GE MDS 4710M Operating instructions

Installation and Operation Guide
GE MDS 05-3628A01, Rev. B
AUGUST 2008
400 MHz Master Station Radio
for MPT 1411 Applications
MDS 4790M

QUICK START GUIDE
1. Install and connect the antenna system to the radio (page 10).
• Use an appropriate antenna aimed at the associated station.
• Use low-loss feedline suited for 400 MHz. Keep the feedline as short as possible.
2. Connect the backup battery, if equipped (page 14).
3. Connect the host computer to the DATA connector on the rear panel (page 17).
4. Verify proper input voltage level and connect power to the radio. Set the power switch(es) to
ON.
5. Observe front panel indicators for proper operation.
Invisible place holder
ACTIVE (green)—This transceiver board (A or B) is the selected unit.
STBY (yellow)—This transceiver board (A or B) is the standby unit (protected version only).
ALARM (red)—General fault not covered by the other alarm categories (RX ALR, TX ALR, I/O ALR).
RX ALR (red)—Difficulty receiving. May be due to an antenna problem, receiver fault, or other condi-
tion causing a low received signal level.
TX ALR (red)—Fault with the transmit circuitry.
I/O ALR (red)—The data rate or format of data at the data interface connector is incompatible with the
radio settings.

MDS 05-3628A01, Rev. B MDS 4790M (MPT 1411) I/O Guide i
TABLE OF CONTENTS
1.0 INTRODUCTION......................................................................... 1
2.0 PRODUCT DESCRIPTION ......................................................... 1
2.1 Network-Wide Diagnostics ...............................................................3
2.2 Redundant versus Non-redundant Operation ..................................3
2.3 Applications ......................................................................................3
Basic MAS Master Station Operation .................................................4
Repeater and Polling Remote Operation............................................4
2.4 Features ...........................................................................................5
2.5 Accessories ......................................................................................5
2.6 Model Number Codes ......................................................................6
2.7 Terms and Abbreviations ..................................................................6
3.0 INSTALLATION PLANNING........................................................ 8
3.1 General Requirements .....................................................................8
Site Selection......................................................................................8
A Word About Interference.................................................................9
3.2 Antenna and Feedline Selection ....................................................10
Antenna System ...............................................................................10
Feedline Selection............................................................................10
4.0 INSTALLATION PROCEDURES ................................................11
4.1 Unpacking and Inspection ..............................................................11
4.2 Mounting the Radio ........................................................................12
Rack Mounting..................................................................................12
Tabletop Mounting ............................................................................12
Remote Front Panel Mounting—Optional Configuration ..................12
4.3 Primary Power ................................................................................13
AC-Powered Units............................................................................13
DC-Powered Units............................................................................13
4.4 Battery Power .................................................................................14
Battery Connection...........................................................................15
Low Voltage Disconnect Feature......................................................15
Battery Reset Switch (SW1).............................................................16
4.5 Antenna System .............................................................................16
Antenna Installation..........................................................................16
Feedline Installation..........................................................................16
4.6 Interface Wiring Connections .........................................................17
Data Connector ................................................................................17
Diagnostics.......................................................................................19
Analog Orderwire..............................................................................19
Alarm Contacts and Battery Back-up Connections...........................19
4-Wire Audio Connector ...................................................................20

ii MDS 4790M (MPT 1411) I/O Guide MDS 05-3628A01, Rev. B
4.7 Post Installation Checks .................................................................20
5.0 START-UP AND OPERATION...................................................21
5.1 Initial Startup ..................................................................................21
Normal Indications............................................................................21
Maximizing RSSI..............................................................................21
5.2 Front Panel Indicators ....................................................................21
LED Indicators..................................................................................22
Front Panel Display ..........................................................................23
6.0 DIAGNOSTICS AND CONTROL...............................................23
6.1 PC Connection ...............................................................................24
6.2 PC Command Summaries .............................................................24
Commands and Command Parameters...........................................25
6.3 Detailed Command Descriptions ....................................................28
ALARM .............................................................................................28
AMASK [0000 0000–FFFF FFFF] ....................................................30
ASENSE [HI/LO]...............................................................................31
BAUD [xxxxx abc].............................................................................31
BUFF [ON/OFF]................................................................................31
CKEY [ON/OFF] ...............................................................................32
CTS [0-255]......................................................................................32
DATAKEY [ON/OFF].........................................................................33
DATE [mmm dd yyyy].......................................................................33
DKEY................................................................................................33
DLINK [ON/OFF/xxxx]......................................................................33
DMGAP [xx]......................................................................................34
DTYPE [NODE/ROOT/GATE/PEER]................................................34
DUMP...............................................................................................34
EMP [ON/OFF] .................................................................................34
HREV................................................................................................35
INIT...................................................................................................35
KEY ..................................................................................................35
LOG [CLR]........................................................................................36
MODEL.............................................................................................36
MODEM [9600M, MPT1411].............................................................36
NMASK [0000 0000–FFFF FFFF] ....................................................36
OPT ..................................................................................................37
OWM [xxxxx] ....................................................................................37
OWN [xxxxx].....................................................................................37
PROG...............................................................................................37
PROGACT........................................................................................37
PTT [0-255].......................................................................................38
RADIO [A/B/AUTO]...........................................................................38
REPEATER [ON/OFF]......................................................................38
RSSI, RSSI!......................................................................................38
RTU [ON/OFF/0-80]..........................................................................39
RX [xxx] ............................................................................................39
RXMUTE ..........................................................................................39
RXLEVEL [–20 to +3] .......................................................................39

