Guardian G25AMK005, G25RMV110 Technical Manual

G25AMK005

G25AMK005

GUARDIAN 110W MOBILE RADIO

TECHNICAL MANUAL

Datron World Communications Inc. 3030 Enterprise Court
Manual Part No. G25AMK005 Vista, CA 92083, USA
Release Date: May 2002 Phone: [phone] Fax: [phone]
Revision: A E-mail: [e-mail]

www.dtwc.com

 2000 Datron World Communications Inc. All Rights Reserved.

GuardianTM Technical Manual for use with the Guardian 110W mobile radio.

This manual, as well as the software described in it, are furnished under license and may only be
used in accordance with the terms of such license. This manual is furnished for informational
use only, is subject to change without notice, and should not be construed as a commitment by
Datron World Communications Inc. Datron assumes no responsibility or liability for any errors
or inaccuracies that may appear in this manual.

Except as permitted by such license, no part of this publication may be reproduced, stored in a
retrieval system, or transmitted, in any form or by any means—electronic, mechanical,
recording, or otherwise—without the prior written permission of Datron World Communications
Inc.

GuardianTM is a trademark of Datron World Communications Inc.

Written and designed at Datron World Communications Inc., 3030 Enterprise Court, Vista,
California 92083 USA.

For defense agencies: Restricted Rights Legend. Use, reproduction, or disclosure is subject to
restrictions set forth in subparagraph (c)(1)(ii) of the Rights in Technical Data and Computer
Software clause at 252.227-7013.

For civilian agencies: Restricted Rights Legend. Use, reproduction, or disclosure is subject to
restrictions set forth in subparagraphs (a) through (d) of the commercial Computer Software
Restricted Rights clause at 52.227-19 and the limitations set forth in Datron’s standard
commercial agreement for this software. Unpublished rights reserved under the copyright laws
of the United States.

The warranty is void if an unauthorized dealer opens or attempt maintenance on the radio.

Manual part number: G25AMK005. Specifications are subject to change without notice or
obligation.

This device made under license of one or more of the following US Patents: 5,164,986;
5,146,497; 5,185,795; 4,636,791; 4,590,473; 5,185,796; 5,148,482; 5,271,017; 5377229;
4,833,701; 4,972,460.

TM

The IMBE

voice coding technology embodied in this product is protected by intellectual
property rights including patent rights, copyrights, and trade secrets of Digital Voice Systems,
Inc. The voice coding technology can only be used as part of the North American land mobile
radio communications system for the APCO Project 25. The user of this technology is explicitly
prohibited from attempting to decompile, reverse engineer, or disassemble the Object Code, or in
any other way convert the Object Code into human-readable form.

Made in the USA

GUARDIAN VHF 110W MOBILE i

WARNING! Maintain a distance of at least 3 feet (1 meter) between the antenna
and people.

To satisfy RF exposure compliance, you, as a qualified user of this radio device
must control the exposure conditions of bystanders to ensure the minimum
distance is maintained between the antenna and nearby persons. The operation
of this transmitter must satisfy the requirements of the Occupational/Controlled
Exposure Environment for work-related use. Transmit only when people are at
least the minimum distance from the properly installed, externally mounted
antenna.

This radio is designed for initial setup by authorized technicians using a
computer and the Guardian
or disable many of the radio’s features from user access per user agency
security policy and legal restrictions. All, some, or none of the features and
functions described in this manual may be available to the user. To successfully
operate the radio, it is important to understand how the radio is programmed
prior to issuance by the user agency. Consult authorized agency personnel for
features and functions made available or restricted to the user. FCC licensees
are prohibited by federal law from enabling the radio to directly enter transmit
frequencies using the radio's controls.

NOTICE TO USER

TM

programming software. Programming can enable

NOTICE TO INSTALLATION TECHNICIANS

Use only a manufacturer- or dealer-supplied antenna.

Antenna minimum safe distance: 3 feet (1 meter).

The Federal Communications Commission (FCC) has adopted a safety
standard for human exposure to Radio Frequency (RF) energy that is below
the Occupational Safety and Health Act (OSHA) limits.

Antenna mounting
dealer must be mounted at a location so that during radio transmission
people cannot come closer than the minimum safe distance to the antenna,
i.e., 3 feet (1 meter).

To comply with current FCC RF exposure limits, the antenna must be
installed at or exceeding the minimum safe distance, and in accordance
with the requirements of the antenna manufacturer or supplier.

Base station installation: The antenna should be fixed-mounted on an
outdoor permanent structure. Address RF exposure compliance at the time
of installation.

Antenna substitution
recommended by the manufacturer or radio dealer. You may be exposing
people to harmful RF radiation. Contact your radio dealer or manufacturer
for further instructions.

: The antenna supplied by the manufacturer or radio

: Do not substitute any antenna for the one supplied or

ii GUARDIAN VHF 110W MOBILE

CONTENTS

CHAPTER 1:

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

1.1 SCOPE .........................................................................................................................................................1-1

1.2 GENERAL DESCRIPTION ..............................................................................................................................1-1

1.3 PERFORMANCE SPECIFICATIONS ................................................................................................................. 1-1

CHAPTER 2: HARDWARE THEORY OF OPERATION.......................................................................... 2-1

2.1 INTRODUCTION ........................................................................................................................................... 2-1

2.2 SYSTEM SPECIFICATIONS ............................................................................................................................2-1

2.3 SYSTEM BLOCK DIAGRAM.......................................................................................................................... 2-2

2.4 RECM CONTROL HARDWARE THEORY OF OPERATION.............................................................................. 2-4

2.4.1 Control Logic..................................................................................................................................... 2-4

2.4.2 DSP .................................................................................................................................................... 2-7

2.4.3 Flash ROM......................................................................................................................................... 2-7

2.4.4 RAM ..................................................................................................................................................2-7

2.4.5 TCXO................................................................................................................................................. 2-7

2.4.6 FPGA ................................................................................................................................................. 2-8

2.4.7 IF ADC............................................................................................................................................... 2-8

2.4.8 Clock Generation ............................................................................................................................... 2-8

2.4.9 Logic Audio CODEC......................................................................................................................... 2-8

2.4.10 Accessory Connector Interface and Filtering.....................................................................................2-8

2.4.11 Transceiver Interface and Filtering ....................................................................................................2-8

2.4.12 Keypad Interface ................................................................................................................................ 2-8

2.4.13 Audio Interface................................................................................................................................... 2-8

2.4.14 Test Interface...................................................................................................................................... 2-9

2.4.15 LED.................................................................................................................................................... 2-9

2.4.16 RECM Power Consumption............................................................................................................... 2-9

2.5 RECM TRANSCEIVER SECTION .................................................................................................................. 2-9

2.5.1 Interface Section.................................................................................................................................2-9

2.5.2 Receiver Section...............................................................................................................................2-10

2.5.3 Digital/Analog Control.....................................................................................................................2-13

2.5.4 Keypad Microcontroller................................................................................................................... 2-14

2.6 AUDIO AMPLIFIER BOARD ........................................................................................................................ 2-14

2.6.1 Description....................................................................................................................................... 2-14

2.6.2 Power Conditioning ......................................................................................................................... 2-14

2.6.3 Communication with Transceiver ....................................................................................................2-15

2.6.4 Audio Amplifiers ............................................................................................................................. 2-15

2.6.5 Power Levels Detector, Converter, and RF/DC Combiner ..............................................................2-15

2.6.6 PA ON/OFF Control (Bypass Mode)............................................................................................... 2-16

2.6.7 RF Power Indication ........................................................................................................................ 2-16

2.6.8 Audio Board Block Diagram............................................................................................................2-16

2.7 DISPLAY BOARD .......................................................................................................................................2-17

Figure 2-4: Guardian Keypad Board............................................................................................................... 2-17

2.7.1 Control Logic Interface.................................................................................................................... 2-18

2.7.2 Keypad ............................................................................................................................................. 2-18

2.7.3 Switch Interface ............................................................................................................................... 2-18

