ISSUE 1-2A
Maintenance Handbook T6R VHF Receivers
CONTENTS Preliminary Pages Title page Contents (this list) Warnings page Amendment Amendme nt record Modification record List of abbreviations used in this handbook
Section 1
-
GENERAL INFORMATION
Section 2
-
TECHNICAL DESCRIPTION
Section 3
- MAINTENANCE
Section 4
-
VIRTUAL FRONT PANEL (VFP)
Section 5
-
PARTS LIST
Section 6
- FIGURES
WARNINGS
LETHAL VOLTAGES
Equipments in operational use contain lethal voltages and operations involving the removal of covers or panels should only be undertaken by skilled personnel who are aware of the hazards involved.
CAUTION ESDs The equipment covered by this handbook contains electrostatic sensitive devices (ESDs). Observe handling precautions to avoid static charges that may damage these devices. UNAUTHORIZED MODIFICATIONS Changes or modifications made to this equipment, not expressly approved by Park Air Electronics or parties authorized by Park Air Electronics could void the user’s authority to operate the equipment.
AMENDMENT RECORD
Amdt.
Incorporated By
Date
Brief Details
ECN
1
Park Air
Sep 03
Section 6, List of Figures, Fig 10 title amended.
-
2A
Park Air
Nov 03
Section 6, List of Figures, drawing numbers added.
-
MODIFICATION RECORD MOD No.
Details
Date
LIST OF ABBREVIATIONS USED IN THIS HANDBOOK
ac A/D AGC AM BIT D/A dc dB dBm DSP ETI ESD Hz I/O kHz LCD LED MARC MHz mm MSK PC PCB
alternating current analogue to digital audio gain control amplitude modulation built-in test digital to analogue direct current decibel decibels relative to 1 mW digital signal processing elapsed time indicator electrostatic sensitive device hertz input/output kilohertz liquid crystal display light emitting diode multi-access remote control system megahertz millimetre minimum shift keying personal computer printed circuit board
Section 1
General Information
Paragraph 1 Introduction 5 Model part number 6 Operating frequency 7 Input supplies 8 Built-in test (BIT) indications 11 Configurations
INTRODUCTION 1 This handbook provides the maintenance personnel with sufficient information to maintain and repair the T6R receiver to module level. It provides an overview of the internal architecture of the receiver and describes the various replaceable modules, their function, part number and how to obtain replacements. In particular it enables the user to:
Conduct scheduled maintenance tasks including checking/setting the reference frequency oscillator to compensate for long term ageing effects
Identify any tools or test equipment required to maintain the receiver
4 The maintenance handbook, lead and software is sold as a T6R maintenance kit part number 70-6100MKIT. Note ... Both the maintenance handbook and user guide are available on CD-ROM. Contact PAE for details.
MODEL PART NUMBER 5
The part number for the T6R receiver is:
B6100
OPERATING FREQUENCY 6 The receiver’s operating frequency is determined by the synthesiser circuit in the Rx RF module and can be changed by the user through the front panel, through the VFP or through an associated MARC system (or compatible control and data system). Details of how to change the operating frequency are contained in the T6R Receiver User Guide, Section 4 of this handbook (VFP) and the MARC User Guide (MARC).
CONFIGURATIONS 11 The connectors used to configure the receiver depend on the required operating mode. The purpose of each connector is described in the following text: Antenna Connector
Used in all operating modes to connect the 50 ohm antenna feeder cable.
Headset/Diagnostics Connector
This is a dual purpose connector. A headset can be connected to enable local AM-voice operation. Alternatively, a PC can be connected to allow use of the VFP, to set the receiver's operational settings, or to download new software.
Reference Connector
Used in all operating modes to check and reset the receiver's reference frequency.
Facilities Connector
Used primarily to connect remote signals when using AM-voice mode and the receiver does not form part of a MARC system. Some auxiliary signals available at this connector, for example the 24 volt (nominal) unregulated output supply, can be utilized irrespective of the operating mode.
MARC Port
The MARC port is used to connect remote signals when the receiver forms part of a MARC system, or other compatible control and data system.