MDS 05-3628A01, Rev. B MDS 4790M (MPT 1411) I/O Guide iii
RXPAD [ON/OFF].............................................................................40
RXTOT [NONE, 1-1440]...................................................................40
SCD [0-255]......................................................................................40
SER..................................................................................................40
SHOW [DC/PWR/CURRENT/RADIO]..............................................40
SNR, SNR! .......................................................................................41
SREV................................................................................................41
STAT.................................................................................................41
TEMP................................................................................................42
TIME [hh:mm:ss] ..............................................................................43
TOT [ON/OFF, 1-255].......................................................................43
TX [xxxx]...........................................................................................43
TXGAIN [ON/OFF]............................................................................44
TXLEVEL [–20 to +3, AUTO]............................................................44
UNIT [10000–65000]........................................................................44
6.4 Configuration and Programming using the Front Panel .................44
Programming and Control Buttons ...................................................47
Navigating Through the Front Panel Screens ..................................47
Switching the Front Panel Display to Configuration Mode ...............48
Use of Control Buttons in Configuration Mode.................................48
Making Changes to Radio Functions................................................48
6.5 Screen Descriptions .......................................................................49
Group 1—Startup Screen and Menu Directory (page 53).................49
Group 2—Configuration Screens (page 53).....................................49
Group 3—Diagnostic Screens (page 61)..........................................49
Group 4—Event Log (page 62) ........................................................50
7.0 LOCAL & NETWORK-WIDE PROBLEM SOLVING.................. 63
7.1 Local Problem-Solving ...................................................................63
Problem-Solving with LED Indicators ...............................................63
Problem-Solving Using a Connected PC..........................................64
Problem-Solving Using the Front Panel Display...............................64
System Bench Testing Set-up ..........................................................65
7.2 Performing Network-Wide Radio Diagnostics ................................65
7.3 Replacing Assemblies ....................................................................67
Transceiver Board and Power Supply Assemblies...........................67
Front Panel.......................................................................................68
Internal Duplexer..............................................................................68
Antenna Switch Module....................................................................70
7.4 Cooling Fan Maintenance .............................................................71
8.0 TECHNICAL REFERENCE....................................................... 72
8.1 Technical Specifications ..........................................................72
8.2 RF Propagation Planning ...............................................................74
Fresnel Zone Clearance...................................................................74
Earth Curvature ................................................................................75
Fade Margins....................................................................................75
Calculating Path Loss.......................................................................75
8.3 Formulas for System Planning .......................................................76
Free Space Path Loss ......................................................................76

iv MDS 4790M (MPT 1411) I/O Guide MDS 05-3628A01, Rev. B
Fresnel Zone Boundary....................................................................76
Theoretical Signal Strength ..............................................................76
Probability of System Fading............................................................76
8.4 Frequency Reference Chart ...........................................................77
8.5 dBm-Volts-watts Conversion Chart ................................................80
Copyright Notice
This Installation and Operation Guide and all software described herein
are protected by copyright: 2008 GE MDS, LLC. All rights reserved.
GE MDS reserves its right to correct any errors and omissions.
Operational Safety Notices
The radio equipment described in this guide emits radio frequency
energy. Although the power level is low, the concentrated energy from
a directional antenna may pose a health hazard. Do not allow people to
come in close proximity to the front of the antenna when the transmitter
is operating.
This manual is intended to guide a professional installer to install,
operate and perform basic system maintenance on the described radio.
ISO 9001 Registration
GE MDS' adherence to this internationally accepted quality system stan-
dard provides one of the strongest assurances of product and service
quality available.
GE MDS Quality Policy Statement
We, the employees of GE MDS, are committed to achieving total cus-
tomer satisfaction in everything we do.
Total Customer Satisfaction in:
• Conception, design, manufacture and marketing of our products.
• Services and support we provide to our internal and external
customers.
Total Customer Satisfaction Achieved Through:
• Processes that are well documented and minimize variations.
• Partnering with suppliers who are committed to providing quality and
service.
• Measuring our performance against customer expectations and
industry leaders.
• Commitment to continuous improvement and employee involvement.
RF Exposure

