Linear AT7400 Owner's Manual

ADVANCED TV

LINE

Model AT7400

400W ATSC UHF Transmitter

OWNERS MANUAL

Linear Industries Incorporation

www.linear-tv.com

Made in USA

AT7400 Owner Manual Rev. 2.0 – October 2006-10-23 1/1

1

AT7400

400W ATSC DTV TRANSMITTER

ADVANCED TV LINE

Owner Manual

Table of Contents

Section 1: Technical Specifications

Typical Final Test Report

Section 2: Master Control Unit

Section 3: Exciter Drawer

Section 4: Intermediate Directional Coupler

Section 5: 220W UHF Power Amplifier

Section 6: Output Directional Coupler, and Filtering

Section 7: Energy Distribution and Control

Annex A: Schematics Diagrams

AT7400 Owner Manual Rev. 2.0 – October 2006-10-23 1/1

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User Notices and WARNINGS

USER NOTICES

IT IS VERY IMPORTANT TO READ THE FOLLOWING MANUAL SECTIONS PRIOR TO OPERATION OF THIS TRANSMITTER!

Notice 1 The transmitter main operating voltage setting is marked on the rear of the AT7250 chassis.

Notice 2

The transmitter operating frequency is set from the factory.

Notice 3 For adjusting the RF output power setting a qualified technician should always employ the use of an

RF Wattmeter and a calibrated dummy load.

Notice 4 Should accident or injury occur to the personnel engaged in the installation, operation, or service of

the equipment should seek proper medical attention. It is advisable that such personnel have familiarity with first-aid practices.

Notice 5 To call our technical support center or for other customer service issues at Linear Inc, refer to the

following number: 630 346 6698.

Notice 6 If you experience some specific difficulty and the technical information available in this manual is not enough to help you, do not hesitate to call LINEAR technical support center.

Notice 7 The technical information presented on this manual is sole intellectual propriety of LINEAR INDUSTRIES Inc. Reproduction of this document in full or partial is prohibiting with out written authorization. This document is legally protected by the copy rights laws.

AT7400 Owner Manual Rev. 2.0 – October 2006-10-23 1/3

WARNING!

THE VOLTAGES AND CURRENTS IN THIS EQUIPMENT ARE DANGEROUS. PERSONEL MUST, AT ALL TIMES, OBSERVE SAFETY WARNINGS, INSTRUCTIONS, AND ANY REGULATIONS.

THIS OWNER’S MANUAL IS INTENDED AS A GENERAL GUIDE FOR TRAINED AND QUALIFIED PERSONNEL WHO ARE AWARE OF THE DANGERS THAT ARE INHERENT IN THE

HANDLING AND OPERATION OF POTENTIALLY HAZARDOUS ELECTRICAL AND ELECTRONIC CIRCUITS. IT IS NOT THE INTENT OF THIS MANUAL TO PROVIDE A COMPLETE SET OF SAFETY INSTRUCTIONS OR PRECAUTIONS THAT SHOULD ALREADY BE UNDERSTOOD BY TRAINED OR EXPERIENCED PERSONNEL IN USING THIS OR OTHER

TYPES OF ELECTRONIC EQUIPMENT.

THE INSTALLATION, OPERATION, AND MAINTENANCE OF THIS EQUIPMENT INVOLVE RISKS TO PERSONNEL AND ALSO TO THE EQUIPMENT. LINEAR, INC. SHALL NOT BE RESPONSIBLE FOR INJURY OR DAMAGE THAT IS THE RESULT OF IMPROPER

PROCEDURES OR USE BY PERSONS IMPROPERLY TRAINED OR LACKING THE KNOWLEDGE TO PERFORM ASSOCIATED TASKS.

ALL LOCAL CODES FOR BUILDING, SAFETY, FIRE, OR RELATED STANDARDS MUST BE OBSERVED. CONSULT LOCAL AUTHORITIES FOR THE STANDARDS FOR THE AREA OR

REGION WHERE THE EQUIPMENT WILL BE INSTALLED AND PUT IN USE.

WARNING!

AT ALL TIMES DISCONECT AC/MAINS POWER BEFORE OPENING COVERS, DOORS, ENCLOSURES, PANELS, OR PROTECTIVE SHIELDS THAT EXPOSE LIVE CIRCUITS. NEVER

PERFORM MAINTENANCE, MAKE ADJUSTMENTS, OR SERVICE THE EQUIPMENT WHEN ALONE OR FATIGUED.

WARNING!

IF ELECTROLYTIC OR OIL FILLED CAPACITORS ARE UTILIZED IN THE EQUIPMENT A ND THE COMPONENT APPEARS LEAKY, OR IS BULGING, OR IF THE CASE OR COVERING OF THE COMPONENT APPEARS DAMAGED OR DISTRESSED ALLOW SUFFICIENT TIME FOR THE UNIT TO COOL OR FULLY DISCHARGE BEFORE SERVICING. SERVICING HOT O R

LEAKY CAPACITORS CAN CAUSE A RUPTURE OF THE CASE AND POSSIBLE INJURY.

AT7400 Owner Manual Rev. 2.0 – October 2006-10-23 2/3

Returns and Exchanges

Equipment (Damaged or undamaged) should not be returned unless written approval and a Merchandise Return Authorization (MRA Number) is received from your Linear Sales representative

or Linear Customer Service. Special shipping instruction will be provided which will assure proper handling. The circumstances and reasons for the return must be included in the request for return. Equipment that is special or “custom” ordered may be not returnable. In situations where return or exchange is at the request of the customer a restocking fee may be charged. All returns must be

sent freight prepaid and properly insured by customer. When communicating with Linear please refer to your Order or Invoice Number.

Unpacking

Use care when unpacking the equipment. First perform a visual inspection of the item(s) to determine if any damage occurred during shipment. Be sure to retain all the shipping materials (crates and boxes or cartons) until such time that it has been determined that the received equipment arrived undamaged. Find all PACKING LISTS and keep them to assist in locating and identifying any components or assemblies that may have been removed for shipping and might

need to be reinstalled in the equipment. Make sure that all shipping straps, supports and packing materials are completely removed from the equipment prior to initialization and use.

AT7400 Owner Manual Rev. 2.0 – October 2006-10-23 3/3

Section 1 – AT7400 Technical Specifications

1. Introduction

The AT7400 is a 400W UHF ATSC/8VSB transmitter assembled and tested in United States by LINEAR INDUSTRIES INC. (www.linear-tv.com

).

Fig1.1: AT7400 Front View, cabinet wheels are optional.

AT7400 Owner Manual Rev. 2.0 – October 2006-10-23 Section 1 - 1/7

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2. AT7400 RF line Up

3. AT7400 Cabinet Air Flux: 0.25m3/sec. - 21ft3/sec.

Air Outlet

Cold Air Inlet

Fig. 1.4: Air flux path at AT4700 cabinet, (lateral view). Darker area denotes the internal heat source, or the RF drawers,

AT7400 Owner Manual Rev. 2.0 – October 2006-10-23 Section 1 - 2/7

(1) Exciter and (2) PA’s.

2

4. AT7400 – 400W UHF ATSC/8VSB Transmitter - Technical Specifications

Electrical

Main 220/240 VAC, bi phase, 50-60 Hz. 3w. Consumption 3200W. PFC Included

Signal Input

Transport Stream Input ATSC/MPEG2, compliant to SMPTE310M Input Data Rate 19.39 Mbps External Reference Signal 10MHz. (0 to +10 dBm). Input Connector 75ȍ (BNC), Reference Input Connector 50ȍ (BNC),

RF

RF Output Power 400w (rms) Modulation Mode 8VSB. All-Digital Complex IF modulation IF 18.833916 MHz. Channel Bandwidth 6MHz. Test Signal PRBS. Pseudo Random Bit Sequence Frequency Range UHF. Ch14 to Ch69, (4 bands). Frequency Step 1 Hz. ± 220kHz Symbol Rate 10.76 MSymbol/sec. Digital/Analog Converter 16 bit All –Digital Linear. Pre-Correction Included Pilot frequency stability overall ± 0.3 ppm. Peak to peak frequency response  0.15 dB. Peak to peak group delay response  15 ns. Phase noise  -104 dBc/Hz @ 20kHz offset. Conducted spurious and harmonics < -60 dBc, FCC 47 Part 74. Radiated spourious and harmonics < -80 dBc, FCC 47 Part 74.

 39dB (modulator output) typical.

