GE MDS 4790 Series Original operating instructions

Installation & Operation Guide
MDS 05-3438A01, Rev. F
SEPTEMBER 2008
400 MHz/900 MHz
Multiple Address System
Master Station Radio
MDS 4790/9790 Series
(including MDS 4790A/C/E/S, MDS 9790A)
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QUICK START GUIDE
1. Install and connect the antenna system to the radio (page 9).
• Use an appropriate antenna aimed at the associated station.
• Use low-loss feedline suited for 400/900 MHz. Keep the feedline as short as possible.
2. Connect the backup battery (page 15).
3. Connect the host computer to the DATA connector on the rear panel (page 23).
4. Verify proper input voltage level and connect power to the radio.
Set the power switch(es) to ON.
5. Configure the data interface baud rate (page 42).
6. 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 (redundant 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
condition 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.
A
B
ACTIVE STBY ALARM RX ALR TX ALR I/O ALR
ACTIVE STBY ALARM RX ALR TX ALR I/O ALR
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MDS 05-3438A01, Rev. F MDS 4790/9790 Series I/O Guide i
TABLE OF CONTENTS
1.0 INTRODUCTION.....................................................................................1
2.0 PRODUCT DESCRIPTION.....................................................................1
2.1 Network-Wide Diagnostics ...............................................................2
2.2 Redundant versus Non-redundant Operation ..................................2
2.3 Applications ......................................................................................3
Basic MAS Master Station Operation................................................3
Repeater and Polling Remote Operation..........................................3
Simplex and Switched Carrier Operation..........................................4
2.4 Features ...........................................................................................4
2.5 Accessories ......................................................................................5
2.6 Model Number Codes ......................................................................6
3.0 INSTALLATION PLANNING....................................................................6
3.1 General Requirements .....................................................................6
Site Selection....................................................................................7
A Word About Interference ...............................................................8
3.2 Antenna and Feedline Selection ......................................................9
Antenna System................................................................................9
Feedline Selection ............................................................................9
4.0 INSTALLATION PROCEDURES...........................................................10
4.1 Unpacking and Inspection ..............................................................11
4.2 Mounting the Radio ........................................................................11
Rack Mounting................................................................................12
Tabletop Mounting...........................................................................12
Remote Front Panel Mounting—Optional Configuration.................12
4.3 Primary Power ................................................................................13
AC-Powered Units ..........................................................................14
DC-Powered Units..........................................................................14
4.4 Backup Battery ...............................................................................15
Location of Battery Backup Switch .................................................15
Low-Voltage Disconnect Feature....................................................16
Battery Reset Switch (SW1/LVD PCB) ...........................................16
4.5 Antenna Installation ........................................................................17
Feedline Installation........................................................................17
4.6 Interface Wiring Connections .........................................................18
TX, Antenna, and RX Coaxial Connectors (Type-N).......................18
Ground Connection.........................................................................21
Diagnostics Connector—J1 ............................................................21
4-Wire Audio Connector—J2..........................................................22
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ii MDS 4790/9790 Series I/O Guide MDS 05-3438A01, Rev. F
Data Interface Connector—J3 ........................................................23
Orderwire Connector—J9...............................................................24
Alarm Contacts—J10......................................................................24
4.7 Post Installation Checks .................................................................26
5.0 START-UP AND OPERATION ..............................................................26
5.1 Initial Startup ..................................................................................26
Normal Indications..........................................................................26
Maximizing RSSI.............................................................................26
Coordinating Activities by Orderwire...............................................27
5.2 Front Panel Indicators ....................................................................27
LED Indicators ................................................................................28
Front Panel Display.........................................................................29
6.0 DIAGNOSTICS AND CONTROL ..........................................................30
6.1 PC Connection ...............................................................................30
6.2 PC Command Summaries .............................................................32
Commands and Command Parameters .........................................33
6.3 Detailed Command Descriptions ....................................................37