MDS 05-3628A01, Rev. B MDS 4790M (MPT 1411) I/O Guide v
Environmental Information
The manufacture of this equipment has required the extraction and use
of natural resources. Improper disposal may contaminate the environ-
ment and present a health risk due to hazardous substances contained
within. To avoid dissemination of these substances into our environ-
ment, and to limit the demand on natural resources, we encourage you
tousetheappropriate recycling systems fordisposal.Thesesystems will
reuse or recycle most of the materials found in this equipment in a sound
way. Please contact GE MDS or your supplier for more information on
the proper disposal of this equipment.
Notice
While every reasonable effort has been made to ensure the accuracy of
this manual, product improvements may result in minor differences
between the manual and the product shipped to you. If you have addi-
tional questions or need an exact specification for a product, please con-
tactourCustomerService Team using theinformationatthebackofthis
guide. In addition, manual updates can often be found on the GE MDS
Web site at www.GEmds.com.

vi MDS 4790M (MPT 1411) I/O Guide MDS 05-3628A01, Rev. B

MDS 05-3628A01, Rev. B MDS 4790M (MPT 1411) I/O Guide 1
1.0 INTRODUCTION
This guide presents installation and operating instructionsfor the MDS 4790M
master station (scanner) radio. It begins with an overall description of the
radio’s features and is followed by the steps required to install the radio and
place it into normal operation.
Additionally, the guide contains troubleshooting tips for resolving system
difficulties that may be encountered. After you install the radio, we
recommend keeping this guide near the radio for future reference.
2.0 PRODUCT DESCRIPTION
The MDS 4790M master station (Figure 1) is a full duplex radio designed to
operate with MDS 4710 remote (outstation) transceivers in the fixed telemetry
and telecontrol radio services bands of 457.5 to 458.5 MHz and 463.0 to
464.0 MHz. It is designed for compliance with the United Kingdom’s MPT
1411 specifications for radio performance and frequency assignment criteria.
Typical applications include utility Supervisory Control and Data Acquisition
(SCADA), distribution automation, online transactional processing and other
point-to-multipoint applications. The radio is available in either a redundant
configuration or a non-redundant configuration. Refer to Section 2.2,
Redundant versus Non-redundant Operation, beginning on page 3 for further
description.
The radio uses microprocessor control and Digital Signal Processing (DSP)
technology to provide highly reliable data communications even under adverse
conditions. DSP adapts to differences between components from unit to unit,
and ensures consistent and repeatable performance in ambient temperatures
from –30 to +60 degrees Celsius. The use of Digital Signal Processing
eliminatesthe variationsinmodem operation thatcandegrade the performance
of analog circuits.
The radio is designed for trouble-free operation with data equipment provided
by other manufacturers, including Remote Terminal Units (RTUs), flow
computers, automatic banking machines, programmable logic controllers
(PLCs), and others.
NOTE: Some features may not be available on all radios, based on the
options purchased. Consult the factory for information on feature
upgrades or available accessories.

2 MDS 4790M (MPT 1411) I/O Guide MDS 05-3628A01, Rev. B
Invisible place holder
Figure 1. MDS 4790M Master Station
All assemblies, including the duplexer and power supply, are contained in the
radio’s compact (2RU high) enclosure. The radio’s compact size allows it to fit
into most existing systems, in either tabletop or rack mounting arrangements.
Connectors are provided on the rear panel for easy connection of power,
antenna, data, alarm and diagnostic functions.