2.8 FRONT PANEL INTERFACE BOARD ............................................................................................................ 2-18

CHAPTER 3: SOFTWARE THEORY OF OPERATION ........................................................................... 3-1

3.1 FUNCTIONAL SYSTEM OPERATION.............................................................................................................. 3-1

3.1.1 General............................................................................................................................................... 3-1

3.1.2 Guardian Block Diagram ................................................................................................................... 3-1

3.1.3 Architecture........................................................................................................................................ 3-2

3.1.4 Board Identification ........................................................................................................................... 3-2

GUARDIAN VHF 110W MOBILE iii

Self-Test on Power-Up....................................................................................................................... 3-2

3.1.5

3.1.6 Flash Software Upgrades ................................................................................................................... 3-2

3.1.7 Voice Coder/Decoder (VOCODER) .................................................................................................. 3-2

3.2 RADIO CONTROL SOFTWARE ...................................................................................................................... 3-2

3.2.1 Audio Control ....................................................................................................................................3-2

3.2.2 DSP Control Software........................................................................................................................ 3-2

3.2.3 Transceiver Board.............................................................................................................................. 3-3

3.2.4 DC Power Control.............................................................................................................................. 3-5

3.2.5 Monitoring .........................................................................................................................................3-5

3.2.6 Radio Control Drivers ........................................................................................................................3-5

3.3 DIGITAL SIGNAL PROCESSING..................................................................................................................... 3-6

3.3.1 DSP Transmit Chain .......................................................................................................................... 3-6

3.3.2 DSP Receive Chain............................................................................................................................ 3-8

3.3.3 DSP Software................................................................................................................................... 3-11

3.4 KEYPAD MPU SOFTWARE ........................................................................................................................3-11

3.4.1 Overview.......................................................................................................................................... 3-11

3.4.2 General............................................................................................................................................. 3-11

3.4.3 Keypad Scanning ............................................................................................................................. 3-11

3.4.4 Push-to-Talk (PTT) Input................................................................................................................. 3-11

3.4.5 Switch Input..................................................................................................................................... 3-11

3.4.6 LED Output...................................................................................................................................... 3-11

3.4.7 Backlight Control............................................................................................................................. 3-11

3.4.8 Serial Interface................................................................................................................................. 3-11

3.5 DATA INTERFACE...................................................................................................................................... 3-12

3.5.1 CAI Data Interface........................................................................................................................... 3-12

3.5.2 Synchronous Serial Data Interface................................................................................................... 3-12

3.5.3 CAI Data Link Layer .......................................................................................................................3-12

3.5.4 Transmit Physical Link Layer.......................................................................................................... 3-13

3.5.5 Receive Physical Link Layer............................................................................................................3-14

3.5.6 DES Encryption ............................................................................................................................... 3-14

3.5.7 Host Interface................................................................................................................................... 3-15

3.5.8 Flash Interface.................................................................................................................................. 3-15

3.5.9 Paging...............................................................................................................................................3-15

3.5.10 Hardware Control............................................................................................................................. 3-16

3.6 CONTROLLER SOFTWARE.......................................................................................................................... 3-16

3.6.1 Overview.......................................................................................................................................... 3-16

3.6.2 Environment..................................................................................................................................... 3-16

3.6.3 Radio Store....................................................................................................................................... 3-18

3.6.4 Program/Fill/Control Interface......................................................................................................... 3-19

3.7 USER INTERFACE ...................................................................................................................................... 3-20

3.7.1 Display ............................................................................................................................................. 3-20

3.7.2 Optional DTMF Microphone ...........................................................................................................3-20

CHAPTER 4: INSTALLATION, ADJUSTMENT, AND OPERATION ....................................................4-1

4.1 RADIO CONFIGURATION ............................................................................................................................. 4-1

4.1.1 Channels............................................................................................................................................. 4-1

4.1.2 Zones.................................................................................................................................................. 4-1

4.1.3 Banks..................................................................................................................................................4-1

4.2 INSTALLATION AND ADJUSTMENT .............................................................................................................. 4-1

4.2.1 Hardware............................................................................................................................................ 4-1

4.2.2 Software............................................................................................................................................. 4-1

4.3 OPERATING PROCEDURES ...........................................................................................................................4-1

4.3.1 Connect the Power Source ................................................................................................................. 4-1

4.3.2 Connect the Antenna.......................................................................................................................... 4-1

4.3.3 Optional External Speaker ................................................................................................................. 4-1

4.3.4 Radio Programming ...........................................................................................................................4-1

iv GUARDIAN VHF 110W MOBILE

Radio Power Up................................................................................................................................. 4-2

4.3.5

4.3.6 Choose a Channel...............................................................................................................................4-2

4.3.7 Transmit a Voice Message ................................................................................................................. 4-2

4.3.8 Receive a Voice Message...................................................................................................................4-2

4.3.9 Programming and Bypass Mode ........................................................................................................4-2

CHAPTER 5: RADIO SET AND ACCESSORIES ....................................................................................... 5-1

5.1 SYSTEM DESCRIPTION ................................................................................................................................5-1

5.1.1 Mobile Radio......................................................................................................................................5-1

5.1.2 Antenna.............................................................................................................................................. 5-1

5.1.3 Guardian PC Programmer .................................................................................................................. 5-1

5.1.4 Cloning Cable.....................................................................................................................................5-2

5.2 CONTROLS, INDICATORS, AND CONNECTORS ............................................................................................. 5-2

5.2.1 Controls.............................................................................................................................................. 5-2

5.2.2 Indicators............................................................................................................................................ 5-3

5.2.3 Connectors ......................................................................................................................................... 5-4

5.3 TRANSCEIVER CHARACTERISTICS ............................................................................................................... 5-4

5.3.1 Transmitter Characteristics ................................................................................................................ 5-4

5.3.2 Receiver Characteristics..................................................................................................................... 5-5

5.4 COMMUNICATION SECURITY ...................................................................................................................... 5-5

5.4.1 Algorithms ......................................................................................................................................... 5-5

5.4.2 Keyfill ................................................................................................................................................ 5-5

5.4.3 Zeroize ............................................................................................................................................... 5-6

CHAPTER 6: SERVICING THE RADIO......................................................................................................6-1

6.1 GENERAL ....................................................................................................................................................6-1

6.2 SELF-TEST AT POWER UP ........................................................................................................................... 6-1

6.3 CAUTION..................................................................................................................................................... 6-1

CHAPTER 7: TROUBLESHOOTING........................................................................................................... 7-1

7.1 INTRODUCTION ........................................................................................................................................... 7-1

7.2 RADIO FUNCTIONAL TESTS......................................................................................................................... 7-1

7.2.1 Power-On Test ................................................................................................................................... 7-1

7.2.2 Buttons and Switches Test ................................................................................................................. 7-1

7.2.3 Transmit Test ..................................................................................................................................... 7-1

7.2.4 Receive Test....................................................................................................................................... 7-1

7.2.5 Audio Test.......................................................................................................................................... 7-1

CHAPTER 8: DEFINITIONS ......................................................................................................................... 8-1

CHAPTER 9: SIGNAL TONES...................................................................................................................... 9-1

CHAPTER 10: INTERFACE ...............................................................ERROR! BOOKMARK NOT DEFINED.

10.1 ACCESSORY CONNECTOR PINS AND FUNCTIONS....................................................................................... 10-1

CHAPTER 11: SCHEMATICS....................................................................................................................... 11-1

FIGURES

Figure 2-1: Guardian Interconnect Diagram .............................................................................................................2-3

Figure 2-2: Guardian Control Logic .........................................................................................................................2-4

Figure 2-3: RECM Power Supply.............................................................................................................................2-5

Figure 2-4: Guardian Keypad Board....................................................................................................................... 2-17

Figure 3-1: Guardian Block Diagram........................................................................................................................3-1

Figure 3-2: Transmit DSP Chain...............................................................................................................................3-7

Figure 3-3: Receive DSP Chain................................................................................................................................ 3-8

Figure 3-4: Controller Software.............................................................................................................................. 3-16

GUARDIAN VHF 110W MOBILE v

CHAPTER 1: GENERAL INFORMATION

1.1 Scope

This manual provides technical information for the Guardian 110 Watt mobile radio system.. This chapter gives a
general description and provides a system block diagram. Chapters 2 and 3 provided detailed theory of operation for
hardware and software portions of the radio. Chapter 4 provides general operation of the radio. Chapter 5 is the
physical description of the radio components and the available accessories. Chapters 6 and 7 describe servicing,
testing, and troubleshooting the radio system. The remaining chapters provide additional technical information and
schematics.

