Microwave Data Systems MDS TransNET 900 Original operating instructions

Installation & Operation Guide Installation & Operation Guide
MDS 05-2708A01, Rev. B
AUGUST 2002
Microwave Data Systems Inc.
MDSTransNET 900
™
Spread Spectrum
DataTransceiver
Model EL805

1. Install and connect the antenna system to the transceiver
• Use a high-quality gain antenna, mounted in the clear.
• Use a low-loss feedline such as LMR 400.
• Preset directional antennas in the direction of desired transmission/reception.
2. Connect the data equipment to the radio’s DB-9F DATA connector
• Connect only the required pins. EIA-232, shown below, typically uses only
TXD, RXD and GND. (See Page 56 EIA-485 interface connections.)
• Verify the connected data equipment is configured as DTE. (Radio is DCE.)
3. Apply DC power to the radio. Use the supplied 2-pin connector
• Input voltage is 6–30 Vdc.Observe proper polarity.The left pin is positive (+)
and the right is negative (–).(See Page 16 for details.)
4. Configure with a PC terminal orTransNET Configuration Software
• Connect computer to radio’s DIAG connector. See Page 54 for cable wiring.
• Set the Mode using the MODE M (Master), MODE R (Remote), or MODE X
(Extension) command. (Note: Only one Master is permitted in a system.)
• Set a unique Network Address (1–65000) using ADDR command. Each radio
in the system must have the same network address. Tip: Use the last four
digits of the Master’s serial number to help avoid conflicts with other
MDS TransNET 900 networks.
• Set the baud rate/data interface parameters.Default setting is 9600 bps, 8
data bits, no parity, 1 stop bit. If changes are required, use the BAUD xxxxx
abc command where xxxxx equals the data rate (1200–115200 bps) and abc
equals the communication parameters as follows:
a = Data Bits (7 or 8)
b = Parity (N for None, O for Odd, E for Even
c = Stop Bits (1 or 2) NOTE: 7N1, 8E2 and 8O2 are not supported.
5. Verify proper operation by observing the LED display
• Refer to Table 4 on Page 19 for a description of the status LEDs.
• Refine directional antenna headings for maximum received signal strength
using the RSSI command. (Remotes must be synchronized with the master.)
QUICK START GUIDE
TXD
RXD
GND
RTS
TXD
RXD
GND
2
3
7
4
3
2
5
DB-25
DATA EQUIPMENT
(DTE)
DB-9
TRANSCEIVER
(DCE)
5
20
6
CTS
DTR
DSR
TXD
RXD
GND
DTR
TXD
RXD
GND
3
2
5
4
3
2
5
DB-9 DB-9
TRANSCEIVER
(DCE)
6
7
8
DSR
RTS
CTS
DATA EQUIPMENT
(DTE)
JUMPERS:
Only if required by RTU.
See manual for additional details.
JUMPERS:
Only if required by RTU.
See manual for additional details.

MDS 05-2708A01, Rev. B MDS TransNET 900 I&O Guide i
CONTENTS
1.0 ABOUT THIS MANUAL..........................................................1
2.0 PRODUCT DESCRIPTION....................................................1
2.1 Transceiver Features .......................................................1
2.2 Model Configuration Codes ............................................2
2.3 Spread Spectrum Radios—How Are They Different? .....3
2.4 Typical Applications .........................................................3
Multiple Address Systems (MAS)....................................3
Point-to-Point System ......................................................4
Adding a Tail-End Link to an Existing Network ................4
Extending a TransNET Network with a Repeater.............5
2.5 Accessories ....................................................................5
3.0 INSTALLATION PLANNING...................................................6
3.1 General Requirements ....................................................6
3.2 Site Selection ..................................................................7
Terrain and Signal Strength .............................................7
Conducting a Site Survey................................................8
3.3 A Word About Radio Interference ...................................9
3.4 Antenna & Feedline Selection .........................................10
Antennas..........................................................................10
Feedlines .........................................................................11
3.5 How Much Output Power Can be Used? ........................12
4.0 INSTALLATION ......................................................................13
4.1 Transceiver Installation ....................................................13
4.2 Configuring Multiple Remote Units .................................17
4.3 Tail-End Links ..................................................................17
4.4 Configuring a Network for Extensions .............................18
4.5 Using the Radio’s Sleep Mode (Remotes Only) ..............18
Sleep Mode Example.......................................................18
5.0 OPERATION ..........................................................................19

