User's Manual
Table Of Contents
- Front Cover
- Contents
- 1 - Foreword 11
- 2 - Safety and General Information 21
- 3 - Introduction 31
- 4 - System Applications 41
- 5 - Models and Specifications 51
- 6 - Approved Accessories 61
- 7 - Setup and Connections 71
- 8 - Operation 81
- 9 - Troubleshooting 91
- Introduction 91
- Recommended Test Equipment 91
- Troubleshooting Procedures 91
- Module Replacement Procedures 925
- General Replacement Information 925
- Anti-Static Precaution 925
- Care of Gold-Plated Connector Contacts 926
- Power Down Station Before Removing/Inserting Modules 926
- Validating Repairs 926
- Module Replacement 926
- Wireline 928
- ASTRO Modem Card/V.24 Interface Card 929
- Receiver 929
- Exciter 931
- Power Amplifier 932
- Power Supply 933
- Backplane 934
- Preselector Field Tuning Procedure 935
- 10 - Functional Theory of Operation 101
- 11 - Block Diagram, Schematics, Electrical Parts List, and Circuit Board Detail 111
- List of Tables
- List of Figures
- Parts Lists
- Foreword
- Safety and General Information
- Introduction
- System Applications
- Models and Specifications
- Approved Accessories
- Setup and Connections
- Operation
- Troubleshooting
- Introduction
- Recommended Test Equipment
- Troubleshooting Procedures
- Module Replacement Procedures
- Preselector Field Tuning Procedure
- Functional Theory of Operation
- Schematics
- Back Cover
68P81093C75-O December 1, 2000 10-1
Functional Theory
of Operation 10
The following functional theory of operation provides an overview
of the station circuitry. For a more thorough functional description
of a particular module, refer to the appropriate section of the
Quantar User’s Guide (68P81095E05). Refer to the block diagram
in Figure 16. for the following functional theory of operation.
Transmitter Circuitry
Operation
Introduction
The Transmitter Circuitry consists of the following:
• Exciter Module
• Power Amplifier (PA) Module
These modules combine to produce the modulated, amplified RF
signal. The RF signal is transmitted via the station transmit antenna.
Exciter Module
Operation
The Exciter Module is a microprocessor-controlled module,
generating a modulated RF signal at the desired transmit frequency.
It sends this signal to the Power Amplifier for amplification. The
circuitry operates as follows:
1. The Synthesizer/Voltage-Control Oscillator (VCO) accepts
frequency programming data from the Station Control Module
(SCM) via the Serial Peripheral Interface (SPI) bus and
generates an RF carrier signal at the specified frequency.
The modulation audio signal from the SCM modulates the carrier,
resulting in a modulated RF signal at approximately +13dBm. The
modulated signal is routed to the Power Amplifier.
2. The TX Power Control Circuitry accepts an output power detect
voltage from the Power Amplifier and compares this signal to a
reference voltage representing the desired output power.
Based on the comparison, a power control voltage is generated to
control the output power from the PA. This feedback and control
loop continually monitors the output power. It adjusts the control
voltage to maintain the proper output power from the PA.