MER (Modulation Error Rate)

RF output connector EIA 7/8” Flanged. Output sample connector N

Remote Control

RS-232 Dial-up network interface via hyper-terminal Ethernet SNMP. IP network interface via Web Browser.

Mechanical

Air Refrigeration

Dimensions 58”(H), 28”(W), 43”(D) Weight Gross: 286.7 Kg NET: 236.70 Kg Foot print 28”(W), 7’(D)

 39 dB (exciter output) typical.  29 dB (transmitter output) typical.

Internal drawer’s air speed: 400 ft/minute. Overall Air flow: 21ft

3

/sec.

AT7400 Owner Manual Rev. 2.0 – October 2006-10-23 Section 1 - 3/7

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5. AT4700 Available Models and Options

Models

A Mono-phase; 220Vac. B 3- phase; 220Vac – 380Vac; 3 wires. C 3- phase; 220Vac – 380Vac; 4 wires.

Options:

01 Integrated GPS receiver 02 Adaptive digital pre-correction 03 Dual Exciter 04 Analog Transmission Mode 05 Cabinet 4 wheels

6. AT7400 Typical Test Report

6.1.Out of Channel Emissions

AT7400 Owner Manual Rev. 2.0 – October 2006-10-23 Section 1 - 4/7

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6.2.Frequency Response a nd Group Delay

6.3.Carrier Phase Noise

AT7400 Owner Manual Rev. 2.0 – October 2006-10-23 Section 1 - 5/7

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6.4.Digital Modulation Error Rate

AT7400 Owner Manual Rev. 2.0 – October 2006-10-23 Section 1 - 6/7

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6.5.Conducted Spurious Emissions

AT7400 Owner Manual Rev. 2.0 – October 2006-10-23 Section 1 - 7/7

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Section 2 – Master Control Unit

Module 4459

1. General Description

The main control unit, MCU, is the logical master unit acting all over the transmitter operational functions. The MCU is constantly connected and exchanging information via RS485 with the UHF power amplifiers units and the

UHF exciter unit. External keyboard allows local changing on parameters and monitoring, displayed on a LCD screen. Via a RS232, it is also possible to implement telemetry using either the Windows Hype Terminal, or via

Ethernet Web Server.

Fig.2.1: – Front View MCU module 4459

2. Following, the main functions of MCU

2.1. Monitor and display the alarm status on each of the transmitter units.

2.2. Monitor the direct and reverse RF power, out from the intermediate directional coupler, module 4488,

avoiding a potential over driver to the power amplifiers.

2.3. Monitor the direct and reverse RF power, out from the output directional coupler, module 4429, and

inhibiting excessive RF power level on either direction.

2.4. Send to the exciter driver local control unit, via RS485 protocol, the set of programmed software instructions

related with the broadcasting channel, and the associated power level.

2.5. MCU is composed by the following printed circuit boards:

2.5.1. 01 control unit; CIM3297.

2.5.2. 01 SNMP interface; CIM3453.

2.5.3. 01 Keyboard; CIM3112.

2.5.4. 01 LCD Display; CIM3108.

AT7400 Owner Manual Rev. 2.0 – October 2006-10-23 Section 2 - 1/9

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2.6.Module 4459 Block Diagram

Fig.2.2: – Module 4459 block diagram and PCBs displacement.

AT7400 Owner Manual Rev. 2.0 – October 2006-10-23 Section 2 - 2/9

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2.7.Unit Control Board CIM3297 at Module 4459

This is the principal board on the MCU module. See Fig.2.5 for the PCB CIM3297 connections. The logic functions performed by the PCB CIM3297 are as follows:

( BK) DTR S NMP ? PIN7–CON-1–CIM3453–SNMPINTERFACE

( OR) DCD SN MP? PIN4–CON-1–CIM3453–SNMPINTERFACE

( GR) RTSS NMP ? PIN5–CON-1–CIM3453–SNMPINTERFACE

( Y L) CTS SNM P ? PIN6–CON-1–CIM3453–SNMPINTERFACE

( RD) RXD SNMP ? PI N8– CON-1– CIM3453– SNMP INTERFACE

(VL) TXD SNMP ? PI N 9 – CON- 1 – CIM 3453 – S NMP I NTERF ACE

(W H) GND SNMP ?PIN2–CON-1 –CIM3453–SNMP INTERFACE

( BK) DTR S NMP ? PIN7–CON-1–CIM3453–SNMPINTERFACE

( OR) DCD SN MP? PIN4–CON-1–CIM3453–SNMPINTERFACE

( GR) RTSS NMP ? PIN5–CON-1–CIM3453–SNMPINTERFACE

( Y L) CTS SNM P ? PIN6–CON-1–CIM3453–SNMPINTERFACE

( RD) RXD SNMP ? PI N8– CON-1– CIM3453– SNMP INTERFACE

(VL) TXD SNMP ? PI N 9 – CON- 1 – CIM 3453 – S NMP I NTERF ACE

(W H) GND SNMP ?PIN2–CON-1 –CIM3453–SNMP INTERFACE

(YL) BL ACK L IGHT DISPL AY ? POINTA – LCD DISPLAY – CIM3 108

(GR) +8V ?PIN7–P1

(WH)GND TODISPLAY? POINT B – LCD DI SPLAY– CIM31 08

(BL) +15V?PIN8–P1

(YL) BL ACK L IGHT DISPL AY ? POINTA – LCD DISPLAY – CIM3 108

(GR) +8V ?PIN7–P1

(WH)GND TODISPLAY? POINT B – LCD DI SPLAY– CIM31 08

(BL) +15V?PIN8–P1

BL

1

GND

VCC

CO N - 1

CI-3

DA1

DA2

+15V

IRQ

SCL

SDA

PM4

PM3

PJ1

PJ0

CI-3.CI-3

.

7

LM358

1

CON-2

AJUSTE

LUM . DISPLAY

AJUSTE

LUM . DISPLAY

TPO-1

14

1

J1

VM

CO N - 1 1

BDM I N

6

CON- 3

1

CON- 3

1

PA 2 1

PA3 1

PA41

PA51

PA61

PA 2 1

PA3 1

PA41

PA51

PA61

6

PA711PA02

CI-1

LM7805

BCX 53

Q1

CI-2

.

M C 34 06 4

CON-4

8

CON-4

8

PA12

PA2 2

PA32

PA42

PA52

PA62

PA72

PA12

PA2 2

PA32

PA42

PA52

PA62

PA72

123

1

PB01

DTR

CTSRXTX

GND

RTS

DC D

DTR

CTSRXTX

GND

RTS

DC D

CON-10

1

7

.

DS229

DS229.DS229

CI -6

-

--

MC9S12A128B

CI-7

.

DS229

CON-6

PB22

DS229.DS229

..

RS485

....

RS485

RS232

J4

J5

J4

J5

8

1

8

1

3

A

B

A

B

GND

PB 7 2

PB62

PB 5 2

PB42

PB3 2

PB 7 2

PB62

PB 5 2

PB42

PB3 2

16MHz

16MHz16MHz

XTAL1

CON-5

8

CON-5

8

1

PB11

PB21

PB31

PB 4 1

PB51

PB61

PB71

PB12

PB11

PB21

PB02

PB31

PB 4 1

PB51

PB61

PB71

PB12

PB02

( GY) OUTPUT REF LECT E D POWER READING ?PIN5–P1

( RD) OUTPUT F ORWARD POWER READING ?PIN6–P1

( VL) 12V BATTER Y RE ADING ?PIN6–P2

( BR) +8V DC/DC CO NV ERTER READING ?PIN4–P2

( BL) + 15V DC /DC CO NVERTER READING ?PIN3–P2

( Y L) E XCITER FORWARD POWER READING ? PIN1–P1

(OR) EXCITER REFLECTEDPOWER READING ?PIN2–P1

( GY) OUTPUT REF LECT E D POWER READING ?PIN5–P1

( RD) OUTPUT F ORWARD POWER READING ?PIN6–P1

( VL) 12V BATTER Y RE ADING ?PIN6–P2

A01

A02

A03

A04

A05

A06

CO N - 9

A07

A08

GND

1991

A09

A10

A11

A12

A13

A14

A15

A16

GND

6CON-7 CON- 8

PC5

PC6

RX

TX

GND

1

CON-12

(WH) GND ?PIN9–P2

( BR) +8V DC/DC CO NV ERTER READING ?PIN4–P2

( BL) + 15V DC /DC CO NVERTER READING ?PIN3–P2

( Y L) E XCITER FORWARD POWER READING ? PIN1–P1

(OR) EXCITER REFLECTEDPOWER READING ?PIN2–P1

(WH) GND ?PIN9–P2

FLAT CABLE 14 VIAS ? CON1– LCD DISPLAY–CIM3108

Fig. 2.3: - Module 4459 connection diagram for PCB CIM3297.

