Tait TM8000 Series, Service Manual

Page: 53 / 244

TM8100 Mobile Radio Service Manual General Description 53
May 2004 © Tait Electronics Limited
Operation of Radio
Figure 2.14 is a simplified block diagram of the transceiver architecture
showing the hardware modules integrated with the software modules.
The same DSP (digital signal processor) device includes the software that
controls the transceiver and the software constituting the digital-signal-
processing blocks in
Figure 2.14 . The operation of the radio is then best
described with reference to Figure 2.14 and with a division into the
following two parts:
■
operation in receive mode
■
operation in transmit mode
Operational descriptions of these two parts are given in Subsection 2.4
(on page 54) and Subsection 2.5 (on page 57) respectively.
2.3 Operation of Control-head Circuitry
User Interface
In this subsection the operation of the control-head circuitry is
summarised. A detailed description of the circuitry is given in
Section 3
(on page 63) . Control heads with UI provide a user interface consisting
of:
■
seven-segment LCD
■
up and down channel-selection keys
■
four programmable function keys
■
ON
/
OFF
push-button key
■
LED indicators
■
volume control
■
internal speaker
■
microphone connector
The LCD displays one or two characters depending on the type of
control head. The microphone connector may also be used for the
connection of a handset or programming lead. If required, a concealed
microphone may be fitted inside the control head.
Connectors and
Circuit Boards
There is an 18-way electrical interface between the control head and
radio body. The physical connection is via an 18-way loom. The control
head normally contains a single PCB assembly called the control-head
board. The differences between the boards for the one- and two-digit-
display control heads are discussed in
Section 3 (on page 63) . If a
dynamic microphone is used or a concealed microphone fitted, a small
circuit board must be mounted on the control-head board. The added
board has the necessary amplification, filtering and switching functions.
The internal speaker is connected to the control-head board via a lead
with a mating connector so that it can be easily disconnected.