Microwave Data Systems iNET 900 Series User manual

MDS 05-2873A01, REV. FCC
AUGUST 2001
Wireless IP/Ethernet Transceiver
MDS iNet 900™

DRAFT 6—8/30/01
Below are the basic steps for installing the MDS iNet 900 transceiver. Detailed instructions are given in
the Section 3.0, INSTALLATION PLANNING , on page 5 of this manual.
1. Install and connect the antenna system to the radio
• Use good quality, low-loss coaxial cable. Keep the feedline as short as possible.
• Preset directional antennas in the direction of desired transmission/reception.
2. Apply DC power to the radio (13.8 Vdc @ 500 mA)
• Connect a DC power source to the i Net’s power connector.(Negative ground only.)
• Observe proper polarity when connecting the DC cable. See Figure 10 on page 16.
3. Review the initial configuration profile
• Connect a computer with HTTP browser to the LAN port, or a terminal to the COM1 port, to identify,
and revise if necessary the MDS i Net 900’s primary operating parameters. (See “Step 5—Review
the Radio’s Configuration” on page 16 for details.)
✓
Operating Mode: Access Point (Master) or Station Adaptor (Remote)
✓ Internet Protocol (IP) Address
✓
Network Name
✓
Time and Date—If event logging is enabled
1
Z?
4. Verify proper operation of the MDS i Net radio-modem
• See Table 2 on page 7 for an explanation of the LED status indicators.
• Refine the antenna heading for maximum received signal strength using the radio signal strength
indicator (
RSSI
) function found on the browser’s home page. The RSSI display will be in dBm.
5. Connect the user’s equipment to the MDS i Net’s LAN, COM1or COM2 ports
• LAN—Use a RJ-45 Ethernet connector/cable.
• COM2—Recommended for serial-based data equipment.
Use a DB-9 female connector. Interface is RS-232/EIA-232 compatible.
• COM1—Reserve, if practical, for use to connect terminal for unit configuration.
Use a DB-9 male connector. Interface is RS-232/EIA-232 compatible.
(See Table 9 on page 34 for pin descriptions and Figure 9 on page 16 for port defaults.)
6. Verify proper operation of the user’s equipment
• A properly configured system will work exactly as it would if the data equipment were communicating
through a conventional wired system. (See Table 4.6 on page 18)
• The LINK LED will blink intermittently under normal operation if it connects with another
MDS iNet 900 transceiver.
• Use the IP “PING” command to verify the Access Point can be contacted by the Station Adapter.
1. While this may be of value, the time and date setting does not seem like a primary parameter and is
beyond the scope of this draft.
QUICK START GUIDE

DRAFT 6—8/30/01

MDS 05-2873A01, Rev.A MDS i Net 900 Installation and Operation Guide i
DRAFT 6—8/29/01
TABLE OF CONTENTS
1.0 ABOUT THIS MANUAL................................................................1
2.0 PRODUCT DESCRIPTION .........................................................1
2.1 Transceiver Features ........................................................................2
2.2 Spread Spectrum Radios—
How Are They Different? ..........................................................................3
2.3 Typical Applications ..........................................................................3
Wireless IP/Ethernet LAN Connectivity ..........................................3
Point-to-Point System .....................................................................3
Dealing with difficult terrain.............................................................4
2.4 Accessories ......................................................................................4
3.0 INSTALLATION PLANNING.........................................................5
3.1 General Requirements .....................................................................5
3.2 Site Selection ...................................................................................6
Terrain and Signal Strength............................................................6
Conducting a Site Survey...............................................................7
3.3 A Word About Radio Interference ....................................................8
3.4 Antenna & Feedline Selection ..........................................................9
Antennas ........................................................................................9
Feedlines......................................................................................11
3.5 How Much Output Power Can be Used? .......................................11
Calculating System Gain ..............................................................12
4.0 INSTALLATION..........................................................................13
4.1 Step 1— Mounting the Transceiver ................................................13
4.2 Step 2—Install the Antenna and Feedline ......................................15
4.3 Step 3—Connect the Data Equipment ...........................................15
4.4 Step 4—Measure & Install Primary Power .....................................16
4.5 Step 5—Review the Radio’s Configuration ....................................16
Procedure.....................................................................................17
4.6 Step 6—Connect the User Data Equipment ..................................18
4.7 Step 7—Check for Normal Operation ............................................18
Procedure.....................................................................................18
4.8 Performance Optimization ..............................................................19
Antenna Aiming ............................................................................19
Antenna SWR Check (Z? Major revision needed?)......................20
5.0 TRADITIONALREPEATERCONFIGURATIONWITHTWORADIOS
20
5.1 Overview ........................................................................................20