AT7400 Owner Manual Rev. 2.0 – October 2006-10-23 Section 2 - 3/9

(BL) RS485 A ?PIN8–P3

(GY) RS485B ?PIN7–P3

(BL) RS485 A ?PIN8–P3

(GY) RS485B ?PIN7–P3

(BR) PHASE DETECTOR ?PIN4–P1

( GR) FAN F USE 1 DETECT OR ?PIN8–P1

( OR) FAN F USE 2 DETECT OR ? PIN7–P1

( GR) FAN F USE 1 DETECT OR ?PIN8–P1

(O R) ? PIN 6 – C ON1 – CIM3112 –KEYBOARD

(GY) ? PIN 5 –C ON 1 – CIM3112 – KEYBOARD

(O R) ? PIN 6 – C ON1 – CIM3112 –KEYBOARD

(GY) ? PIN 5 –C ON 1 – CIM3112 – KEYBOARD

( BL) CT R SNMP ? PIN3–CON-1–CI M3453 – SNM P INTERFACE

(YL) CO AXIAL RELAY COMM ANDER (OPTIO NAL DOUBLE EXCITER) ?PIN1–P2

( OR) FAN F USE 2 DETECT OR ? PIN7–P1

(B R ) ? PIN4–CON1–KEYBOARD–CIM3112

( RD) ? PI N 3 – CON1 – KEYBOARD– CIM 3112

(BL) ? PI N2 – CON1 –KEYBOIARD– CIM 3112

( BK) ? PI N 1 – CON1 – KEYBOARD– CIM 3112

( RD) ? PI N 3 – CON1 – KEYBOARD– CIM 3112

(BL) ? PI N2 – CON1 –KEYBOIARD– CIM 3112

( BK) ? PI N 1 – CON1 – KEYBOARD– CIM 3112

3

Fig.2.4: – Module 4459, CIM 3297 the transmitter main microcontroller.

2.7.1. Digital Control

o The integrated circuit CI-4 (A128) is a 16 bit microcontroller, programmed on assembler language. This integrated circuit controls this module, 4459, and also the entire transmitter. This IC carries a controlled software

version, and is programmed on factory.

o In case of subst itution of the CI-4 or even the entire PCB CIM3297, it is mandatory to inform the factory

prior replacement, the programming identification number that is clearly indicated at the CI-4 body.

AT7400 Owner Manual Rev. 2.0 – October 2006-10-23 Section 2 - 4/9

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2.7.2. Analog Readings

Information on analog format is available at the connectors P1 and P2 on the module 4459’s panel, which are routed to CON-9 at the PCB CIM3297. On P1- P2 connectors are available the following analog reading from

external measurements:

Fig. 2.5: - Module 4459 external connections and internal connections view.

AT7400 Owner Manual Rev. 2.0 – October 2006-10-23 Section 2 - 5/9

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2.7.2.1 Direct RF power, and reverse RF power. From the RF output directional coupler, module 4429.

2.7.2.2 Direct RF driver power, and reverse RF driver power. From the RF intermediate directional coupler,

module 4429.

2.7.2.3 +8V, from the DC/DC converter; module 4147.

2.7.2.4 +15V, from the DC/DC converter; module 4147.

2.7.2.5 The 12V/7Ah battery voltage.

From the connector CON-9 these readings feed the microcontroller CI-4, from where those are digitalized and processed. By software decision, the microcontroller sets the nominal value for these readings always +4V,

meaning, to all nominal values the +4V will be assigned, and will be available at the CON-9. These values are transferred to the main LCD display on the MCU.

On the intermediate and final directional couplers, module 4488 and 4429, as well on the mains module, 4147, there are test points where the +4V nominal reference voltage are set. For instance:

 Once on operation and at the time the transmitter is set for its nominal RF output

power, the trim pot TP01 at PCB CIM3128A located at the module 4429 should be adjust on such way that the +4V is measured at pin 8, on the connector CON-9 located

at PCB CIM3297. More details will be shown on specific sections of this manual.

2.7.3. Alarm Detection

The system alarms are routed to MCU module 4459 via P1 and P2 connectors. These alarms are routed to CON5 at PCB CIM3297. These alarms are:

2.7.3.1 Lack of AC phase on mains, detected at module 4147.

2.7.3.2 Open fuse for fan #1, detected at module 4147.

2.7.3.3 Open fuse for fan #2, detected at module 4147. (For 2 racks systems only).

At the time when the system is on normal operation, no alarms, a +5V voltage is sent to the CON-5 via P1-P2 connectors. When an abnormal condition happens, that requires attention and generates an alarm status; a

lower voltage is than sent, usually 0V. When a lower voltage is detected by the microcontroller, the transmission is halted.

2.7.3.4 The alarm status is shown at the LCD screen on the front panel of the MCU. The alarms events are

classified in two categories regarding the time line occurrence:

2.7.3.4.1. On going alarm situation, noted by the sign “!”.

2.7.3.4.2. Old alarm situation, noted by the sign “#”.

At the time when an alarm source cease, the transmission is reestablished, and the “!” sign is switched to a “#”

sign, and registered. Old records can be manually erased by pressing the key “CLEAR” on the MCU front panel keyboard.

AT7400 Owner Manual Rev. 2.0 – October 2006-10-23 Section 2 - 6/9

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2.7.4. RS485 Communication bus

On the PCB CIM3297, pin 1 and pin 2, at the CON-12 perform the RS485 communication link among the MCU, the UHF exciter driver drawer and the UHF power amplifier drawers.

2.7.5. Interface SNMP

The interface SNMP is the PCB CIM3453. The connectors CON-4 and CON-10 located at the PCB CIM 3297 links the 2 PCBs.

Fig. 2.6: - Module 4459 SNPM interface, PCB CIM3453, internal and external view.

AT7400 Owner Manual Rev. 2.0 – October 2006-10-23 Section 2 - 7/9

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2.7.6. Displaying the Exciter and Power Amplifier Drawers Alarms

Each drawer has its own local control units. The local processed data is link to the MCU via RS485 protocol. The

MCU unit analyze, command actions and display at the LCD, the overall system status.

Alarms from the drawers, are displayed as drawers alarms, followed by one of each signs “!”, or “#”. Any alarm

originated on any internal module belonging to the UHF exciter drawer, that is followed by the sign “!”, (on going alarm), will cease the transmission. On other hand, any alarm originated on the UHF power amplifier drawer, also

followed by the sign “!”, will cause a proportional RF power reduction, implemented by the MCU logic control.

2.7.7. Keyboard, PCB CIM3112

This PCB holds the 8 key pads, which externally allows local manual interface with the transmitter MCU. This

PCB is a switch matrix. CON-1 transfers the CH1-CH8 keyboard ON/OFF operations to the MCU main board.

Fig. 2.7: - Module 4459 local command keyboard, external view.

2.7.8. LCD board, PCB CIM3108

This board is 4 rows, 40 columns liquid crystal display, LCD. The board is DC powered by the PCB CIM 3297, a

+5V feed into the point A, (yellow wire) and ground at point K (white wire). A multi-via connector receive a pinto-pin data out from CON-2 at PCB CIM 3297, exception for the pin 13 and pin 14 that have each other

exchanged its positions by the flat cable.

Fig. 2.8: - Module 4459 local command keyboard and LCD panel external view.

AT7400 Owner Manual Rev. 2.0 – October 2006-10-23 Section 2 - 8/9

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2.7.9. Module 4459 Internal Wiring

Fig. 29: - Module 4459 wiring diagram.

2.7.10. Module 4459 Schematic Diagrams: SEE ANNEX A

2.7.10.1 - PCB CIM3297

2.7.10.2 - PCB CIM3112

2.7.10.3 - PCB CIM3108

2.7.10.4- PCB CIM3453

AT7400 Owner Manual Rev. 2.0 – October 2006-10-23 Section 2 - 9/9

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Section 3 – 20W UHF ATSC Exciter

Unit/Drawer GAV4452

1.General Description

The 20W UHF ATSC exciter drawer performs several important functions, as follows:

a. The 8VSB modulation. Incoming SMPTE310 data stream, over an IF carrier, 21.52MHz. b. Insert the pre-distortion function over the modulated IF signal.