MDS 05-3628A01, Rev. B MDS 4790M (MPT 1411) I/O Guide 3
2.1 Network-Wide Diagnostics
Newer GE MDS remote and master station radios, including the MDS 4790M,
offer network-wide diagnostics capability. Network-wide diagnostics
communications is a modern, packetized mode that has several advantages
over DTMF diagnostics communications (used by older GE MDS radios):
• Diagnostic data can be gathered over a large radio network without
disrupting system communications flow.
• When required, diagnostics communications speed can be increased
by actively collecting diagnostic data.
• Diagnostic data for each radio in the network can be accessed from
any radio diagnostics port in the network.
• Certain messages can be broadcast to all radios in the system
simultaneously.
The master station can be used to poll remote radios in its radio system for
diagnostic data. For more information on the implementation of network
diagnostics, refer to the GE MDS Network-Wide Diagnostics Handbook (P/N
05-3467A01).
2.2 Redundant versus Non-redundant Operation
A redundant configuration means that the master station has two complete
transceiver boards installed in the enclosure. In the event of a primary board
failure, the controlling logic causes a switch-over to the stand-by transceiver
board. The redundant transceiver configuration has a stand-by transceiver
board that is constantly operating and its operational readiness is monitored.
However, the transmitter power amplifier in the stand-by transceiver board is
not operating when it is in stand-by mode.
In a non-redundant configuration, there is only one transceiver board installed
in the “A” slot of the enclosure, and back-up transceiver board operation is not
possible.
Transceiver boards may be moved from one master station to another, or an
additional transceiver board may be added to a non-redundant master station.
You do not need to specify redundant or non-redundant operation, or select the
active transceiver board. Installing or replacing a transceiver board will cause
the boards to communicate briefly with each other to establish which board will
operate as the active board and which operates as the stand-by. For more
information, see “Transceiver Board and Power Supply Assemblies” on page 67.
2.3 Applications
Themaster station is designedforpoint-to-multipointdatatransmissioninutility
monitoring systems, telecommunications networks, and transactional data
applications. An MASnetwork provides communications between a central host
computer and remote terminal units (RTUs) orotherdata collectiondevices.The
operation of the radio system is transparent to the computer equipment.

4 MDS 4790M (MPT 1411) I/O Guide MDS 05-3628A01, Rev. B
Basic MAS Master Station Operation
Figure 2 shows a typical point-to-multipoint system using an MDS 4790M
master station.
The most basic system consists of a central master station and several
associated remote units, as shown in Figure 2.
Figure 2. Typical MAS Network
Repeater and Polling Remote Operation
AnMASsystemusing repeaterandpolling-remoteradios is shown inFigure 3.
Notice that the polling remote radio is operating in half-duplex mode and the
repeater is operating in full-duplex mode. Configuring the radio for repeater
operation can be as simple as typing REPEATER ON with a PC connected to the
rear panel diagnostic port. (See “DIAGNOSTICS AND CONTROL” on page
23 for details.)
Figure 3. Typical Repeater and Polling-Remote Network
–
IDIAG13.8VDC
PWR
+
–
HOST SYSTEM
REMOTE RADIO
SWC OFF
RTU
RTU
RTU
RTU
–
IDIAG13.8 VDC
PWR
+
–
–
IDIAG13.8 VDC
PWR
+
–
–
IDIAG13.8 VDC
PWR
+
–
–
IDIAG 13.8 VDC
PWR
+–
RTU
MDS MASTER
STATION
CONTINUOUSLY
KEYED REMOTE RADIO
SWC OFF
REMOTE RADIO
SWC OFF
REMOTE RADIO
SWC OFF
REMOTE RADIO
SWC OFF
–
IDIAG13.8 VDC
PWR
+–
HOST SYSTEM
REMOTE RADIO
RTU
RTU
RTU
RTU
–
IDIAG 13.8 V
DC
PWR
+
–
–
IDIAG 13.8 VDC
PWR
+
–
–
IDIAG13.8 VDC
PWR
+
–
–
IDIAG13.8 VDC
PWR
+
–
RTU
CONTINUOUSLY
KEYED REMOTE RADIO
REMOTE RADIO
REMOTE RADIO
REMOTE RADIO
POLLING REMOTE
REPEATER
HALF-DUPLEX
SWITCHED CARRIER
TX HIGH
RX LOW
TX LOW
RX HIGH
TX LOW
RX HIGH
TX LOW
RX HIGH
TX LOW
RX HIGH
TX LOW
RX HIGH
TX LOW
RX HIGH

