Receiver Operation - Tait TB7100 Service Manual

Frequency Bands
and Sub-bands
RS-232 Signals
Fan Signals
Speaker Signal
Power and Ground
3.1

Receiver Operation

Parts of Receiver
Board
20 Functional Description
The circuitry in the base station modules is common to all frequency bands,
and is therefore covered by a single description in this manual. Where the
circuitry differs between bands, separate descriptions are provided for each
frequency band. For more information refer to
page 11.
External data communications all occur directly between the connected
computer (or other electrical equipment) and the transmitter and receiver
modules over the RS-232 serial lines.
The power and ground signals for the fans are routed from the SI board to
the fans behind the front panel. These signals are electrically isolated from
all other system signals to ensure fan noise is not transferred to other sensitive
system components.
If there is a fault in the fan circuitry, the transmitter module is protected from
overheating by its internal foldback circuitry.
Received audio is sent from the receiver module to the UI board.
The volume is controlled by the volume potentiometer on the UI board.
The audio signal is then passed to the speaker for monitoring purposes.
The SI board provides power to the transmitter and receiver modules.
The receiver modules provides power to the UI board.
The main circuit parts of the receiver modules are:
receiver
frequency synthesizer
CODEC (coder-decoder) and audio circuitry
power supply
interface circuitry
Software plays a prominent role in the functioning of the radio.
When describing the operation of the radio the software must be included
with the above. This is considered further below.
These functional parts are described in detail below.
"Frequency Bands" on
TB7100 Service Manual
© Tait Electronics Limited October 2005