Fig.3.1: Top GAV4452 front view, bottom GAV4452 rear view.

c. Up-convert the IF signal on UHF ATSC broadcast channel. d. The output RF power control. e. Generates the 172MHz Master Clock signal, out from a 10MHz stable reference internally originated,

OCXO/0.3ppm oscillator, or externally originated like a GPS source. Automatically switch from INT/EXT master clock signal source in presence or absence or the EXT signal.

f. Via a DDS circuitry, generates 1Hz steps over the UHF channel frequency. g. Generates DC voltages for all internal modules, and the +32V externally to the DC/DC converter,

module 4147.

h. The 30W/47dB gain UHF/ATSC power amplifier.

AT7400 Owner Manual Rev. 2.0 – October 2006-10-23 Section 3 - 1/39

The modules assembled into the GAV4452 are:

x 01 Module 4454 - 8VSB Modulator and MASTER Clock Generator x 01 Module 4453 - IF/UHF Up-Converter x 01 Module 4466 - DDS x 01 Module 4464 - 20W UHF / ATSC x 01 Module 4456 - Power Supply x 01 Subordinate Control Unit (SCU) – CIM3297

Fig.3.2: GAV4452 modules displacement, top view.

AT7400 Owner Manual Rev. 2.0 – October 2006-10-23 Section 3 - 2/39

2.GAV4452 – 30W UHF/ATSC Exciter – Block Diagram

RFOUT

+3 2 V

RESTARTED

+12V+5V

SM PT E I N

10MHzREF IN

SM PT E I N

10MHzREF IN

+15V+1.2V -15V+3.3V +5V

8VSB

CLOCK

MODULE 4454

MODULATOR

AN D M A ST E R

MODULATOR

AN D M A ST E R

MODULATOR

AN D M A ST E R

I I’ Q Q’

UHF A TSC

CHANN ELTV

UHF

MO DULE 4455

30W UHF ATSC EXCITER

MO DULE 4453

UPCONV ERTER

+32V+15V+5V -15V+3 . 3V + 12 V

+32V+15V+5V -15V+3 . 3V + 12 V +32 V+15V+5V -15V+3 . 3V + 12 V

172MHz

SYNTHESIZER

DIRE CT DIG IT AL

+15V +5 V

DIRE CT DIG IT AL

+15V +5 V

DATAI N – DATAOUT

DATAOUT– DATAIN

MODULATORCLOCK

MODULATORENABLE

MODULATORREAD

LOCK CLOCKALARM

DATAI N – DATAOUT

DATAOUT– DATAIN

MODULATORCLOCK

MODULATORENABLE

MODULATORREAD

LOCK CLOCKALARM

+15V

DIRECT

RS 232

5 32

32

RS48 5

+1 . 2 V+3.3V+8V+12V

IO RESET

SEND I O

SEND CL OCK

IO UPDA TEC LO CK

MASTER RESET

IO RESET

SEND I O

SEND CL OCK

IO UPDA TEC LO CK

MASTER RESET

SUBORDINATE

CONTROL UNIT

RS485B

RS485A

RS485B

RS485A

RS232RX

RS232 T X

RS232RX

RS232 T X

RS232 GND

VOLTAGE

MO DULE 4470

RE GULATORS

635241

SUPPLY

14MHz

(D DS )

MOD ULE 4 466

ALC (POWER CONTROL)

VCO1C ONTROL

VCO2 CONTROL

VCO3C ONTROL

VCO4 CONTROL

DIV0

DIV1

DIV2

DIV3

DIV4

DIV5

NOIF ALARM

SERIALDATA OUT

(SCU)

+5V +2 . 5 V

+15V

ALC (POWER CONTROL)

VCO1C ONTROL

VCO2 CONTROL

CIM3 297

POWERSUP PL YS HUTDO WN

32V O UTPUT VOLTAGEREADING

POWER SUPPLY RE CONNECTI ON

+32V OUTPUTCURR ENTREA DING

+2.5V

+5V

-15V

+15V

+15V +15VDIR.

+15VDIR.

+32V REST.

+32V

PHASE2

ORNEUTRAL

+32V

ON/OFF

SWITCH

OR NE UTRAL

PHAS E 2

4

PHASE1

12

3

12

3

LOCK DETECTOR AL ARM

MODU LE 4 456

EXCITER TEMPERATURE ALARM

DIV5

NOIF ALARM

LOCK DETECTOR AL ARM

EXCITER TEMPERATURE ALARM

:

FAN1

AC

FAN 2

PHASE 1:208V

PHASE 1/ PHASE2:120V

PHASE 1:208V

PHASE 1/ PHASE2:120V

208VMO NOPHASI C AND 360VT RIPHAS IC EQUIPAMENTS:

•

•NE UTRAL

208VBI PHASI C AND 208VT RIPHAS IC E QUIPAMENTS

•

208VMO NOPHASI C AND 360VT RIPHAS IC EQUIPAMENTS:

•

•NE UTRAL

208VBI PHASI C AND 208VT RIPHAS IC E QUIPAMENTS

•

VCO3C ONTROL

VCO4 CONTROL

DIV0

DIV1

DIV2

DIV3

DIV4

PO WER SU P PL Y

AC

20 8V

PHASE1

10AFUSE

AT7400 Owner Manual Rev. 2.0 – October 2006-10-23 Section 3 - 3/39

3.GAV4452 - Module 4454 – 8VSB Modulators and Master Clock

3.1. General Functional Description

The module 4454 can be break down in 2 printed circuit boards. These boards are physically located as the figure below:

CON-7

(WH) GROUN D ? CON-5–CIM3458–MOD.4470–VOLTAGEREGULATORS

(BR) + 5V ? CON-2–CIM3459–MOD.4456–POWERSUPPLY

(BK) -1 5V ? CON-3 – CIM34 61 – MOD.4 456 – POWER SUPPLY

(BL) +1 5V ? CON-2–CIM3461–MOD.4456– POWERSUPPLY

(OR)+3. 3V ? CON-8–CIM3458–MOD.4470–VOLTAGEREGULATORS

(GY) LOCK CLOCK A LARM ? PIN4–CON-6–CIM3297–SCU

172MHz MASTERCLOCK

6 5

4 3

2 1

CON-3

CON-4

CON-7

CON-6

CON-5

CON-4

CON-3

CON-9

1

(WH) GR OUND ? CON-5 – C IM3 45 8 – MOD .4 470 – VOL TAGE REGU LATORS

2

(WH) GR OUND ? CON-5 – C IM3 45 8 – MOD .4 470 – VOL TAGE REGU LATORS

3

(OR) +3 .3V ? CON-8 – CIM 3458 – MOD.44 70 – VOLTAGEREGULATORS

4

(OR) +3 .3V ? CON-8 – CIM 3458 – MOD.44 70 – VOLTAGEREGULATORS

(50OBELDEN CABLE) I+SIGNAL ? CON-1 – CIM34 42 – MOD.4453 – UHF UPCONVERTER

–

(50OBELDEN CABLE) I

(50 O BELDEN CABL E) Q+SIGNAL? CON-4–CIM3442–MOD.4453–UHFUPCONVERTER

(50OBELDEN CABLE) Q– SIG NAL? CON-5 – CIM3442 – MOD.4453 – UHF UPCONVERTER

SIGNAL ? CON-2 – CIM34 42 – MOD.4453 – UHF UPCONVERTER

(50OBELDEN CABLE) 172M Hz MASTERCLOCK ? CON-1 – CIM345 6 – MOD.44 66 – DDS

10 MH z EXT ERN AL REF EREN CE IN

MASTER CLOCK

CIM3445

SMPTE I N

8VSB MODU LAT OR

CIM 3444

CON-5

MASTER C L OCK

CIM3445

CON-11

CON-10

8VSB MODULATOR

CIM3444

Fig.3.3: Module 4454 – Left: Front View, Right: Top View.