ALARM............................................................................................37
AMASK [0000 0000–FFFF FFFF]...................................................40
ASENSE [HI/LO].............................................................................41
BATT(ery) [ON/OFF].......................................................................41
BAUD [xxxxx abc]...........................................................................42
BUFF [ON/OFF]..............................................................................42
CKEY [ON/OFF]..............................................................................43
CTS [0-255].....................................................................................43
DATAKEY [ON/OFF].......................................................................44
DATE [mmm dd yyyy] .....................................................................44
DKEY..............................................................................................45
DLINK [ON/OFF/xxxx].....................................................................45
DMGAP [xx]....................................................................................45
DTYPE [NODE/ROOT/GATE/PEER]..............................................46
EMP [ON/OFF]................................................................................46
HREV..............................................................................................46
INIT.................................................................................................46
KEY.................................................................................................47
LOG [CLR]......................................................................................48
MADDR [NONE, 1–255] .................................................................48
MODEL...........................................................................................48
MODEM [NONE/4800/9600/19200/DEFAULT]...............................48
NMASK [0000 0000–FFFF FFFF]...................................................49
OPT.................................................................................................50
OWM [xxxxx]...................................................................................50
OWN [xxxxx]...................................................................................50
PTT [0-255].....................................................................................50
PWR [20–37]...................................................................................51
RADIO [AUTO/A/B].........................................................................51
REPEATER [ON/OFF] ....................................................................51
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MDS 05-3438A01, Rev. F MDS 4790/9790 Series I/O Guide iii
RSSI, RSSI!....................................................................................52
RTU [ON/OFF/0-80]........................................................................52
RX [xxx]...........................................................................................52
RXLEVEL [–20 to +3]......................................................................53
RXMUTE [ON/OFF/Time in msec]..................................................53
RXPAD [ON/OFF]...........................................................................53
RXTOT [NONE, 1-1440] .................................................................53
SCD [0-255]....................................................................................54
SER.................................................................................................54
SHOW [DC/PWR/CURRENT/RADIO]............................................54
SNR, SNR!......................................................................................55
SREV..............................................................................................55
STANDBY [ON/OFF].......................................................................56
STAT ...............................................................................................56
TEMP..............................................................................................57
TIME [hh:mm:ss].............................................................................57
TOT [ON/OFF, 1-255] .....................................................................58
TX [xxxx].........................................................................................58
TXGAIN [ON/OFF]..........................................................................59
TXLEVEL [–20 to +3, AUTO]..........................................................59
UNIT [10000–65000].......................................................................59
6.4 Configuration and Programming using the Front Panel .................60
Programming and Control Buttons..................................................62
Navigating Through the Front Panel Screens.................................62
Switching the Front Panel Display to Configuration Mode..............63
Use of Control Buttons in Configuration Mode................................63
Changing radio functions................................................................64
6.5 Screen Descriptions .......................................................................64
Group 1—Startup Screen and Menu Directory (page 69)...............64
Group 2—Configuration Screens (Page 69)...................................64
Group 3—Diagnostic Screens (Page 78)........................................65
Group 4—Event Log (Page 80) ......................................................65
7.0 LOCAL & NETWORK-WIDE PROBLEM SOLVING..............................79
7.1 Local Problem-Solving ...................................................................80
Front Panel LEDs............................................................................80
Chassis-Mounted LEDs..................................................................81
Problem Solving Using a Connected PC........................................82
Problem Solving Using the Front Panel Display .............................82
System Bench Testing Set-up.........................................................83