ii MDS i Net 900 Installation Guide MDS 05-2873A01, Rev. A
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5.2 Antennas ........................................................................................21
5.3 Network Name ...............................................................................21
5.4 Interface Wiring ..............................................................................21
6.0 PROGRAMMING.......................................................................21
6.1 ProgrammingVia an HTTP/Web Browser ......................................22
Making the Connection.................................................................22
Start-up Screen ............................................................................22
System Configuration Screen.......................................................23
Radio/Modem Screen Z?..............................................................23
6.2 ProgrammingVia COM1 Port & aTerminal Program .....................24
Making the Connection.................................................................24
Communicating with the iNet transceiver .....................................24
Using the Menu-Based Management Toolbox..............................24
Review and Changing Essential Parameters................................26
7.0 TROUBLESHOOTING...............................................................26
7.1 LED Indicators ................................................................................27
7.2 Troubleshooting Chart ....................................................................27
8.0 REPEATER ASSITED LANS.....................................................28
Repeater Systems........................................................................28
Option 1—Traditional with two-radio repeater ..............................28
Option 2—With Store-and-Forward Station..................................29
9.0 TECHNICAL REFERENCE .......................................................30
9.1 Technical Specifications .................................................................30
9.2 Data Interface Connectors—
LAN, COM1 & DATA Ports .....................................................................32
LAN (Local Area Network) Port—RJ-45 Ethernet Interface..........32
COM1 Port ...................................................................................33
COM2 Port....................................................................................34
9.3 Table-Top Test Setup ......................................................................34
9.4 Using a Personal Computer to Configure the iNet Radio ...............35
Connecting a PC to iNet’s LAN (Ethernet) Port............................35
Connecting a PC to iNet’s COM1 Port..........................................35
10.0 GLOSSARY OF TERMS..........................................................36
10.1 dBm-Watts-Volts Conversion Chart ..............................................39
Copyright Notice
This Installation and Operation Guide and all software described herein
are protected by copyright. Copyright 2001, Microwave Data Systems,
Inc. All rights reserved.

MDS 05-2873A01, Rev.A MDS i Net 900 Installation and Operation Guide iii
DRAFT 6—8/29/01
Serviceability of this Manual
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 Service Team usingthe information at thebackof this
guide. Microwave Data Systems Incorporated reserves its right to cor-
rect any errors and omissions. Updated information may also be avail-
able on our Web site at www.microwavedata.com.
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 within two meters (6 feet) of the antenna when the transmitter is
operating.
This manual is intended to guide a professional installer in installing,
operating and performing basic system maintenance on the described
equipment.
FM/UL/CSA Notice
MDS i Net 900 When Approved
This product is available for use in Class I, Division 2, Groups A, B,
C & D Hazardous Locations. Such locations are defined in Article 500
of the National Fire Protection Association (NFPA) publication NFPA
70, otherwise known as the National Electrical Code.
Thetransceiver has beenrecognized for usein these hazardous locations
by three independent agencies —Underwriters Laboratories (UL), Fac-
tory Mutual Research Corporation (FMRC) and the Canadian Standards
Association (CSA). The UL certification for the transceiver is as a Rec-
ognized Component for use in these hazardous locations, in accordance
with UL Standard 1604. The FMRC Approval is in accordance with
FMRC Standard 3611. The CSA Certification is in accordance with
CSA STD C22.2 No. 213-M1987.
FM/UL/CSA Conditions of Approval
MDS i Net 900 When Approved
The transceiver is not acceptable as a stand-alone unit for use in the haz-
ardous locations described above. It must either be mounted within
anotherpiece of equipment which iscertified for hazardous locations, or
installed within guidelines, or conditions of approval, as set forth by the
approving agencies. These conditions of approval are as follows:
1. The transceiver must be mounted within a separate enclosure which
is suitable for the intended application.
RF Exposure