1

(WH)GROUND ? CON-5–CIM3458–MOD.4470–VOLTAGEREGULATORS

2

(BK) DATA IN – DATA OUT? PIN2–CON-3–CIM3297–SCU

3

(BL)D ATA OUT – DATA IN? PIN1–CON-6–CIM3297–SCU

4

(YL)MODULATORCLOCK ? PIN3–CON-3–CIM3297–SCU

5

(GR)MODULATORENABLE? PIN4–CON-3–CIM3297–SCU

6

(OR) M ODULATOR READ ? PIN5–CON-3–CIM3297–SCU

1

(WH) GR OUND ? CON-5 – C IM3 45 8 – MOD .4 470 – VOL TAGE REGU LATORS

2

(YL) +1. 2V ? CON-9– CIM3458 – MOD.4470– VOLTAGEREGULATORS

3

(YL) +1. 2V ? CON-9– CIM3458 – MOD.4470– VOLTAGEREGULATORS

4

(YL) +1. 2V ? CON-9– CIM3458 – MOD.4470– VOLTAGEREGULATORS

5

(WH) GR OUND ? CON-5 – C IM3 45 8 – MOD .4 470 – VOL TAGE REGU LATORS

6

(OR) +3 .3V ? CON-8 – CIM 3458 – MOD.44 70 – VOLTAGEREGULATORS

7

(OR) +3 .3V ? CON-8 – CIM 3458 – MOD.44 70 – VOLTAGEREGULATORS

8

(OR) +3 .3V ? CON-8– CIM3458 – MOD.4470 – VOLTAGE REGULATORS

9

(WH) GR OUND ? CON-5 – C IM3 45 8 – MOD .4 470 – VOL TAGE REGU LATORS

AT7400 Owner Manual Rev. 2.0 – October 2006-10-23 Section 3 - 4/39

SMPTE 310

CIP8357

8VSB Modulator

&

pre-distortion

CIP8355

I I'

Q

Q'

Mixer & ALC

RF UHF

-2.3dBm

External

Refer e nc e

10MHz

Master Clock

172.16MHz

CIP8358

Sub-module 4454

PLL + DDS

4xVCO/offset

CIP8356

Sub-module 4453

Fig.3.4: Module 4454- 8VSB Modulation and IF/UHF up-conversion structure

3.1.1. Module 4454 - PCB CIM3444: 8VSB Modulator/Pre-Corrector

The PCB CIM3444, is part of the Module 4454. It is the modulator that process the transport stream (TS) that carries up to 4 broadcast programming including, audio, video and data. All information compressed and

multiplexedinaMPEG2format

The 8VSB channel modulator inserts the forward error correction, (FEC), into the transport stream MPEG2. The modulator follows the ATSC standard A/53 annex D.

AT7400 Owner Manual Rev. 2.0 – October 2006-10-23 Section 3 - 5/39

Fig.3.5: CIM3444 – Block Diagram

3.1.1.1 PCB CIM3444 – General Functional Description

The ADVANCE TV series is designed to receive as input signal, programming stream, standard SMPTE310M,with 19.39M bps, amplitude of 800 mVpp, @75ȍ. The input BNC connector is located on the top

cover of the transmitter rack.

First the circuit to recover the clock rate used to perform the protocol interface. After that there is a rate equalization of the transport stream, TS, performed by the insertion or delete of the null packets, at the end the

symbol rate is ready to be stabilized and locked with a external/local reference of 10MHz and no longer with the TS stream that is limited to 2.8ppm accuracy. During this processing is also used the re-stamping for multiple

programs, termed as PCR.

After the data processing as described below, the data stream is ready to receive the channel coding, that is break down on the following steps:

3.1.1.1.1. Frame Synchronization

For each 188 bytes on the MPEG2 package, this circuit identifies and removes the 47h byte.

3.1.1.1.2. Randomizer

This circuit equally spread the modulated signal energy over the channel band. The final energy density is similar to a AWGN noise, with this technique, it is possible to achieve a higher bandwidth usage efficiency.

3.1.1.1.3. Reed-Solomom

Reed- Solomon is a block coder, (207,187) that adds 20 redundant bytes on each 187 bytes of the MPEG2 package. With this method it is possible to correct on the reception site, some possible data errors that may had occurred during the transmission of the RF signal.

3.1.1.1.4. Interleaving

The interleaving technique helps to spread the errors around the time line, making them even less susceptible to burst errors.

3.1.1.1.5. Trellis Code

Trellis code is closely related to the channel modulation. It is a convolution coder using 2/3 rate, meaning for each 2 bits at the input, there are 3 coded bits at the output creating the 8 symbols used on the 8VSB modulation

process, (- 7, -5, -3, -1, +1, +3, +5, +7), having as ultimate goal improve the threshold on the signal-to-noise ratio of the system.

3.1.1.1.6. S ynchronism Insertion

The synchronism insertion built the symbol overall structure, creating the fields and frames as specified on the A/53E standard.

AT7400 Owner Manual Rev. 2.0 – October 2006-10-23 Section 3 - 6/39

3.1.1.1.7. Pilot Insertion

This part of the circuit adds a small DC level into the carrier to allow a safer and robust reception of the signal. This DC level is equivalent to 1.25 CU (Constellation Units).

The entire modulation process is digital. This process includes the FIR filters, and do not uses SAW filters to create the VSB band. Digital modulation increase the quality of the modulated signal measured via a proportional

increase of the MER, (Modulation Error Rate). The modulation process generates 2 identical but orthogonal signals, termed signals; I and Q. The frequency of the IF carrier is 21.52MHz, and the center of the channel is

18.8MHz.

The value for the system when working with 2 orthogonal carriers is because it is possible to implement corrections on non-linear distortions, or simply implement digital pre-distortion. The digital pre-correction is

possible using LUT, (Look up Tables). This table synthesizes inverted responses regarding the RF power amplifier transfer function, reducing the IMD products.

The digital processing generates I and Q distorted, and these 2 signals are than converted to the analog format via a 16 bits DAC, with 2 balanced outputs, on a total of 4 output analog signals. These signals are termed; I, I’, Q

and Q’, and are respectively present at the CN9, CN8, CN6, and CN5 connectors at CIM3444. These 4 signals will become the UHF Up-Converter input signals, Module 4453.

3.1.2. Module 4454 - PCB CIM3445: Master Clock

The Master Clock PCB CIM3445, embedded into the module 4454, out from a 10MHz internal/external reference signal, synthesizes a

172.16MHz oscillator that represents 16 times the symbol rate of the modulator 8VSB

This oscillator signal is squared by a schimitt trigger circuit with amplitude equal to 0-3.3 volts. This square wave type signal is the master clock

signal that will synchronizes all the digital circuits on this equipment except the control signals.

Fig.3.6: External Reference input BNC connector

AT7400 Owner Manual Rev. 2.0 – October 2006-10-23 Section 3 - 7/39

3.1.3. PCB CIM3445 – Master Clock - Block Diagram

3.1.4. PCB CIM3445 – General Functional Description

The 172.16MHz frequency is synthesized via a PLL, a VCO and a DDS circuit. The 10MHz reference is one out of the two inputs of the phase comparator. This signal comes to CIP8358 via a SMB connector, CON-2. The second

one is also a 10MHz generated by the DDS circuit out from the free running 172.16MHz oscillator. The loop filter performs the integration of the phase comparator output, generating the error signal that is feed

back to the VCO. On this way the VCO is locked to the reference signal. The oscillator signal is delivery via 3 connectors. Two of those are routed to the 8VSB Modulator, PCB CIM3444,

and the third one is routed to the DDS circuit, module 4456.

3.2. Module 4453 - UHF ATSC Up-Converter

The Up-Converter module is composed by the mixer circuitry, PCB CIM3442, and a local oscillator, PCB CIM3443.