1.2 General Description

The Guardian 110W mobile radio system is compliant with the APCO project 25 FDMA common air interface, and
is also compatible with conventional wideband FM systems and newer narrowband FM systems. It provides fully
digital encrypted communication suitable for use by modern public safety and commercial users. The radio system is
built from a remote power amplifier and a control head. The 110W RF power amplifier mounts in a remote location
such as a vehicle trunk, while the control unit is mounted in the cabin. The two are connected by a single coaxial
cable. The cable carries both the RF signal and control signals (PTT, and power level setting).

1.3 Performance Specifications

Model Designation Guardian VHF Mobile Radio

General Model G25RMV110

Frequency Range 136.000 to 174.000 MHz

Banks, Zones, Channels, Shadow 4 banks, 16 zones, 256 channels, 7 shadow

Voice Digital Mode Voice Coding

Frame Re-sync Interval

Error Correction Method

Input Voltage 13.6 Vdc, negative chassis ground

Current Drain @ 13.8V: Standby

Receive @ Rated Audio

Transmit @ Rated Power

Mounting Dashboard mounted, including bracket

Dimensions 2.75” x 7.1” x 5.5” (H x W x D)

Weight
Control Head
Remote Unit

Case Metal and plastic

Temperature Range -30° to +60°C

Channel Spacing 12.5 and 25 kHz, selectable in 2.5 or

IMBE™ 4.4 kb

180 msec

RS, golay, hamming

0.5A

3.0A

28.0A

2.5 lb
12 lb

3.125 kHz steps

FCC Type Acceptance Number Pending

Industry Canada Pending

GUARDIAN VHF 110W MOBILE 1-1

Model Designation Guardian VHF Mobile Radio

Receiver

Sensitivity Digital Mode: 5% BER

(Measurements per TIA/EIA 603 Standards)

-116 dBm or greater

Analog Mode: 12 dB SINAD

Spurious -70 dB

Intermodulation -70 dB

Audio Output Power 10W, 4Ω external, 5W, 8Ω internal speaker

Audio Distortion (at 1000 Hz) 3%

Frequency Stability (-30° to 60°C) ± 1 ppm

Maximum Frequency Separation Full-band split

Transmitter

(Measurements per TIA/EIA 603 Standards)

RF Power Output 25W to 110W, adjustable

Spurious and Harmonic Emissions -70 dB

FM Hum and Noise (wideband) -46 dB @ 25 kHz/-40 dB @ 12.5 kHz

FCC Modulation Designators 16K0F3E, 11K0F3E, 20K0F1E

Audio Distortion (at 1000 Hz) 2%

Audio Response (1000 Hz Ref.) ± 3 dB, 300 to 3000 (EIA/TIA 603)

Frequency Stability (-30°C to 60°C) ± 2.5 ppm

Maximum Frequency Separation Full bandwidth

Environment Specifications (MIL-SPEC)

Environment 810C 810D 810E

Method Procedure Method Procedure Method Procedure

Low Pressure 500.1 I 500.2 I 500.3 II

High Temp. 501.1 I, II 501.2 I, II 501.3 I, II

Low Temp. 502.1 I 502.2 I 502.3 I

Temp. Shock 503.1 I 503.2 I 503.3 I

Solar Radiation 505.1 I 505.2 I 505.3 I

Humidity 507.1 II 507.2 II (5) 507.3 II (5)

Salt Fog 509.1 I 509.2 I 509.3 I

Dust and Sand 510.1 I 510.2 I 510.3 I, II

Vibration 514.2 VII(W) 514.3 I (1) 514.4 I (1)

Shock 516.2 I, II, V 516.3 I 516.4 I

1-2 GUARDIAN VHF 110W MOBILE

CHAPTER 2: HARDWARE THEORY OF OPERATION

2.1 Introduction

The Control Module contains the Receiver Exciter Control Module (RECM), Audio amplifier
board, Interface board, and display and keypad assemblies. The RECM is a shielded assembly
containing the transceiver and all control and signal processing hardware and firmware, except
the RF and audio power amplifiers. The trunk-mounted RF power amplifier contains a single PC
assembly.

Schematics for all the boards are located in the back of the manual.

2.2 System Specifications

Table 2-1: Guardian G25RMV110 Technical Specifications

Specification Description
General

Frequency Range 136.000 to 174.0000 MHz
Banks, Zones, Channels, Shadow 4 banks, 16 zones, 256 channels, 7 shadow
Voice Digital
Mode Voice Coding
Frame Re-sync Interval 180 msec
Error Correction Method RS, golay, hamming
Mounting Under dashboard using bracket
Dimensions 2.94”x7.13”x7.06” (H x W x D)
Weight 5 lbs. Approximately
Case Metal and plastic
Temperature Range
Channel Spacing 12.5 and 25 kHz, selectable in 2.5 or 3.125 kHz steps
FCC Type Acceptance Number Pending
Industry Canada Pending
Receiver (Measurements per TIA/EIA 603 Standards)
Sensitivity
Digital Mode: 5% BER
Analog Mode: 12 dB SINAD
Spurious -70 dB
Intermodulation -70 dB
Audio Output Power 5W internal, 10W external speaker
Audio Distortion (at 1000 Hz) 5%

Frequency Stability (-30° to +60°C) ±2.5 ppm

Maximum Frequency Separation Full-band split

Transmitter (Measurements per TIA/EIA 603 Standards)

Duty Cycle 3%, 3 min continuous
RF Power Output 25W, 50W, 110W; also bypass mode
Spurious and Harmonic Emissions -70 dB
FM Hum and Noise (wide/narrowband) -48/-47 dB typical
FCC Modulation Designators 11K0F3E, 16K0F3E, 22K0F3E, 14K6F1E
Audio Distortion (at 1000 Hz) 5%
Audio Response (1000 Hz Ref.)

Frequency Stability (-30° to +60°C) ±2.5 ppm

IMBE 4.4 kb

-30° to +60°C

-116 dBm maximum

±3 dB 300 to 3000 (EIA/TIA 603)

GUARDIAN VHF 110W MOBILE 2-1

Specification Description

Maximum Frequency Separation Full bandwidth

DES Encryption

Encryption Keys 16
Code Key Generator External
SBCF Analog DES Encryption Standard feature

Environmental Specifications MIL-STD-810F

Test Method/Procedure
Low Pressure (Altitude) 500.4/II
High Temperature 501.4/I, II
Low Temperature 502.4/I
Temperature Shock 503.4/I
Solar Radiation (Sunshine) 505.4/I
Humidity 507.4/I
Salt Fog 509.4/I
Sand and Dust 510.4/I, II
Vibration 514.5/I
Shock 516.5/I

Standard Accessories Optional Accessories

5W Internal Speaker 10W External Speaker
Palm Microphone DTMF Microphone
Mounting Bracket Key Variable Loader
14 ft Power Cable 25 ft Power Cable

2.3 System Block Diagram

2-2 GUARDIAN VHF 110W MOBILE

Ignition and Emergency Switch

Fused DC Power

Speaker out

System Control and

Programming

Coax

Control

Cable

PA

control

DTMF

control

MIC

connector

DB9

(LCD,Keypad and switches)

Control Head

Power ON/OFF and R/T

switches

Control

DB25

RECM

Front panel interface

Fused DC Cable

DC

connector

R

GUARDIAN VHF 110W MOBILE 2-3

AMP

AMP

Filter&

combiner

T

Power
spliter

T

R

output power

control monitor

power sensor

Mounted Power Amplifier

Figure 2-1: Interconnect Block Diagram

Antenna ConnectionIn/Out

2.4 RECM Control Hardware Theory of Operation

2.4.1 Control Logic

The control logic interfaces to the keypad logic, transceiver, internal audio, and Motherboard. The control logic
implements the main radio control function and all the baseband signal processing.