iv MDS i Net 900 Installation Guide MDS 05-2873A01, Rev. A
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2. The antenna feedline, DC power cable and interface cable must be
routed through conduit in accordance with the National Electrical
Code.
3. Installation, operation and maintenance of the transceiver should be
in accordance with the transceiver's installation manual, and the
National Electrical Code.
4. Tampering or replacement with non-factory components may
adversely affect the safe use of the transceiver in hazardous loca-
tions, and may void the approval.
5. When installed in a Class I, Div. 2, GroupsA, B, C or D hazardous
location, observe the following:
Do not disconnect equipment unless power has been
switched off or the area is know to be non-hazardous.
Refer to Articles 500 through 502 of the National Electrical
Code (NFPA 70) for further information on hazardous loca-
tions and approved Division 2 wiring methods.
1
Z?
FCC Notice, U.S.A.
MDS i Net 900 When Approved
The MDS iNet 900 transceivers comply with Part 15 of the FCC Rules.
Operation is subject to the following two conditions: (1) this device may
not cause harmful interference, and (2) this device must accept any
interference received, including interference that may cause undesired
operation.
This device is specifically designed to be used under Section 15.247 of
the FCC Rules and Regulations. Any unauthorized modification or
changes to this device without the express approval of Microwave Data
Systems may void the user’s authority to operate this device.
Furthermore, this device is indented to be used only when installed in
accordance with the instructions outlined in this manual. Failure to
comply with these instructions may also void the user’s authority to
operate this device.
FCC Information
This equipment has been tested and found to comply with the limits for
a Class A digital device, pursuant to Part 15 of the FCC Rules. These
limits are designed to provide reasonable protection against harmful
interference when the equipment is operated in a commercial environ-
1. This seem like this note should be a DANGER classification if there is a
potential for an explosion. Please verify.
EXPLOSION
HAZARD

MDS 05-2873A01, Rev.A MDS i Net 900 Installation and Operation Guide v
DRAFT 6—8/29/01
ment. This equipment generates, uses, and can radiate radio frequency
energy and, if not installed and used in accordance with the instruction
manual, may cause harmful interference to radio communications.
Operation of this equipment in a residential area is likely to cause
harmful interference in which case the user will be required to correct
the interference at his own expense.

MDS 05-2873A01, Rev.A MDS i Net 900 Installation and Operation Guide 1
DRAFT 6—8/29/01
1.0 ABOUTTHIS MANUAL
This guide presents installation and basic operating instructions for the
MDS i Net 900™ transceiver. Following installation, we suggest
keeping this guide near the equipment for future reference.
The terms Access Point and Station Adapter are abbreviated as “
A.P.”
and “
S.A.”
in various technical illustrations and tables used in this
manual wherever space is at a premium.
Thismanualdoesnot coverallpossibleMDS iNet 900 user-controllable
parameters and/or diagnostic tools. For an in-depth description of all of
the features and controls of the MDS iNet 900, please read the
MDS iNet Network Manager’s Manual , P/N 05-xxxxA01.
2.0 PRODUCT DESCRIPTION
The MDS i Net 900 transceiver, shown in Figure 1, is designed to pro-
vide network managers with a easy-to-install wireless local area net-
work (LAN) services with plug-and-play hardware. For basic services,
just hook up an antenna, connect your Ethernet LAN to the radio’s LAN
port, apply primary power, and you are done. And, no license is
required.
The transceiver is a spread-spectrum radio designed for operation in the
license-free 900 MHz frequency band. The MDS i Net 900 provides reli-
able communications up to distances of 30 miles (50 km), even in the
presence of weak signals or interference.
Only two user-controllable parameters need to be checked at the time of
installation—the radio’s Access Point/Station Adapter operating mode,
and “network name” of the unit.
The MDS i Net 900 transceiver is based on the IEEE 802.11 wireless
LAN specification. From this perspective, i Net transceivers serve as
“Access Points” and “Station Adapters”. An Access Point is a wireless
hub that provides connectivity into a wired Ethernet LAN. This connec-
tivity is achieved through remote Station Adapters. From a radio per-
spective, an Access Point also works as a “master station” providing
synchronization signaling for the remote radios (Access Point units).
A Station Adapter provides wireless connectivity to and Access Point to
one or more Ethernet devices connected to its local interface. From a
radio perspective, the Station Adapter also works as a remote radio that
communicates to a master radio (Access Point).