AT7400 Owner Manual Rev. 2.0 – October 2006-10-23 Section 3 - 8/39

3.2.1. Module 4453 - External Connections

CON-2

9

LO O UTPUT

9 8

8 7

7 6

6 5

5 4

4 3

3 2

2 1

1

CON-3

CON-4

CON-1

9

9 8

8 7

7 6

6 5

5 4

4 3

3 2

2 1

1

(WH) G ROUND ? CON-5 – CIM3458 – MOD.4470 – VOLTAGE REGULATORS

(OR) +3.3V ?CON-8–CIM3458–MOD.4470–VOLTAGEREGULATORS

(BK) -15V ? CON-3–CIM3461–MOD.4456–POWERSUPPLY

(BL) +15V? CON-2–CIM3461–MOD. 4456–POWERSUPPLY

(VM) +32V ? CON-10 – CIM3447– MOD.4456 – POWER SUPPLY

(OR) VCO4 CONTROL ? PIN8 –CON-4–CIM3297–SCU

(VL) VCO 3 CON TROL ? PIN6–CON-4–CIM3297–SCU

(GY) VCO2 CONTROL ? PIN2 –CON-4–CIM3297 –SCU

(GY) VCO2 CONTROL ? PIN2 –CON-4–CIM3297 –SCU (BR) VCO1 CONTROL ? PIN6 –CON-3–CIM3297 –SCU

(BR) VCO1 CONTROL ? PIN6 –CON-3–CIM3297 –SCU

(WH) G ROUND ? CON-5 – CIM3458 – MOD.4470 – VOLTAGE REGULATORS

(GR) LOCK DETECTOR ALARM ? PIN3–CON-6–CIM3297 –SCU

(CZ) DIV0 ? PIN 6 – CON-5 – CIM3297 – SCU

(CZ) DIV0 ? PIN 6 – CON-5 – CIM3297 – SCU (BR) DIV1 ? PIN5–CON-5–CIM3297–SCU

(BR) DIV1 ? PIN5–CON-5–CIM3297–SCU (OR) DIV2? PIN 4 – CON-5 – C IM3297 – SCU

(OR) DIV2? PIN 4 – CON-5 – C IM3297 – SCU (BK) DIV3 ? PIN 3 – CO N-5 – CIM3297 – SCU

(BK) DIV3 ? PIN 3 – CO N-5 – CIM3297 – SCU

(VL) DIV4 ? PIN2–CON-5–CIM3297–SCU

(VM) DIV5 ? PIN1 –CON-5–CIM3297–SCU

CON-7

CON-1

CON-2

CON-3

CON-4

CON-5

1

1 2

2 3

3 4

4 5

5

(GY) +12V? CON-6–CIM3458–MOD.4470–VOLTAGEREGULATORS

6

(BR) +5V? CON-2–CIM3459–MOD.4456–POWERSUPPLY

7

(BK) NO IF ALARM ? PIN5- CON-6–CIM3297 –SCU

8

(WH / RD) ALC (POWER CON TROL) ? PIN 4 – CO N-1– CIM3297 – SCU

9

(SH) GROUND ? PIN2–CON-1–CIM3297–SCU

(50ȍBE LDEN CABLE) I+SIGNAL ? CON-9–CIM3444–MOD.4454–8VSBMODULATOR

–

(50ȍBE LDEN CABLE) I

(50ȍBE LDEN CABLE) Q+SIGN AL ? CON- 6 – CIM3444 – MOD.4454 – 8VSB MODULATOR

(50ȍBE LDEN CABLE) Q–SIGN AL? CON-6 – CIM3444 – MOD.4454 – 8VSB MODULATOR

–

SIGNAL ? CON-8 – CIM3444 – MOD.4454 – 8VSB MO DULATOR

(50ȍ BELDEN CABLE ) 1 4MHz REFERENCE ? CON-2–CIM3456–MOD.4466–DDS

CON-5

CON-6

LOCAL OSCILATOR

CIM3443

CON- 6

MIXER

CIM3 442

(50ȍBE LDEN CABLE) UHF / ATSC CHANNEL TV ? CON -1 – CIM3446 – MOD.4455 – 30W UHF EXCITER

AT7400 Owner Manual Rev. 2.0 – October 2006-10-23 Section 3 - 9/39

3.2.2. PCB CIM3443 – Local Oscillator

The local oscillator is designed based on a PLL circuit. This oscillator is able to synthesize frequencies within the band from 450MHz up to 900MHz. To guarantee a high quality signal generation out from the local oscillator, 4

VCO’s (voltage controlled oscillator) were implemented with a shift frequency range of 125MHz each. Just one VCO works at the time to avoid interferences. On this arrangement, a 102dBc@20Hz phase noise is achieved.

The synthesizer on the feedback loop select the desired frequency inside the choose VCO band.

The VCO’s signal outputs are isolated among them via a sum and inverted circuits. The reference frequency generated by a DDS circuitry complete the Up-conversion frequency process. The output local oscillator signal

power is +5dBm.

3.2.3. PCB CIM3443 – Local Oscillator – Block Diagram

3.3. PCB CIM3442 – UHF Mixer

The mixing operation translates the IF modulated signal frequency up to the assigned UHF broadcasting channel, the operation utilizes the complex approach considering the orthogonal pair of signals (I-, I+) and (Q-,Q+) allowing

rejection of one side band, and the oscillator itself. The rejection is around 40dB, facilitating the post filtering steps.

Right after the mixing operation, the now RF signal is 10dB broadband (VHF and UHF) amplified under a typical 2dB roll-off characteristic. The RF output pass through a 25dB dynamic range variable attenuator. The control of

this attenuator is related with the DC level generated by the ALC (Automatic Level Control). In case of absence of a IF signal or valid IF signal (locked via PLL) of any of the 4 possible IF signals, the attenuator assumes it higher

level of attenuation, and shutting down the RF chain of amplification.

AT7400 Owner Manual Rev. 2.0 – October 2006 -10-23 Section 3 - 10/39

3.3.1. PCB CIM3442 – UHF Mixer – Block Diagram

AT7400 Owner Manual Rev. 2.0 – October 2006 -10-23 Section 3 - 11/39

3.3.2. PCB CIM3442 – UHF Mixer – Test Points Diagram

AT7400 Owner Manual Rev. 2.0 – October 2006 -10-23 Section 3 - 12/39

3.3.3. PCB CIM3442 – UHF Mixer – Adjustment Procedures

The mixer-ALC circuitries have 2 types of adjustments. The first one is a DC level that polarizes each branch of the input of the complex mixer. Each one of the DC levels must be adjusted seeking for the max rejection on the un-desired vestigial side band, in conjunction with the LO rejection as well. The level adjustments are performed

by the trim pots: TPO-1, TPO -2, TPO-3, and TPO-4. Voltage range of +1.4V to +1.6V should be present on the following test points.

x TPO-1: readings on L17 x TPO-2: readings on L18 x TPO-3: readings on L19 x TPO-4: readings on L20

The second set of adjustments follows the first one. Once the first set is completed, the fine tuning adjustment should be performed. It is necessary to connect the spectrum analyzer to the UHF RF output of the sub-module

4453. At this point, either the LO signal, as the superior RF spectral image of the UHF/ATSC RF channel, must be attenuated by 40dBc.

40dBc

UHF / ATSC

CHANNEL DTV

(BEL OW MI XING)

LOCAL OSCILATOR

SIGNAL

UHF / ATSC

CHANNEL DTV

(ABOVE MIXING)

Fig.3.7: Level references for mixer-ALC fine tuning

The second adjust detects the protection signal at the center of the band. In absence of 1 out of 4 controls IF signals, this DC level exceed the min threshold and shut down the RF output signal. The DC threshold adjust is

performed by TPO-5, and should be set for +2.5V.

3.4. Module 4466 – Direct Digital Synthesizer (DDS)

The module 4466 is a signal reference generator based on a DDS circuit. This module is able to synthesize frequencies up to 50MHz under mHertz precision range. The signal is used as PLL reference on the UHF Up-

Converter module 4453 – PCB CIM3442. The RF channel 10kHz off-set if necessary, is pre-set on the DDS circuitry. The phase noise on the reference signal generated on this module is better than 110dBc/Hz.

The SCU unit – PCB CIM3297 – configures the DDS’s circuitry parameters via a serial communication port. The DDS module receives a signal out from the master clock module 4454 - PCB CIM3445; perform the programming

operation for the RF output channel as required under mHertz precision. At the end, is expected a frequency error around 1Hz max., when measured at the output of the UHF mixer circuit. Before leaves the module, the DDS signal is amplified and filtered.

AT7400 Owner Manual Rev. 2.0 – October 2006 -10-23 Section 3 - 13/39

3.5. Module 4466 – External Connections

AT7400 Owner Manual Rev. 2.0 – October 2006 -10-23 Section 3 - 14/39

3.6. Module 4464 – 20W UHF ATSC Power Amplifier

The RF/UHF signal, already set to the assigned channel, is than power amplified up to 20W. The RF amplifier is type class AB. LDMOS transistors are also used on this amplification stage. Fig.:3.2; illustrates the RF chain of

the module 4464.