7.2 Performing Network-Wide Radio Diagnostics ................................84
8.0 REPLACING ASSEMBLIES..................................................................86
8.1 Transceiver Board and Power Supply Assemblies ........................86
8.2 Installation & Removal of Backup Battery
(P/N 28-1575Axx) ...................................................................................87
8.3 Front Panel .....................................................................................88
8.4 Operating Frequency Change Considerations ...............................89
MDS 4790—400 MHz Notch-Type Duplexers ................................90
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iv MDS 4790/9790 Series I/O Guide MDS 05-3438A01, Rev. F
MDS 9790—Bandpass-Type Duplexers .........................................90
MDS 4790/9790 Simplex Radios—With Antenna Switch Modules.91
MDS 4790/970—Front End Helical Coil Alignment.........................91
8.5 Testing and Removing an Internal Duplexer ..................................91
Testing.............................................................................................91
Removing the Internal Duplexer .....................................................92
8.6 Testing and Removing the Antenna Switch Module .......................93
Testing.............................................................................................93
Removing the Antenna Switch........................................................94
8.7 Cooling Fan Maintenance .............................................................95
9.0 RADIO SOFTWARE UPGRADES ........................................................95
9.1 Obtaining New Code ......................................................................95
9.2 Preparing for Download .................................................................96
9.3 Downloading New Code—Procedure ............................................96
10.0 TECHNICAL REFERENCE.................................................................97
10.1 Technical Specifications ...............................................................97
10.2 RF Propagation Planning .............................................................99
Fresnel Zone Clearance ...............................................................100
Earth Curvature.............................................................................101
Fade Margins................................................................................101
Calculating Path Loss...................................................................102
10.3 Formulas for System Planning ...................................................102
Free Space Path Loss...................................................................102
Fresnel Zone Boundary ................................................................102
Theoretical Signal Strength...........................................................102
Probability of System Fading........................................................103
10.4 dBm-Volts-Watts Conversion Chart ............................................104
Copyright Notice
This Installation and Operation Guide and all software described herein
are protected by copyright: 2008 GE MDS. All rights reserved.
GE MDS reserves its right to correct any errors and omissions in this
publication.
Operational Safety Notices
The radio equipment described in this guide uses radio frequency trans-
mitters. 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.
RF Exposure
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MDS 05-3438A01, Rev. F MDS 4790/9790 Series I/O Guide v
ISO 9001 Registration
GE MDS adheres to this internationally-accepted quality system stan-
dard.
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.
Revision 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-
tactour Customer ServiceTeam using the informationat the back ofthis
guide. In addition, manual updates can often be found on our Web site
at www.GEmds.com.
Warning—400 MHz Distress Beacons
In the U.S.A., the 406 to 406.1 MHz band is reserved for use by distress
beacons. Since the MDS 4790 Series radio can transmit in this band,
take precautions to prevent the radio from transmitting between 406 and
406.1 MHz.
ESD Notice
To prevent malfunction or damage to this radio, which may be caused
by Electrostatic Discharge (ESD), the radio should be properly
groundedbyconnectionto the ground stud on the rear panel.Inaddition,
the installer or operator should follow proper ESD precautions, such as
touching a grounded bare metal object to dissipate body charge, prior to
connecting and disconnecting cables on the front or rear panels.
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vi MDS 4790/9790 Series I/O Guide MDS 05-3438A01, Rev. F
Environmental Information
The equipment that you purchased has required the extraction and use
of natural resources for its production. Improper disposal may contami-
nate the environment and present a health risk due to hazardous sub-
stances contained within. To avoid dissemination of these substances
into our environment, and to diminish the demand on natural resources,
we encourage you to use the appropriate recycling systems for disposal.
These systems 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.
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MDS 05-3438A01, Rev. F MDS 4790/9790 Series I/O Guide 1
1.0 INTRODUCTION
This guide presents installation and operating instructions for the
MDS 4790 and MDS 9790 Series Master Station Radio. It begins with
an overall description of radio features and is followed by the steps
required to install the unit and place it into normal operation.
Additionally, the guide contains troubleshooting tips for resolving
system difficulties that you might encounter. After you install the radio,
keep this guide near the radio for future reference.
2.0 PRODUCT DESCRIPTION
The master station radio (Figure 1) is a full-duplex data telemetry radio
suitable for use in Multiple Address System (MAS) and Supervisory
Control and Data Acquisition (SCADA) applications. The radio uses
microprocessor control and Digital Signal Processing (DSP) technology
to provide highly reliable communications even under adverse condi-
tions.