MDS 05-3628A01, Rev. B MDS 4790M (MPT 1411) I/O Guide 5
Simplex and Switched Carrier Operation
System-wide simplex operation is achieved by switching the master station
carrier on to transmit, then off to receive. The same frequency is used for both
transmit and receive.
Switched carrier, half-duplex mode is also achieved by switching the master
station carrier on to transmit, then off to receive. However, different
frequencies are used for transmit and receive.
2.4 Features
Reliability is a hallmark of the MDS 4790M design. The radio employs a
one-piece transceiver board which minimizes RF losses and eliminates the
need for inter-board cabling. This also allows easy plug-in replacement should
servicing become necessary.
In addition, the optional redundant version of the radio includes redundant
transceiver boards and power supply modules that automatically become active
in the event of a failure in either of the transceiver boards or power supplies.
This ensures continued operation in the event of most transceiver board failures.
The following list highlights many of the radio’s key features. For a full listing of
specifications, see Section 8.1,
Technical Specifications , beginning on page 72.
• Operation from 24, 48, or 125 V dc; or 90 to 267 V ac mains
• Configuration, control and diagnostics from front panel display or
connected PC
• Remote diagnostics via a connected PC and radio software
• Time stamping of alarms and major events
• Flexible mounting (rack or table); front panel can optionally be
mounted separately from unit
2.5 Accessories
The radio can be used with one or more of the accessories listed in Table 1.
GE MDS publishes an Accessories Selection Guide which lists a complete
array of additional items for use with this product. Please contact your factory
representative or visit www.GEmds.com to obtain a copy of this guide.
Table 1. Radio Accessories
Option Description Part No.
Diagnostics and
Control Software Computer software that allows PC control, diagnostics, and software upgrades. 03-3475A01
Diagnostic and
Control Interface
Cable
Allows connection of a PC for control and
diagnostics and of the radio (DB-9 to DB-9). 97-1971A04
Auxiliary Front Panel
Mounting Bracket Allows rack mounting of the detachable front panel. 82-3189A01
Orderwire Handset Allows orderwire communications with
remote radios. 12-1307A01

6 MDS 4790M (MPT 1411) I/O Guide MDS 05-3628A01, Rev. B
2.6 Model Number Codes
The radio model number is printed on the serial number label, which is affixed
to the radio chassis. The following figures show the significance of the
characters in the model number string for standard models. Contact the factory
for specific information on optional configurations.
Invisible place holder
Figure 4. MDS 4790M Model Number Codes
2.7 Terms and Abbreviations
If you are new to digital radio systems, some of the terms used in this guide
may be unfamiliar. The glossary below defines many of these terms and will
prove helpful in understanding radio operation.
Active Messaging—This is a mode of diagnostic gathering that may interrupt
SCADA system polling communications (contrast with passive messaging).
Active (or intrusive) messaging is much faster than passive messaging because
it is not dependent upon the RTU polling cycle.
BERT—Bit-error rate test. The results of a BERT are normally expressed as a
ratio (power of 10) of the number of bits received in error compared to the total
number received.
BER—Bit-error rate. See also BERT.
Bit—Binary digit. The smallest unit of digital data, often represented by a one
or a zero. Eight bits usually comprise a byte.
bps—Bits-per-second. A measure of the information transfer rate of digital
data across a communication channel.
Byte—A digital “word” usually made up of eight bits.
dBi—Decibelsofgain relative toanisotropicradiator.(A hypotheticalantenna
which radiates equally in all directions.) Used to express antenna gain.
dBm—Decibels relative to one milliwatt. An absolute unit used to measure
signal power, as in transmitter power output or received signal strength.
THIS INFORMATION IS
SUBJECT TO CHANGE.
DO NOT USE FOR
PRODUCT ORDERING.
MODE
(N) Non -Redundant
(R) Redundant BANDWIDTH
(1) 12.5 kHz
RECEIVE FREQ.
(J) 457.5-458.5 MHz
(K) 463.0-464.0 MHz AGENCY
(N) N/A
SAFETY CERT.
(N) N/A
DUPLEXER
(0) None (Ext. wiring)
(2) 400-512 MHz (5-30 MHz Split)
(B) Simplex 430-512 MHz
(S) None (Int. wiring)
FEATURES
(0) Full
(D) Demo
TRANSMIT FREQ.
(D) 457.5-458.5 MHz
(E) 463.0-464.0 MHz
INPUT VOLTAGE
(1) 24 VDC
(2) 48 VDC
(3) 24-48 VDC
(A) 110/220 VAC W/O Batt.
(B) 110/220 VAC W/ Batt.
125 VAC to 12 VDC W/ Ext. Converter
OPERATION
(B) Base
(R) Remote
(P) Repeater
MODEM
(B) 9600 BPS
(MPT 1411)
DIAGNOSTICS
(0) None
(1) Network wide
4790M

