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DSP Exciter

USER MANUAL

P N 9110 . 0 0172 (old part number = 916-T70A-003)

REV N

RELEASED

Specifications subject to change without notice

means—graphic, electronic, or mechanical, including photocopying, recording, taping, or

information-retrieval system—without written permission of ISC Technologies.

DSP Exciter Issue 1, Rev. N: 09/25/11

Document Change Record Issue 1, Rev. N: 09/25/11

Document Change Record

Issue: Rev D

Date: 4/25/96

Changes: changed VCO-2 status reading

Issue: Rev E

Date: 5/14/96

Changes: added Over-The-Link and On-The-Fly information

Issue: Rev F

Date: 5/23/96

Changes: added one RU space for reinstallation and net channel change time for setup

Issue: Rev G

Date: 9/03/96

Changes: changed PA fault input pin 11 on Table 4-4

Issue: Rev H

Date: 9/20/96

Changes: revised chapter 4 jumper information, added Table 4-5

Issue: Rev I

Date: 01/15/97

Changes: added and changed VCO board numbers in Table 3-1

Issue: Rev J

Date: 09/22/97

Changes: changed channel select 1 to J4-22, channel select 2 to J4-10, channel select 3 to

J4-6 in remote select input vs. channel table; changed channel select 1 to J1-7, channel select

2 to J1-26, and channel select 3 to J1-8 in remote select input vs channel I20 table; changed

mode select 2 line to channel select 4 as J1-9, and mode select 1 to J1-27 in remote select

input vs. mode I20 table

Issue: Rev K

Date: 11/12/97

Changes: changed multi-channel adjustment procedure to a reading of 2.8 volts

Issue: Rev L

Date: 05/14/99

Changes: added nominal powers for different frequency ranges in exciter specifications

table

Issue: Rev M

Date: 07/12/99

Changes: added GL-T8200 to part numbers of VCO/RF amplifier boards table

Issue: Rev N

Date: 9/25/11

DSP Exciter ISC Technologies Document Number: 9110.00172

Changes: Changes made to support Narrowband Directive

Table of Contents

1 GENERAL ................................................................................................................... 1-1

1.1 Manual Scope ..................................................................................................... 1-1

1.1.1 Applicable Documents .................................................................... 1-1

1.2 Manual Sections .................................................................................................. 1-1

1.3 Exciter Identification ..................................................................................... 1-1

2 SPECIFICATIONS ..................................................................................................... 2-1

3 DESCRIPTION ........................................................................................................... 3-1

3.1 Introduction ................................................................................................... 3-1

3.2 Physical Description ........................................................................................... 3-1

3.3 Simplified Block-Diagram Description .............................................................. 3-2

4 INSTALLATION AND SETUP ................................................................................. 4-1

4.1 Precautions and Hazards ..................................................................................... 4-1

4.2 Test Equipment and Tools Required ................................................................... 4-1

4.3 Component and Adjustment Locations ............................................................... 4-1

4.4 Installation ..................................................................................................... 4-1

4.4.1 Inspection ........................................................................................ 4-1

4.4.2 Power Requirement ................................................................................ 4-2

4.4.3 Input/Output Connections ............................................................... 4-2

4.4.4 Signal Functions .............................................................................. 4-2

4.4.5 Switches and Jumpers ..................................................................... 4-4

4.5 Setup .............................................................................................................. 4-4

4.6 Ultimate Disposition ........................................................................................... 4-4

5 OPERATION .............................................................................................................. 5-1

5.1 Front-Panel Controls and Indicators .............................................................. 5-1

5.2 Operating Instructions ................................................................................... 5-1

6 THEORY OF OPERATION ...................................................................................... 6-1

6.1 Exciter/PA Control ............................................................................................. 6-1

6.1.1 Reference Source ............................................................................. 6-1

6.1.2 Main Circuit Frequencies ................................................................ 6-1

ISC Technologies Document Number: 9110.00172 DSP Exciter

Issue 1, Rev. N: 09/25/11 Table of Contents

6.1.3 Controller Interface Connector Functions ....................................... 6-1

6.2 Interface to Controller ......................................................................................... 6-3

6.2.1 General ............................................................................................ 6-3

6.2.2 Interface Conversion Functions ....................................................... 6-3

6.3 DSP Modulator ................................................................................................... 6-4

6.3.1 General ............................................................................................ 6-4

Table of Contents Issue 1, Rev. N: 09/25/11

6.3.2 DSP Modulator Signal Flow ................................................................. 6-4

6.4 IF Stage .............................................................................................................. 6-7

6.4.1 Mixer-1 ........................................................................................... 6-7

6.4.2 Filter ............................................................................................... 6-7

6.4.3 VCO-1 ............................................................................................ 6-7

6.4.4 Synthesizer-1 .................................................................................. 6-7

6.5 MCU ................................................................................................................... 6-8

6.5.1 Microcontroller Unit (MCU) .......................................................... 6-8

6.5.2 Digital-to-Analog (D/A) Converter ................................................ 6-9

6.5.3 8/16-Bit Converter .......................................................................... 6-9

6.5.4 Read-Only Memory ............................................................................... 6-9

6.5.5 VSWR-Fault Detector ......................................................................... 6-14

6.5.6 Alarm Data-to-Logic Conversion ........................................................ 6-14

6.6 RF Assemblies .................................................................................................. 6-14

6.6.1 RF Stage Location ........................................................................ 6-14

6.6.2 RF Assemblies .............................................................................. 6-14

6.7 Voltage Regulator Circuit ................................................................................. 6-16

7 MAINTENANCE ....................................................................................................... 7-1

7.1 Location of Maintenance Procedures ................................................................. 7-1

7.2 Test Equipment Required ................................................................................... 7-1

7.3 VCO-2 Adjustment Procedure ........................................................................... 7-1

7.3.1 VCO-2 Multichannel Adjustment Procedure ........................................ 7-1

7.3.2 VCO-2 Single-Channel Adjustment Procedure ..................................... 7-1

7.4 Over-The-Link Downloading ............................................................................. 7-2

7.5 On-The-Fly Channel/Mode Changing ................................................................ 7-2

7.5.1 Programming Example ................................................................... 7-3

7.6 16-Channel Operation ........................................................................................ 7-4

7.7 On-The-Fly Interface .......................................................................................... 7-5

8 CHECKOUT AND TROUBLESHOOTING ........................................................... 8-1

8.1 CHECKOUT ...................................................................................................... 8-1

DSP Exciter ISC Technologies Document Number: 9110.00172

8.2 TROUBLESHOOTING ..................................................................................... 8-1

9 REMOVAL AND REINSTALLATION ................................................................... 9-1

9.1 Exciter/PA Control Chassis ................................................................................ 9-1

9.1.1 Removal Procedure ......................................................................... 9-1

9.1.2 Reinstallation Procedure ................................................................. 9-1

9.2 Exciter Cover ...................................................................................................... 9-2

9.2.1 Removal Procedure ......................................................................... 9-2

9.2.2 Reinstallation Procedure .................................................................. 9-2

9.3 Exciter/Control Board ......................................................................................... 9-5

9.3.1 Removal Procedure ......................................................................... 9-5

9.3.2 Reinstallation Procedure .................................................................. 9-5

9.4 Interface Board ................................................................................................... 9-8

9.4.1 Removal Procedure ......................................................................... 9-8

9.4.2 Reinstallation Procedure .................................................................. 9-8

9.5 VCO/RF Amplifier Board ................................................................................... 9-8

9.5.1 Removal Procedure ......................................................................... 9-9

9.5.2 Reinstallation Procedure .................................................................. 9-9

10 OPTIONS ................................................................................................................. 10-1

10.1 Exciter/PA Control with QT-1000 Interface ................................................... 10-1

10.1.1 Reference Source ............................................................................... 10-1

10.1.2 Controller Interface Connector Functions .......................................... 10-1

10.1.3 QT-1000 Interface Conversion Functions .......................................... 10-1

10.2 Exciter/PA Control with Standard Interface ................................................... 10-5

10.2.1 Reference Source ............................................................................... 10-5

10.2.2 Controller Interface Connector Functions .......................................... 10-6

10.2.3 Standard Interface Conversion Functions .......................................... 10-6

ISC Technologies Document Number: 9110.00172 DSP Exciter

Issue 1, Rev. N: 09/25/11 Table of Contents

10.3 Exciter/PA Control with I20 Interface ............................................................ 10-9

10.3.1 Reference Source ............................................................................... 10-9

10.3.2 Controller Interface Connector Functions .......................................... 10-9

10.3.3 I20 Interface Conversion Functions ................................................... 10-9

Table of Contents Issue 1, Rev. N: 09/25/11

DSP Exciter ISC Technologies Document Number: 9110.00172

Issue 1, Rev. N: 09/25/11 List of Figures

List of Figures

Figure 1-1 DSP Exciter Isometric View ......................................................................... 1-2

Figure 3-1 DSP Exciter Rear View ................................................................................. 3-3

Figure 3-2 DSP Exciter Top View

with Internal Controls and Indicators ........................................................ 3-4

Figure 3-3 DSP Exciter Simplified Functional Diagram ................................................ 3-5

Figure 4-1 DSP Exciter/PA Control Circuit Boards

Interconnection Diagram ........................................................................... 4-5

Figure 5-1 Front-Panel Controls and Indicators .............................................................. 5-2

Figure 6-1 DSP Exciter RF Stage Functional Diagram .................................................. 6-2

Figure 6-2 DSP Exciter MCU Circuit Functional Diagram ............................................ 6-6

Figure 6-3 DSP Exciter-to-Controller Functional Diagram ............................................ 6-10

Figure 6-4 DSP Exciter Detailed Functional Diagram .................................................... 6-12

Figure 6-5 DSP Exciter IF-Stage Detailed

Functional Diagram ................................................................................... 6-13

Figure 7-1 On-The-Fly C2000 Control Lines to DSP Exciter ........................................ 7-5

Figure 9-1 DSP Exciter Chassis Removal

and Reinstallation ...................................................................................... 9-3

Figure 9-2 DSP Exciter Cover Removal

and Reinstallation ...................................................................................... 9-4

Figure 9-3 DSP Exciter Control Board Removal and Reinstallation .............................. 9-7

ISC Technologies Document Number: 9110.00172 DSP Exciter

Figure 9-4 DSP Exciter External Interface I/O Board

Removal and Reinstallation ....................................................................... 9-10

Figure 9-5 DSP Exciter Interface Board Removal and Reinstallation ............................ 9-11

List of Figures Issue 1, Rev. N: 09/25/11

DSP Exciter ISC Technologies Document Number: 9110.00172

Issue 1, Rev. N: 09/25/11 List of Tables

List of Tables

Table 1-1 Manual Contents ...................................................................................... 1-1

Table 2-1 Exciter Specifications .............................................................................. 2-1

Table 3-1 Part Numbers of VCO/RF Amplifier Boards ........................................... 3-1

Table 3-2 Part Numbers of Interface Boards ............................................................ 3-1

Table 3-3 Part Numbers of Interface I/O Boards ...................................................... 3-2

Table 3-4 Assembly and Control Board Numbers ................................................... 3-2

Table 4-1 Test Equipment Required ......................................................................... 4-1

Table 4-2 DSP Exciter I/O Connectors .................................................................... 4-2

Table 4-3 VT100 Interface Connector J3 Pin Assignments ..................................... 4-3

Table 4-4 Control Board Connector J6 Pin Assignments ......................................... 4-3

Table 4-5 Exciter Control Board Jumper Positions .................................................. 4-4

Table 6-1 Exciter RF/Main Circuit Frequencies ...................................................... 6-1

Table 7-1 Deviation and Offset Programming ......................................................... 7-3

Table 10-1 Interface Board Connector J4 (QT-1000) ................................................... 10-3

Table 10-2 Receiver Connector J5 Pin Functions

(QT-1000 with external I/O board) .......................................................... 10-4

Table 10-3 Remote Select Input vs. Channel (QT-1000) .............................................. 10-4

Table 10-4 Remote Select Input vs. Mode (QT-1000) .................................................. 10-5

Table 10-5 Interface Board Connector J4 (Standard) ................................................... 10-7

Table 10-6 Remote Select Input vs. Channel (standard) ............................................... 10-8

Table 10-7 Remote Select Input vs. Mode (standard) ................................................... 10-8

ISC Technologies Document Number: 9110.00172 DSP Exciter

Table 10-8 Interface Board Connector J1 ................................................................... 10-10

Table 10-9 Interface Board Connector J2 ................................................................... 10-11

Table 10-10 Remote Select Input vs. Channel (I20) ................................................... 10-12

Table 10-11 Remote Select Input vs. Mode (I20) ....................................................... 10-12

List of Tables Issue 1, Rev. N: 09/25/11

DSP Exciter ISC Technologies Document Number: 9110.00172

Issue 1, Rev. N: 09/25/11 GENERAL

1 GENERAL

1.1 Manual Scope

This manual is intended for use as a technical reference guide to the ISC Technologies DSP

exciter and contains information on exciter connection, setup, and maintenance.