The MDS 4790 is intended to be used in systems with compatible
MDS 4710 Series remote radios; it operates in the 400 MHz frequency
band (380 to 512 MHz for A and C models; 400 to 480 MHz for E
models). The MDS 4790S uses an over-the-air data rate of 9600 bps.
The MDS 9790 is used with compatible MDS 9710 Series remote
radios, and it operates between 800 and 960 MHz. Radios are available
in either a redundant configuration or a non-redundant configuration.
Refer to Section 2.2, Redundant versus Non-redundant Operation,
beginning on Page 2 for more information.
Invisible place holder
Figure 1. MDS 4790/9790 Series Master Station
ENTER
ESCAPE
ACTIVE
ACTIVE
STBY ALARM RX ALR TX ALR
STBY ALARM RX ALR TX ALR LINE
LINE
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2 MDS 4790/9790 Series I/O Guide MDS 05-3438A01, Rev. F
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
mounted configurations. Connectors are provided on the rear panel for
easy connection of power, antenna, data, alarm, and diagnostic func-
tions.
2.1 Network-Wide Diagnostics
Newer GE MDS remote and master station radios, including the
MDS 4790/9790 Series, offer network-wide diagnostics capability. Net-
work-wide diagnostics communications is a modern, packetized mode
that has several advantages over DTMF diagnostics communications
(used by older GE MDS radios):
• You can gather diagnostic data over a large radio network with-
out disrupting the system communications flow.
• When required, you can increase diagnostics communications
speed by actively collecting diagnostic data.
• You can access diagnostic data for each radio in the network
from any radio diagnostics port in the network.
• You can broadcast certain messages to all radios in the system
simultaneously.
You can use the MDS 4790/9790 Series Master Station to poll remote
radios in its radio system for diagnostic data. For more information on
the implementation of network-wide 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 com-
pletetransceiver boards andpower supplies installed in the enclosure. In
the event of a failure in the primary equipment, the controlling logic
switches to the stand-by unit. The stand-by transceiver board is con-
stantly operating and its operational readiness is monitored. However,
the power amplifier in the stand-by 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
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MDS 05-3438A01, Rev. F MDS 4790/9790 Series I/O Guide 3
a transceiver board causes 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,
refer to “Transceiver Board and Power Supply Assemblies” on Page 86.
2.3 Applications
The MDS 4790/9790 Series radios are designed for point-to-multipoint
data transmission in oil and gas pipeline communications, transactional
systems, and telecommunications systems. A MAS network provides
communications between a central host computer and remote terminal
units (RTUs) or other data collection devices. The operation of the radio
system is transparent to the computer equipment.
Basic MAS Master Station Operation
Figure 2 shows a typical point-to-multipoint system using an
MDS 4790/9790 Series master station. This is a basic system consisting
of a central master station and several associated remote units.
Figure 2. Typical MAS Network
Repeater and Polling Remote Operation
A MAS system using repeater and polling remote radios is shown in
Figure 3 on Page 4. Notice that the polling remote radio operates in
half-duplex mode and the repeater operates in full-duplex mode. Con-
figuring the radio for repeater operation is as simple as typing REPEATER
ON with a PC connected to the rear panel diagnostic port. Refer to
“DIAGNOSTICS AND CONTROL” on Page 30 for details.
–
IDIAG13.8VDC
PWR
+
–
HOST SYSTEM
REMOTE RADIO
SWC OFF
RTU
RTU
RTU
RTU
–
IDIAG13.8 VDC
PWR
+
–
–
IDIAG 13.8 V
DC
PWR
+
–
–
IDIAG 13.8 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
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4 MDS 4790/9790 Series I/O Guide MDS 05-3438A01, Rev. F
Figure 3. Typical Repeater and Polling-Remote Network
Simplex and Switched Carrier Operation
System-wide simplex operation is achieved by switching the master sta-
tion carrier on to transmit, then off to receive. The same frequency is
used for both transmit and receive.