ii MDSTransNET 900 I&O Guide MDS 05-2708A01, Rev. B
5.1 Initial Start-up .................................................................19
5.2 Performance Optimization ..............................................19
Antenna Aiming...............................................................20
Antenna SWR Check......................................................20
Data Buffer Setting..........................................................20
Hoptime Setting...............................................................20
Operation at 115200 bps.................................................20
Baud Rate Setting...........................................................21
Radio Interference Checks..............................................21
6.0 RADIO PROGRAMMING......................................................21
6.1 Radio Programming Methods .........................................21
Terminal Interface............................................................21
PC-Based Configuration Tool..........................................21
6.2 User Commands ............................................................22
Entering Commands .......................................................22
6.3 Detailed Command Descriptions ....................................27
ADDR [1–65000].............................................................27
AMASK [0000 0000–FFFF FFFF]...................................28
ASENSE [HI/LO].............................................................28
BAUD [xxxxx abc]............................................................28
BUFF [ON, OFF].............................................................28
CODE [NONE, 1…255]...................................................29
CTS [0–255]....................................................................29
CTSHOLD [0–60000]......................................................30
DEVICE [DCE, CTS KEY]..............................................30
DLINK [xxxxx/ON/OFF]...................................................30
DKEY ..............................................................................31
DTYPE [NODE/ROOT]....................................................31
FEC [ON, OFF] ...............................................................31
HOPTIME [7, 28].............................................................31
INIT .................................................................................31
HREV..............................................................................32
KEY.................................................................................32
MODE [M, R, X] ..............................................................32
OWM [xxxxx]...................................................................32
OWN [xxxxx]....................................................................32
PORT [RS232, RS485] ...................................................32
PWR [20–30]...................................................................34

MDS 05-2708A01, Rev. B MDS TransNET 900 I&O Guide iii
REPEAT [0–10]................................................................34
RETRY [0–10]..................................................................34
RSSI ................................................................................34
RTU [ON, OFF, 0-80].......................................................35
RX [xxxx]..........................................................................35
RXTOT [NONE, 0–1440] .................................................35
SAF [ON, OFF]................................................................35
SETUP.............................................................................35
SER .................................................................................36
SHOW PWR ....................................................................36
SHOW SYNC...................................................................36
SKIP [NONE, 1...8]..........................................................36
SLEEP [ON, OFF]............................................................37
SREV...............................................................................37
STAT ................................................................................37
TEMP...............................................................................37
TX [xxxx]..........................................................................37
UNIT [10000–65000] .......................................................37
XADDR [0–31].................................................................38
XMAP [00000000-FFFFFFFF].........................................38
XPRI [0–31] .....................................................................38
XRSSI [NONE, –40...–120]..............................................38
ZONE CLEAR..................................................................38
ZONE DATA.....................................................................38
7.0 TROUBLESHOOTING ...........................................................39
7.1 LED Indicators ................................................................40
7.2 Alarm Codes ...................................................................40
Checking for Alarms—STAT command............................40
Major Alarms vs. Minor Alarms........................................40
Alarm Code Definitions....................................................41
7.3 Troubleshooting Chart .....................................................42
7.4 Performing Network-Wide Remote Diagnostics ..............43
7.5 Internal Fuse Replacement .............................................44
8.0 RADIO FIRMWARE UPGRADES..........................................45
8.1 Obtaining new firmware ..................................................45
Saving a Web-site firmware file to your PC......................45
8.2 Installing firmware in your radio ......................................45

iv MDSTransNET 900 I&O Guide MDS 05-2708A01, Rev. B
9.0 OPERATING PRINCIPLES AND CONFIGURATION............46
9.1 Synchronization—Basic Network ...................................46
9.2 Extension Operation with SAF .......................................46
Retransmission and ARQ operation................................48
Synchronizing Network Units..........................................48
9.3 Configuration Parameters for Store & Fwd Services ......49
9.4 Security ..........................................................................51
10.0 TECHNICAL REFERENCE.................................................53
10.1 Product Specifications ..................................................53
10.2 Diagnostic Interface Connections (RJ-11) ....................54
10.3 Data Interface Connections (DB-9F) ............................54
Pin Descriptions—RS/EIA-232 Mode..............................55
Pin Descriptions—RS/EIA-422/485 Mode.......................56
10.4 dBm-Watts-Volts Conversion Chart ..............................57
Copyright Notice
This Installation and Operation Guide and all software described herein are Copyright 2002 by
Microwave Data Systems Inc. All rights reserved. Microwave Data Systems Inc. reserves its
right to correct any errors and omissions in this manual.
MDS Quality Policy Statement
We, the employees of Microwave Data Systems, are committed to
understanding and exceeding our customer’s needs and expectations.
• We appreciate our customers’ patronage. They are our business.
• We promise to serve them and anticipate their needs.
• We are committed to providing solutions that are cost effective,
innovative and reliable, with consistently high levels of quality.
We are committed to the continuous improvement of all of our systems and
processes, to improve product quality and increase customer satisfaction.
RF Exposure Notice
ISO 9 1 Registration
Microwave Data Systems adheres to the internationally-accepted ISO 9001 quality system stan-
dard.
Professional installation required. The radio equipment described in this guide emits radio fre-
quency 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 closer than 23 cm (9 inches) to
theantennawhenthetransmitterisoperatinginindoororoutdoorenvironments.Moreinformation
on RF exposure is available on the Internet at www.fcc.gov/oet/info/documents/bulletins.
RF EXPOSURE