1.1.1 Applicable Documents

Applicable ISC Technologies documents are listed in the applicable system manual.

1.2 Manual Sections

Refer to Table 1-1, Manual Contents. Also refer to table of contents in this manual.

Table 1-1 Manual Contents

section No. and

title

contents

1 General

this section

2 Specifications

exciter specifications

3 Descriptions

listing of options and assemblies covered, simplified description,

physical description, simplified block theory of operation

4 Installation and

Setup

exciter installation, setup, and lists of connections

5 Operation

list, description, and location of operator controls and indicators

6 Theory of Opera-

tion

assembly-level description of exciter operation

7 Maintenance

exciter maintenance

8 Checkout and

Troubleshooting

exciter checkout and troubleshooting

9 Removal and Re-

installation

procedures for removing and reinstalling exciter and exciter as-

semblies

10 Options

list and discussion of user selectable options

1.3 Exciter Identification

Refer to Figure Figure 1-1, DSP Exciter Isometric View, for an overall view of the exciter.

ISC Technologies Document Number: 9110.00172 DSP Exciter

GENERAL Issue 1, Rev. N: 09/25/11

v0 2 5 0. hg l

Figure 1-1 DSP Exciter Isometric View

DSP Exciter ISC Technologies Document Number: 9110.00172

Issue 1, Rev. N: 09/25/11 SPECIFICATIONS

2 SPECIFICATIONS

Refer to Table 2-1, Exciter Specifications, which lists the DSP exciter specifications.

Where possible, EIA or I-EIS A measuring methods were used in determining specifica-

tions. Note that some specifications are not addressed by either set of standards or the

prescribed methods were impractical.

Table 2-1 Exciter Specifications

characteristic

condition

specification

adjacent-channel noise

25-kHz channel spacing, in analog mode

-85 dBc

25-kHz channel spacing, in FSK mode

-75 dBc

alternate channel noise

25-kHz channel spacing

-95 dBc

spurious

-90 dBc

operating frequency range

determined by installed VCO/RF board

refer to Table 3-1

RF output power (mW, nominal)

keyed

150 MHz

280

300

450

900 (GL-T8500/GL-T8600)

900 (GL-T8501/GL-T8601)

250

500

1000

300

carrier frequency stability

steady state, -30° to

+60° C

10-MHz reference, int=0.005 ppm/yr,

ext=0.1 ppm/yr

FSK frequency/modulation stability

relative to carrier frequency stability

+/- 10 Hz max

FSK adjustment accuracy

+/- 10 Hz

analog offset resolution

1 Hz

number of channels

up to 8, depending on interface board and

controller

frequency spread

3 MHz at 900 MHz (12 MHz wideband

option)

7.5 MHz at 450 MHz

5 MHz at 150 MHz

audio input

level

-25 to +10 dBm (N/A for 138.0-174.0

MHZ & 406.0-470.0 MHz)

ISC Technologies Document Number: 9110.00172 DSP Exciter

impedance with transformer

600 ohm or 5 kohms balanced

SPECIFICATIONS Issue 1, Rev. N: 09/25/11

Table 2-1 Exciter Specifications (continued)

characteristic

condition

specification

audio response (N/A for 138.0-174.0

MHZ & 406.0-470.0 MHz)

flat, 50 to 2800 Hz; not referenced to 1

kHz; 60% deviation

+/-0.5 dB

preemphasized 6 dB per octave, 300 to

3000 Hz; 60% deviation

+/-0.75 dB

audio distortion (1-kHz reference at

60% deviation) (N/A for 138.0-174.0

MHZ & 406.0-470.0 MHz)

25-kHz channel spacing

less than 1.5%

audio response (tracking between

units) (N/A for 138.0-174.0 MHZ &

406.0-470.0 MHz)

level

0.1 dB max

delay

2 usec max

FM hum and noise (1-kHz reference

at 60% deviation) (N/A for 138.0-

174.0 MHZ & 406.0-470.0 MHz)

25-kHz spacing flat, 15-kHz bandwidth

-40 dB

25-kHz channel spacing preemphasized,

300 to 3000 Hz

-55 dB

AM hum and noise

standard

-34 dB

modulation types

analog, 2-level FSK, 4-level FSK avail-

able with some interfaces (No Analog for

138.0-174.0 MHZ & 406.0-470.0 MHz)

channel spacing

6.25 kHz

audio-backward compatibility

Standard (N/A for 138.0-174.0 MHZ &

406.0-470.0 MHz)

emissions

FCC

15K0F2D, 16K0F1D, 16K0F3E

9K6F1D for 138.0-174.0 MHZ & 406.0-470.0 MHz

5K60F2D for 138.0-174.0 MHz

power requirement

22-29 Vdc

less than 3 A

humidity

noncondensing

0 to 95% relative

external 10-MHz reference input

level

2Vp-p min

impedance

50 ohms

spurious above 8 MHz

-65 dBc max

spurious below 8 MHz

-50 dBc max

weight

4.8 lb (2.2 kg)

dimensions

8.75 in (22.25 cm) d x 19 in (48.25 cm) w

x 1.75 in (4.5 cm) h

temperature range

operating (nonderated)

-30° to +60° C

storage

-55° to +70° C

DSP Exciter ISC Technologies Document Number: 9110.00172

maximum elevation

to 10,000 ft (3050 m)

Issue 1, Rev. N: 09/25/11 DESCRIPTION

3 DESCRIPTION

3.1 Introduction

The DSP exciter contains a microprocessor that allows remote or local control of the exciter

and consolidates logic for varying degrees of PA control and monitoring through a video

display terminal (VDT). Operating characteristics of the exciter are controlled by the

selection of hardware options. It is frequency selectable by specifying the appropriate

internal frequency determining hardware and software. It is also capable of communicating

with several operating protocols through the proper selection of interface boards.

3.2 Physical Description

The exciter front panel of one RU (1.75 in) in height contains eight LEDs, two adjustments,

and one connector (also see section 5). The exciter chassis is nine inches deep and contains

three circuit boards and space for an oscillator (not used with some controllers).

Refer to Table 3-1, Part Numbers of VCO/RF Amplifier Boards, which shows

subassemblies used for various transmitter operating ranges.

ISC Technologies Document Number: 9110.00172 DSP Exciter

DESCRIPTION Issue 1, Rev. N: 09/25/11

Table 3-1 Part Numbers of VCO/RF Amplifier Boards

transmitter model

VCO/RF-amplifier board

frequency band (MHz)

VCO board assembly part

No.

control board

assembly part

No.

GL-T85/8601

929-941

263-0082-072

265-0082-001

936-948

263-0082-070

265-0082-001

924-936

263-0082-069

265-0082-001

GL-T85/8600

900-960 (wb)

263-0082-051/052/053/054/

055/062

265-0082-024/032

948-960

263-0082-055

265-0082-001

936-948

263-0082-054

265-0082-001

929-941

263-0082-068

265-0082-001

924-936

263-0082-053

265-0082-001

GL-T8200

929-941

263-0082-068

265-0082-001

ISC-T53/5540

406-470

263-0084-003

not yet available

GL-T83/8531

320-330

263-0082-049

265-0082-001

GL-T83/8521

275-285

263-0082-047

265-0082-001

ISC-T84/8611

167-175

2100.00094

265-0082-024

162-172

2100.00093

265-0082-024

157-167

2100.00092

265-0082-024

152-162

2100.00091

265-0082-024

147-157

2100.00090

265-0082-024

142-152

2100.00089

265-0082-024

138-148

2100.00088

265-0082-024

Refer to Table 3-2, Part Numbers of Interface Boards.

Table 3-2 Part Numbers of Interface Boards

DSP exciter-to-controller interface boards

interface board part No.

QT-1000 interface bd

265-0082-007

standard Interface bd

263-0082-036

I20 interface bd

265-0082-032, 2000.00436

DSP Exciter ISC Technologies Document Number: 9110.00172

Issue 1, Rev. N: 09/25/11 DESCRIPTION

Refer to Figure 3-1, DSP Exciter Rear View, which shows the exciter rear panel. The back

panel contains three BNC-type connectors J3/J7/J8, a DB-15 connector J6, and a terminal

board TB 1 as standard items. Other back panel connectors vary depending on which

interface and I/O boards are installed. Figure 3-2, DSP Exciter Top View with Internal

Controls and Indicators, shows a top view of the exciter with its cover removed.

Refer to Table 3-3, Part Numbers of Interface I/O Boards, which shows interface and I/O

board part numbers. The I/O boards comprise the means to connect various controllers to

the DSP exciter..

Table 3-3 Part Numbers of Interface I/O Boards

interface I/O board (control type)

interface I/O board part No.

QT-1000 Interface I/O bd

261-0082-003

Standard Interface I/O bd

261-0082-004

I20 Interface I/O bd

N/A

Table 3-4 Assembly and Control Board Numbers

exciter assembly No.

control board No.

Various

265-0082-001

Various

265-0084-024

Various

2000.02090

3.3 Simplified Block-Diagram Description

Refer to Figure 3-3, DSP Exciter Simplified Functional Diagram, in the following discus-

sion. Inputs from the transmitter controller usually are one or two data bits, two channel-

select bits, and keying input. Outputs to the controller are keying output indicator, various

ISC Technologies Document Number: 9110.00172 DSP Exciter

fault outputs, forward-power sample, and reflected-power sample.

DESCRIPTION Issue 1, Rev. N: 09/25/11

v0 3 4 3. hg l

Figure 3-1 DSP Exciter Rear View

DSP Exciter ISC Technologies Document Number: 9110.00172

Issue 1, Rev. N: 09/25/11 DESCRIPTION

v0 3 4 4. hg l

ISC Technologies Document Number: 9110.00172 DSP Exciter

(N/A for 138.0-174.0 MHZ &

406.0-470.0 MHz)

DESCRIPTION Issue 1, Rev. N: 09/25/11

v0 2 5 1. hg l

Figure 3-3 DSP Exciter Simplified Functional Diagram

DSP Exciter ISC Technologies Document Number: 9110.00172

4 INSTALLATION AND SETUP

4.1 Precautions and Hazards

Caution

PC boards within this assembly use

static-sensitive components. Follow

IC-handling precautions.

Caution

The exciter contains internal memory which is used

to characterize exciter operation. Upon exciter

replacement, ensure that replacement exciter

contains appropriate items in its memory.

4.2 Test Equipment and Tools Required

Table 4-1, Test Equipment Required, lists required test equipment. Common hand tools may

also be required for most procedures.

Table 4-1 Test Equipment Required

item

description

tuning tool

Johanson 8777 or equivalent

RF power meter

Bird model 8327 or equivalent with appropriate RF adapters

voltmeter

Fluke model 77 DVM or equivalent

RF dummy load

50-ohm load

4.3 Component and Adjustment Locations

Figure 3-3, DSP Exciter Simplified Functional Diagram, shows the location of assemblies,

internal user-adjustable controls, and I/O locations. Note that most adjustments are

performed via the front-panel VT100 interface.