Section 2 Paragraph 1 INTRODUCTION 4 MODULES AND ASSEMBLIES 7 DSP module 8 Central processor 9 Digital signal processing 10 Programmable gate array 11 Speech coding/decoding 12 Computer interface 13 Serial remote control/data port 14 Facilities port 15 Front panel interface 16 Analogue control interfaces 18 Digital control interfaces 19 Rx RF module 20 RF converter 22 IF filter/converter 25 Synthesiser 28 BIT 29 Front panel module 30 LCD module 31 Rotary encoded switch 32 Indicators
Technical Description
INTRODUCTION 1 This section describes the modules and assemblies that comprise the T6R receiver and details the equipment’s connectors. Designed for rack mounting in a standard 19 inch rack the unit operates from standard 120/240 V ac supplies with automatic changeover to 28 V dc in the event of mains failure. The majority of user connections are made through rear mounted connectors. 2 A front panel connector is used for the connection of a headset for local operation or for the connection of a PC for Virtual Front Panel (VFP) control. Operational settings are configured at the front panel, through the VFP, or through an associated MARC system (or compatible control and data system). At the receiver, operational settings are selected and displayed using the front panel Scroll/Select switch and the LCD. 3 The receiver is housed in a sheet metal chassis with top and bottom lids. Two compartments (top and bottom) contain most modules and assemblies with front and rear panels straddling the compartments.
MODULES AND ASSEMBLIES 4
The receiver comprises the following replaceable modules and assemblies:
DSP module
Rx RF module
Front panel module
Digital Signal Processing 9 The Super H processor is supported by two Analogue Devices 2171 DSP microprocessors providing the computational power required to implement the demodulation algorithms.
Programmable Gate Array 10 Circuit functions are register mapped into the Super H address space using a Xilinx FPGA. This allows the hardware configuration to be altered or upgraded by downloading new firmware.
Speech Coding/Decoding 11 The A/D and D/A functions required to interface the digital processing to the analogue lines are provided by an A Law speech CODEC. Audio output is used to drive a front panel connected headset or loudspeaker. Audio is also routed out via the Facilities port.
Computer Interface 12 Two RS422 full duplex synchronous serial ports, using HDLC protocol, provide the interface to an external computer for use in digital modulation modes. A set of four input lines and four output lines, operating at RS232 voltage levels, are also provided to allow a receiver to be linked to a transmitter to form a base station.
Table 1 Facilities Port Connections Inputs: Squelch Defeat Rx Disable Bit Interruptive Test
Outputs: Line out (+) Line out (-) Squelch Common Squelch RSSI Ready Tape Output Unregulated Supply Squelch output
Front Panel Interface 15 An 8-bit data bus and associated control signals are provided to drive the Front Panel LCD module with separate lines also provided to drive the LEDs and to read the rotary encoder. An RS232 asynchronous serial port provides the diagnostics link.
Analogue Control Interfaces
Digital Control Interfaces 18 To interface to the Rx RF module, digital I/O signals, as shown in Table 2, are used. Table 2 Digital I/O Signals Outputs
Inputs
Filter Value (5 bits)
BIT Synth Lock
Narrow/Wide
8.33 (Rx RF)
BIT Control (3 bits)
Tx/Rx Detect
Power Down Synth Control (4 bits)
RX RF MODULE 19 This module combines a synthesiser, an RF converter and an IF filter/converter onto one PCB.
RF Converter 20 The RF Converter section converts the RF input signal down to the IF frequency. Two digitally tuned
27 A BIT output signal (BIT Synth Lock) is provided when the synthesiser is in lock.
BIT 28 The Rx RF module is able to provide a module interruptive BIT to determine if it is at fault. This is done by injecting a noise signal, controlled by the DSP module via the BIT Control line, into the front end of the RF conversion stage, after the RF AGC. The RF AGC is held low during this test to prevent antenna radiation. The noise source is a broadband VHF oscillator on the Rx RF module. The noise signal should pass through the RF and IF conversion stages to be demodulated by the DSP module as would a real signal.
FRONT PANEL MODULE 29 The Front Panel module consists of the following elements:
LCD Module 30 A 16 character by 4 lines liquid crystal display module with backlight displays the radio menu system. It is controlled by an 8-bit data bus from the DSP module accompanied by 3 control lines (a separate control line is used to switch the backlight on and off).