MDS 05-3628A01, Rev. B MDS 4790M (MPT 1411) I/O Guide 7
DCE— Data (circuit terminating) Communications Equipment. In data
communications terminology, this is the “modem” side of a
computer-to-modem connection. The transceiver board is a DCE device which
is designed to connect to a DTE device.
Decibel (dB)—A measure of the ratio between two signal levels. Frequently
used to express the gain or loss of a system.
DSP—Digital Signal Processing. Advanced circuit technique to increase radio
performance, primarily in modulation and demodulation.
DTE—Data Terminal Equipment. In data communications terminology, this
is the computer side of a computer-to-modem connection. (Connects to the
DCE device.)
Fade Margin—The maximum tolerable reduction in received signal strength
whichstill providesanacceptablesignalquality. This compensatesforreduced
signal strength due to multipath, slight antenna movement or changing
atmospheric losses. Expressed in decibels.
Frame—A segment of data that adheres to a specific data protocol and
contains definite start and end points. It provides a method of synchronizing
transmissions.
Fresnel Zone—A point of maximum width or girth of the transmitted radio
signal. Obstructions in this region (the “first Fresnel zone”) can have a
detrimental effect on reception quality. As a general rule, 60 percent of the first
Fresnel zone should be free of obstructions in a well-designed system.
(Additional considerations are also required when planning an RF path. A
detailed discussion of the subject is presented in Section 8.2, RF Propagation
Planning, beginning on page 74.)
Half-Power Beamwidth—The customary way of measuring the width of a
directional antenna’s radiation pattern. This beamwidth is measured in degrees
between the half-power points (the point at which the power is reduced 3 dB
with respect to the main beam).
kbps—Kilobits-per-second.
Master Station (Scanner)—Radio which is connected to the host computer.
It is the point at which polling enters the network.
Menu Directory—Front panel display screen that is the entry point to screens
for displaying radio status and programming the radio. It contains the main
menu items Configuration, Diagnostics, and Event Log.
Multipath Fading—Signals arriving at the receiver out of phase, which have
a tendency to cancel each other. It is caused by reflections of the transmitted
wave and results in distortion at the receiver or weak received signal strength.
Network-Wide Diagnostics—An advanced method of controlling and
interrogating GE MDS radios in a radio network.
Non-intrusive diagnostics—See Passive messaging.
Passive messaging—This is a mode of diagnostic gathering that does not
interruptSCADAsystempolling communications.Diagnosticdata iscollected
non-intrusively over a period of time; polling messages are carried with
SCADA system data (contrast with active messaging).
Payload data—This is the application’s user communication data which is
sent over the radio network. It is the radio data that is the primary purpose of
the radio communications.
Remote Station (Outstation)—A radio in a network that communicates with
an associated master station.

8 MDS 4790M (MPT 1411) I/O Guide MDS 05-3628A01, Rev. B
RSSI—Received signal strength indication. Expressed in dBm.
RTU—Remote Terminal Unit. A data collection device installed at a remote
radio site. An internal RTU simulator is provided with the radio to isolate
faults to either the external RTU or the radio. For more information see “RTU
[ON/OFF/0-80]” on page 39
SNR—Signal-to-noise ratio. Expressed in decibels (dB).
SWR—Standing Wave Ratio. A parameter related to the ratio between
forward transmitter power and the reflected power from the antenna system.
As a general guideline, reflected power should not exceed 10% of the forward
power (≈2:1 SWR).
3.0 INSTALLATION PLANNING
The installation of the radio is not difficult, but it does require some planning
to ensure reliability and efficiency. This section provides tips for selecting an
appropriate site, choosing antennas and feedlines, and minimizing the chance
of interference. This material should be reviewed before beginning equipment
installation.
3.1 General Requirements
There are three main requirements for installing the radio—adequate and
stable primary power, a good antenna system, and the correct interface
between the radio and the data device. Figure 5 shows a typical station
arrangement.
Invisible place holder
Figure 5. Typical Station Arrangement
Site Selection
For a successful installation, careful thought must be given to selecting the site
for the master station and the remote radios. Suitable sites should offer:
TO INPUT
POWER SOURCE
LOW LOSS
COAXIAL CABLE
OMNIDIRECTIONAL
ANTENNA HOST COMPUTER
DIAGNOSTICS
COMPUTER