Module 4455: 20W power amplifier

Printed Circuit Board CIM 3440

BLF861A

RF UHF

-2.3dBm

Printed Circuit Board CIM 3446

SG9289 BLF1822

BLF1822SG9289

RF UHF

0.5W

G = 32dB

Fig.3.8: UHF 48dB gain RF amplification chain, simplified block diagram

H

BLF861A

H H

BLF861A

G = 16dB

H

RF UHF 20W

Fig.3.9: Module 20W UHF ATSC power amplifier – module 4464

AT7400 Owner Manual Rev. 2.0 – October 2006 -10-23 Section 3 - 15/39

3.1.3.1 General Functional Description

The PCB CIM 3390 delivers is the output nominal ATSC UHF 20W output power for the module 4455 – intermediate directional coupler. Despite the amplifier being designed as a broadband amplifier, due optimization

reasons, the amplifier is built in 4 frequency operational bands, as follows:

x channel 14 to 25 (B1) - channel 26 to 38 (B2) - channel 39 to 53 (B3) - channel 54 to 69 (B4)

Despite the different bands, the PCB remains the same, as indicated on the table below:

CIRCUIT CIM CIP

DRIVER 3446 8359

FINAL STAGE 3440 8352

Table 3.1: Module- 4464 PCB assembles references.

NOTE: CIM stands for the PCB version, and CIP stands for the bill of material version.

AT7400 Owner Manual Rev. 2.0 – October 2006 -10-23 Section 3 - 16/39

20W UHF / ATSC EXCITER - MODULE 4464

3.9.1. Module 4464 – Technical Specifications

CHARACTERISTIC SPECIFICATION

SMPTE310M INPUT

FREQUENCY 470 - 862MHz

IMPE D A NC E 7 5 Ohm s

CONNECTOR BNC F EMAL E

RETURN LOSS

³22dB

RF OUTPUT

GAIN FROM 45 TO 48 dB

ATSC

AVERAGE POWER

HARMONICS

SPURIOUS

EMISSION

UNTIL 2 0W

£ -60dB

< -54dB

INTERMODUL ATION < -52 dB

CONECTOR N FEMALE

POWER SUPPLY +32V / +12V / +5V

CONSUMPTION 14A (AB CLASS)

AT7400 Owner Manual Rev. 2.0 – October 2006 -10-23 Section 3 - 17/39

GENERAL

3.9.2. Module 4464 – PCB CIM3446 – 32dB Gain Driver 0.5w Amplifier

The PCB CIM 3446 is the driver amplifier for the 20W final amplifier. This circuit is 2 parallels cells, type class A polarization, 90 degree out of phase, able to delivery up to 1W of power usable for DTV/ATSC standard over the

470MHz – 806MHz UHF band.

Fig.3.9: Module 4464 – CIM3446 – block diagram

Each amplification cell is composed first by a BJT transistor followed by a LDMOS transistor. The serial connection of these 2 devices delivery 500mW.The parallel combination of these 2 cells via H-2 hybrid, is able

than to delivery 1W of RF power.

AT7400 Owner Manual Rev. 2.0 – October 2006 -10-23 Section 3 - 18/39

3.9.3. Module 4464 – CIM 3446 – Technical Specifications

AT7400 Owner Manual Rev. 2.0 – October 2006 -10-23 Section 3 - 19/39

3.9.4. Module 4464 – PCB 3446 – Adjustment Procedures

The PCB CIM3446 can be adjusted either locally, meaning inside of the equipment, (recommended for simplicity) or outside of the equipment. On either situation, one MUST always use a 50ȍ load connected at the RF output.

NETW ORK ANAL YZER

RF

OUT

EXCITER TEMPERATURE

+5V / 1AVOLTAGE

ALARM

+12V / 1A VOLTAGE

SUPPLY SUPPLY

+32V / 2A VOLTAGE SUPPLY

1

4

2

5

3

6

C13

T1

C4

CON-1

RF

IN

+12V

HI-1

(BR)

T3

C41

835 9

LINE AR

+32V

TPO -1

VGST2

(RD)

T2

R7

(GY)

.

+5V

R23

TPO-2

VGST4

R13R28

BLF1822

R14

R15

HI -2

T4

BLF1822

(RD)

30dB / 50W

ATTENUATO

R

C5

TPO-1

VGSADJ

T1

.

CI-1

CI-2

HC-1

TPO-2

T2

VGSADJ

C35

.

RF

IN

T1

C9

T3

T4

C39

BLF861A

C13

R9

CI-7

S1

CI-4

+32V/ 2A

BLF861A

T2

.

CI-5

.

CI-8

R10 +32V

CI-3

.

R11

CON-2 +32V

ID1

ID2

TEMP

CON-3

CON-2

MODULE 4464

3.9.4.1 Drain Current, (ID) - Adjust for T2 and T4

No RF signal should be present at the RF input of the module 4464. Turn the module ON and wait for 3 minutes for thermal stabilization of the circuit. Use a good quality multi-meter able to read mVdc, avoid to used auto-range

multi-meters.

AT7400 Owner Manual Rev. 2.0 – October 2006 -10-23 Section 3 - 20/39

3.9.4.1.1. Transistor T2

1 – Turn TPO-1’s knob all way counter clock wise, no T2 -ID will be present. 2 – Connect the multi-meter over the terminals of R13, the T2-drain resistor.

3 – Slowly start to turn TPO-1 knob clock wise up to the point that T2 starts to conduct, meaning few mili-volts will be read at the multi-meter. Continue it up to a 3Vdc reading be shown over R13.

3.9.4.1.2. Transistor T4

1 – Turn TPO-2’s knob all way counter clock wise, no T4-ID will be present. 2 – Connect the multi-meter over the terminals of R28, the T4- drain resistor.

3 – Slowly start to turn TPO-2’s knob clock wise up to the point that T4 starts to conduct, meaning few mili-volts will be read at the multi-meter. Continue it up to a 3Vdc reading be shown over R28.

IMPORTANT: The amplifiers at CIM3446 are type class A; the drain currents are independent of the presence, or not of the RF input signal.

3.9.5. Module 4464 – PCB CIM3440 -16dB gain final 20W amplifier

This stage is built with 4 LDMOS transistors distributed in 2 cells of amplification. These 2 cells were designed on push-pull class AB configuration, and than combined. The optimization process by band is also implemented.

The same PCB hardware is used for all 4 bands, the CIP8053. The nominal RF output power of each cell is

12.5W, totaling 20W following the output combiner. The overall gain of this stage is between 13dB and 16dB depending on the assigned channel 6MHz UHF band.

AT7400 Owner Manual Rev. 2.0 – October 2006 -10-23 Section 3 - 21/39

50ȍ / 60W

According with the Fig. 3.2: block diagram:

(T2)

AM P L IF IE R

B2 O UT PUT

INPUT

C43

C39

INPUT

MATCHER

C35

BA LUN

IN P U T

MATCHER

(L 1 0 )(C 5 7 )

FI LT E R

(C53-C55)

DC BL O C KE R

+32 V (VB)

(C31)

(R1 / / R2)

50ȍ /10W

(H C - 1 )

R F HYBR ID

OUTPUT

MAT CHE R

(TPO-2)

(C 56)

BALUN

DC BLOCKER

(R11)

3dB C O UP L IN G

3dB C O UP L IN G3dB C O UP L IN G

BALUN

OUTPUT

MATCHER

(TPO-2)

T2GATE BIAS

(T2)

AMPLIFIER

B1 O UT PUT

AMPLIFIER

B1 O UT PUT

TPO-1

T 1 ID ADJUST C URRENT: 60mV R39/ /R35

wi thout R F s ig nal in put – AB clas s

TPO-1

T 1 ID ADJUST C URRENT: 60mV R39/ /R35

wi thout R F s ig nal in put – AB clas s

TPO-2

T 2 ID ADJUST C URRENT: 60mV R36/ /R37

witho ut R F s ig nal inp ut – AB clas s

TPO-2

T 2 ID ADJUST C URRENT: 60mV R36/ /R37

witho ut R F s ig nal inp ut – AB clas s

(T1)

AMPLIFIER

A2 O UT PUT

IN P U T

OU T PUT

MATCHER

RFO UTP UT

DC

(C26)

BALUN

BLOCKER

+1 2V

+ 12V

REGULATOR

+ 32V (V A)

BALUN

OU T PUT

MATCHER

(CI-4)

(TP O - 1 )

T1 GATE BIAS

(T1)

AMP LIF IER

A1 OU T P UT

(S1)

SENSOR

THERMAL

+12 V

IN P U T

MATCHER

C9

C5

C9

C5

C13

+1 2V +1 2V

FILTER

DC

+12 V

+1 2V

BALUN

INPUT

MATCHER

(L5)(C27)

(C22-C25)

(CI-3)

AMPLIFIER

+ 15V

+32 V (VA)

HISTERES E

(C1)

RF I NP UT

DC BLOCKER

COM PAR ATOR

RF I NP UT

TE MPER AT U RE READI NG

(CI-3)

AT7400 Owner Manual Rev. 2.0 – October 2006 -10-23 Section 3 - 22/39

3.9.5.1 RF Hybrid Input

This hybrid equally splits the incoming RF signal, keeping the input impedance at 50ȍ level on an eventual amplification cell malfunction. This hybrid is built out of 2 coupled transmission lines. In one end of the first

transmission line is connected the RF input signal, and on the other end a 50ȍ/10W (R1 parallel with R2) resistive termination. On the ends of the second transmission line the coupled RF signal feeds the 2 amplification cells.