4.4 Installation

4.4.1 Inspection

Inspect exciter to ensure air flow is not obstructed and cables and wires are securely

fastened to their respective connectors.

ISC Technologies Document Number: 9110.00172 DSP Exciter

Issue 1, Rev. N: 09/25/11 INSTALLATION AND SETUP

4.4.2 Power Requirement

The DSP exciter, when used as a component of a transmitter, draws its power from system

wiring. Current draw is less than three amperes at 22 to 29 volts. It is normally powered by the

transmitter power supply but can be powered by an auxiliary supply.

4.4.3 Input/Output Connections

Figure 3-3, DSP Exciter Simplified Functional Diagram, shows the locations of I/O

connectors; Table 4-2, DSP Exciter I/O Connectors, lists I/O connectors and describes their

functions. Normally the exciter is delivered as part of an entire transmitter and has already

been installed in a rack, with all connections already made, except for connections to

equipment that was not installed in the rack before shipment. If I/O connections are

required, refer to the system-interconnect diagram and other instructions in the transmitter

manual.

4.4.4 Signal Functions

See Table 4-2, DSP Exciter I/O Connectors, which references other tables that describe pinby-

pin functions of multipin connectors. Figure 4-1, DSP Exciter/PA Control Circuit Boards

Interconnection Diagram, shows interconnections among internal assemblies.

Table 4-2 DSP Exciter I/O Connectors

stencil/connector

description

additional

detail

VT100 INTERFACE: J3

VT100 interface to VDT (front)

Table 4-3

RF OUT: J3

RF out, on frequency

Figure 6-1

QT-1000 interface I/O J4

interface to QT-1000 interface board

Table 10-1

QT-1000 interface I/O J5

DB-9 connector, to receiver

Table 10-2

standard interface I/O J4

interface to standard interface I/O board

Table 10-1

GL-C2000 interface I/O J4

interface to GL-C2000 interface I/O board

PA CONTROL: J6

connects to PA

Table 4-4

ISOLATOR IN: J7

VSWR input from PA

Figure 3-1

10 MHZ IN: J8

external reference input from interface

Figure 3-1

+26 VDC: TB1

exciter input power, +22-29 Vdc

Figure 3-1

DSP Exciter ISC Technologies Document Number: 9110.00172

INSTALLATION AND SETUP Issue 1, Rev. N: 09/25/11

Table 4-3 VT100 Interface Connector J3 Pin Assignments

J3-X (front)

signal

description

TXD

transmit data line

RXD

receive data line

GND

ground

1,4,6,7,8,9

not used

Table 4-4 Control Board Connector J6 Pin Assignments

J6-X

signal

description

J6-X

signal

description

A/D1+

multiplex analog

input from PA No. 1

multiplexer

A/D2+

multiplex analog input

from PA No. 2 multi-

plexer

A/D3+

multiplex analog

input from PA No. 3

multiplexer

A/D4+

multiplexed analog input

from PA No. 4 multi-

plexer

AGC REF+

GC reference voltage

output to PA, 1-12 Vdc

PA FAULT

PA fault input, HI=fault

PA GROUND

no connection

PA GROUND

no connection

PA GROUND

no connection

INPUT

SELECT 1

one of four select outputs

to PA multiplexers,

LO=20 digit enabled for

mux input decoder

INPUT

SELECT 2/

KEY OUT

one of four select out-

puts to PA multiplexers,

LO=21

INPUT

SELECT 3

one of four select outputs

to PA multiplexers,

LO=22 digit enabled for

mux input decoder

INPUT

SELECT 4/

KEY OUT

one of four select out-

puts to PA multiplexers,

not used

AUX LATCH

ENABLE

latch-enable output to PA

multiplexers, LO=mux

input decoder reads the

three select inputs

REF SAMPLE

reflected power sample

input from PA

ISC Technologies Document Number: 9110.00172 DSP Exciter

Issue 1, Rev. N: 09/25/11 INSTALLATION AND SETUP

4.4.5 Switches and Jumpers

Figure 3-2, DSP Exciter Top View with Internal Controls and Indicators, shows the

locations of user-adjustable switches and jumpers. Refer to Table 4-5 for a list of software

related jumper positions found on the exciter/control board. No switches are available to

maintenance personnel.

Table 4-5 Exciter Control Board Jumper Positions

Jumper

pre version 2.10 software

version 2.10 software

JW 1

set to A for external 10 MHz oscillator

set to B for internal 10 MHz oscillator

JW2

set to A for password protection

set to B to bypass password protection

JW3

set to A for external VSWR protection

always set to B (for internal and/or ex-

ternal VSWR protection)

set to B for internal VSWR protection

4.5 Setup

Note

When doing a setup for a wideband DSP exciter, the net channel change

time must be set for 300 ms.

Refer to the DSP exciter VDT Menus and user manual for transmitter-control setup infor-

mation. All setup is done via the front-panel VT100 interface.

4.6 Ultimate Disposition

Caution

This equipment may contain hazardous materials.

Check with the local EPA or other environmental

authority before disposing of this equipment.

DSP Exciter ISC Technologies Document Number: 9110.00172

INSTALLATION AND SETUP Issue 1, Rev. N: 09/25/11

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Figure 4-1 DSP Exciter/PA Control Circuit Boards

Interconnection Diagram

ISC Technologies Document Number: 9110.00172 DSP Exciter

Issue 1, Rev. N: 09/25/11 INSTALLATION AND SETUP

DSP Exciter ISC Technologies Document Number: 9110.00172

INSTALLATION AND SETUP Issue 1, Rev. N: 09/25/11

5.1 Front-Panel Controls and Indicators

Refer to Figure 5-1, Front-Panel Controls and Indicators, which shows and describes

front-panel indicators. The DSP exciter contains no front-panel controls. A front-panel

access to VCO adjustment is for maintenance purposes only.

5.2 Operating Instructions

The transmitter controller operates the exciter and transmitter in an unattended manner

during normal system operation. The VT100 interface with a VDT enables the maintenance

technician to perform maintenance and observe operational parameters. Refer to the DSP

exciter VDT Menus and user manual for detailed operating information.

ISC Technologies Document Number: 9110.00172 DSP Exciter

Issue 1, Rev. N: 09/25/11 OPERATION

5 OPERATION

OPERATION Issue 1, Rev. N: 09/25/11

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Figure 5-1 Front-Panel Controls and Indicators

DSP Exciter ISC Technologies Document Number: 9110.00172

6 THEORY OF OPERATION

6.1 Exciter/PA Control

Refer to Figure 6-1, DSP Exciter RF Stage Functional Diagram, which describes the signal

flow in the DSP exciter with the transmitter controller interface. The following major para-

graphs describe the operation of the major items within the figure. Additional detailed

figures are referenced, as required.

6.1.1 Reference Source

The ten-MHz reference signal is provided by the transmitter controller or by an optional

internal reference oscillator. All other inputs and outputs, except for RF output, are routed

through the interface board.

6.1.2 Main Circuit Frequencies

The VCO/RF amplifier board installed determines the frequency for the RF output. Table

6-1, Exciter RF/Main Circuit Frequencies lists VCO/RF amplifier board frequencies and the

corresponding exciter/output frequencies.

Table 6-1 Exciter RF/Main Circuit Frequencies

exciter

output

frequency

(MHz)

first IF

frequency

(kHz)

second IF

frequency

(MHz)

VCO-1

frequency

(MHz)

VCO-2

frequency

(MHz)

900-960

100

89.9

810-870

445-470

100

89.9

355-380

275-330

100

89.9

365-420

130-180

100

89.9

220-270

6.1.3 Controller Interface Connector Functions

Refer to Table 4-2, DSP Exciter I/O Connectors and subsequent tables for a pin-by-pin

description of signal functions. The exciter interfaces with the transmitter controller

through the exciter interface I/O board. Connector P4 on the internal interface board

connects directly to J4 on the exciter. Alarm signals, consisting of transmitter alarm, fault,

and status signals, are supplied directly to the transmitter controller.

ISC Technologies Document Number: 9110.00172 DSP Exciter

Issue 1, Rev. N: 09/25/11 THEORY OF OPERATION

THEORY OF OPERATION Issue 1, Rev. N: 09/25/11

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Figure 6-1 DSP Exciter RF Stage Functional Diagram

DSP Exciter ISC Technologies Document Number: 9110.00172

6.2 Interface to Controller

6.2.1 General

The controller interface is the portion of exciter circuitry that connects the transmitter

controller to the exciter. The interface board dictates what kind of transmitter controller

may operate the transmitter. The transmitter can be operated through one of several control-

lers depending on which interface board is installed in the exciter. The internal interface

board may also exhibit an external I/O board.

Control commands from the transmitter controller are connected through the interface

circuit. This circuit supplies remote control to the microcontroller unit (MCU) control

circuit. The VT-100 VDT supplies local control. The MCU control circuit generates all

control signals for the other circuits, and monitors their status. The MCU control circuit

reports status back to the VT-100 VDT and the interface circuit, which supplies the status to

the transmitter controller.

6.2.2 Interface Conversion Functions

Some signals exchanged between the controller and the exciter originate with a format,

voltage, or requirement incompatible with their destination. The interface performs any

signal conversions necessary to provide compatibility between the controller and the

exciter. None, some, or all of the following conversion functions may be done by any one

particular interface board.

6.2.2.1 Analog-Mode A/D Conversion (N/A for 138.0-174.0 MHz &

406.0-470.0 MHz

The DSP modulator circuit reads synchronized serial data for its analog mode input signal. if

the transmitter controller provides an analog signal, the controller interface converts the

analog to the appropriate data form for the DSP. The analog (FLAT AUDIO+, -) terminates

across a balanced input circuit that also provides a level adjustment. The adjustment, when

properly set by the AUDIO INPUT ADJUST pot through the exciter cover, provides analog

to an A/D converter at the optimum zero-dBm level. The A/D converts the analog into

serial data, which is applied to the DSP through a synchronous data link. A synchronous

data link is characterized by an exchange of pulse streams for timing purposes. The A/D

converter is clocked by a pulse generator circuit driven by the ten-MHz reference circuit.

6.2.2.2 FSK-Data-Bit Strapping

The DSP modulator circuit can read up to four bits for its digital FSK mode input signal. If

the controller provides only bit 1 (DATA 1), operation in the four-level mode or higher is

precluded. Bits 2 through 4 (DATA2 through DATA4) are available as FSK data inputs;

whether they are used or not is a function of the particular controller interface used and the

transmitter controller. Refer to Section 10. The controller interface disables unused bits by

ground straps.

ISC Technologies Document Number: 9110.00172 DSP Exciter

Issue 1, Rev. N: 09/25/11 THEORY OF OPERATION

6.2.2.3 Channel-Select-Bit Strapping

The MCU control circuit reads three bits to determine the remotely selected channel. If the

controller provides only bits 1 and 2 (CH SEL 1, 2), the controller can command only four

channels. The operation of bit 3 is a function of the controller interface. Refer to Section 10.

6.2.2.4 Mode-Select-Bit Strapping

The MCU control circuit reads two bits to determine the remotely selected mode. If the

controller provides only bit 1 (MODE CONTROL), the controller can command only two

transmitter modes. The operation of bit 2 is a function of the controller interface. Refer to

Section 10. If the controller interface does not use bit 2, it straps it to ground (low).

6.2.2.5 Power Sample D/A Conversion

The controller reads sample voltages for its forward and reflected power sample inputs,

which are stored as data in the MCU control circuit. In some cases the controller interface

converts the data to voltages of the appropriate range for the controller. Data from the MCU

representing the forward and reflected powers is written into a dual D/A converter, which

converts the data into two proportional dc voltages, which are applied to the controller.

Control logic gates ensure that data is written to the proper half of the D/A converter.