MDS 05-3628A01, Rev. B MDS 4790M (MPT 1411) I/O Guide 9
• An antenna location that provides an unobstructed path to all the
remote radios in the system
• A source of adequate and stable primary power
• Suitable entrances for antenna, interface or other required cabling.
These requirements can be quickly determined in most cases. A possible
exception is the first item—verifying that an unobstructed transmission path
exists. UHF radio signals travel primarily by line-of-sight, and obstructions
between the sending and receiving stations will affect system performance.
If you are not familiar with the effects of terrain and other obstructions on radio
transmission, the following discussion will provide helpful background.
Terrain and Signal Strength
A line-of-sight path between stations is highly desirable and provides the most
reliable communications link in all cases. A line-of-sight path can often be
achieved by mountingeach station antenna on a tower or other elevated structure
that raises it high enough to clear surrounding terrain and other obstructions.
The requirement for a clear transmission path depends on the distance to be
covered by the system. If the system is to cover only a limited distance, say 5
km, then some obstructions in the transmission path may be tolerable. For
longer range systems, any obstruction could compromise the performance of
the system, or block transmission entirely.
The signal strength at the receiver must exceed the receiver sensitivity by an
amount known as the fade margin (defined on page 7) to provide reliable
operation under various conditions.
Section 8.2, RF Propagation Planning, beginning on page 74 includes a
detailed discussion of path planning, and should be reviewed before beginning
an installation. Computer software is also available for this purpose that can
greatly simplify the steps involved in planning a path.
On-the-Air Test
If you’ve analysed the proposed transmission path and feel that it is acceptable,
an on-the-air test of the equipment and path should be conducted. This not only
verifies the path study results, but allows you to see firsthand the factors
involved at each installation site.
The test can be performed by installing a radio at each end of the proposed link
and checking the RSSI value reported at the radio’s front panel display. (See
“Front Panel Indicators” on page 21 for procedures.) If adequate signal strength
cannot be obtained, it may be necessary to mount the station antennas higher,
use higher gain antennas, or select a different site for one or both stations.
To prepare the equipment for an on-the-air test, follow the general installation
and operation procedures given in this guide and become familiar with the
operating instructions given in Section 5.0, START-UP AND OPERATION,
beginning on page 21.
A Word About Interference
Interference is possible in any radio system. However, since the radio is
designed for use in a licensed system, interference is less likely because
geographic location and existing operating frequencies are normally taken into
account when allocating frequencies.
The risk of interference can be further reduced through prudent system design and
configuration. Allow adequate separation between frequencies and radio systems.
Keep the following points in mind when setting up your radio system:

10 MDS 4790M (MPT 1411) I/O Guide MDS 05-3628A01, Rev. B
1. Systems installed in lightly populated areas are least likely to encounter
interference; those in urban and suburban environments are more likely to
be affected by other devices operating in the 400 MHz frequency band and
adjacent services.
2. Directional antennas should be used at the remote end of the link. They
confine the transmission and reception pattern to a comparatively narrow
beam, which minimizes interference to and from stations located outside the
pattern.
3. If interference is suspected from another system, it may be helpful to use
antenna polarization that is opposite to the interfering system’s antennas. An
additional 20 dB (or more) of attenuation to interference can be achieved by
using opposite antenna polarization.
3.2 Antenna and Feedline Selection
Antenna System
The antenna system is perhaps the most crucial part of the system design. An
antenna system that uses poor quality feedline, or is improperly aligned with the
companion site, will result in poor performance, or no communication at all.
Generally speaking, an omni-directional antenna is used at the master station
site and the remote radios use directional antennas.
GE MDS can also furnish antennas for use with the radio. Consult your GE
MDS representative for details.
Feedline Selection
For maximum performance, a good-quality feedline must be used to connect
the radio to the antenna. For short-range transmission, or where very short
lengths of cable are used (up to 8 meters [26 feet]), an inexpensive coax cable
such as Type RG-213 may be acceptable.
For example, 100 feet (30 meters) of RG-58A/U cable (commonly used for
frequencies below 100 MHz) has an insertion loss of 5 dB at 450 MHz. A 5
watt transmitter operating into such a feedline would produce only 1.6 watt at
the antenna; a similar loss in receiver sensitivity would result, and no amount
of gain within the receiver can recover the signal lost in the feedline.
Conversely, a 100 foot (30 meters) length of 1-5/8 inch cable has a loss of 0.52
dB at the same frequency, but its cost is many times greater than RG-58A/U.
For systems covering short distances, feedline loss is relatively unimportant,
and 6 dB or more of loss may be completely acceptable. For systems designed
for maximum range however, each dB of loss directly affects signal-to-noise
ratio at the receiver. It is good practice to keep feedline losses as low as
possible and certainly under 3 dB. Remember that for each 3 dB of feedline
loss, half the transmitter power is lost, and twice the receive signal power is
needed to produce the same signal-to-noise ratio.
The RG-8A/U cable is a widely available and inexpensive feedline that is
suitable for systems with short ranges or those with short feedlines. For longer
feedlines and lower losses, Andrew HELIAX™semi-rigid coaxial cable or
similar products are a good choice. Table 2 shows the length of various types
of cable and the resulting degradation in signal strength.
Mount the antenna and feedline securely to the supporting structure to avoid
damage from wind and ice loading. Refer to the instructions provided by the
antenna and feedline manufacturers to ensure a safe and reliable installation.