2 MDS i Net 900 Installation Guide MDS 05-2873A01, Rev. A
DRAFT 6—8/29/01
Users with a mixture of equipment with Ethernet and serial data inter-
faces can choose to use one of the two user-configurable serial ports.
This flexibility allows the iNet transceiver to provide services in data
networks that are on a path from legacy serial/EIA/RS-232-based hard-
ware to the faster and more easily interfaced Ethernet world. The radio
and data interfaces are easily arranged via the
COM1
port or via the
LAN
(Ethernet) port using HTTP.
Figure 1. The MDS iNet 900 Transceiver
The transceiver is housed in a compact and rugged cast-aluminum case
that needs only be protected from direct exposure to the weather. It con-
tains a single printed circuit board with all necessary components for
radio operation and data communications.
2.1 Transceiver Features
Listed below are several key features of the MDS i Net 900 transceivers.
These are designed to ease the installation and configuration of the
radio, while retaining the ability to make changes in the future.
• Plug-and-Play Connectivity—Ethernet bridge configuration
option requires virtually no setup
• High Speed—512 kbps is 50-times faster than 9.6 kbps radios
• Long Range—30 miles (50 km) in wireless LAN configuration
• Robust Radio Communications—Designed to operate in
high-interference environments
• Industrial-Grade Product—Extended temperature range for
trouble-free operation in extreme environments
• Serial Ports—IP gateway to legacy serial interface based equip-
ment
• Same hardware for Access Point and Station Adaptor configu-
rations

MDS 05-2873A01, Rev.A MDS i Net 900 Installation and Operation Guide 3
DRAFT 6—8/29/01
2.2 Spread Spectrum Radios—
How Are They Different?
The main difference between a traditional (licensed) radio system and
the i Net transceivers is that these units “hop” from channel to channel
many times per second using a specific hop pattern applied to all radios
in the network. A distinct hopping pattern is provided for each of the
networkname, thereby minimizingthe chanceof interference withother
spread spectrum systems. In the USA, and certain other countries, no
license is required to install and operate this type of radio system.
2.3 Typical Applications
Wireless IP/Ethernet LAN Connectivity
This is the most common application of the MDS i Net 900 transceiver.
It consists of a central control station (Access Point) and one or more
associated Station Adapter units, as shown in Figure 2. A LAN 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 with the Access Point
station serving as the gateway to the WAN or host computer.
Invisible place holder
Figure 2. Typical wireless LAN
Point-to-Point System
A point-to-point configuration (Figure 3) is a simple arrangement con-
sisting of just two radios—a Access Point and a Station Adapter. This
provides communications link for the transfer of data between two loca-
tions.
iNet S.A.
iNet S.A.
iNet S.A.
iNet A.P.
iNet S.A.
iNet S.A.
HOST
COMPUTER
RTU
RTU
RTU
RTU
RTU

4 MDS i Net 900 Installation Guide MDS 05-2873A01, Rev. A
DRAFT 6—8/29/01
Invisible place holder
Figure 3. Typical point-to-point link
(A LAN connection may be used in place of a Host Computer)
Dealing with difficult terrain
In some geographical areas there may be obstacles that make communi-
cation between iNet transceivers difficult. These obstacles commonly
are large buildings, natural geological formations or dense foliage.
These obstacles can often be overcome with a repeater station. See
“REPEATER ASSITED LANS” on page 28 for descriptions of basic
repeater configurations.
2.4 Accessories
The MDS iNet 900 transceiver can be used with one or more of the
accessories listed in Table 1. Contact the factory for ordering details.
RTU
HOST
COMPUTER iNet A.P. iNet S.A.
Table 1. Accessories
Accessory Description MDS P/N
A/C Power
Adapter A small switching power supply module designed for continuous service. UL approved.
Output 13.8 Vdc @ 500 mA.s
03-xxxxA01
LAN Antenna Small and flexible 1/4 wavelength antenna
plugged directly into the radio’s ANTENNA
port. Suitable for short-range local area
networks.
03-xxxxA01
TNC to N
Adapter Short length of coaxial cable (6”/15 cm) used to connect the radio’s TNC antenna connector to
a Type N commonly used on large diameter
coaxial cables.
03-xxxxA01
EthernetRJ-45
Cross-over
Cable
Cable assembly used to cross-connect the
Ethernet ports of two iNet radios used in a
repeater configuration. (Cable length = 3’/1M)
03-xxxxA01
Flat-Surface
Mounting
Brackets
Brackets:2”x3”platesdesigned to bescrewed
onto the bottom of the transceiver for
surface-mounting the radio.
82-1753-A01
Screws: 6-32/1/4˝with locking adhesive.
(Industry Standard MS 51957-26) 70-2620-A01
19˝Rail
Mounting
Brackets
Adaptor for mounting one MDS iNet 900 radio
in a standard 19-inch equipment rack. 03-xxxxA01

