Theory Of Operation; Overview; Controller; Figure 2-1. Controller Block Diagram - Motorola CDM1550 LS+ Detailed Service Manual

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2-1
Chapter 2
Theory of Operation
2.1 Overview
This chapter provides a detailed theory of operation for the radio and its components. The radio is
designed as a single board unit consisting of a transmitter, receiver, and controller circuits. The
board also accepts one additional option board that can provide functions such as secure voice/
data, voice storage, or a signalling decoder.
A control head, mounted directly on the front of the radio or remotely connected by an extension
cable, provides a user interface for controlling the various features of the radio. The control head
contains LED indicators, microphone connector, and buttons depending on the radio type, display,
and speaker.
The rear of the radio provides connections for a power, antenna, and accessory cable. The
accessory cable provides connections for items such as an external speaker, emergency switch,
foot operated PTT, and ignition sensing, etc.
2.2 Controller
The radio controller, shown in Figure 2-1, is divided into three main functions:
Digital control
Audio processing
Voltage regulation.
The digital control section of the radio consists of a microprocessor (IJP), support memory, support
logic, signal MUX ICs, on/off circuit, and general purpose input/output circuits.
To Synthesizer
16.8 MHz
Reference Clock
from Synthesizer
5V
from Synthesizer
Mod Out
r - - - -
--- -------,
Audio/Signalling
ASFIC_CMP
External
Microphone
External
Speaker
Section (5V_RF)
- o r - - - - _ _ ; ; ,
_ _ _ _ .J
Internal
Speaker
To RF Section ....
l - - - - - - - - - - - - - - 1
IJP Clock
... SCI to
rDigital - -
= - =
=
=I
= = . : ; - ,
Accessory &
I R L
1
Control Head
I SV AM I
I
I Connector
1
Regu lator
I 1
EEPROM
r
HC11 FLO
I
1
I (5VD)
I
I
FLAS H
1-
I
I
~ ------~---- -~.J
Figure 2-1. Controller Block Diagram