MDS 05-3628A01, Rev. B MDS 4790M (MPT 1411) I/O Guide 11
4.0 INSTALLATION PROCEDURES
Thissection presentsthesteps necessary forinstalling the radioand connecting
itto associated equipment.Aftercompletingthese steps,the radiowill beready
for in-service operation.
4.1 Unpacking and Inspection
Figure 6 shows a typical radio shipment. Check the contents against the
packing list secured to the outside of the shipping box. Accessories and spare
parts kits, if any, are wrapped separately. Inspect all items for signs of damage.
Save all packing materials in case you need to ship the radio in the future.
Invisible place holder
Figure 6. Typical Shipment Contents
Table 2. Feedline Loss Chart (450 MHz)
Cable Type 3.05 Meters
(10 Feet) 15.24 Meters (50 Feet) 30.48 Meters (100 Feet) 152.4 Meters (500 Feet)
RG-8A/U 0.51 dB 2.53 dB 5.07 dB 25.35 dB
1/2 in. HELIAX 0.15 dB 0.76 dB 1.51 dB 7.55 dB
7/8 in. HELIAX 0.08 dB 0.42 dB 0.83 dB 4.15 dB
1-1/4 in. HELIAX 0.06 dB 0.31 dB 0.62 dB 3.10 dB
1-5/8 in. HELIAX 0.05 dB 0.26 dB 0.52 dB 2.60 dB
PC DIAGNOSTICS & CONTROL
DISK (OPTIONAL)
POWER CORD
(AC cord shown)
ADHESIVE FEET (4)*
(For tabletop mounting)
RACK-MOUNT BRACKETS (2)*
INSTALLATION
& OPERATION GUIDE
* These items may already be installed
on the radio chassis.

12 MDS 4790M (MPT 1411) I/O Guide MDS 05-3628A01, Rev. B
4.2 Mounting the Radio
The radio should be located in a relatively clean, dust-free environment that
allows easy access to the rear panel connectors as well as the front panel
controls and indicators. Air must be able to pass freely over the heatsink on the
rear panel.
Figure 7 shows the mounting dimensions of the radio. Most commonly, it is
installed in a 2U 3.5 inch (88.90 mm) rack-mount configuration, but it can also
be installed in a simple tabletop arrangement if desired.
Rack Mounting
To rack-mount the radio, use the supplied mounting brackets (GE MDS P/N
82-3184A01) to secure the chassis to the rack cabinet. The brackets can be
attached at any of fourpoints onthe sidesof the enclosure—front,back, middle
facing front, and middle facing back (see Figure 7). This flexibility ensures
compatibility with most rack mounting arrangements.
Tabletop Mounting
As an alternative to rack mounting, the radio can be placed on any sturdy shelf
or tabletop that will support the weight of the unit. Adhesive- backed rubber
feet are provided with the radio for use in tabletop installations. These should
be placed underneath the chassis near each corner to prevent scratching of the
mounting surface.
Invisible place holder
Figure 7. Mounting Dimensions and Bracket Details
Remote Front Panel Mounting—Optional Configuration
If desired, the front panel can be detached from the radio and mounted
separately to the rack cabinet. This option is needed inrack-mountinstallations
where all connections and control will be performed from one side of the unit.
An Auxiliary Mounting Plate (P/N 82-3189A01) is available for this type of
mounting.
To remove the front panel from the radio and re-mount it to the Auxiliary
Mounting Plate, follow these steps:
1. Detach the panel from the radio by grasping it firmly along its bottom edge
and pulling away from the radio chassis (Figure 8).