Keypad Board and Front Panel Interface

DB25 Accessory Connector

TCVR Module

Grey areas connect

through the 80-pin

connector on the

Motherboard.

2.4.1.1 Power Supply Unit

This block of circuitry takes the 7.8V regulated voltage together with a number of control signals to generate a
number of power supply outputs.

2-4 GUARDIAN VHF 110W MOBILE

Power Supply

Figure 2-2: Guardian Control Logic

2.4.1.2 On/Off Switching

The main continuous supply 10V control is passed through a front panel on/off switch to generate 10V SW from the
main radio supply. In normal operation the on/off switching is controlled by the radio on/off rotary switch by the
control /RADON. Once switched on the main controller can hold the radio on by setting PWRHOLD. In addition
to the radio rotary on/off switch, the on/off switching can be controlled by the external line /RADOFF via the
accessory connector. This line overrides the /RADON line and can be used to force the radio off regardless of the
rotary switch setting. However, the H8 controller uses the PWRHOLD and PWROFF lines to implement a clean
controlled switch off.

2.4.1.3 Transmit Power Switching

A single FET switch controlled by CTX is used to provide a switched 10VTX high-current supply (1.5A) for the
transmitter.

2.4.1.4 4.5V Switch Mode Power Supply

This circuit uses a switch mode power supply device to generate a 4.5V supply at 450 mA maximum for the radio
logic. The switch mode device is synchronous and uses an externally provided power supply clock at 384 kHz. The
power supply circuit includes input and output filters to limit the conduction of the fundamental switching
components and their harmonics in the VHF band, both onwards into the logic and back into the power supply.

GUARDIAN VHF 110W MOBILE 2-5

Figure 2-3: RECM Power Supply

2.4.1.5 3.3V Linear Logic Supply

The output from the 4.5V switch mode power supply is passed through 3.3V linear power supplies to remove any
remaining power supply switching noise on the main logic supply. One 3.3V supply is used for control logic, the
other 3.3V, 50 mA supply is used for control logic analog circuitry.

2.4.1.6 Reset Generator

This circuit uses a MPU supervisory device (MAX825) to generate a reset pulse of at least 140 ms whenever the

3.3V logic supply drops below 3.08V. The circuit also generates a reset signal when the watchdog input is asserted
by H8 or DSP.

2.4.1.7 5V Linear Logic Supply

This circuit generates a 5V logic supply at 50 mA maximum for use on the control logic.

2.4.1.8 Audio Supplies

Two linear regulators providing clean filtered supplies for the audio at 5V are provided. The audio power amplifiers
use the 5V, 800 mA audio supply. The audio supply is used for the low-current microphone amplifier. A linear 5V
bias supply to the internal microphone is also provided.

2.4.1.9 H8 Microcontroller

H8 is the main controller for the radio and is a HD6433044 ROM-less microcontroller. H8 is configured with an
expanded bus connected to the Flash, RAM, and DSP. The H8 integral bus arbitration logic allows H8 and DSP to
both have access to the Flash and RAM. H8 is clocked by the external TCXO.

H8 is powered from the 3.3V logic supply, and reset by the hardware /RES line. A watchdog output to the hardware­reset circuitry is provided. H8 generates chip select outputs to allow the Flash, RAM, FPGA, and DSP host port to
be separately addressed.

One serial port of H8 is used to implement a bidirectional synchronous serial interface to the keypad board. This
interface is used to communicate with the keypad MPU and directly load the LCD controller. The clock on this
interface runs at 100 kHz. An associated interrupt input to H8 is used to initiate transfers from the keypad to H8.
This serial interface is also used to load the output expander in the FPGA, and also to configure the FPGA.

One serial port of H8 is used to implement a bidirectional asynchronous serial interface to an external PC used for
programming, filling, and controlling the radio. This interface uses programmable standard baud rates (default 9600
baud) and standard data formats. There are no handshaking parallel lines associated with this interface. Two parallel
I/O lines on H8 are used to generate an I

2

C interface to allow the EEPROM on the transceiver to be accessed. Four
parallel output lines on H8 are used to generate a synchronous serial output bus with clock and data and separate
strobe lines for the DAC, control shift register, and synthesizer on the transceiver.

One H8 DAC output is used to generate simple audio tones of varying volume for use as audio alerts. The second
H8 DAC output is available for VCTCXOP control. The six-channel ADC is used to measure: the raw supply
voltage, WRU radio input, reference crystal temperature, PA temperature, PA current, and RSSI. Two I/O lines are
used to implement software UART, used for debug outputs in the development environment.

2.4.1.10 H8 Input Requirements

The total requirements for parallel input signals to H8, which need to be polled on a regular basis are:

 OOL: Out-of-lock (OOL) signal from the transceiver synthesizer
 EXT PTT: External PTT
 PWROFF: On/off switch position
 CONFDONE: Configuration status of FPGA

2.4.1.11 H8 Output Requirements

The total requirements for parallel output signals from H8, which need to be controlled are as below. A serial load
output latch in the FPGA expands the output capabilities of H8.

2-6 GUARDIAN VHF 110W MOBILE

 LCDA0: LCD controller A0 command/ data select
 LCDCS: LCD chip select
 SCL: I

2

C and synthesizer clock

 DACSDA: Transceiver serial data, synthesizer, DAC, S-R
 SYNTHENA: Synthesizer framing pulse
 DACENA: DAC framing pulse
 SRENA: S-R framing pulse
 /DINT: Interrupt to DSP from H8
 /RESO: Watchdog output from H8

2.4.1.12 H8 Input/Output Requirements

The total requirements for parallel input/output signals on H8, which need to be read and controlled are:

 BATBUS: Not used in the mobile configurations
 SDA: I

2

C data

2.4.1.13 H8 Input Interrupt Requirements

The total requirements for parallel input interrupt signals on H8 are:

 LBOUT: Not used in the mobile configuration
 DSPINT DSP: Interrupt

2.4.2 DSP

The DSP56309 (or DSP56302) processor implements all baseband signal-processing functions in the radio. It
interfaces with the transceiver through one ESSI port, to the user for voice through the second ESSI port. The DSP
function is controlled by H8 through the DSP host port. The DSP has direct access to the main Flash memory
through the bus arbitration logic in H8, this allows it to download program images. The initial power-on code
download is through the host port. The hardware-reset line resets the DSP. The TCXO clock output line clocks the
DSP at 12.288 MHz. The DSP ESSI 1 port is used to provide a synchronous interface to the IF ADC and the
transceiver 12-bit DAC. In receive modes that interface is capable of writing to the DAC at 48 ksps while still
reading the ADC at 96 ksps. The DSP ESSI “0” port is used to provide a full-duplex synchronous interface to the
audio CODEC using 8 kHz sampling rate and 13 bit samples. The data transfer is at 2.048 MHz using a DSP
sourced clock and framing pulse.

2.4.3 Flash ROM

A 512k x16 Flash ROM is used as the main program store for the H8 controller and DSP. The Flash ROM uses a
protected boot sector that is factory programmed via the DSP JTAG port. Normal reprogramming is implemented
by running H8 from the boot sector and using 3V, programming the bulk of the device. The Flash is used to provide
a parameter storage area for nonvolatile data storage of frequencies and keys, etc. This storage area is capable of in
excess of 100k write cycles.

2.4.4 RAM

A 128k x 8 static RAM is used for temporary storage of data by the H8 controller. This RAM is powered by a
continuous supply that maintains its contents as long as a power source is present. Additionally the RAM has a
backup capacitor to retain its contents over power interruptions.