6.3 DSP Modulator

6.3.1 General

The DSP modulator circuit converts the data into the first IF signal, which is fully modu-

lated. The IF stage circuit converts the first IF signal into the second IF signal. The RF stage

circuit converts the second IF signal into the RF output. Ten MHz is used as frequency

reference by each conversion stage. The DSP modulator is the portion of exciter circuitry

between the controller interface and the IF stage. The DSP modulator uses digital signal

processing to modulate and up-convert the paging information into the first IF signal. The

modulation type depends on the transmitter operating mode. The IF stage is the portion of

exciter circuitry between the DSP modulator and the RF stage. The IF stage uses hetero-

dyne mixing to generate the optimum second IF signal frequency, which depends on the

requirement of the VCO/RF amplifier board installed. The MCU control circuit is the

command and control hub of the transmitter. The type of control software depends on the

transmitter frequency and power output. The following text describes main exciter circuitry

that works for all software programs, modulation schemes, and IF signal frequencies.

Figure 6-2, DSP Exciter MCU Circuit Functional Diagram shows additional details.

6.3.2 DSP Modulator Signal Flow

Refer to Figure 6-2, DSP Exciter MCU Circuit Functional Diagram, in the following

discussion. The inputs that provide the paging information to the DSP modulator circuit are

digitized audio and FSK data, supplied by the controller interface circuit through connector

pair P 1/J1. Digitized audio arrives as serial data. FSK data arrives as parallel data. The DSP

modulator circuit processes the digitized audio in the analog mode or the FSK data in the

digital mode. The result of this processing is the exciter’s first IF signal, which is applied

DSP Exciter ISC Technologies Document Number: 9110.00172

THEORY OF OPERATION Issue 1, Rev. N: 09/25/11

to the IF stage circuit. To produce the first IF signal, the DSP modulator contains two DSPs

(a signal modulator and a quadrature modulator), a digital-to-analog converter, and a read-

only memory. The following text describes these four components and their signal flow.

6.3.2.1 Digital Signal Modulator

The signal modulator (SM) generates modulation that contains the paging information,

which is supplied by digitized audio or FSK data. The digitized audio is input into a serial

input port. An external edge detector is required to input the FSK data. The SM converts

one of the data inputs into a modulated signal, which is mathematically represented within

the SM as a vector signal, defined by its rectangular coordinates. These coordinates,

commonly known as I and Q, are supplied to the digital quadrature modulator as 16-bit

parallel data. The modulated signal output from the SM depends on the following signal

characteristics:

 modulation scheme

 frequency response or rise time

 input logic or data inversion

 deviation level or bandwidth

 offset from carrier frequency

 analog gain and deviation limit

The SM also performs all communications between the DSP modulator circuit and the

MCU control circuit. These communications are through the SM 16-bit parallel data port.

External input and output latches expand the capabilities of this port. Control inputs consist of

commands such as reset, request status, set paging signal parameter, change mode, and boot

program. Requested status outputs consist of current mode, deviation levels, input level,

input gain, modulation detected, and current polarity. Nonrequested status outputs indicate

the existence of analog limiting and modulation.

6.3.2.2 Digital Quadrature Modulator

The digital quadrature modulator (DQM) performs interpolation and up-conversion of the

modulated signal. The modulated signal input to the DQM is applied by the SM as I and Q

components (16-bit parallel data). The DQM performs trigonometric computations at a

much higher sampling rate, which determines the first IF signal value and frequency. The

modulated signal output from the DQM is supplied from its serial data port to the D/A

converter.

6.3.2.3 Digital-to-Analog Converter

The digital input to the digital-to-analog (D/A) converter is the modulated signal from the

DQM. This data arrives as serial data. The analog output from the D/A converter is the first

IF signal. In addition to the IF stage circuit, the first IF signal is supplied to the MCU

control circuit, where it is rectified and filtered to generate fault logic.

ISC Technologies Document Number: 9110.00172 DSP Exciter

Issue 1, Rev. N: 09/25/11 THEORY OF OPERATION

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Figure 6-2 DSP Exciter MCU Circuit Functional Diagram

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6.3.2.4 Read-Only Memory

A programmable and erasable read-only memory (PEROM) stores the modulator programs

for both DSPs. These programs are transferred to the SM when the exciter is booted up

(powered up), then the SM transfers the program to the DQM. The nonvolatile PEROM

retains its program for years. Its memory may be individually reprogrammed without

erasing the entire chip.

6.4 IF Stage

Refer to Figure 6-1, DSP Exciter RF Stage Functional Diagram. The input to the IF stage is

the first IF signal, which is supplied by the DSP modulator circuit. The first IF signal

carries all the paging information on an intermediate carrier frequency. The IF stage

performs direct up-conversion of the first IF signal to create the second IF signal, which

carries the same paging information as the first IF signal, but on a higher carrier frequency.

The second IF signal is applied to the RF stage through connector pair J10/P 10. To produce

the second IF signal, the IF stage contains mixer-1 and filter circuits. Supporting these

circuits are VCO-1 and synthesizer-1 circuits. Figure 6-2, DSP Exciter MCU Circuit Func-

tional Diagram, and Figure 6-3, DSP Exciter-to-Controller Functional Diagram, show

additional detail.

6.4.1 Mixer-1

Mixer-1 is the first heterodyne mixer. Inputs to mixer-1 are a modulated IF and a carrier.

The modulated IF input is the first IF signal. The carrier input is supplied by VCO-1. The

output from mixer-1 consists of two modulated carriers that are sums and difference

frequencies of the inputs. These two frequencies are applied to the filter circuit.

6.4.2 Filter

The filter is centered at the second IF signal frequency with a 45-kHz bandwidth. The input

to the filter consists of two modulated carriers. These are sum and difference frequencies

supplied by mixer-1. The output from the filter is only the sum frequency. This modulated

output is the second IF signal.

6.4.3 VCO-1

VCO-1 is the local oscillator for the IF stage. The input to VCO-1 is a dc control voltage.

This voltage controls VCO-1 carrier frequency and is supplied by synthesizer-1. The output

from VCO-1 is a sine-wave carrier. The output is applied to mixer-1.

6.4.4 Synthesizer-1

Synthesizer-1 controls VCO-1 carrier frequency by means of a phase-locked loop (PLL).

PLL inputs are a carrier and a phase reference. The reference input is a ten-MHz carrier

supplied by the ten-MHz reference circuit. The carrier input is from VCO-1. The PLL

output is a dc control voltage. This voltage, set to cause the VCO-1 carrier to lock phases

with the reference, is supplied to VCO-1.

ISC Technologies Document Number: 9110.00172 DSP Exciter

Issue 1, Rev. N: 09/25/11 THEORY OF OPERATION

Synthesizer-1 also performs all communications between the IF stage circuit and the MCU

control circuit. A control input specifies the VCO-1 carrier frequency; this data is received

over a serial data link when the exciter is booting or changing channels. Status outputs are a

lock fault and a VCO1 level. The lock fault indicates loss of the carrier/reference phase lock.

The VCO1 level is the VCO-1 control voltage.

6.5 MCU

Refer to Figure 6-4, DSP Exciter Detailed Functional Diagram. Control outputs are

supplied by the MCU control circuit to the other functional circuits. Likewise, status inputs

are applied to the MCU control circuit from the other functional circuits. Discussions of

these control and status signals are included with the information on the other major func-

tional circuits. To interface these control and status signals, the MCU control circuit

contains an MCU, D/A converter, 8/16 bit converter, read-only memory, and a VSWR-fault

detector. To light the front-panel LEDs, the MCU control circuit contains a bank of PNP

switching transistors.

Refer to Figure 6-2, DSP Exciter MCU Circuit Functional Diagram, in the following text

which describes this circuitry and its signal flow.

6.5.1 Microcontroller Unit (MCU)

The MCU contains a central processing unit (CPU), memories, peripherals, and other

hardware on a single chip. The primary internal functions of the MCU and their application

in the exciter are described in the following list.

 An eight-bit remote input port accepts discrete low power mode, emission mode, keyline,

and channel selects from the controller interface circuit. An external edge detector is

required to input the channel selects.

 Interrupt logic stops RF transmission when a fault or reset input is received, e.g. a VSWR

or PA fault.

 An on-board oscillator/clock generator, driven by an external crystal, times internal

MCU functions. A synchronized clock output times external functions.

 The MCU performs most interfacing through a parallel communications link: eight-bit

data bus, sixteen-bit address bus, and a read/write line. External input and output latches

expand the capability of this link.

 An eight-bit input/output port supplies discrete keyline, RF status, and chip select

controls to the exciter and the PA.

 A serial peripheral interface (SPI) supplies synchronous serial frequency data to the IF

stage and RF stage circuits. Individual commands load the program into either IF stage’s

synthesizer-1 or RF stage synthesizer-2.

 An 8-input analog-to-digital (A/D) converter measures voltage inputs from the exciter

and the PA. An external multiplexer expands MCU analog inputs to fifteen.

 A serial communications interface (SCI) exchanges asynchronous serial RS-232 data

with the VT-100 VDT. An external RS-232 driver buffers the MCU data, allowing it to be

exchanged through external connector J3.

 A random-access memory (RAM) temporarily stores transmitter fault and alarm values.

DSP Exciter ISC Technologies Document Number: 9110.00172

THEORY OF OPERATION Issue 1, Rev. N: 09/25/11

• An electrically-erasable read-only memory (EEPROM) permanently stores transmitter

signal parameters.

6.5.2 Digital-to-Analog (D/A) Converter

A D/A converter generates an AGC reference voltage. The D/A converter inputs are data

and select logic. The data, supplied by the MCU when the D/A is selected, represents the

desired transmitter power output. The D/A converter output is an AGC reference voltage.

This voltage represents a level proportional to the desired transmitter power output. The

AGC reference voltage, output through connector J6, is used by the PA to generate an AGC

voltage.

6.5.3 8/16-Bit Converter

An 8/16-bit converter allows the MCU eight-bit data bus to communicate with the 16-bit

data bus of the DSP modulator circuit. The MCU must perform two read or write proce-

dures, a low byte and a high byte, to each one of the DSP modulator circuit. The converter

provides two status outputs to the MCU and the DSP modulator circuit. A data-availableto-

MCU status indicates that the DSP modulator circuit has written data into the converter that

the MCU must read. A data-available-to-DSP status indicates that the MCU has written data

into the converter that the DSP modulator circuit must read. In the event that the DSP

modulator circuit does not read data that the MCU has written, a DSP communications fault

is generated.

6.5.4 Read-Only Memory

A programmable and erasable read-only memory (PEROM) stores the control program for

the transmitter. This program is transferred to the MCU when the exciter is booted up. The

nonvolatile PEROM retains its program for years. Its memory may be individually repro-

grammed without erasing the entire chip.

ISC Technologies Document Number: 9110.00172 DSP Exciter

Issue 1, Rev. N: 09/25/11 THEORY OF OPERATION

Figure 6-3 DSP Exciter-to-Controller Functional Diagram

v0 34 5l 7

DSP Exciter ISC Technologies Document Number: 9110.00172

THEORY OF OPERATION Issue 1, Rev. N: 09/25/11

v0 3 4 5R .h gl

ISC Technologies Document Number: 9110.00172 DSP Exciter

Issue 1, Rev. N: 09/25/11 THEORY OF OPERATION

Figure 6-3 DSP Exciter-to-Controller Functional Diagram

(Continued)

v0081.hgll

Figure 6-4 DSP Exciter Detailed Functional Diagram

DSP Exciter ISC Technologies Document Number: 9110.00172

THEORY OF OPERATION Issue 1, Rev. N: 09/25/11

v0 07 7. hg lr

Figure 6-5 DSP Exciter IF-Stage Detailed

Functional Diagram

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Issue 1, Rev. N: 09/25/11 THEORY OF OPERATION

6.5.5 VSWR-Fault Detector

The exciter receives a VSWR signal from the PA through connector J7. This signal is a

rectified dc voltage sample generated by the isolator. The voltage sample is monitored by the

MCU to provide the value for the total reflected-power indication. The voltage sample is also

monitored by a fault circuit in the exciter. If a factory-preset voltage is exceeded, the fault

circuit shuts down the transmitter by an interrupt to the MCU.