MDS 05-2708A01, Rev. B MDS TransNET 900 I&O Guide v
UL/CSA Notice
This product is available for use in Class I, Division 2, Groups A, B, C & D Hazardous Loca-
tions. Such locations are defined in Article 500 of the National Fire Protection Association
(NFPA) publication NFPA 70 , otherwise known as the National Electrical Code.
The transceiver has been recognized for use in these hazardous locations by two independent
agencies—Underwriters Laboratories(UL) and theCanadian StandardsAssociation(CSA). The
UL certification for the transceiver is as a Recognized Component for use in these hazardous
locations, in accordance with UL Standard 1604. The CSA Certification is in accordance with
CSA STD C22.2 No. 213-M1987.
UL/CSA Conditions of Approval: The transceiver is not acceptable as a stand-alone unit for use
in the hazardous locations described above. It must either be mounted within another piece of
equipment which is certified 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.
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 locations, and may void the approval.
5. A power connector with screw-type retaining screws as supplied by MDS must be used.
When installed in a Class I, Div. 2, Groups A, B, C or D hazardous location, observe the fol-
lowing: WARNING EXPLOSION HAZARD 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 infor-
mation on hazardous locations and approved Division 2 wiring methods.
FCC Part 15 Notice
The MDS TransNET 900™ transceivers comply with Part 15 of the FCC Rules. Operation is sub-
ject 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 undes-
ired 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 intended 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.
Manual Revision and Accuracy
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 additional questions or need an exact specification for a product, please contact
our Customer Service Team using the information at the back of this guide. In addition, manual
updates can often be found on the MDS Web site at
www.microwavedata.com
.

vi MDSTransNET 900 I&O Guide MDS 05-2708A01, Rev. B
RXD
TXD
SYNC
PWR

MDS 05-2708A01, Rev. B MDS TransNET 900 I&O Guide 1
1.0 ABOUT THIS MANUAL
This manual presents installation and operating instructions of the
MDS TransNET 900™ transceiver for use by a professional installer. This
person is expected to install, operate, and perform basic system maintenance
on the described radio. Following installation, we suggest keeping this
manual near the equipment for future reference.
2.0 PRODUCT DESCRIPTION
The transceiver, shown in Figure 1, is a spread spectrum radio designed for
license-free operation in the 900 MHz frequency band. Employing Digital
Signal Processing (DSP) technology, it is highly reliable for long-distance
communications, even in the presence of weak signals or interference.
DSP technology also makes it possible to obtain information about radio
operation and troubleshoot problems, without going to the remote radio site.
Using appropriate software at the master station, diagnostic data can be
obtained on any DSP radio in the system, even while payload data is being
transmitted. (See “Performing Network-Wide Remote Diagnostics” on
Page 43.)
The MDS TransNET 900 is housed in a compact and rugged die-cast
enclosure that need only be protected from direct exposure to the weather. It
contains a single printed circuit board with all necessary components for
radio operation. No jumper settings or manual adjustments are required to
configure the radio for operation.
2.1 Transceiver Features
Listed below are several key features of the MDS TransNET 900 transceiver.
These are designed to ease the installation and configuration of the radio,
while retaining the ability to make changes in the future.
• 128 frequencies over 902–928 MHz, subdivided into eight frequency
zones
• Configurable operating zones to omit frequencies with constant
interference
• 65,000 available network addresses
Figure 1.
MDS TransNET 900™
Transceiver