2.4.5 TCXO

This oscillator serves as the reference for all logic and power supply clocks within the control logic and keypad. It
provides the data rate clocks for radio operation, and is the source of the ADC/DAC/CODEC conversion clocks. The
TCXO is at 12.288 MHz, with a temperature tolerance of +
a typical temperature tolerance of ± 1.0 ppm, a trimmer to set the initial frequency is provided. A Schmitt trigger
buffer squares up the TCXO sine wave output before being output to H8 and DSP.

GUARDIAN VHF 110W MOBILE 2-7

2.5 ppm. Additional calibration is performed to provide

2.4.6 FPGA

The control logic uses an Altera 8282 FPGA device to provide a flexible serial data routing function, I/O expansion
for H8 and DSP, clock generation, data multiplexing, and to absorb discrete logic functions.

The synchronous serial bus routing function involves routing the synchronous serial port of H8 either to the keypad
and LCD, or to the I/O expansion in the FPGA. High-order address pins from H8 control this routing and a FPGA
dummy write with dedicated FPGA chip select from H8. The FPGA includes a serial load parallel output shift
register that is used for parallel output expansion for H8.

The discrete logic functions of the FPGA, includes logic to control an inverter for one of the LCD control outputs.
The data multiplexing function involves rerouting serial pins between the accessory connector and the DSP SCI port
to allow data transmission and keyfill operations.

2.4.6.1 FPGA Configuration

The FPGA is configured at start-up from the main Flash memory using a serial load from H8. During configuration
outputs are tri-stated and pulled to a safe level by committing resistors to prevent audio and RF bursts at power up.

2.4.7 IF ADC

The IF sampling ADC is a 12-bit ADC capable of sub-sampling a 455 kHz, IF signal at 96 kHz sampling rate. It is
connected by a serial interface to the DSP ESSI port 1. The serial data interface is clocked at 1536 kHz.

2.4.8 Clock Generation

The clock generation logic is used to generate clocks for the synchronous power supplies, the ADC serial interface,
and the keypad microcontroller. The clock generator logic is implemented in the FPGA.

2.4.9 Logic Audio CODEC

The audio CODEC is an integrated ADC/DAC and audio filter device capable of full-duplex operation on voice
bandwidth signals at 8 ksps. The samples have a resolution of 13-bits linear. The CODEC is connected to the DSP
ESSI port “0” with serial data transfer rate of 2.048 MHz. The CODEC is continuously powered from the 3V logic
and 3V audio supplies. DSP parallel control lines are used to mute the input and output sections as required.

2.4.10 Accessory Connector Interface and Filtering

All outputs are filtered to limit their bandwidth to the minimum and current limited to protect them from output
short circuits to ground or up to 16V. All inputs are filtered and protected from continuous application of ground or
+16V. There is no protection against negative applied voltages. Inputs and outputs are protected from static
discharge of at least 10 kV air discharge. All inputs and outputs incorporate RF bypass filter capacitors adjacent to
the connector, except for ground.

2.4.11 Transceiver Interface and Filtering

Most of the signals crossing the interface are filtered to limit their bandwidth to the minimum consistent with correct
operation. Outputs from the control are filtered with series resistors on the RECM and grounded capacitors on the
transceiver adjacent to the connector. Outputs from the transceiver to the control use the reverse configuration.

2.4.12 Keypad Interface

Some filtering is provided on this interface, but all outputs are protected from short circuits by series resistors.
Where possible, inputs are also protected from damage by series resistors.

2.4.13 Audio Interface

The audio interface is implemented with four-way wire connectors directly via the 80-pin interface through the
Motherboard to the integral speaker and microphone.

2-8 GUARDIAN VHF 110W MOBILE

2.4.14 Test Interface

The test interface provides the following functions:

 Joint test action group (JTAG) connector access for board test and Flash boot sector programming
 Board reset and control access
 Board power supply and on-off switching access
 H8 serial debug port access

2.4.15 LED

The control logic incorporates a 3-color LED used for status information. It is controlled by the FPGA to show red,
green, or off. It is optically coupled to the top face of the radio by a light pipe. The hardware is configured so
during hardware reset, before the keypad MPU software is running, the LEDs are off.

2.4.16 RECM Power Consumption

The control logic operates at input voltage 7.7V. The average current consumption of the control logic is:

 Standby mode: 60 mA
 Receive mode @ 500 mW: 330 mA
 Transmit mode @ 2W: 1,000 mA
 Transmit mode @ 5W: 1,500 mA

2.5 RECM Transceiver

RF shields covers the board.

2.5.1 Interface

J2 is the transceiver antenna connector. RF signals are transmitted and received through this surface mount RF
connector. Transmitted and received RF signals are routed from this connector through a short RF cable to the
RX/TX relay on the Motherboard.

2.5.1.1 Transmit Chain

The pre-driver amplifier (Q7, etc.) amplifies the TXLO signal from the synthesizer section. The Q7 output power is
typically 13 dBm measured at C77/R44/R49 node.

R44, R49, and R52 are part of a 3 dB pie attenuator network. The gain control is made up of CR5, CR6, and
associated components. This circuit yields more than 50 dB of useful attenuation range. The circuit is part of a
DAC controlled closed loop system, in conjunction with the detector/power control circuit (U12, U13, and
associated components), which controls the transmitter output power level. The power amplifier (PA) is a
Mitsubishi M68776, 7.2V, 6W gained controlled power amplifier.

The harmonic filter (C209, L30, C81, C82, L31, C83, and C84) attenuates harmonics created by the power
amplifier. The harmonic filter insertion loss is 0.4 dB typically at 174 MHz. The output of the harmonic filter
connects to the 20 dB coupler (U12). This coupler is part of a DAC-controlled closed loop system designed to set
the transmitter output power level. The insertion loss through the coupler (U12-1 to U12-3) is 0.2 dB typically.

2.5.1.2 Power Amplifier Control

Transmit output power level is controlled by the detector/power control circuit and the gain control amplifier input
via VCONTROL. This closed loop system is designed to keep the transmitter output power constant over variations
in temperature, transmitter supply voltage (7.5VT), and RF power levels into the transmit chain. The detector/power
control circuit is made up of the 20 dB coupler (U12), an RF rectifier circuit (CR11, CR12, etc.), and an integrator
(U13). The DAC line labeled PWRSET at the non-inverting input of U13 sets the transmitter to the desired power
level. U12-2 samples the transmit signal. The sampled RF signal is rectified by the temperature stable circuitry of
CR11, CR12, etc, and is routed to the inverting input of the integrator at U13-4. The output of the integrator at U13­1, labeled VCONTROL, controls the gain of the power amplifier. Any change in transmitter output power level is
automatically corrected by the loop.

GUARDIAN VHF 110W MOBILE 2-9

2.5.1.3 PIN Diode Switch

The antenna PIN diode switch is made up of CR7, CR8, CR9, CR10, and other associated components. This switch
is a four-port design. The four ports are antenna 1 (TOP RF), antenna 2 (SIDE RF), receive, and transmit. Receive
and transmit ports can be switched to only one of the two antenna ports. Transmit signals are routed from the
transmit/receive PIN diode switch (to be discussed in the following paragraph) to the antenna port. The receive
signal is routed from the selected antenna port to the transmit/receive PIN diode switch. The antenna PIN diode
switch and receiver circuits share current in the receive mode of operation via the signal labeled RXSINK at Q11,
pin 3. The insertion loss through the antenna pin switch is 0.2 dB typically.

The transmit/receive PIN diode switch is made up of C6, L60, L38, L40, L39, D9, D7, D10, C97, C98, C104, C105,
C106, C107, and other associated components. C127, C114, L42, and C115 are the 1/4 wave simulator circuit. The
1/4 wave simulator is critical to the design of the switch. In the transmit mode of operation CR13 and CR14 are
forward biased. C116 resonates with the internal series inductance of CR14 at 155 MHz and the receive port (RX
INPUT) is RF shorted to ground. With the receive port RF shorted to ground; the parallel combination of C127,
C114, and L42 forms a tank circuit resonating at 155 MHz. Consequently, the receive port appears as an open
circuit to the transmit signal and is routed to the antenna PIN diode switch. In the receive mode of operation, CR13
and CR14 are biased off so C114/L42/C115 appears as a low-pass filter (LPF) to signals at the antenna port of the
switch. The insertion loss through the transmit/receive PIN diode switch is 0.4 dB in the transmit mode and 0.2 dB
in the receive mode typically.