6.5.6 Alarm Data-to-Logic Conversion

The transmitter controller reads logic alarm inputs; most of these alarms are stored as data in

the MCU control circuit. If the controller interface converts the data to individual logic

signals for the controller, data from MCU control representing the alarms is clocked into a

pair of latches. The latches convert the data into continuous logic signals. These signals and

others control a bank of NPN switching transistors that supply the actual logic signal to the

controller. Control logic gates convert chip controls from the MCU into a clock input for

the latches.

6.6 RF Assemblies

6.6.1 RF Stage Location

Refer to Figure 3-3, DSP Exciter Simplified Functional Diagram, to locate the assembly. The

RF stage circuits are located on two circuit boards, both housed within the exciter

chassis.The exciter/control board is the main circuit board and the VCO/RF amplifier board

is a selected option. The exciter/control board connects to the VCO/RF amplifier board

through three connector pairs: J4/P4, J9/P9, and J10/P10. The VCO/RF amplifier board

also contains BNC connector J3, which extends through the rear panel of the exciter. This

board contains most of the RF stage components inside an RF shield. A hole in the shield and

the front panel provide access to an RF stage adjustment, which is marked VCO ADJ on the

front panel.

6.6.2 RF Assemblies

6.6.2.1 RF Stage Description

The RF stage is the portion of exciter circuitry between the IF stage and RF out and is the

final maj or functional circuit, the RF stage determines the transmitter RF output frequency,

and dictates the highest and lowest possible RF output frequencies (RF band). The trans-

mitter can be operated at several RF bands, depending on the RF stage circuitry installed in

the exciter.

6.6.2.2 RF Stage Bands

The selected VCO/RF amplifier board determines the RF band of the transmitter. Table 3-1,

Part Numbers of VCO/RF Amplifier Boards, lists the RF bands and the part number of the

board with that RF band.

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THEORY OF OPERATION Issue 1, Rev. N: 09/25/11

6.6.2.3 RF Stage Signal Flow

Refer to Figure 6-1, DSP Exciter RF Stage Functional Diagram. The input to the RF stage is

the second IF signal, supplied by the IF stage circuit through connector pair J10/P 10. The

second IF signal carries the paging information on a modulated carrier at the exciter’s

second intermediate frequency. The RF stage converts the second IF signal into the

exciter’s RF output. This RF output carries the same paging information as the second IF

signal, but on a modulated carrier of radio frequency. The RF output is normally applied to

the PA through connector J3. To produce the RF output, the RF stage contains mixer-2, a

filter, and an amplifier. Supporting these circuits are VCO-2 and synth-2. The following

text describes these five circuits and their signal flow.

6.6.2.3.1 Mixer-2

Mixer-2 is the second heterodyne mixer. Inputs to mixer-2 are a modulated IF and a carrier.

The modulated IF is the second IF signal. The carrier is supplied by VCO-2. Output from

mixer-2 consists of sum and difference frequencies of the inputs. The sum frequency is

centered near the channel carrier, and the difference frequency about twice the second IF

frequency below that. These two modulated RF carriers are applied to the filter circuit.

6.6.2.3.2 Filter

The filter is factory-selected and tuned, with a bandwidth determined by carrier frequency of

the transmitter. The inputs to the filter consist of two modulated RF carriers and a key

control.The two carriers are sum and difference frequencies, supplied by mixer-2. The key

control is supplied by the MCU control circuit through J4/P4. The output from the filter,

supplied when the key control is received, is only the sum frequency. This modulated RF,

centered near the channel on-frequency, is supplied to the amplifier.

6.6.2.3.3 Amplifier

The amplifier provides amplification to the value listed in the specifications as exciter RF

power out. The inputs to the amplifier consist of modulated RF and a key control. The

modulated RF, mixer-2 sum output frequency, is supplied through the filter. Key control is

supplied by the MCU control circuit through J4/P4. Output from the amplifier, supplied

when the key control is received, is an amplified version of the modulated RF. This

amplified output is the exciter RF output.

6.6.2.3.4 VCO-2

VCO-2 is the RF stage local oscillator. Inputs to VCO-2 are a dc control voltage and an

adjustment. Dc control voltage is supplied by synthesizer-2. The adjustment, which varies the

VCO2 control voltage level, is controlled through the front-panel VCO ADJ access. This

control provides the means for VCO-2 to output a carrier frequency that would otherwise

be beyond the range of the control voltage input. The carrier output, always second IF

frequency below the channel carrier frequency, is applied to mixer-2.

ISC Technologies Document Number: 9110.00172 DSP Exciter

Issue 1, Rev. N: 09/25/11 THEORY OF OPERATION

6.6.2.3.5 Synthesizer-2

Synthesizer-2 controls VCO-2 carrier frequency by means of a phase-locked loop (PLL).

PLL inputs to synthesizer-2 are a carrier and a phase reference. The reference is a ten-MHz

carrier supplied by the ten-MHz reference circuit. The carrier is the VCO-2 output. The PLL

output from synthesizer-2 is a dc control voltage. This voltage, set to cause VCO-2 to lock

phases with the reference, is applied to the VCO-2 control input.

Synthesizer-2 also performs all communications between the RF stage circuit and the MCU

control circuit. A control input to synthesizer-2 specifies VCO-2 carrier frequency. This data

is received over a serial data link when the exciter is booting or changing channels. Status

outputs from synthesizer-2 are a lock fault and a VCO2 level. The lock fault indicates loss of

the carrier/reference phase lock. VCO2 level is the VCO-2 control voltage.

6.7 Voltage Regulator Circuit

Refer to Figure 6-4, DSP Exciter Detailed Functional Diagram (center, toward bottom) in the

following discussion. The exciter receives 26-volt operating power through terminal board

TB 1. The dc power indicator on the exciter front panel is connected to this input. This

voltage is supplied to a 26-volt bus and is monitored by the MCU. An intermediate regulator

reduces the 26 volts to 16.5 volts, which is supplied to the two final regulators. One

regulator generates 13.5 volts, which is supplied to a 13.5-volt bus and monitored by the

MCU. The other regulator generates 5 volts, which is supplied to a five-volt bus and

monitored by the MCU.

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7 MAINTENANCE

7.1 Location of Maintenance Procedures

The DSP exciter is central to performing transmitter maintenance. Most maintenance of

electrical assemblies is done via the VT100 interface. Any maintenance procedures which

require adjusting controls within the exciter chassis are listed in this section.

Replace the exciter if it has input power, as indicated by the front-panel LED, but does not

allow the user to make connection via the VT100 interface.

7.2 Test Equipment Required

Table 4-1, Test Equipment Required, lists test equipment required to perform maintenance

procedures.

7.3 VCO-2 Adjustment Procedure

Perform the VCO-2 adjustment procedure after installing new VCO/RF amplifier board or

after setting new channel carrier frequency. If the transmitter is to operate at more than one

frequency, perform the multichannel adjustment procedure. If the transmitter is to operate at

only one frequency, perform the single-channel adjustment procedure. Refer to the DSP

exciter VDT manual as necessary.

7.3.1 VCO-2 Multichannel Adjustment Procedure

1. Set up VT-100 VDT and select local control (see VDT manual).

2. Select transmitter channel of lowest frequency if not already selected.

3. Use tuning tool supplied to adjust VCO ADJ control through exciter front panel. Ad-

just for a reading of 2.8 volts (3.5 volts for wideband VCO 263-0082-062), on VCO2

status display.

4. Return transmitter to service.

Procedure is complete.

7.3.2 VCO-2 Single-Channel Adjustment Procedure

This procedure does not apply to wideband option.

1. Set up VT-100 VDT and select local control (see VDT manual).

2. Select transmitter channel of operating frequency if not already selected.

3. Use tuning tool supplied to adjust VCO ADJ control through exciter front panel. Ad-

just for reading of 5.0 Vdc on VCO2 status display.

4. Return transmitter to service.

Procedure is complete.

ISC Technologies Document Number: 9110.00172 DSP Exciter

Issue 1, Rev. N: 09/25/11 MAINTENANCE

7.4 Over-The-Link Downloading

Over-the-link (OTL) code downloading allows C2000 transmitter controller (C2000)

software, alarm matrix setup, and exciter software to be downloaded over the C2000 link

channel.

To properly use OTL downloading, C2000 units must be programmed for the correct

control group, site ID, and unit ID, which are integral to C2000 hardware and software.

When information is downloaded over the link channel, the control group, site IDs and/or

unit IDs that are to receive the code must be specified.

Caution

If the control group, site ID, and unit ID are not

specified, all units in the system accept the

download information. In a mixed system, this can

result in some of the transmitters being off the air.

An example of this would be a GL-T8600 exciter

receiving a GL-T8500 exciter programming code.

The GL-T8600 exciter would not operate with this

software and could result in a site visit to correct

the problem.

Programming of control groups and site IDs is done via the C2000 front port with a local

connection or through a modem from a remote location. The control groups should be setup

as a group of transmitters having the same configuration. For example, all GL-T8500 trans-

mitters could be in one control group and GL-T8600 transmitters be in another. This would

allow one to download exciter software to all GL-T8500 transmitters at one time by

selecting their control group. Any transmitter with a different control group would not

accept the download information.

Site ID must be different for each site location, and is used when downloading information to

a specific site location. If there are multiple units at the same site, the site ID and unit ID need

to be specified to download to a specific unit. If the unit ID is not specified, all units at that

site accept the download.

Unit ID is programmed with a rotary switch in the C2000; it must be different for each

C2000 at a site location. To download one specific unit, both site and unit ID must be

specified for that unit; the unit with that site ID and unit ID is the only one that accepts the

download.

For assistance on how to perform a download, call ISC Technologies customer support at

217-221-0985.

7.5 On-The-Fly Channel/Mode Changing

Different paging formats may require different digital deviation and offsets of paging data on

the same RF carrier frequency. In the past, the only way to meet the different deviation

requirements on the same frequency was to program two different channels for the same

RF carrier frequency and then program those same two channels for a different digital

DSP Exciter ISC Technologies Document Number: 9110.00172

MAINTENANCE Issue 1, Rev. N: 09/25/11

deviation and offset. By changing channels, the deviation requirements of the paging

formats were met. However, a channel change requires that the transmitter be unkeyed to

allow time for PLL lock-up, which is a loss of air time.

The on-the-fly feature allows the following:

 Each channel can be programmed for four different digital modes (A, B, C, D)

 Each mode allows different digital deviation and offsets to be programmed

During normal paging operation, the C-2000 controller sends information to the transmitter

telling it what channel to operate on and which one of the four digital modes to use. The

four different digital modes of operation are controlled by the data 2 and data 3 lines into

the C-2000 interface board on the DSP exciter. If the paging data requires a different devi-

ation, the C-2000 transmitter controller can change the mode without having to change the

channel. This allows the DSP exciter to accommodate different paging format requirements

without unkeying the transmitter to change channels.

7.5.1 Programming Example

To set up the exciter for the proper digital deviation and offset programming, make up a

table similar to the one shown below. Next, access Digital Mode Setup menu and select

View Channel Frequencies submenu.

Table 7-1 Deviation and Offset Programming

Channel

1&9

2&10

3&11

4&12

5&13

6&14

7&15

8&16

Mode/Dev.A

4500

Mode/Offset A

+400

-400

+300

-300

Mode/Dev.B

4800

Mode/Offset B

+200

-200

+400

-400

Mode/Dev.C

2400

4200

2400

4200

2400

4200

Mode/Offset C

Mode/Dev.D

4200

2400

4200

2400

4200

2400

Mode/Offset D

+400

-400

Note

Initial release has setup similar to above table. Subsequent releases may

have more programming variations

ISC Technologies Document Number: 9110.00172 DSP Exciter

Issue 1, Rev. N: 09/25/11 MAINTENANCE

Note

When on-the-fly software is used with a QT-1000 interface board

installed in the exciter, only the deviation and offset programming for

mode D is available. References in the exciter menus pertaining to modes

A, B, and C are blanked out.

7.5.1.1 Release 2.10 DSP Exciter

The C-2000 transmitter controller detects a FLEX baud rate of 1600. When this condition is

detected, the mode control lines to the DSP exciter change it to mode B. If the FLEX baud

rate is not detected, the mode control lines are set for mode A. This requires that mode A

deviation (and offset) be set for POCSAG (512, 1200 or 2400 baud), Golay, NEC and any

other paging format other than FLEX requirements. Mode B deviation and offset must be

set for FLEX. Mode C and D are not used.

