDS

Letter Freq. Band

L 1000 - 2000 MHz
S 2000 - 4000 MHz
C 4000 - 8000 MHz
X 8000 - 12000 MHz
Ku 12 - 18 GHz
K 18 - 27 GHz
Ka 27 - 40 GHz
V 40 - 75 GHz
W 75 - 110 GHz

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6X Series Liquid-Cooled Transmitter Chapter 1, Introduction

ABBREVIATIONS/ACRONYMS

AC Alternating Current

AFC Automatic Frequency
Control

AGC Automatic Gain Control

ALC Automatic Level Control

AM Amplitude modulation

ASI Asynchronous Digital Interface

ATSC Advanced Television

Systems Committee (Digital)

AWG American wire gauge

BER Bit Error Rate

BW Bandwidth

CE Product has met EU consumer

safety, health or environmental
requirements.

COFDM Coded Orthogonal Frequency

Division Multiplexing modulation
scheme

DC Direct Current

D/A Digital to analog

DSP Digital Signal Processing

DTV Digital Television

DVB Digital Video Broadcasting

dB Decibel

dBm Decibel referenced to

1 milliwatt

dBmV Decibel referenced to
1 millivolt

dBw Decibel referenced to 1 watt

FCC Federal Communications

Commission

FEC Forward Error Correction

FM Frequency modulation

FPGA Field Programmable Gate

Array

HXB High Power Transmitter, B-line

Hz Hertz

ICPM Incidental Carrier Phase
Modulation

I/P Input

IF Intermediate Frequency

LED Light emitting diode

LSB Lower Sideband

LDMOS Lateral Diffused Metal Oxide

Semiconductor Field Effect
Transistor

MPEG Motion Pictures Expert
Group

NTSC National Television
Systems Committee (Analog)

O/P Output

PLL Phase Locked Loop

PCB Printed circuit board

QAM Quadrature Amplitude

Modulation

SMPTE Society of Motion Picture
and Television Engineers

SNMP Simple Network Management

Protocol

VSB Vestigial Side Band

Instruction Manual, Rev. 0 1-11

6X Series Liquid-Cooled Transmitter Chapter 2, System Description

Chapter 2

System Description

The 6X Series Liquid-Cooled Transmitter is made up of a frequency agile exciter and
a multi tray power amplifier system. The 6X Series is a state-of-the-art liquid cooled
transmitter which uses our frequency agile exciter and the latest LDMOS devices for
broadband operation across the entire UHF band. The power amplifier system
operates at the highest power density available, reducing floor space requirements.
The 6X Series transmitter is available in power levels up to 40kW ATSC in a very
small footprint.

The very compact and completely modular design uses parallel amplifier and power
supply modules which can be removed and replaced while the transmitter is on the
air. This allows users to minimize spare parts stock and also enables simple and
inexpensive channel changes. Additionally, the modular construction provides a
clear upgrade path, allowing broadcasters to begin with a low power transmitter and
add modules and combiners to achieve any power level desired.

2.1: Digital Modulator

The Axciter adaptive digital television modulator utilizes a patented VSB modulation
technique, which makes it possible to generate a virtually perfect 8VSB IF signal.
Since the Axciter is a completely reprogrammable digital television exciter, it can be
easily upgraded in the field with new software versions through the convenient front
panel USB port. Critical parameters can be set and queried directly on the color LCD
screen or through an interface to a personal computer.

The DSP circuitry also handles frequency offsets allowing an unlimited number of
user selectable offsets. In addition, asynchronous resampling techniques

Instruction Manual, Rev. 0 2-1

6X Series Liquid-Cooled Transmitter Chapter 2, System Description

compensate for errors in the SMPTE-310M input sample rate, ensuring the best
possible signal generation.

Non-volatile operation is achieved through flash-RAM (random access memory),
which instantaneously stores all digital settings for the entire exciter-modulator
system. This ensures that in case of power loss, the system will return to the
previously selected settings when power is restored, saving time by eliminating the
need to re-enter operating parameters.

Standard with all Axciters, Axcera Adaptive Correction Technology (AXACT™)
provides dynamic digital pre-correction that automatically tracks and corrects for
distortions, both linear and non-linear, in the complete transmitter system. All
adaptive operations are performed in the high-speed processor, which is capable of
equalizing a complete transmitter system in just sixty seconds, and completing a full
system optimization in about two minutes.

To obtain the necessary data, AXACT continuously samples the transmitter system
output, both before and after the mask filter, this is done through a down converter
located in the upconverter/driver tray. The modulator processes the data and the
necessary digital pre-correction is applied to the modulator output signal, resulting in
consistent transmitter system performance, independent of environmental changes.

The Axciter also performs over fifteen safety tests upon each adaptive correction run
to confirm that the new correction values are appropriate before applying them to
the on-air signal. This ensures that the signal will not be negatively affected by a
failure of an RF component in the sample path, such as an RF coupler, connector,
relay or cable.

DTVision Digital Signal Analysis and Test System is available as an option to the
Axciter. This system samples the transmitter output and measures critical
transmitter performance parameters. The information is then displayed in high­resolution graphical format on the modulator's front panel display. Available
performance parameters include, digital SNR, error vector magnitude (EVM), eye
diagram, graphs of adaptive equalizer performance and RF spectrum, constellation
diagram, and more.

The Axciter employs dual processors to ensure on-air reliability. The low-level
control computer is a simple, highly reliable processor that is dedicated to running
the modulator hardware, thereby generating the ATSC signal. This processor uses a
highly reliable real-time operating system based on uC/OS for the mission critical
8VSB signal generation.

A second computer is dedicated to providing the adaptive processing, user interface,
diagnostics and graphics, using the very stable and reliable Linux operating system.
This high performance computer handles the processor intensive functions of
performing all adaptive correction and processing the data for the optional DTVision
signal analysis measurement and display, all without negatively affecting the critical
on-air signal path. In the unlikely event of a failure of this computer, the Axciter
remains on the air with a fully corrected ATSC signal. The Linux computer may even
be rebooted with no interruption of the on-air signal, and the Axciter is capable of a
cold start without the Linux computer.

Instruction Manual, Rev. 0 2-2