Q10 to Q19 and associated components are switching transistors used to control the antenna and transmit/ receive
PIN diode switches. The current flowing through the entire PIN diode circuit is approximately 45 mA in the
transmit mode of operation. In the receive mode of operation the transmit/receive PIN diode switch is disabled, and
nominal 85 mA flows through the antenna PIN diode switch.

2.5.2 Receiver

The VHF signal enters into the RX INPUT via the PIN diode switch (discussed previously). D1 and D2 are
Schottky protection diodes to protect the front-end circuitry from RF overloads that could occur if the PIN diode
switch failed to work properly or if a transmitter is very close to a receiver. Typical insertion loss is 0.1 dB for the
protection diodes. L25/C61 form a band-stop filter (BSF) at the first IF frequency of 45 MHz. Typical insertion
loss for the BSF is 15 dB at 45 MHz but less than 0.1 dB in the VHF band.

L14, L6, CR3, CR4, L7, CR27, CR28, L8, and L15 make up the very high frequency (VHF) preselector band-pass
filter (BPF). The BPF is inductively coupled for improved high-side attenuation. This filter provides attenuation to
spurious signals such as the first image and the half-IF. The BPF is varactor diode tuned by DAC line RXVTF.
Typical insertion loss (138 to 174 MHz) is 1 dB for the VHF BPF.

The RF amplifier (Q1, T1, etc.) utilizes loss-less feedback to deliver reasonable gain, low-noise figure, and a high
third order intercept point simultaneously. Typical gain (136 to 174 MHz) is 11.5 dB for the RF amplifier.

C14, L1, C9, C15, L2, C10, C16, L3, C11, C17, and L9 form a VHF LPF. This filter provides additional RX
spurious attenuation as well as image noise attenuation. L4, C12, L16, C25, L5, and C13 form a BSF at the first IF
frequency of 45 MHz. The insertion loss is 1.0 to 2.0 dB (136 to 174 MHz) typically for the cascade. The IF BSF
insertion loss is typically 40 dB at 45 MHz, but less than 0.3 dB in the VHF band.

U1 is a double-balanced mixer (DBM). U1 converts the desired RF signal down to the first IF of 45 MHz. High­side local oscillator (LO) injection is used. Therefore, the LO is 45 MHz higher than the receiver tuned frequency.
The LO drive level is +10 dBm nominal at U1, pin 1. The conversion loss of the mixer (RF to IF) is 5.5 dB
typically.

The LO signal is generated in the synthesizer section (to be discussed later). The LO signal is designated RXLO on
the schematic diagram. The LO signal is routed to a LPF consisting of C31, L21, C87, C30, L20, C75, and C28.
L19 and C28 are also used to impedance match the LO port of the mixer. The insertion loss of the VHF LO LPF is

0.3 dB typically at 174 MHz.

R4, L17, C6, L10, R5, and C23 make up the diplexer network. This network properly terminates the DBM both in
and out of band. The diplexer also provides some additional half-IF spurious rejection. The diplexer insertion loss
is 0.8 dB typically at 45 MHz.

2-10 GUARDIAN VHF 110W MOBILE

There are two 45 MHz IF amplifier circuits. The first (Q2, T2, etc.) utilizes loss-less feedback to deliver reasonable
gain, low-noise figure, and a high third order intercept point simultaneously. Typical gain is 10.5 dB for the first IF
amplifier.

There are two crystal BPFs and a second 45 MHz IF amplifier. The BPFs provide attenuation for the adjacent and
alternate channels, and also for the second image response. FL1 is a four-pole crystal filter with a 20 kHz
bandwidth centered at 45 MHz. FL4 is a two-pole crystal filter with a 30 kHz bandwidth centered at 45 MHz. The
second 45 MHz IF amplifier provides high gain to prevent further degradation of receive sensitivity. C57, L12,
C18, C19, and L13 are impedance matching elements for the input of FL1. The output of FL1 is impedance
matched to the second 45-MHz IF amplifier (Q36, etc.) by C285, L64, and C242.

The output of the second 45-MHz IF amplifier is impedance matched to FL4 by C287, L61, C286, C237, L60, and
C235. The entire cascade provides 21 dB of gain and has a 3 dB bandwidth of 20 kHz typically. Typical insertion
loss is 1.5 dB for each crystal BPF.

The IF IC (U28) contains the second mixer and an IF amplifier chain. The 45 MHz IF signal enters U28 at pin 6
from the crystal BPF (FL4). FL4 is impedance matched to the IF IC input by C294, L62, and C288. The incoming
45 MHz IF signal is mixed with the second LO (to be discussed later). The second mixer IF output is at U28, pin 8
and the second IF frequency is 455 kHz.

The signal from U28-8 is routed to FL3. FL3 is a ceramic BPF operating at 455 kHz. The insertion loss of the
ceramic BPF is 6 dB typically in a 1500-ohm system.

The 455 kHz IF signal enters U28-10, is amplified by a cascade of IF amplifiers, and exits at U28-14. The signal
from U28-14 then enters a second ceramic BPF, FL2. FL2 is the final ceramic BPF with a typical insertion loss of 8
dB in a 1000-ohm system. The 455 kHz IF signal enters its final stage of amplification at U29-3. U29 is configured
as a non-inverting operational amplifier and is capable of driving a 50-ohm load. The amplifier is set for a voltage
gain of 2.5. With the receiver set to full gain the signal level at J4 (455 kHz IF OUT MONITOR) is -20 dBm "3 dB
into 50 ohm with a -119 dBm unmodulated 136 MHz signal injected at J2 (TOP RF) or J3 (SIDE RF). The second
LO consists of CR26, R33, Y1, L24, C59, C226, C227, and Q35. The oscillator is a Colpitts type with the crystal
operating in the series mode. CR24 is a varactor diode used to set the oscillator on frequency using the DAC output
labeled 2

nd

LO. The second LO operating frequency is 44.545 MHz (low-side injection). L65 and C223 impedance
match the output of Q35 to the LPF (C289, C293, L63, and C284). The signal is attenuated by R282, R283, and
R284 and sent on to the second mixer. The signal level at U28-4 is -16 dBm nominal.

U4 is a voltage regulator used to power the receiver circuits. The dc voltage appearing at U4, pin 1, labeled
RXSINK on the schematic diagram, is routed from the antenna PIN diode switch. As previously discussed, the PIN
diode switch and the receiver circuits share current to reduce receive power consumption. The control line +3.3V
RXEN is used to enable the regulator while the transceiver is in the receive mode of operation. The regulator is
disabled during the transmit mode of operation.

2.5.2.1 Synthesizer and Reference Oscillator

U19 is a fractional-N synthesizer IC programmed for a specific frequency by loading appropriate serial data into the
IC. It controls the receive VCO when the transceiver is in the receive mode of operation, and the transmit VCO
when in the transmit mode. The programming lines are labeled 3VSCL, 3VSDA and 3VSYNTHENA on the
schematic diagram. These are all CMOS logic level inputs. R118 (RF) and R123 (RN) are the fractional
compensation and phase detector current setting resistors, respectively. These resistors are critical to the operation
of the synthesizer system and must be checked when troubleshooting around U19. The phase detector output pins
(U19-13 and U19-14) are fed to the passive loop filter (R140, C177, C172, R134, and C173) and on to the VCO
control varactor diodes (CR17/CR19) for frequency control. The buffered, filtered output from the VCO is fed into
U19-5 (RF IN) to close the phase-locked-loop. The level is typically -10 dBm into U19-5. The reference oscillator
is made up of CR22, Y2, Q28, C197, and C198 and associated components. The reference oscillator operates at

12.8 MHz. The reference oscillator operating frequency is adjusted by varying the dc voltage at the DAC controlled
line that is labeled REFOSCMOD. This line is also used to modulate the reference oscillator during the
transceiver’s transmit mode of operation. The 12.8 MHz signal is fed into the synthesizer chip at U19-8 (REF IN)
using a coupling capacitor, C194. The AC signal level at U19-8 is 1V p-p typically.