7.6 16-Channel Operation

With 16-channel capability, the on-the-fly digital mode programming is only programmable

on 8 channels. When channels 1 through 8 are programmed for different modes, channels 9

through 16 follow the same mode programming respectively (i.e. channel 9 is the same as

1, channel 10 is the same as 2, etc.). Selecting additional channels (9 through 16) is

achieved by the C-2000 controller pulling mode-1 line low to the C-2000 interface board.

DSP Exciter ISC Technologies Document Number: 9110.00172

MAINTENANCE Issue 1, Rev. N: 09/25/11

7.7 On-The-Fly Interface

Figure 7-1 On-The-Fly C2000 Control Lines to DSP Exciter

ISC Technologies Document Number: 9110.00172 DSP Exciter

Issue 1, Rev. N: 09/25/11 MAINTENANCE

Notes:

A C-2000 interface board in the DSP exciter must be used with on-the-fly software

All J1 pin connections shown on the above diagram are at the input to the C-2000 interface

board in the DSP exciter

Data 0 at the input of the C-2000 interface board controls Data 1 at its output

Data 1 at the input of the C-2000 interface board controls Data 2 at its output

Data 2 at the input of the C-2000 interface board controls Data 3 at its output

Data 3 at the input of the C-2000 interface board controls Data 4 at its output

Mode 0 at the input of the C-2000 interface board controls Mode sel 1 at its output

Mode 1 at the input of the C-2000 interface board controls Mode sel 2 at its output

Freq 0 at the input of the C-2000 interface board controls Ch select 1 at its output

Freq 1 at the input of the C-2000 interface board controls Ch select 2 at its output

Freq 2 at the input of the C-2000 interface board controls Ch select 3 at its output

DSP Exciter ISC Technologies Document Number: 9110.00172

MAINTENANCE Issue 1, Rev. N: 09/25/11

Issue 1, Rev. N: 09/25/11 CHECKOUT AND TROUBLESHOOTING

8 CHECKOUT AND TROUBLESHOOTING

8.1 CHECKOUT

The DSP exciter has two functions; it produces on-frequency RF and has a microprocessor to

handle input from the PA and transmitter controller. Checkout involves verifying that RF is

produced and unkeying occurs during a fault condition.

8.2 TROUBLESHOOTING

The recommended troubleshooting level for the exciter is at the unit level. That is, if the

exciter fails to provide the transmitter system with a usable, modulated RF-drive signal and

all the exciter’s power, control, and signal inputs are normal, you should replace the exciter

with a spare.

ISC Technologies Document Number: 9110.00172 DSP Exciter

DSP Exciter ISC Technologies Document Number: 9110.00172

CHECKOUT AND TROUBLESHOOTING Issue 1, Rev. N: 09/25/11

Issue 1, Rev. N: 09/25/11 REMOVAL AND REINSTALLATION

9 REMOVAL AND REINSTALLATION

Remove all input power from transmitter cabinet before performing these procedures.

9.1 Exciter/PA Control Chassis

Refer to Figure 9-1, DSP Exciter Chassis Removal and Reinstallation , for a detailed

drawing.

Note

Memory PROMs in the replacement exciter should be the same as in the

original exciter unless the maintenance technician intends to modify

exciter characteristics. Also, parameters, such as channel frequencies,

may be stored in nonvolatile RAM. Ensure that the replacement exciter is

programmed correctly.

9.1.1 Removal Procedure

1. Support exciter while removing the four screws from the front panel that secure it to

the cabinet. Save screws for installation procedure.

2. Remove exciter from cabinet far enough to access back panel.

3. Disconnect connector J3 from connector P3 that is pigtailed off terminal board TB 1

(dc power input).

4. If a controller interface I/O panel is mounted on exciter back panel, remove I/O panel;

leave all wires connected to I/O panel.

5. Tag all connectors attached to the exciter back panel.

6. Remove all connectors attached to the exciter back panel. Leave P3 connector/wiring

assembly connected to terminal board TB1 for now.

7. Remove exciter.

8. Tag wires connected to terminal board TB1 on P3 connector/wiring assembly.

9. Disconnect tagged wires from terminal board TB1. Save P3 connector/wiring assem-

bly for installation procedure.

Procedure is complete.

9.1.2 Reinstallation Procedure

Note

A wideband DSP exciter that is installed in a GL-T8500 or GL-T8600

transmitter must have one rack unit of space between it and the power

amplifier chassis.

ISC Technologies Document Number: 9110.00172 DSP Exciter

1. Before installing exciter, connect wires on P3 connector/wiring assembly to terminal

board TB 1 on exciter back panel. P3 connector/wiring assembly is saved from removal

procedure.

2. Connect connectors on transmitter to exciter back panel.

3. If controller requires interface I/O panel, install external interface I/O board on exciter

back panel (see Paragraph 9. 4).

4. Connect connector J3 to connector P3 that is pigtailed off of terminal board TB 1.

5. Locate connector P3 that is pigtailed off of terminal board TB 1. Disconnect connector

P3 from connector J3.

6. Slide exciter into cabinet and secure with four screws saved from removal procedure.

Procedure is complete. Perform setup, adjustment, or calibration procedures as required.

9.2 Exciter Cover

These procedures must be performed with the exciter removed from the transmitter cabinet.

Refer to Figure 9-2, DSP Exciter Cover Removal and Reinstallation throughout these

procedures.

9.2.1 Removal Procedure

1. Remove two sem screws from sides of exciter cover. Save sem screws for installation

procedure.

2. Raise front of cover and extract back of cover from channel in back panel extrusion.

3. Remove exciter cover.

Procedure is complete.

9.2.2 Reinstallation Procedure

1. Insert exciter cover into channel on exciter back panel extrusion.

2. Lower cover so that fingerstock is behind exciter front panel.

3. While pressing down slightly on exciter cover: install two sem screws saved from re-

moval procedure through sides of exciter cover.

Procedure is complete.

DSP Exciter ISC Technologies Document Number: 9110.00172

REMOVAL AND REINSTALLATION Issue 1, Rev. N: 09/25/11

Issue 1, Rev. N: 09/25/11 REMOVAL AND REINSTALLATION

ISC Technologies Document Number: 9110.00172 DSP Exciter

v0 1 7 1. hg l

Figure 9-2 DSP Exciter Cover Removal

and Reinstallation

DSP Exciter ISC Technologies Document Number: 9110.00172

REMOVAL AND REINSTALLATION Issue 1, Rev. N: 09/25/11

Issue 1, Rev. N: 09/25/11 REMOVAL AND REINSTALLATION

9.3 Exciter/Control Board

These procedures must be performed with the exciter removed from the transmitter cabinet,

and the exciter cover removed. Refer to Figure 9-3, DSP Exciter Control Board Removal and

Reinstallation, throughout these procedures.

9.3.1 Removal Procedure Note

Save all hardware for installation procedure.

1. Remove controller interface board (see Table Paragraph 9.4 ).

2. Remove VCO/RF amplifier board (see Table Paragraph 9.5 ).

3. Remove three kep nuts and three screws from regulators U1, U2, and U58.

4. Remove shoulder washer from regulator U58.

5. Remove two jam nuts and two lock washers from connectors J7 and J8.

6. Remove two jack socket screws attached to connector J6 through back panel.

7. Remove four sem screws from back panel and remove back panel from exciter chas-

sis. Some exciters use three sem screws and one standoff.

8. Remove insulator between back panel and regulator U58.

9. Remove two jack socket screws attached to connector J3 through front panel.

10. Remove two studded standoffs through exciter/control board.

11. Remove nine sem screws that attach exciter/control board to exciter chassis, and re-

move exciter/control board.

Procedure is complete.

9.3.2 Reinstallation Procedure

Note

Use hardware saved from installation procedure.

1. Position exciter/control board onto exciter chassis and secure with nine sem screws.

2. Install two studded standoffs through exciter/control board.

3. Apply Vibra Tite or similar nonpermanent self-locking liquid adhesive to threads of

the two jack socket screws to be used for connector J3. Apply only to top 1/4 inch of

thread on each jack socket screw.

4. Install two jack socket screws into connector J3 through front panel.

5. Apply thermal compound as follows: between regulator U1 and back panel, between

regulator U2 and back panel, between regulator U58 and insulator, and between insulator

and back panel.

ISC Technologies Document Number: 9110.00172 DSP Exciter

6. Install insulator between regulator U58 and back panel.

7. Position back panel on exciter chassis and secure with four sem screws. Some excit-

ers use three sem screws and one standoff in the bottom right corner.

8. Apply Vibra Tite or similar nonpermanent self-locking liquid adhesive to threads of

the two jack socket screws to be used for connector J6. Apply only to top 1/4 inch of

thread on each jack socket screw.

9. Install two jack socket screws into connector J6 through back panel.

10. Install two lock washers and two jam nuts over connectors J7 and J8.

11. Install shoulder washer into regulator U58.

12. Install three kep nuts and three screws through regulators U1, U2, and U58.

13. Install VCO/RF amplifier board (see Table Paragraph 9.5 ).

14. Install controller interface board (see Table Paragraph 9.4 ).

Procedure is complete. After exciter is installed in transmitter cabinet: perform setup

procedure if necessary (refer to the system and menu manuals).

DSP Exciter ISC Technologies Document Number: 9110.00172

REMOVAL AND REINSTALLATION Issue 1, Rev. N: 09/25/11

Issue 1, Rev. N: 09/25/11 REMOVAL AND REINSTALLATION

v0 1 7 0. hg l

Figure 9-3 DSP Exciter Control Board Removal and Reinstallation

ISC Technologies Document Number: 9110.00172 DSP Exciter

9.4 Interface Board

These procedures must be performed with the exciter removed from the transmitter cabinet

(see Paragraph 9.1), and the exciter cover removed (see Paragraph 9.2). Refer to Figure 9-

4, DSP Exciter External Interface I/O Board Removal and Reinstallation, throughout the

following procedures.

9.4.1 Removal Procedure

1. Remove jack socket screws (2 or 6) securing connector J4 (J1 and J2 not always used)

to the rear panel of the exciter. Save jack socket screws for installation procedure.

2. Remove two sem screws securing interface board to standoffs. Save sem screws for

installation procedure.

3. Grasp interface board at the center of connector P 1. Pull up on board with a firm ver-

tical motion to disengage connector P1 from connector J1 on the exciter/control board.

4. Remove interface board.

Procedure is complete.

9.4.2 Reinstallation Procedure

1. Position interface board into place by inserting connector J4 (and J1 and J2 if used)

through openings in exciter rear panel.

2. Carefully align connector P1 on interface board with connector J1 on exciter/control

board and engage.

3. Secure interface board to standoffs with two sem screws saved from removal proce-

dure.

4. Apply Vibra Tite or similar nonpermanent self-locking liquid adhesive to threads of the

six jack socket screws saved from removal procedure. Apply only to top 1/4 inch of

thread on each jack socket screw.

5. Screw the six jack socket screws through holes on exciter rear panel at either sides of

connectors J1, J4, and J2.

Procedure is complete. After exciter is installed into transmitter cabinet, perform audio

input adjustment procedure (see Section 7).

9.5 VCO/RF Amplifier Board

These procedures must be performed with the exciter removed from the transmitter cabinet

(see Paragraph 9.1), and the exciter cover removed (see Paragraph 9.2). Refer to Figure 9-

5, DSP Exciter Interface Board Removal and Reinstallation, throughout these procedures.

DSP Exciter ISC Technologies Document Number: 9110.00172

REMOVAL AND REINSTALLATION Issue 1, Rev. N: 09/25/11

Issue 1, Rev. N: 09/25/11 REMOVAL AND REINSTALLATION

9.5.1 Removal Procedure

1. Remove jam nut and lock washer from connector J3 on rear of exciter. Save jam nut

and lock washer for installation procedure.

