User's Manual

System Description 1-4
DataNex EMS Wireless, DATA-20 Digital Radio
1.5 System Description (QAM)
1.5.1 Introduction
The product is a full-duplex digital radio. The following sections describe the TX system, RX
system, followed by sub-system components. Please reference the accompanying block
diagrams for clarification.
We will follow the typical end-to-end progression of a radio system starting with the TX baseband
inputs, to the QAM modulator, followed by the upconversion process and the power amplifier.
We then proceed to the RX preamplifier input, the downconversion process, followed by the QAM
demodulator and baseband outputs.
RF Linear
PA
Back
Pl
Antenna
12.8 MHz
Data, Address, I
2
C, SPI Bus
Duplexer
Front Panel
Ribbon Cable
Uni ver sal
Input AC
(DC Optional)
System
Monitor
(A/D)
RF Module
Down Converter
Up Converter
IF Card
Down Converter
Up Converter
400 MHz-
1.5 GHz
TX
RX
70 MHz
QAM Modem
Demodulator
Mod ulator
Intelligent
MUX
+5/+15 VDC
130 Watt
Power
Supply
BarGraph
4 x 20 LCD Display
Status LEDs
Front
Panel
System CPU
NMS
Remote I/ O
Front Panel Interface
Serial PC Interface
Status/Command/Control I/O
4 Port
Data/Voice
Interface
Channel 1
Channel 2
Channel 3
Channel 4
Trun k
Transfer Panel I/O
QAM Modem Module
+15 VDC
PA Control/
Current
Sense
Figure 1-3. DATA-20 System Block Diagram
.
All modules (excluding the Front Panel and Power Amplifier) are interconnected via the
backplane that traverses the entire width of the unit. The backplane contains the various
communication buses as well as the PA (Power Amplifier) control and redundant transfer
circuitry. The power supply levels and status are monitored on the backplane and the NMS/CPU
card processes the data.