GUARDIAN VHF 110W MOBILE 2-11

U22 is the reference oscillator temperature sensor used to monitor the temperature near Y2. Its output is labeled
XTALTEMP on the schematic diagram. This line is normally monitored by the microprocessor so the reference
oscillator can be adjusted for drift due to changes in temperature.

2.5.2.2 Receive/Transmit VCOs and Buffer Amplifiers

The receive VCO operates from 181 to 219 MHz since high side LO injection is used and the first IF is
45 MHz. The transmit VCO operates from 136 to 174 MHz. Each VCO is a Colpitts type design utilizing a low
noise, bipolar transistor as the active device. The receive VCO uses Q24 and the transmit VCO uses Q21, each in
the common collector configuration. The Colpitts capacitors are C169/C180 (receive VCO), and C137/C142
(transmit VCO). These capacitors enable Q24 to oscillate in the 181 to 219 MHz frequency range and Q21 to
oscillate in the 136 to 174 MHz frequency range. L53 is the resonating inductor for the receive VCO and L45/L46
are the resonating inductors for the transmit VCO. CR20/CR21, and CR16/CR18 are the coarse tuning varactor
diodes for the receive and transmit VCO respectively. These diodes are used to coarse tune the VCO such that the
LPF, phase detector output voltage (from U19) at TP10 equals 1.65 Vdc. The receive and transmit VCOs share the
coarse tuning DAC controlled line labeled CTUNE. Coarse tune dc voltage swings from nominal 1.8 to 22 Vdc.
CR19 (receive VCO) and CR17 (transmit VCO) are the fine-tuning varactor diodes controlled by U19 as was
explained previously. CR15 is the modulation varactor diode for the transmit VCO. The output from the receive
VCO is coupled off Q24-E using C174. The output from the transmit VCO is coupled off Q21-E using C139. The
signal is measured at the C174/R146 node (receive) and the C139/R107 node (transmit), and measures -15 dBm
typically.

Q26 and Q22, and associated components, form the first VCO receive and transmit buffer amplifiers respectively.
These amplifiers buffer the VCO output from changing-output voltage standing wave ratios (VSWR) that could pull
the VCO off frequency. The output from each measures -5 dBm typically. The buffer is measured at the
C170/R141 node (receive) and the C138/R131 node (transmit). Q25 is the second buffer amplifier. This amplifier is
common to both the receive and the transmit VCOs. R131, R141, and R142 are the combining elements used to
make this possible. This buffer outputs a signal large enough, after subsequent attenuation and filtering, to properly
drive the RF IN pin of the synthesizer (U19-5). The output from this buffer is measured at the C167/C53/L52/C175
node and measures 0 dBm typically.

The output from the Q25 buffer is filtered by C175, C53, L52, and C176. This LPF prevents the synthesizer IC
(U19) from locking on to harmonics of the desired frequency. The insertion loss of the LPF is 0.4 dB typically.

The signal is then split by R138, R139, and R144, and sent on to the appropriate receive or transmit final buffer
amplifier. The signal measured at R139/C150/ C186 node is -6 dBm, and the signal measured at R144/R143/C168
node is -6 dBm.

Q23 (receive) and Q27 (transmit) is the final buffer amplifier. Q23 amplifies the signal up to the level needed to
properly drive the LO port of the DBM (discussed previously). Q27 amplifies the signal up to the level needed to
properly drive the PA pre-driver (previously discussed). The signal measured at RXLO is +7 dBm typically. The
signal measured at TXLO is +7 dBm typically.

U17, Q20, etc. form the voltage regulator for the receive and transmit VCO/buffer amplifiers. R67, C124, and Q20
form a super filter, which attenuates voltage regulator noise that may otherwise degrade the synthesizer phase noise
performance.

U20, U21, Q29, Q30, CR23, CR24, CR35, C199, C202, C203, etc. create a voltage multiplier. The circuit is
configured as a voltage quadrupler. Circuit losses and output loading lowers the voltage down from 24 Vdc to about
22 Vdc. The driver circuit (U21) switches at about 192 kHz. This frequency was selected so harmonics would not
land at or near the second IF frequency of 455 kHz. The 22 Vdc supply is used to power the DAC supporting quad
op-amp U18.

The shift register (U24) is used to control transceiver modes of operation and functions. The line labeled STD/SIDE
selects the desired antenna port of the transceiver. The line labeled TX/RX selects either the transmit or receive
mode of operation. +3.3V RXEN turns the receiver on and off (previously discussed). Q34/Q32 and Q33/Q31
enable and disable the receive and transmit VCOs and buffers respectively (discussed previously). U16 is the
voltage regulator that supplies all 5V digital circuitry on the transceiver.

2-12 GUARDIAN VHF 110W MOBILE

2.5.3 Digital/Analog Control

Digital/analog control is shown on page 1 of the RECM schematic. The transceiver is fitted with an EEPROM
(U15). The IC is used to store calibration and curve fit data, which is needed when the transceiver is configured
with the Guardian radio. Each transceiver has its calibration and curve fit data stored within the EEPROM. The
calibration and curve fit data is written to the EEPROM at the successful conclusion of level 2 testing. Two quad 8­bit serial DACs, a quad 12-bit serial DAC, and supporting operational-amplifiers (U2, U6, U13, U18, and U30)
control much of the transceiver, as has been discussed previously. U32 is a 2.5 Vdc reference used by the Quad 12­bit DAC and the variable IF attenuator (discussed previously).

U18D and associated components amplifies the dc signal supplied by U31-3.

As was discussed previously, REFOSCMOD is the dc signal, which varies the operating frequency of the reference
oscillator. Normally under DSP and microprocessor control, this line is used to FM modulate the reference
oscillator, which in turn FM modulates the RF carrier in transmit mode. This line is used to temperature compensate
the reference oscillator as well.

The DAC controlled line TXVCOMOD at U31-4 is transmit data normally controlled by DSP and a microprocessor.
This signal is routed to U18C and associated components. U18C and associated components form an active
LPF/attenuator to shape the transmit data before modulating the RF carrier in the transmit mode. The cutoff
frequency of the LPF occurs at 20 kHz. The 1 kHz peak-to-peak signal level at the active LPF output (U18-8) is
one-fourth TXVCOMOD at 2.5 Vdc.

The synthesizer reference oscillator and the transmit VCO are simultaneously modulated to balance the FM
modulation. We refer to this technique as two-point modulation. The DAC values required to balance the
modulation are dependent on RF frequency.

The dc signal at U31-17 is routed to U30 and associated components. This op-amp is configured for a voltage gain
of 2. The dc signal VATT controls the variable IF attenuator (discussed previously) in the receiver chain. Under
DSP and microprocessor control, the attenuator is normally set for a desired amount of attenuation by this DAC
controlled signal.

Q37, Q38, Q39, Q40, Q41, and associated components are used to enable and disable the 14 dB step attenuator in
the receiver chain (discussed previously). Normally under DSP and microprocessor control, the attenuator is set to
the desired state of operation via U31-13. A logic level “1” at this pin enables the attenuator. Conversely, a logic
level “0” at this pin disables the attenuator (bypass mode).

U18B and associated components amplifies the dc signal supplied by U33-2. As discussed previously, CTUNE is
the dc signal which coarse tunes the receive and transmit VCOs. Under microprocessor control, the appropriate
VCO is normally coarse tuned to a desired frequency based on curve fit data stored in the EEPROM (U15). Curve
fit data is obtained and stored in the EEPROM during coarse tune calibration procedures performed at level 2
testing.