2. Remove five sem screws securing VCO/RF amplifier board to standoffs on exciter.

Save sem screws for installation procedure.

3. Grasp VCO/RF amplifier board near connector P4. Pull up on board with a short ver-

tical motion to disengage connectors P4/P9/P10 from connectors J4/J9/J10 on exciter/

control board.

4. Remove VCO/RF amplifier board.

Procedure is complete.

9.5.2 Reinstallation Procedure

1. Before installing VCO/RF amplifier board, verify that RF band includes desired

transmitter operating frequencies (refer to Section 10).

2. Position VCO/RF amplifier board into place by inserting connector J3 through hole in

rear of exciter.

3. Carefully align connectors P4/P9/P10 on VCO/RF amplifier board with connectors

J4/J9/J10 on exciter/control board and engage.

4. Secure VCO/RF amplifier board to standoffs on exciter using five sem screws saved

from removal procedure.

5. Install lockwasher and jam nut to connector J3 on rear of exciter using lockwasher

and jam nut saved from removal procedure.

Procedure is complete. After exciter is installed into transmitter cabinet, perform VCO2

adjustment procedure in Section 7.

ISC Technologies Document Number: 9110.00172 DSP Exciter

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Figure 9-4 DSP Exciter External Interface I/O Board

Removal and Reinstallation

DSP Exciter ISC Technologies Document Number: 9110.00172

REMOVAL AND REINSTALLATION Issue 1, Rev. N: 09/25/11

Issue 1, Rev. N: 09/25/11 REMOVAL AND REINSTALLATION

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Figure 9-5 DSP Exciter Interface Board Removal and Reinstallation

ISC Technologies Document Number: 9110.00172 DSP Exciter

DSP Exciter ISC Technologies Document Number: 9110.00172

REMOVAL AND REINSTALLATION Issue 1, Rev. N: 09/25/11

Issue 1, Rev. N: 09/25/11 OPTIONS

10 OPTIONS

10.1 Exciter/PA Control with QT-1000 Interface

The controller interface is the portion of exciter circuitry that connects the transmitter

controller to the exciter. The controller interface dictates what kind of transmitter controller

may operate the transmitter. The transmitter can be operated through one of several control-

lers depending on the interface circuitry installed with the exciter.

Two boards form this interface, the internal QT-1000 interface board and the external

interface I/O board.

Control commands from the transmitter controller are connected through the interface

circuit. This circuit supplies remote control to the microcontroller unit (MCU) control

circuit. The VT-100 VDT supplies local control. The MCU control circuit generates all

control signals for the other circuits, and monitors their status. The MCU control circuit

reports status back to the VT-100 VDT and the interface circuit, which supplies the status to

the transmitter controller.

10.1.1 Reference Source

The ten-MHz reference signal is provided by the controller via J8 on the exciter/control

board.

10.1.2 Controller Interface Connector Functions

Refer to Figure 10-1, Table 10-1, and Table 10-2 for a pin-by-pin description of signal

functions. The controller interfaces with the transmitter through connectors J1, J2, and J5 and

terminal board TB2 at the exciter back panel. J5 on the external I/O board connects to a

standard RL-XX3 receiver, if installed. If a standard receiver is not installed, TB2 on the

external I/O board connects to any generic receiver. TB2 also makes connections to

optional configurable QT-1000 alarm inputs and switching outputs. J1 on the internal

interface board connects directly to TXC connector J1, and interfaces all signals except

alarms. Alarm signals, consisting of transmitter alarm, fault, and status signals, are supplied

directly to the QT-1000 controller connector J2 though J2 on the internal interface board.

10.1.3 QT-1000 Interface Conversion Functions

Many of the signals exchanged between the controller and the exciter originate with a

format, voltage, or requirement incompatible with their destination. The QT-1000 interface

performs any signal conversions necessary to provide compatibility between the controller

and the exciter. The following text describes any signal conversions made by the controller

interface.

ISC Technologies Document Number: 9110.00172 DSP Exciter

ISC Technologies Document Number:

9110.00172 Issue 1, Rev.

N: 09/25/11

10.1.3.1 Analog-Mode A/D Conversion

The exciter DSP modulator circuit reads synchronized serial data for its analog mode input

signal, but the QT-1000 controller provides an analog signal. The controller interface

converts the analog to the appropriate data form for the DSP. The analog (FLAT AUDIO+,-)

terminates across a balanced input circuit that also provides a level adjustment. The

adjustment, when properly set by the AUDIO INPUT ADJUST pot through the exciter

cover, provides analog to an A/D converter at the optimum zero-dBm level. The A/D

converts the analog into serial data, which is applied to the DSP through a synchronous data

link. A synchronous data link is characterized by an exchange of pulse streams for timing

purposes. The A/D converter is clocked by a pulse generator circuit driven by the ten-MHz

reference circuit.

10.1.3.2 FSK-Data-Bit Strapping

The exciter DSP modulator circuit can read up to four bits for its digital FSK mode input

signal, but the controller provides two active bits 1 and 2 (DATA1, DATA2). This allows

transmitter operation in the two-level or four-level mode.

10.1.3.3 Channel-Select-Bit Strapping

The exciter MCU control circuit reads three bits to determine the remotely selected

channel, but the QT-1000 controller provides only bits 1 and 2 (CH SEL 1,2). As a result,

the QT-1000 controller can command only four channels. The controller interface keeps bit 3

open (high). Table 10-2 defines the transmitter operating channel resulting from the

channel select inputs.

10.1.3.4 Mode-Select-Bit Strapping

The exciter MCU control circuit reads two bits to determine the remotely selected mode,

but the QT-1000 controller provides only bit 1 (MODE CONTROL). As a result, the QT-

1000 controller can command only two modes. The controller interface straps bit 2 to

ground (low). Table 10-3 defines the transmitter operating mode resulting from the model

select input.

10.1.3.5 Power Sample D/A Conversion

The QT-1000 controller reads two 0-to-2.5-volt voltages for its forward and reflected power

sample inputs, but these power values are stored as data in the exciter MCU control circuit.

The controller interface converts the data to voltages of the appropriate range for the QT-

1000 controller. Data from the MCU representing the forward and reflected powers is

written into a dual D/A converter. The D/A converts the data into two proportional dc

voltages ranging from 0 volt to 2.5 volts (FWD PWR SAMPLE, REF PWR SAMPLE),

which are applied to the QT-1000 controller. Control logic gates ensure that data is written to

the proper half of the D/A converter.

DSP Exciter

OPTIONS

Issue 1, Rev. N: 09/25/11 OPTIONS

Table 10-1 Interface Board Connector J4 (QT-1000)

J4-X

signal/description

J4-X

signal/description

FWD PWR SAMPLE, input from

AUDIO INPUT +, input from re-

ceiver or tx controller

AUDIO INPUT -, common

REF PWR SAMPLE, input from

TX GND

TONE DECODER OUTPUT,

logic output to tx controller

KEY IN, input from tx controller

DATA 1, digital data input from tx

controller

DATA 2, digital data input from tx

controller

DATA 3, digital data input from tx

controller

CH SELECT 3, digital command

input from tx controller

MODE SELECT 1, digital com-

mand input from tx controller

MODE SELECT 2, digital com-

mand input from tx controller

LOW POWER MODE, logic

input from PA

FAULT ALARM, digital output to

tx controller

VSWR ALARM, logic output to

tx controller

DATA4/CLK, input from tx con-

troller

CH SELECT 1, logic input from

tx controller

CH SELECT 2, logic input from

tx controller

MOD IND, logic output to tx con-

troller

LOW POWER ALARM, output

to tx controller

TEMP ALARM, logic output to tx

controller

SHUTDOWN ALARM, output to

tx controller

RF INPUT ALARM, logic output

to tx controller

not used

ISC Technologies Document Number: 9110.00172 DSP Exciter

ISC Technologies Document Number:

9110.00172 Issue 1, Rev.

N: 09/25/11

Table 10-2 Receiver Connector J5 Pin Functions

(QT-1000 with external I/O board)

J5-X

function

J5-X

function

no connection

standard receiver audio input for

interface, 2 Vp-p, nominal

no connection

return for standard receiver audio

no connection

standard receiver RSSI input for

interface, 0.5-6.0 Vdc

no connection

standard receiver ground for inter-

face

standard receiver-fault alarm input

for interface, LO=OK

no connection

standard receiver squelch output

for interface, HI=unsquelched

Table 10-3 Remote Select Input vs. Channel (QT-1000)

ch sel 1

J1-5

ch sel 2

J1-24

ch sel 3

selecte

channel

command

open (HI)

command

open (HI)

command

ground (LO)

command

open (HI)

command

open (HI)

command

ground (LO)

open (HI)

command

ground (LO)

command

ground (LO)

open (HI)

DSP Exciter

OPTIONS

Table 10-4 Remote Select Input vs. Mode (QT-1000)

mode sel 1

mode sel 2

J1-25

J2-1

selected

mode

command

ground (LO)

analog

command

open (HI)

ground (LO)

2-level

command

open (HI)

command

open (HI)

4-level

Note

Not all transmitters can do all the modes.

10.2 Exciter/PA Control with Standard Interface

The following major paragraphs describe the operation of the major items within the

standard interface. Detailed figures are referenced, as required.

The controller interface is the portion of exciter circuitry that connects the transmitter

controller to the exciter. The controller interface dictates what kind of transmitter controller

may operate the transmitter. The transmitter can be operated through one of several control-

lers depending on the interface circuitry installed at the exciter. The remainder of section

10.2 describes standard controller interface circuitry.

Two boards form this interface, the internal standard interface board and the external

exciter standard interface I/O board.

Control commands from the transmitter controller are connected through the interface

circuit. This circuit supplies remote control to the microcontroller unit (MCU) control

circuit. The VT-100 VDT supplies local control. The MCU control circuit generates all

control signals for the other circuits, and monitors their status. The MCU control circuit

reports status back to the VT-100 VDT and the interface circuit, which supplies the status to

the transmitter controller.

10.2.1 Reference Source

The ten-MHz reference signal is provided by the controller via J8 on the exciter/control

board. All other inputs and outputs, except for RF output, are routed through the standard

interface board.

ISC Technologies Document Number: 9110.00172 DSP Exciter

Issue 1, Rev. N: 09/25/11 OPTIONS

ISC Technologies Document Number:

9110.00172 Issue 1, Rev.

N: 09/25/11

10.2.2 Controller Interface Connector Functions

Refer to Table 10-1, Interface Board Connector J4 (QT-1000) for a pin-by-pin description of

signal functions. The controller interfaces with the transmitter through connector J4 and

terminal board TB2 at the exciter back panel. TB2 also makes connections to optional

configurable alarm inputs and switching outputs.

10.2.3 Standard Interface Conversion Functions

Many of the signals exchanged between the controller and the exciter originate with a

format, voltage, or requirement incompatible with their destination. The standard interface

performs any signal conversions necessary to provide compatibility between the controller

and the exciter. The following text describes any signal conversions made by the controller

interface.

10.2.3.1 Analog-Mode A/D Conversion (No Analog for 138.0-174.0

MHZ & 406.0-470.0 MHz)

The exciter DSP modulator circuit reads synchronized serial data for its analog mode input

signal, but the transmitter controller provides an analog signal. The controller interface

converts the analog to the appropriate data form for the DSP. The analog (FLAT AUDIO +,-)

terminates across a balanced input circuit that also provides a level adjustment. The

adjustment, when properly set by the AUDIO INPUT ADJUST pot through the exciter

cover, provides analog to an A/D converter at the optimum zero-dBm level. The A/D

converts the analog into serial data, which is applied to the DSP through a synchronous data

link. A synchronous data link is characterized by an exchange of pulse streams for timing

purposes. The A/D converter is clocked by a pulse generator circuit driven by the exciter’s

ten-MHz reference circuit.

10.2.3.2 FSK-Data-Bit Strapping

The exciter DSP modulator circuit can read up to four bits for its digital FSK mode input

signal, but the controller provides two active bits 1 and 2 (DATA1, DATA2). This allows

transmitter operation in the two-level or four-level mode.