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3.0 INSTALLATION PLANNING
The installation of the radio is not difficult, but it does require some
planning to ensure station reliability and efficiency. This section pro-
vides tips for selecting an appropriate site, choosing an antenna system,
and reducing the chance of harmful interference.
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 transceiver and the data device.
Figure 4 shows a typical Station Adapter installation. An external direc-
tional antenna is normally used and an RTU/PLC is connected to one of
the serial ports (COM1/COM2). 13.8 Vdc is supplied to the Station
Adapter by an external source.
Invisible place holder
Figure 4. Typical Station Adapter arrangement
(RTU can be connected to any compatible LAN or COM Port)
DIN Rail
Mounting
Brackets
Adaptor for mounting one MDS iNet 900 radio
in a DIN standard equipment rack. 03-xxxxA01
Short-Range
Antenna Short 1/2-wave antenna. Mounts directly onto the radio’s coaxial connector. Suitable only for
short-range LANs, such as within a building or
small campus.
03-xxxxA01
Table 1. Accessories (Continued)
LAN PORT
POWER SUPPLY
13.6 VDC @
500 mA (MIN.)
REMOTE
TERMINAL
UNIT
ANTENNA
SYSTEM
LOW-LOSS FEEDLINE
iNet RADIO
TRANSCEIVER

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3.2 Site Selection
For a successful installation, careful thought must be given to selecting
proper sites for the Access Points and Station Adapters. Suitable sites
should provide:
• Protection from direct weather exposure
• A source of adequate and stable primary power
• Suitable entrances for antenna, interface or other required
cabling
• Antenna location that provides an unobstructed transmission
path in the direction of the associated station
( s )
Theserequirements can be quickly determinedin most cases. Apossible
exception is the last item—verifying that an unobstructed transmission
path exists. Radio signals travel primarily by line-of-sight, and obstruc-
tions between the sending and receiving stations will affect system per-
formance. If you are not familiar with the effects of terrain and other
obstructions on radio transmission, the discussion below will provide
helpful background.
Terrain and Signal Strength
While the 900 MHz band offers many advantages over VHF and lower
UHF frequencies for data transmission, the band is more prone to signal
attenuation from obstructions such as terrain, foliage or buildings in the
transmission path.
A line-of-sight transmission path between the central Access Point sta-
tion and its associated remote access station site
(
s
)
is highly desirable
and provides the most reliable communications link. A line-of-sight
path can often be achieved by mounting the station antenna on a tower
or other elevated structure that raises it to a level sufficient to clear sur-
rounding terrain and other obstructions.
The importance of a clear transmission path relates closely to the dis-
tanceto be covered bythe system. If thesystem is to coveronly a limited
geographic area, say up to 3 miles (4.8 km), then some obstructions in
the transmission path can usually be tolerated with minimal impact. For
longer range systems, any substantial obstruction in the transmission
path could compromise the performance of the system, or block trans-
mission entirely.
Much depends on the minimum signal strength that can be tolerated in
a given system. Although the exact figure will differ from one system to
another, a Received Signal Strength Indication (RSSI) of –80 dBm or
stronger will provide acceptable performance in many systems. While
the equipment will work at lower signal strengths, this provides a “fade

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DRAFT 6—8/29/01
margin” to account for variations in signal strength which may occur
from time-to-time. RSSI can be measured with a terminal connected to
the
COM1
Port or with a HTTP browser to the LAN (Ethernet) connector.
(See Section 4.6 on page 18 for details.)
Conducting a Site Survey
If you are in doubt about the suitability of the radio sites in your system,
it is best to evaluate them before a permanent installation is begun. This
can be done with an on-the-air test (preferred method); or indirectly,
using path-study software.
An on-the-air test is preferred because it allows you to see firsthand the
factors involved at an installation site and to directly observe the quality
of system operation. Even if a computer path study was conducted ear-
lier, this test should be done to verify the predicted results.
The test can be performed by first installing a radio and antenna at the
proposed Access Point station site and then visiting each Station
Adapter site with a transceiver and a hand-held antenna. (A PC with a
network adapter can be connected to each radio in the network to simu-
late data during this test using the PING command.)
With the hand-held antenna positioned near the proposed mounting
spot, a technician can check for synchronization with the Access Point
station (shown by a lit LINK LED on the front panel) and measure the
reported RSSI value. (See Section 4.6 on page 18 for details.) If ade-
quate signal strength cannot be obtained, it may be necessary to mount
the station antennas higher, use higher gain antennas, select a different
site or consider installing a repeater station. To prepare the equipment
for an on-the-air test, follow the general installation procedures given in
this guide and become familiar with the operating instructions found in
Section 4.0 on page 13.
If time is short, and a site survey is impractical, a computer path study
is a good alternative. Factors such as terrain, distance, transmitter
power, receiver sensitivity, and other conditions are taken into account
to predict the performance of a proposed system. Contact MDS for more
information on path study services.
Table 2.iNet Front Panel LED Functions
LED Label Activity Indication
LAN ON Link integrity OK
Blinking Data TX/RX
OFF LAN not detected
COM1
(Console) ON Not Defined
Blinking Data TX/RX
OFF No data detected