2 MDSTransNET 900 I&O Guide MDS 05-2708A01, Rev. B
• Network-wide configuration from the master station; eliminates most
trips to remote sites
• Data transparency–ensures compatibility with virtually all
asynchronous SCADA system RTUs
• Peak-hold RSSI, averaged over eight hop cycles
• Operation at up to 115,200 bps continuous data flow
• Store-and-Forward repeater operation
• Data latency typically less than 10 ms
• Same hardware for master or remote configuration
• Supports RS/EIA-232 and RS/EIA-485 user interface
• Low current consumption—Less than 8 mA in “sleep” mode.
NOTE:
Some MDS TransNET 900 radio features may not be available on all radios,
based on the options purchased and the applicable regulatory constraints for
the region in which the radio will operate.
2.2 Model Configuration Codes
The model number code is printed on the radio enclosure, and provides key
information about how the radio was configured when it left the factory. See
Figure 2 for an explanation of the model number characters. (Note: This
information is subject to change and should not be used for product ordering.)
Figure 2. MDS TransNET 900 transceiver model configuration codes
BAND
(9) 900 MHz
ENCLOSURE
(1) With Enclosure
AGENCY
(N) None
(F) FCC/IC
SAFETY CERT.
(N) N/A
(F) UL/CSA
MTG. BRACKETS
(A) Standard
(B) None
OPERATION
(X) Remote/Master
EL805
OPTIONS
(A) None OPTION
(N) None
DIAGNOSTICS
(N) None
(W) Network-wide
SPARE
(N) None
19N N ANX

MDS 05-2708A01, Rev. B MDS TransNET 900 I&O Guide 3
2.3 Spread Spectrum Radios—
How Are They Different?
The main difference between a traditional (licensed) radio and the
MDS TransNET 900 transceiver is that this unit “hops” 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
65,000 available network addresses, thereby minimizing the chance of
interference with other spread spectrum systems. In the USA, and certain
other countries, no license is required to install and operate this type of radio
system, provided that RF power and antenna gain restrictions are observed.
2.4 Typical Applications
Multiple Address Systems (MAS)
This is the most common application of the MDS TransNET 900 transceiver.
It consists of a central control station (master) and two or more associated
remote units, as shown in Figure 3. An 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. When used in this application, the
transceiver provides an excellent alternative to traditional (licensed) MAS
radio systems.
Invisibleplaceholder
Figure 3. Typical MAS network
MDSTransNET
Remote
MDSTransNET
Remote
MDSTransNET
Master
MDSTransNET
Remote
MDSTransNET
Remote
RTU
RTU
RTU
RTU
Host System
RXD
TXD
SYNC
PWR
RXD
TXD
SYNC
PWR
RXD
TXD
SYNC
PWR
RXD
TXD
SYNC
PWR
RXD
TXD
SYNC
PWR

4 MDSTransNET 900 I&O Guide MDS 05-2708A01, Rev. B
Point-to-Point System
A point-to-point configuration (Figure 4) is a simple arrangement consisting
of just two radios—a master and a remote. This provides a half-duplex
communications link for the transfer of data between two locations.
Invisibleplaceholder
Figure 4. Typical point-to-point link
Adding a Tail-End Link to an Existing Network
Atail-end link can beusedto extend the rangeofa traditional (licensed) MAS
system. This might be required if an outlying site is blocked from the MAS
master station by a natural or man-made obstruction. In this arrangement, an
MDS TransNET 900 radio links the outlying remote site into the rest of a
licensed MAS system by sending data from that site to an associated
MDS TransNET 900 installed at one of the licensed remote sites. (See
Figure 5).
As the data from the outlying site is received at the licensed remote site, it is
transferred to the licensed radio (via a local cable connection) and is then
transmitted to the MAS master station in the usual manner. Additional details
for tail-end links are given in Section 4.3 (Page 17).
Invisibleplaceholder
Figure 5. Typical tail-end link arrangement
MDSTransNET
Master MDSTransNET Remote
Host System
RXD
TXD
SYNC
PWR
PWRSYNCTXDRXD
PWRSYNCTXDRXD
MDSTransNET
Master
REPEATER STATION
MDS x710B
Series Radio
ENTER
ESCAPE
ACTIVE
ACTIVE
STBYALARMRXALRTXALR
STBYALARMRXALRTXALRLINE
LINE
PWRSYNCTXDRXD
Null-Modem Cable
Remote
Radio
Remote
Radio
MDSTransNET
Remote
Master Station
SPREADSPECTRUMLINK
TOOUTLYINGSITE
OUTLYING
REMOTE SITE
MAS SYSTEM (LICENSED OR UNLICENSED) LICENSE-FREE SPREAD SPECTRUM SYSTEM
RTU
RTU RTU