10.2.3.3 Channel-Select-Bit Strapping

The exciter MCU control circuit reads three bits to determine the remotely selected

channel, and the transmitter controller provides bits 1, 2, and 3 (CH SEL 1,2,3). As a result,

the transmitter controller can command all eight of the possible channels. Table 10-3,

Remote Select Input vs. Channel (QT-1000), defines the transmitter operating channel

resulting from the channel select inputs.

10.2.3.4 Mode-Select-Bit Strapping

The exciter MCU control circuit reads two bits to determine the remotely selected mode,

but the transmitter controller provides only bit 1 (MODE CONTROL). As a result, the

transmitter controller can command three of the transmitter’s four possible modes. Table

10-4, Remote Select Input vs. Mode (QT-1000), defines the transmitter operating mode

DSP Exciter

OPTIONS

resulting from the model select input.

10.2.3.5 Power Sample D/A Conversion

The transmitter controller reads two 0-to-2.5-volt voltages for its forward and reflected

power sample inputs, but these power values are stored as data within the exciter’s MCU

control circuit. The controller interface converts the data to voltages of the appropriate

range for the transmitter controller. Data from the MCU representing the forward and

reflected powers is written into a dual D/A converter. The D/A converts the data into two

proportional dc voltages ranging from 0 volt to 2.5 volts (FWD PWR SAMPLE, REF PWR

SAMPLE), which are applied to the transmitter controller. Control logic gates ensure that

data is written to the proper half of the D/A converter.

Table 10-5 Interface Board Connector J4 (Standard)

J4-X

signal/description

J4-X

signal/description

FWD PWR SAMPLE, input

from PA

AUDIO INPUT -, input from re-

ceiver or tx controller (No Analog

for 138.0-174.0 MHZ & 406.0-

470.0 MHz)

AUDIO INPUT +, common (No

Analog for 138.0-174.0 MHZ &

406.0-470.0 MHz)

REF PWR SAMPLE, input from

TX GND

TONE DECODER OUTPUT,

logic output to tx controller

KEY IN, input from tx controller

DATA 1, digital data input from

tx controller

DATA 2, digital data input from

tx controller

DATA 3, digital data input from

tx controller

CH SELECT 3, digital command

input from tx controller

MODE SELECT 1, digital com-

mand input from tx controller

MODE SELECT 2, digital com-

mand input from tx controller

LOW POWER MODE, logic

input from PA

FAULT ALARM, digital output

to tx controller

VSWR ALARM, logic output to

tx controller

DATA4/CLK, input from tx con-

troller

CH SELECT 1, logic input from

tx controller

CH SELECT 2, logic input from

tx controller

MOD IND, logic output to tx

controller

LOW POWER ALARM, output

to tx controller

TEMP ALARM, logic output to

tx controller

SHUTDOWN ALARM, output

to tx controller

RF INPUT ALARM, logic out-

put to tx controller

not used

ISC Technologies Document Number: 9110.00172 DSP Exciter

Issue 1, Rev. N: 09/25/11 OPTIONS

ISC Technologies Document Number:

9110.00172 Issue 1, Rev.

N: 09/25/11

Table 10-6 Remote Select Input vs. Channel (standard)

ch sel 1

ch sel 2

ch sel 3

J4-22

J4-10

J4-6

selected

channel

command

open (HI)

command

open (HI)

command

ground (LO)

command

open (HI)

command

open (HI)

command

ground (LO)

open (HI)

command

ground (LO)

command

ground (LO)

open (HI)

command

open (HI)

command

open (HI)

command

ground (LO)

command

ground (LO)

command

open (HI)

command

ground (LO)

command

open (HI)

command

ground (LO)

command

ground (LO)

command

ground (LO)

command

ground (LO)

command

ground (LO)

Table 10-7 Remote Select Input vs. Mode (standard)

mode sel 1

mode sel 2

J4-19

J4-7

selected

mode

command

ground (LO)

analog

command

open (HI)

ground (LO)

2-level

command

open (HI)

command

open (HI)

4-level

Note

DSP Exciter

OPTIONS

Not all transmitters can do all the modes.

10.3 Exciter/PA Control with I20 Interface

The following major paragraphs describe the operation of the major items within the I20

interface. Detailed figures are referenced, as required.

The controller interface is the portion of exciter circuitry that connects the transmitter

controller to the exciter. The controller interface dictates what kind of transmitter controller

may operate the transmitter. The transmitter can be operated through one of several control-

lers depending on the interface circuitry installed at the exciter. The remainder of section

10.3 describes I20 controller interface circuitry.

Two boards form this interface, the internal I20 interface board and the external I20

interface I/O board.

Control commands from the transmitter controller are connected through the interface

circuit. This circuit supplies remote control to the microcontroller unit (MCU) control

circuit. The VT-100 VDT supplies local control. The MCU control circuit generates all

control signals for the other circuits, and monitors their status. The MCU control circuit

reports status back to the VT-100 VDT and the interface circuit, which supplies the status to

the transmitter controller.

10.3.1 Reference Source

The ten-MHz reference signal is provided by the controller via J8 on the exciter/control

board.

10.3.2 Controller Interface Connector Functions

Refer to Table 10-8 and Table 10-9 for a pin-by-pin description of signal functions. The

exciter interfaces with the transmitter through connector J2 and the controller through J1.

10.3.3 I20 Interface Conversion Functions

Many of the signals exchanged between the controller and the exciter originate with a

format, voltage, or requirement incompatible with their destination. The I20 interface

performs any signal conversions necessary to provide compatibility between the controller

and the exciter. The following text describes any signal conversions made by the controller

interface.

10.3.3.1 Analog-Mode A/D Conversion

The exciter DSP modulator circuit reads synchronized serial data for its analog mode input

signal, but the transmitter controller provides an analog signal. The controller interface

converts the analog to the appropriate data form for the DSP. The analog (FLAT AUDIO +,-)

terminates across a balanced input circuit that also provides a level adjustment. The

adjustment, when properly set by the AUDIO INPUT ADJUST pot through the exciter

cover, provides analog to an A/D converter at the optimum zero-dBm level. The A/D

converts the analog into serial data, which is applied to the DSP through a synchronous data

ISC Technologies Document Number: 9110.00172 DSP Exciter

Issue 1, Rev. N: 09/25/11 OPTIONS

ISC Technologies Document Number:

9110.00172 Issue 1, Rev.

N: 09/25/11

link. A synchronous data link is characterized by an exchange of pulse streams for timing

purposes. The A/D converter is clocked by a pulse generator circuit driven by the ten-MHz

reference circuit.

10.3.3.2 FSK-Data-Bit Strapping

The exciter DSP modulator circuit can read up to four bits for its digital FSK mode input

signal, but the controller provides two active bits 1 and 2 (DATA1, DATA2). This allows

transmitter operation in the two-level or four-level mode.

10.3.3.3 Channel-Select-Bit Strapping

The exciter MCU control circuit reads three bits to determine the remotely selected channel,

and the transmitter controller provides bits 1, 2, and 3 (CH SEL 1,2,3). As a result, the

transmitter controller can command all eight of the possible channels. Table 10-3 defines

the transmitter operating channel resulting from the channel select inputs.

10.3.3.4 Mode-Select-Bit Strapping

The exciter MCU control circuit reads two bits to determine the remotely selected mode,

and the transmitter controller provides two bits (MODE SELECT 1, MODE SELECT 2).

As a result, the transmitter controller can command three of the transmitter’s four possible

modes. Table 10-4 defines the transmitter operating mode resulting from the model select

input.

10.3.3.5 Power Sample D/A Conversion

The transmitter controller reads two 0-to-2.5-volt voltages for its forward and reflected

power sample inputs, but these power values are stored as data within the exciter’s MCU

control circuit. The controller interface converts the data to voltages of the appropriate

range for the transmitter controller. Data from the MCU representing the forward and

reflected powers is written into a dual D/A converter. The D/A converts the data into two

proportional dc voltages ranging from 0 volt to 2.5 volts (FWD PWR SAMPLE, REF PWR

SAMPLE), which are applied to the transmitter controller. Control logic gates ensure that

data is written to the proper half of the D/A converter.

Table 10-8 Interface Board Connector J1

J1-X

signal/description

J1-X

signal/description

CHASSIS

CLOCK-

CLOCK+

DATA0-

DATA0+

DATA1-

DATA1+

DATA2-

DATA2+

DATA3-

DSP Exciter

OPTIONS

Table 10-8 Interface Board Connector J1 (continued)

J1-X

signal/description

J1-X

signal/description

DATA3+

GND

FREQ0

FREQ1

FREQ2

MODE 0

MODE 1

MODE/AUX

ANALOG+

ANALOG-

GND

RxD-

RxD+

TxD-

TxD+

KEY-

KEY+

DIG OUT 6

DIG OUT 7

DIG OUT 4

DIG OUT 5

DIG OUT 2

DIG OUT 3

DIG OUT 0

DIG OUT 1

_RESET

Table 10-9 Interface Board Connector J2

J2-X

signal/description

J2-X

signal/description

not used

GND

TxD+

TxD-

KEY+

KEY-

RxD+

RxD-

DATA0+

DATA0-

CLOCK+

CLOCK-

DATA1+

DATA1-

ISC Technologies Document Number: 9110.00172 DSP Exciter

Issue 1, Rev. N: 09/25/11 OPTIONS

ISC Technologies Document Number:

9110.00172 Issue 1, Rev.

N: 09/25/11

Table 10-10 Remote Select Input vs. Channel (I20)

ch sel 1

ch sel 2

ch sel 3

ch sel 4

J1-7

J1-26

J1-8

J1-9

selected

channel

command

open (HI)

command

open (HI)

command

ground (LO)

command

open (HI)

command

open (HI)

command

ground (LO)

open (HI)

command

ground (LO)

command

ground (LO)

open (HI)

command

open (HI)

command

open (HI)

command

ground (LO)

open (HI)

command

ground (LO)

command

open (HI)

command

ground (LO)

open (HI)

command

open (HI)

command

ground (LO)

command

ground (LO)

open (HI)

command

ground (LO)

command

ground (LO)

command

ground (LO)

open (HI)

command

open (HI)

command

open (HI)

command

ground

(LO)

command

ground (LO)

command

open (HI)

command

ground

(LO)

command

open (HI)

command

ground (LO)

open (HI)

command

ground

(LO)

command

ground (LO)

command

ground (LO)

open (HI)

command

ground

(LO)

command

open (HI)

command

open (HI)

command

ground (LO)

command

ground

(LO)

command

ground (LO)

command

open (HI)

command

ground (LO)

command

ground

(LO)

DSP Exciter

OPTIONS

command

open (HI)

command

ground (LO)

command

ground (LO)

command

ground

(LO)

Issue 1, Rev. N: 09/25/11 OPTIONS

Table 10-10 Remote Select Input vs. Channel (I20) (continued)

ch sel 1

ch sel 2

ch sel 3

ch sel 4

J1-7

J1-26

J1-8

J1-9

selected

channel

command

ground (LO)

command

ground (LO)

command

ground (LO)

command

ground

(LO)

Table 10-11 Remote Select Input vs. Mode (I20)

mode sel 1

J1-27

selected

mode

command

ground (LO)

analog

command

open (HI)

digital

ISC Technologies Document Number: 9110.00172 DSP Exciter

Issue 1, Rev. N: 09/25/11 List of Referenced Graphic Files

List of Referenced Graphic Files

/pics/v0077.hgl 6-13

/pics/v0079.hgl 5-2

/pics/v0081.hgl 6-12

/pics/v0083.hgl 6-6

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/pics/v0345r. hgl 6-11

/pics/v0854.hgl 7-5

s /pics/v0164.hgl 4-5

/pics/v0250.hgl 1-2

/pics/v0251.hgl 3-5

/pics/v0343.hgl 3-3

/pics/v0344.hgl 3-4

ISC Technologies Document Number: 9110.00172 DSP Exciter

ISC Technologies ISC-T8311 Licensed Non-Broadcast Station Transmitter User Manual User s Manual

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