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3.3 A Word About Radio Interference
The iNet 900 transceivers share frequency spectrums with other ser-
vices and other Part 15 (unlicensed) devices in the USA. As such, near
100% error-free communications may not be achieved in a given loca-
tion, and some level of interference should be expected. However, the
radio’s flexible design and hopping techniques should allow adequate
performance as long as care is taken in choosing station location, con-
figuration of radio parameters and software/protocol techniques.
In general, keep the following points in mind when setting up your com-
munications network:
1. Systems installed in rural areas are least likely to encounter
interference; those in suburban and urban environments are more
likely to be affected by other devices operating in the license-free
frequency band and by adjacent licensed services.
2. If possible, use a directional antenna at remote sites.Although these
antennas may be more costly than omnidirectional types, they con-
fine the transmission and reception pattern to a comparatively nar-
row lobe, which minimizes interference to (and from) stations
located outside the pattern.
3. If interference is suspected from a nearby licensed system (such as a
paging transmitter), it may be helpful to use horizontal polarization
of all antennas in the network. Because most other services use ver-
tical polarization in this band, an additional 20 dB of attenuation to
interference can be achieved by using horizontal polarization.
COM2 ON Not Defined
Blinking Data TX/RX
OFF No data detected
PWR ON Primary power (DC)
present
Blinking Slow = Sleep mode
Quick = Alarm present
OFF Primary power (DC)
absent
LINK
(Access Point) ON Default state
Blinking Data Tx/Rx
OFF Not Defined
LINK
(Station
Adapter)
ON Associated to AP
Blinking Data Tx/Rx
OFF Data Tx/Rx
Table 2.iNet Front Panel LED Functions
LED Label Activity Indication

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4. Multiple iNet 900 Access Point transceivers can co-exist in proxim-
ity to each other with only very minor interference as long as they
are each assigned a unique network name. Each network name has a
different hop pattern. Additional isolation can be achieved by using
separate directional antennas with as much vertical or horizontal
separation as is practical.
5. If constant interference is present in a particular frequency zone, it
may be necessary to “lock out” that zone from the radio’s hopping
pattern. The radio includes built-in software to help users identify
and remove blocked frequency zones from its hopping pattern.
6. If interference problems persist even after removing blocked zones,
try reducing the length of data streams. Groups of short data streams
have a better chance of getting through in the presence of interfer-
ence than do long streams.
7. The power output of all radios in a system should be set for the low-
est level necessary for reliable communications. This lessens the
chance of causing unnecessary interference to nearby systems.
3.4 Antenna & Feedline Selection
Antennas
The equipment can be used with a number of antennas. The exact style
used depends on the physical size and layout of a system. Contact your
MDS representative for specific recommendations on antenna types and
hardware sources.
In general, an omnidirectional antenna (Figure 5) is used at the Access
Point station site. This provides equal coverage to all of the Station
Adapter sites.
NOTE: Antenna polarization is important. If the wrong polarization is
used, a signal reduction of 20 dB or more will result. Most
systems using a gain-type omnidirectional antenna at the
Access Point station employ vertical polarization of the signal;
therefore, the remote antenna(s) must also be vertically polar-
ized (elements oriented perpendicular to the horizon).
When required, horizontally polarized omnidirectional
antennas are also available. Contact your MDS representative
for details.