Switched carrier, half-duplex mode works in the same way, except dif-
ferent frequencies are used for transmit and receive.
2.4 Features
Reliability is a hallmark of the MDS 4790/9790 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 if servicing is necessary.
In addition, the optional redundant version of the radio includes redun-
dant transceiver boards and power supply modules that automatically
activate if a failure in either of the transceiver boards or power supplies
occurs. This ensures continued operation in the event of most trans-
ceiver board failures.
The following list highlights many of the radio’s key features. For a full
listing of specifications, refer to Section 10.1, Technical Specifications,
beginning on Page 97.
–
IDIAG 13.8VDC
PWR
+
–
HOST SYSTEM
REMOTE RADIO
RTU
RTU
RTU
RTU
–
IDIAG 13.8 VDC
PWR
+
–
–
IDIAG13.8V
DC
PWR
+
–
–
IDIAG 13.8 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 HIG
H
TX LOW
RX HIGH
TX LOW
RX HIGH
TX LOW
RX HIGH
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MDS 05-3438A01, Rev. F MDS 4790/9790 Series I/O Guide 5
• Primary power options for: 15, 24, 48, or 125
volt DC and 115/230 volts AC sources.
• Configuration, control, and diagnostics from the front panel dis-
play or a connected PC.
• Remote diagnostics using a connected PC and radio software.
• Time stamping of alarms and major events.
• Flexible mounting (rack or tabletop); front panel can be (option-
ally) mounted separately from the radio chassis.
2.5 Accessories
You can use the radio with one or more of the accessories listed in
Table 1. Contact the factory for ordering information.
Table 1. Radio Accessories
Option Description Part No.
Diagnostics and
Control Software PC-based software for control, diagnostics, and software upgrades of the radio. 03-3533A01
Diagnostic and
Control Interface
Cable
Allows connection of a PC to the radio for
control and diagnostics (DB-9 to DB-9). 03-2198A17
Front Panel Rack
Mounting Kit Allows rear-rack mounting of the detachable front panel. Used in installations where all
controls and indicators must be accessible
from the rear of the radio.
03-3228A01
Orderwire Handset Allows orderwire communications with other
stations in the network. 12-1307A01
Cavity Filter Kit
(For MDS 9790x) Removes or attenuates interfering 900 MHz signals from the receiver input. Might be
necessary in areas with high powered
stationsnearby, such aspagingtransmitters.
Available for use with an internal or external
duplexer.
03-3621Axx
RF Combiner
Panel, 9/24 MHz
splits
(MDS 9790x only)
Combines the outputs from two master
stations into one antenna. Designed for
installations whereonemaster uses a9 MHz
split and the other uses a 24 MHz split.
03-3665Axx
VOX Board Voice-activated transmit board that keys the
transmitter when an audio signal is present
on the radio’s audio input pin.
03-1098A02
Lightning
Protectors Polyphaser Surge Protector, IS-50NX-C2, DC blocked, 125 MHz to 1000 MHz, N
female connectors, surface (flange) mount
Polyphaser Surge Protector, IS-B50LN-C2,
DC blocked, 125 MHz to 1000 MHz, N
female connectors, bulkhead mount
97-1680A01
97-1680A05
Redundant Radio
Upgrade Kit Adds an additional transceiver board and power supply to a single-radio chassis.
Operating frequency must be specified when
ordering.
Consult
Factory
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6 MDS 4790/9790 Series I/O Guide MDS 05-3438A01, Rev. F
2.6 Model Number Codes
The radio model number is printed on the serial number label, which is
affixed to the radio chassis. The alpha-numeric string describes the
unit’s hardware and software configuration as it was shipped from the
factory. This model number is an important reference when speaking
with, or writing to, the factory for assistance.