Fig.3.10: ID current adjust trim-pots location on PCB CIM 3440

3.9.5.2 UHF 12.5W Drive Amplifier – Cell A, Transistor T1

On this cell, the trim-pot TPO-1 at the same time adjusts the VGS1 voltage for T1, and the drained current ID. Trimmers C5, C9 and C13, tunes and adjusts the input impedance. A combination among the trimmers’ physical

position and transmission lines’ length determines the bandwidth behavior. At the input, the capacitor C1 is a input DC de-coupling, and at the output C26 as well.

AT7400 Owner Manual Rev. 2.0 – October 2006 -10-23 Section 3 - 23/39

3.9.5.3 UHF 12.5W Driver Amplifier – Cell B, Transistor 2

On this cell, the trim-pot TPO-3 at the same time adjusts the VGS2 voltage for T2, and the drained current ID. The trimmers C35, C39 and C43, tunes and adjusts the input impedance. A combination among the trimmers’

physical position and transmission lines’ length determines the bandwidth behavior. At the input, the capacitor C31 is a input DC de-coupling, and at the output C56 as well.

3.9.5.4 Output Combiner

The 12.5W RF signals at the output of cells A and B are combined. The combination circuit is completed with the absorber load, R11 (50ȍ/60W). R11 dissipates the extra power in case of failure of one cell, not disturbing the

output impedance on the cell that did not fail.

3.9.5.5 Temperature Alarm

The module 4464 is protected against high temperature levels. In case the internal temperature reaches or exceeds 149°F, (65°C). The alarm circuitry is located at PCB CIM3440, and is composed by an thermal sensor

S1, by an integrated circuit CI-3. The temperature readings are DC converted and can be measure. This DC voltage is routed directly to the pin #7 at the CON-6 at SCU (PCB CIM3297). If the module temperature exceeds

the limits on the module 4464, as consequence, the SCU will send a command to the sub-module 4456 that disrupts the +32V to the module 4464.

AT7400 Owner Manual Rev. 2.0 – October 2006 -10-23 Section 3 - 24/39

3.9.6. Module 4464 – PCB CIM3440 – Technical Specifications

FEAT URE SPECIF ICATION

INPUT

FREQUENCY 470 - 862MHz

IMPEDANCE 50 Ohms

RETURN L OSS

³22dB

OUT PUT

GAIN 13 TO 16dB

RF POWER UNTIL 20WRMS

HARMONICS

SPURIOUS

EMISSION

£ -60dB

< -54dB

INTERMOD ULATION < -4 6 dB

IMPEDANCE 50 Ohms

GENERAL

VOLTAGE SUPPLY +32V

CONSUMPTION 12A (AB CLASS)

3.9.7. Module 4464 – PCB CIM3440- Adjustment Procedures

Always proceed to adjustment with the CIM3440 terminated by a 50ȍ RF load, and make sure t hat there is no RF signal present at the input of the module during the ID current adjustments.

AT7400 Owner Manual Rev. 2.0 – October 2006 -10-23 Section 3 - 25/39

3.9.7.1 Drain Current ID, Adjustment

Turn the unit ON and wait 3 minutes for thermal stability. Use a good quality multi-meter able to read mVdc, avoid to used auto-range multi-meters.

3.9.7.1.1. Transistor T1

1 - Set the trim-pot TPO-1 all way counterclockwise. On this condition no current flow over the transistor. 2 – Measure the voltage drop over R9. Set the multi-meter for 100mVdc full scale.

3 – Slowly start to turn the TPO-1 trim-pot clockwise up to the point one read 60mVdc over R9.

3.9.7.1.2. Transistor T2

1 – Set the trim- pot TPO-1 all way counterclockwise. On this condition no current flow over the transistor. 2 – Measure the voltage drop over R10. Set the multi-meter for 100mVdc full scale.

3 – Slowly start to turn the TPO-1 trim-pot clockwise up to the point one read 60mVdc over R10.

IMPORTANT: The amplifiers at CIM3440 are type class AB; the drain currents are dependent of the presence, or not of the RF input signal. Higher the RF input signal, higher the ID current will be.

3.9.7.2 Module 4464 – PCB CIM3440 – Curve Response Adjustment

The module 4464 is a broadband UHF amplifier. The curve response is however optimized by band, ch14 to ch25, ch25 to ch38, ch39 to ch53, and ch54 to ch69. The curve response optimization is factory performed and

should remain valid even an eventual LDMOS transistor replacement. The cap trimmers are tuning point for the PCB, they should be tune seeking for best curve/gain response.

AT7400 Owner Manual Rev. 2.0 – October 2006 -10-23 Section 3 - 26/39

Fig.3.11: Cap trimmers location on PCB CIM 3440

NETWORK ANALYZER

RF

IN

BLF861A

BLF861ABLF861A

S1 S1

S1

+32V / 2A

BLF861A

BLF8 61A

BLF861A

T2

IN

30dB / 50W

ATT EN U ATO R

R11

CON-2

CON-2 +32V

+32V

R9

CI-7

R9

CI-7

R9R9

CI-7

.

..

.

CI-5

.

CI-5

.

..

CI-8

R10 +32V

3

3 CON

-

ID1

CON

-

ID1

CON

-

ID1 ID2

ID2

TEMP

CON-2

RF

OUT

+32V/ 2A

RF

OUT

T1

C5

C9

C5

TPO-1

VGS ADJ

T1

.

..

CI-1

.

CI-2

TPO-2

T2

VGS ADJ

C35

CI-2

.

..

HC-1

RF

IN

HC-1

C13

C9

C13

C9

C13

T3

CI-3

.

..

4 4

4

-

CI

T4

C39

-

C42

C39

MODULE 4464

Fig. 3.12: Suggested gain and curve response evaluation for PCB CIM3440

The network analyzer level should be set upfront for -20dBm at the assigned UHF channel band. Monitor the results at the output of the PCB CIM3440. Tune the cap trimmers for best curve response, flat shape inside the

band. Watch the gain according with the indication below:

x 16dB – Band 1: ch14 to ch25. x 15dB – Band 2: ch26 to ch38. x 15dB – Band 3: ch39 to ch53. x 14dB – Band 4: ch54 to ch69.

3.10. Module 4456 – 60A Multiple Power Supply

In the ADVANCED TV line all DC power supplies uses a switching technology, type full-bridge powered by 208 up to 240 Vac, showing overall efficiency above 80%. As part of the power supply design, there is a power factor corrector, PFC, circuit. Besides correct the power factor to close to 1, this circuit also contributes to reduce the

harmonic content returning from the unit into the AC mains.

AT7400 Owner Manual Rev. 2.0 – October 2006 -10-23 Section 3 - 27/39

Fig. 3.13: Module 4456 – 60A multiple power supply

The module 4456 generates the following voltage values for this drawer internal use only:

Voltage Current

+32V Fixed 2A +32V ON/OFF according to command. 15A +15V Direct 1A +15V 2A

-15V 200 mA +5V 5 A +2.5V 5 A

Table 2 - Module 4456: Listing of Voltage and current, per each power supply.

The multiple power supply module 4456 is composed by the following PCB’s:

AT7400 Owner Manual Rev. 2.0 – October 2006 -10-23 Section 3 - 28/39

Fig. 3.13: Module 4456 - Circuit functions: electrical schematic diagram, (CIM), and printed circuit board, (CIP).

AT7400 Owner Manual Rev. 2.0 – October 2006 -10-23 Section 3 - 29/39

3.10.1. Module 4456 – Block Diagram

AT7400 Owner Manual Rev. 2.0 – October 2006 -10-23 Section 3 - 30/39