10 MDS iNet 900 Installation Guide MDS 05-2873A01, Rev. A
DRAFT 6—8/29/01
Invisible place holder
Figure 5. Omnidirectional antenna for iNet 900 transceiver
Invisible place holder
Figure 6. Omnidirectional antenna for
iNet 900 transceiver (mounted to mast)
At Station Adapter sites and units in point-to-point LANs, a directional
Yagi (Figure 7) antenna is generally recommended to minimize interfer-
ence to and from other users. Antennas are available from a number of
manufacturers.
Invisible place holder
Figure 7. Typical Yagi antenna (mounted to mast)

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Feedlines
The choice of feedline used with the antenna should be carefully consid-
ered. Poor-quality coaxial cables should be avoided, as they will
degrade system performance for both transmission and reception. The
cable should be kept as short as possible to minimize signal loss.
For cable runs of less than 20 feet (6 meters), or for short range trans-
mission, an inexpensive type such as Type RG8A/U may be acceptable.
Otherwise, we recommend using a low-loss cable type suited for 900
MHz, such as Heliax®.
Table 3 lists several types of popular feedlines and indicates the signal
losses (in dB) that result when using various lengths of cable at
900 MHz. The choice of cable will depend on the required length, cost
considerations, and the amount of signal loss that can be tolerated.
3.5 How Much Output Power Can be Used?
The transceiver is normally supplied from the factory set for a nominal
+30 dBm (1 Watt) RF power output setting; this is the maximum trans-
mitter output power allowed under FCC rules. The power must be
decreased from this level if the antenna system gain exceeds 6 dBi. The
allowable level is dependent on the antenna gain, feedline loss, and the
transmitter output power setting. Power considerations for point-to-mul-
tipoint and point-to-point systems using the iNet 900 transceivers are
discussed in the next sections.
NOTE: In some countries, the maximum allowable RF output may be
limited to less than 1 watt (For example, 100 mW /+20 dBm).
Be sure to check for and comply with the requirements for
your area.
Table 3. Length vs. loss in coaxial cables at 900 MHz
Cable Type 10 Feet (3.05
Meters)
50 Feet
(15.24
Meters)
100 Feet
(30.48
Meters)
500 Feet
(152.4
Meters)
RG-8A/U 0.85 dB 4.27 dB 8.54 dB 42.70 dB
1/2 inch HELIAX 0.23 dB 1.15 dB 2.29 dB 11.45 dB
7/8 inch HELIAX 0.13 dB 0.64 dB 1.28 dB 6.40 dB
1-1/4 inch HELIAX 0.10 dB 0.48 dB 0.95 dB 4.75 dB
1-5/8 inch HELIAX 0.08 dB 0.40 dB 0.80 dB 4.00 dB

12 MDS iNet 900 Installation Guide MDS 05-2873A01, Rev. A
DRAFT 6—8/29/01
Calculating System Gain
To determine the maximum allowable power setting of the radio, per-
form the following steps:
1. Determine the antenna system gain by subtracting the feedline loss
(in dB) from the antenna gain (in dBi). For example, if the antenna
gain is 9.5 dBi, and the feedline loss is 1.5 dB, the antenna system
gain would be 8 dB. (If the antenna system gain is 6 dB or less, no
power adjustment is required.)
2. Subtract the antenna system gain from 36 dBm (the maximum
allowable EIRP). The result indicates the maximum transmitter
power (in dBm) allowed under the rules. In the example above, this
is 28 dBm.
3. If the maximum transmitter power allowed is less than 30 dBm, use
one of the transceiver’s control tools as described in PROGRAM-
MING on page 21 to set the power accordingly.
For convenience, Table 4 lists several antenna system gains and shows
the maximum allowable power setting of the radio. Note that a gain of 6
dBor less entitles you to operatethe radio at full poweroutput—30 dBm
(1 watt).
* Most antenna manufacturers rate antenna gain in dBd in their
literature. To convert to dBi, add 2.15 dB.
† Feedline loss varies by cable type and length. To determine the
loss for common lengths of feedline, see Table 3 on page 11.
For details on how to set the power level via the Ethernet/HTTP inter-
face, See “Programming Via an HTTP/Web Browser” on page 22 for
details.
Table 4. Antenna system gain vs. power output setting (USA)
Antenna System Gain
(Antenna Gain in dBi*
minus Feedline Loss in dB†)
Maximum Power
Setting
(in dBm) EIRP (in dBm)
6 (or less) 30 36
82836
10 26 36
12 24 36
14 22 36
16 20 36