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. Review this material 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 inter-
face between the radio and the data device. Figure 4 shows a typical sta-
tion arrangement.
Invisible place holder
Figure 4. Typical Station Arrangement
TO INPUT
POWER SOURCE
LOW LOSS
COAXIAL CABLE
OMNIDIRECTIONAL
ANTENNA
HOST COMPUTER
DIAGNOSTICS
COMPUTER
ENTER
ESCAPE
ACTIVE
ACTIVE
STBY ALARM RX ALR TX ALR
STBY ALARM RX ALR TX ALR LINE
LINE
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MDS 05-3438A01, Rev. F MDS 4790/9790 Series I/O Guide 7
Site Selection
For a successful installation, carefully select the site for the master sta-
tion and the remote radios. Suitable sites offer:
• Anantennalocation that provides anunobstructed 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.
You can quickly determine these requirements 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 affect system
performance.
If you are not familiar with the effects of terrain and other obstructions
on radio transmission, the following discussion provides helpful back-
ground.
Terrain and Signal Strength
A line-of-sight path between stations is highly desirable and provides
the most reliable communications link in all cases. You can often
achieve a line-of-sight path by mounting each station antenna on a tower
or other elevated structurethat raises it highenough to clear surrounding
terrain and other obstructions.
The requirement for a clear transmission path depends on the distance
covered by the system. If the system covers only a limited distance, say
3.1 miles (5 km), then some obstructions in the transmission path might
be acceptable. For longer range systems, any obstruction might compro-
mise the performance of the system, or block transmission entirely.
The signal strength at the receiver must exceed the sensitivity limit by
an amount known as the fade margin to provide reliable operation under
various conditions.
Section 10.2, RF Propagation Planning, beginning on Page 99 includes
a detailed discussion of path planning. Review this section before begin-
ningan installation. Computer softwareis also available forthis purpose
that greatly simplifies the steps involved in planning a path.
On-the-Air Test
If you’ve analyzed the proposed transmission path and feel that it is
acceptable, conduct an on-the-air test of the equipment and path. This
not only verifies the path study results, but allows you to see firsthand
the factors involved at each installation site.
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8 MDS 4790/9790 Series I/O Guide MDS 05-3438A01, Rev. F
The test can be performed by installing a radio at each end of the pro-
posed link and checking the RSSI value reported at the radio’s front
panel display (refer to “Front Panel Indicators” on Page 27). If you do
not obtain adequate signal strength, it might 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 provided in Section 5.0,
START-UP AND OPERATION, beginning on Page 26.
A Word About Interference
Interference is possible in any radio system. However, since the
MDS 4790/9790 Series is designed for use in a licensed system, inter-
ference is less likely because geographic location and existing operating
frequencies are taken into account when allocating frequencies.
The risk of interference can be further reduced through prudent system
design and configuration. Allow adequate separation between frequen-
cies and radio systems.
Keep the following points in mind when setting up your radio system:
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 on nearby
frequencies.
2. Directional antennas should be used at the remote end of the link.
They confine the transmission and reception pattern to a narrow
beam, which minimizes interference to and from stations located
outside the pattern.
3. If interference is suspected from another system, it might be helpful
to use antenna polarization that is opposite to the interfering sys-
tem’s antennas. An additional 20 dB (or more) of attenuation to
interference can be achieved by using opposite antenna polarization.
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MDS 05-3438A01, Rev. F MDS 4790/9790 Series I/O Guide 9
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 improp-
erly aligned with the companion site, will result in poor performance or
no communication at all.
Generally speaking, an omni-directional antenna (Figure 5) is used at
the master station site. This type of antenna provides equal coverage to
all of the remote sites. At remote stations, directional antennas such as
Yagis, are typically used.
Figure 5. Typical Omnidirectional Antenna for Master Station
(Shown mounted to mast)
Feedline Selection
For maximum performance, use a good-quality feedline to connect the
radio to the antenna. For short-range transmission, or where short
lengths of cable are used (up to 8 meters [26 feet]), an inexpensive coax
cable such as Type RG-213 might 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 pro-
duce only 1.6 watts at the antenna; a similar loss in receiver sensitivity
would result, and no amount of receiver gain can recover the signal lost
in the feedline.
