After Sales Technical Documentation
THX–4 Series Transceiver
Chapter 3
TRANSCEIVER
OVERVIEW
Original, 09/94
THX–4
After Sales
Transceiver Overview
Technical Documentation
CHAPTER 3 – TRANSCEIVER OVERVIEW
CONTENTS
Page No
Introduction 3–3
System Module 3–3
Display Module 3–3
List of Figures
Figure 1: RF Block Diagram 3–4
Figure 2: Baseband Block Diagram 3–5
Original, 09/94Page 3–2
After Sales
THX–4
Technical Documentation
Introduction
The THX–4 series is an advanced analogue handportable cellular
telephone for operation on the E–TACS cellular system. The design is
fully compatible with the TACS Mobile Station / Land Station specification.
The telephone contains many advanced user facilities and is designed for
ease of maintenance.
The transceiver consists of two modules: a system module and a display
module.
System Module
The system module performs the following functions:
received audio processing
transmitted audio processing
Transceiver Overview
data reception and transmission
channel selection
RF signal reception and detection of the modulated
information to baseband
modulation of the baseband microphone and data
signal to the selected channel and amplification of the
RF signal to the selected power level
The system module contains a microprocessor, which controls the main
functions of the phone, and parts of the HW dependent user interface
(earphone, microphone, and alarm–beeper).
For convenience the non–RF sub–systems are referred to as the
’Baseband functions’, and the RF sub–systems as the ’RF functions’.
Figures 1 and 2 show the rf and baseband functional blocks respectively.
The RF functions provide the RF interface with the cellular system and
demodulated audio signals to the analogue sub–system. They also
modulate audio signals from the analogue sub–system.
The baseband functions cover both analogue sub–systems (responsible
for all audio processing functions) and digital sub–systems (responsible
for all digital signal processing functions) and the microcontroller /
software (responsible for control and data processing functions).
Display Module
The display module comprises a supertwist–LCD, a display driver and
keyboard contacts, volume and on/off switches.
Original, 09/94 Page 3–3
ANT
917–950 MHz
Transceiver Overview
Figure 1: RF Block Diagram
THX–4
Original, 09/94Page 3–4
ANT
SWITCH
EXT
ANT
NOKIA MOBILE PHONES UK LTD
H500 TACS
DRAWN
ISSUE
FILENAME
DATE
DUPLEXER LNA SAW MIXER
933 MHz
33 MHz bw
15 dB
COUPLER
DETECT
872–905 MHz
RX VCO
962–995 MHz
POWER AMP
POWER
CONTROL
TXI
V_ALC
45 MHz
25 kHz bw
IF CHIP
450 kHz
25 kHz bw
DISC/
RSSI
DAF
RSSI
128/
129
44.55 MHz
X3
RX SYNTH
PLL
14.85 MHZ
VTCXO
VCTCXO
SYNDAT
SYNCLK
RXLE
TXLE
ISOLA TION AMP
BIAS_PD
Tx VCO
128/
129
TX SYNTH
PLL
BIAS_PA
VDRIVER
TX
4V8_RX
RX
VGG
MOD
VMOD
VBAT
VREF
Technical Documentation
VDRIVER_EN
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PA SWITCH
5 VRXEN
P AV_EN
After Sales
THX–4
Technical Documentation
Figure 2: Baseband Block Diagram
Transceiver Overview
Original, 09/94 Page 3–5
THX–4
After Sales
Transceiver Overview
Technical Documentation
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Original, 09/94Page 3–6
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