The DAC controlled DC signal 2
Normally under microprocessor control, the 2
EEPROM (U15). The correct DAC value is obtained and stored in the EEPROM during the 2

nd

LO sets the 2nd LO (discussed previously) on frequency at 44.545 MHz.

nd

LO is set on frequency based on a DAC value stored in the

nd

LO calibration

procedure at level “2” testing.

The DAC controlled dc signal RXVTF appropriately sets the varactor tuned BPF (discussed previously) based on
the receiver tuned frequency. Normally under microprocessor control, the varactor tuned BPF is set based on curve
fit data stored in the EEPROM (U15). The curve fit is based on statistical data obtained during the testing of
hundreds of units.

The DAC controlled dc signal PWRSET sets the power amplifier (discussed previously) to a desired power level.
Normally under microprocessor control, the power amplifier is set to the desired level based on curve fit data stored
in the EEPROM (U15). The curve fit data is obtained and stored in the EEPROM during transmit power calibration
procedures at level 2 testing. The power calibration procedure obtains curve fit data for five power level settings
(0.1W, 0.5W, 1.0W, 2.0W, and 5.W) over the entire transmitter operating frequency range (136 to 174 MHz).

The DAC controlled dc signals PA1 and PA2 set the gate bias for each power transistor (Q6 and Q9 respectively) in
the power amplifier circuit (discussed previously). These two signals are routed to op-amps U2 and U6, which are

GUARDIAN VHF 110W MOBILE 2-13

configured for a voltage gain of 2. The outputs at U2-1 and U6-1, labeled PABIAS1 and PABIAS2 respectively, are
then routed to the gates of the power transistors. The correct DAC values for the bias current are stored in the
EEPROM (U15). The correct DAC value is obtained and stored in the EEPROM during the power amplifier bias
calibration procedure at level 2 testing. Each gate is biased such that 100 mA of current flows through each power
transistor with PWRSET set to a DAC value of zero in the transmit mode. Level 2 software monitors the U10
output line labeled IMONITOR when calibrating PA bias.

2.5.4 Keypad Microcontroller

The keypad board is controlled by an Atmel AVR4414 microcontroller. This is a Flash programmable device. The
microcontroller implements these functions:

 Keypad scanning
 PTT switch input
 Auxiliary keys input
 Volume switch input
 Channel switch input
 Emergency switch input
 Synchronous bidirectional serial interface to main controller at 100 kHz
 Keypad and LCD backlight control

A clock derived from the main reference clock, clocks the keypad microcontroller at 1.5 MHz. The keypad
microcontroller is powered by the 3.3V supply as the LCD driver device.

2.6 Audio Amplifier Board

2.6.1 Description

The Audio amplifier board contains the internal and external audio and control circuitry. It also houses the DB25
accessory connector, the DB9 power connector, and the RF control connector that protrudes through the rear panel.
The board is located in the Control Module. The board contains the following functions:

 RFI and transient protection and system on/off switch

 Voltage regulator and 7.8V on/off switch

 Communication with transceiver

 Audio power amplifiers

 Power levels detector and converter and the RF and DC combiner

 PA on off control

 RFI and transient protection

2.6.2 Power Conditioning

Power for the Guardian 110W control head enters this board on J5 the DB9 connector. Dual low R
FET Q10 serves as reverse polarity protection and on-off switching. Transistor Q7 pulls down the gates of Q10
when the ON/OFF signal is high, allowing Q10 to conduct. With ON/OFF control low, Q10 is cut off, and will not
pass forward or reverse polarity. An over-voltage condition is detected by D2 and Q6, which cause Q7 to cut off and
turn off power.

DS(on)

P-channel

Back-to-back transorbers D1 and D4 are used to eliminate voltage spikes before the on/off switch. The input power
is routed to the clamp circuit via an LC filter. The filter eliminates unwanted signals from being conducted to the
vehicle power line.

2-14 GUARDIAN VHF 110W MOBILE

2.6.2.1 Voltage Regulator and 7.8V On/Off Switch

Linear regulator U5 provides +7.8V to the RF power control circuitry and to the other two PC assemblies in the
control head. The regulator is powered via Q10 body diode at all time. When the unit is turned off all the circuits
are disconnected from power except the transceiver in the control head. The transceiver in this case is in the off
state. The power consumption in this case is less than 2 mA powering the boat backup memory circuits.

2.6.3 Communication with Transceiver

Twenty pin IDC headers J2 and J3 carry control and status signals from the transceiver and front panel via the
Control PCA.

2.6.4 Audio Amplifiers

The board contains two identical audio amplifiers. Each audio amplifier has 20 dB gain and is capable of delivering
more than 10W to a 4-ohm load in a bridge-tied-load configuration. They are fed from the transceiver audio output.
A front panel switch selects either or both amplifiers; an unselected amplifier is placed in a mute condition by the
appropriate disable signal. When there is no received signal, both amplifiers are placed in a low-current standby
mode by squelch comparator.

2.6.5 Power Levels Detector, Converter, and RF/DC Combiner

ON /OFF, PTT and RF output power control signals to the 110W power amplifier are generated on this board.
These are present as DC signals on the center conductor of the coaxial cable connecting the control head to the
remote RF PA. A low-pass filter prevents RF from reaching the control circuitry. The voltage levels are as follows:

DC Control Voltage Range PA State

0 to 0.4V DC on/off switch – OFF

>0.7V DC on/off switch – ON

0.7 to 1.2V PA is in bypass – RECEIVE mode

2.1V Power output set 25W

3.6V Power output set 50W

6.5V Power output set to 110W

The transceiver power levels are detected via the connection to TP21. The voltages are as follows:

TP 21 Control Voltage Boat Power Output

2.85 5W

1.87 2W

1.28 1W

The control circuits converts an input above 2.2V (5W setting) to a control signal to 6.5V, which results in 110W
generated in the remote RF power module. Accordingly it converts the 2W and 1W control levels to the indicated
PA control. Input control of less than 1V is converted to 2.6V. The PA puts out 25W also for the 0.5W input power
setting but will fail to do so at the 0.1W setting. In this case power output is not specified, and the red LED will not
light.

GUARDIAN VHF 110W MOBILE 2-15

2.6.6 PA ON/OFF Control (Bypass Mode)

It is possible to operate the system not utilizing the PA (PA in by pass mode.) This is done by turning on control
head on with the PTT depressed. An orange TX light indicates to the user that he is operating in by pass mode. In
this mode, output power is about 1dB lower that the nominal levels delivered from the transceiver, as indicated in
the table above. In normal mode, Q16 conducts at start-up, causing Q14 to conduct, which keeps Q15 off. When
using this mode, Q16 conducts in the reverse direction, Q14 remains off and Q15 conducts, which prevents bias
voltage from being sent to the RF power amplifier.

2.6.7 RF Power Indication

Operational amplifier U3A forces the output control voltage at Q8-E to be equal to that at U3-3. After high power
transmit is detected at the PA output. The RF PA test circuit forces additional current back into this line. The op­amp loop holds the voltage at the input level, so the additional current is forced out Q8-C and through R44. This
forces Q9 to conduct and sink additional current from the LED_TX. The LED_TX turns off the green light. When
the unit is in bypass (low power) mode the Tx lamplights orange because the red and the green LED’s are on.

2.6.8 Audio Board Block Diagram

Audio Block diagram

D

input voltage

B

9

D
B

25

RFI filter&

transient

protection

power level input

7.8volts

switched

voltage

ragulator

on off switch

power level

voltage

converter

PA on off

control

Switch PTT

7.8volts

7.8volts

switched

audio in

RF&DC

combiner

j

4

audio out p

internal

audio amplifier

audio out n

audio out p

external

audio amplifier

audio out n

RF &control out/in

RF IN

J2 - IDC 20 pin J3 - IDC 20 pin

2-16 GUARDIAN VHF 110W MOBILE

Figure 2-4: Audio Board Block Diagram