Conversely, 100 feet (30 meter) of 1-5/8 inch cable has a loss of 0.52 dB
at the same frequency, but its cost is considerably higher than
RG-58A/U.
For systems covering short distances, feedline loss is relatively unim-
portant, and 6 dB or more of loss might be 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
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10 MDS 4790/9790 Series I/O Guide MDS 05-3438A01, Rev. F
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. Follow the instructions pro-
vided by the antenna and feedline manufacturers to ensure a safe and
reliable installation.
4.0 INSTALLATION PROCEDURES
This section presents the steps necessary for installing the radio and con-
necting it to associated equipment. After completing these steps, the
radio is ready for in-service operation.
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
Table 3. Feedline Loss Chart (960 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 0.85 dB 4.27 dB 8.54 dB 42.70 dB
1/2 in. HELIAX 0.23 dB 1.15 dB 2.29 dB 11.45 dB
7/8 in. HELIAX 0.13 dB 0.64 dB 1.28 dB 6.40 dB
1-1/4 in. HELIAX 0.10 dB 0.48 dB 0.95 dB 4.75 dB
1-5/8 in. HELIAX 0.08 dB 0.40 dB 0.80 dB 4.00 dB
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MDS 05-3438A01, Rev. F MDS 4790/9790 Series I/O Guide 11
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
4.2 Mounting the Radio
Install the radio in a relatively clean, dust-free environment that allows
easy access to the rear panel connectors as well as the front panel con-
trols and indicators. Air must pass freely over the heatsink on the rear
panel.
Figure 7 on Page 12 shows the mounting dimensions of the radio. Most
commonly, the radio is installed in a 2U/3.5 inch (88.90 mm)
rack-mount configuration, but you can also install it in a simple tabletop
arrangement if desired.
PC DIAGNOSTICS & CONTROL
CD-ROM (OPTIONAL) RACK-MOUNT BRACKETS (2
)*
A
B
ESCAPE
ENTER
INSTALLATION
& OPERATION GUIDE
ADHESIVE FEET (4)*
(For tabletop mounting)
POWER CORD
(AC cord shown)
*These items may already be installe
d
on the radio chassis.
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12 MDS 4790/9790 Series I/O Guide MDS 05-3438A01, Rev. F
Rack Mounting
To rack-mount the radio, use the supplied mounting brackets
(MDS P/N 82-3184A01) to secure the chassis to the rack cabinet.
Attach the brackets at any of four points on the sides of the enclosure—
front, back, middle facing front, and middle facing back (see Figure 7).
This flexibility ensures compatibility with most rack mounting arrange-
ments.
Tabletop Mounting
You can place the radio on any sturdy shelf or tabletop that will support
its weight. Adhesive-backed rubber feet are provided with the radio for
use in tabletop installations. Place the feet under the chassis near each
corner to prevent scratching of the mounting surface.
Invisible place holder
Figure 7. Mounting Dimensions
Remote Front Panel Mounting—Optional Configuration
If desired, you can detach the front panel from the radio and mount it
separately from the radio chassis. This optional kit, MDS P/N
03-3228A01, is intended for rack-mount installations where all connec-
tions and control must be performed from the rear of the radio. The Aux-
iliary Mounting Plate (P/N 82-3189A01) is included in the kit.
To remove the front panel from the radio and re-mount it to the Auxil-
iary Mounting Plate, follow these steps:
1. Detach the front panel from the radio by grasping it firmly along its
bottom edge and pulling away from the radio chassis (Figure 8 on
Page 13).
2. Release the modular RJ-11 connector and cable from the back of the
panel.
3
.5 inches
(
88.9 mm)
17.2 inches
(437 mm)
14.29 inches
(363 mm)
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