MDS 05-2708A01, Rev. B MDS TransNET 900 I&O Guide 5
Extending a TransNET Network with a Repeater
Similar to a Tail-End Link, Store-and-Forward (SAF) offers a way to
physically extend the range of a TransNET network, but in a simplified
economical manner. SAF operates by dividing a network into a vertical
hierarchy of two or more sub-networks. Extension radios (designated as
MODE X) serve as single-radio repeaters that link adjacent sub-networks,
and move data from one sub-network to the next one.
Invisibleplaceholder
Figure 6. TransNET Repeater Network
2.5 Accessories
MDS TransNET 900 transceivers can be used with one or more of the
accessories listed in Table 1. Contact the factory for ordering details.
Table 1. Accessories
Accessory Description MDS Part No.
AC Power
Adapter Small power supply module designed for con- tinuous service. UL approved. Input: 120/220;
Output: 12 Vdc @ 500 mA (20 Watts)
Consult factory
Omnidirectional
Antennas Rugged antennas suited for use at Master stations. Consult MDS for details. Various
Yagi Antenna Rugged directional antennas suited for use at
Remote stations. Consult MDS for details. 6.4 dB gain: 97-3194A13
10 dB gain:
97-3194A14
Bandpass Filter Antenna system filter to aid in eliminating inter-
ference from paging system transmissions. 20-2822A02
TNC-to-N
Adapter Cable 3 foot/1 meter length of coaxial cable used to connect the radio’s TNC antenna connector to
a Type-N style commonly used on large diam-
eter coaxial cables.
97-1677A159
MDSTransNET
Extension
MODE X
REPEATER STATION
MDSTransNET
Remote
MODE R
SPREADSPECTRUMLINK
TOOUTLYINGSITE
OUTLYING
REMOTE SITE
MDSTransNET
Remote
MODE R
MDSTransNET
Remote
MODE R
MDSTransNET
Master
MODE M
RTU
RTU RTU
RTU

6 MDSTransNET 900 I&O Guide MDS 05-2708A01, Rev. B
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 provides 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 interface
between the transceiver and the data device.
Figure 7 shows a typical remote station arrangement. Master stations are
similar, but an omni-directional antenna is normally used instead of a
directional type, and a host computer replaces the data terminal equipment.
TNC-to-N
Adapter Cable 6foot/1.8meter lengthofcoaxial cableusedto connect the radio’s TNC antenna connector to
a Type-N style commonly used on large diam-
eter coaxial cables.
97-1677A160
TNC-to-N RF
Adaptor Plug Adapts radio’s antenna connector to Type-N style commonly used on large diameter coaxi-
al cables.
97-1677A161
RS/EIA-232
Cable Shielded data cable fitted with DB-9 male and DB-9 female, 6 ft./1.8 meter. 97-1971A03
RJ-11 to DB-9
Adapter Cable For connecting a PC terminal to the transceiv- er via the radio’s DIAG(notics) connector.
Used for programming and diagnostics.
03-3246A01
Flat-Surface
Mtg. Brackets Brackets: 2”x 3”plates designed to be screwed onto the bottom of the transceiver for
surface-mounting the radio.
82-1753-A01
Mtg. Bracket
Screws Screws: 6-32/1/4˝with locking adhesive. (Industry Standard MS 51957-26) 70-2620-A01
19˝Rail Mtg.
Brackets Adaptor for mounting the radio in a standard 19-inch equipment rack. Consult factory
Table 1. Accessories (Continued)

MDS 05-2708A01, Rev. B MDS TransNET 900 I&O Guide 7
Invisibleplaceholder
Figure 7. Typical remote station arrangement
3.2 Site Selection
Forasuccessfulinstallation,carefulthoughtmustbegiventoselectingproper
sites for the master and remote stations. Suitable sites should provide the
following:
• 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)
These requirements can be quickly determined in most cases. A possible
exception is the last item—verifying that an unobstructed transmission path
exists. 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 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, it is also more prone to signal attenuation
from obstructions such as terrain, foliage or buildings in the transmission
path.
POWER SUPPLY
13.8 VDC @ 500 mA
(6–30 Vdc)
DATATERMINAL
EQUIPMENT
MDS TransNET 900s
LOW-LOSS FEEDLINE
ANTENNA
SYSTEM

8 MDSTransNET 900 I&O Guide MDS 05-2708A01, Rev. B
A line-of-sight transmission path between the master station and its
associated remote 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 surrounding terrain and other obstructions.
The importance of a clear transmission path relates closely to the distance to
be covered by the system. If the system is to cover only a limited geographic
area, say up to 3 miles (4.8 km), then some obstructions in the
communications path can usually be tolerated with minimal impact. For
longer range systems, any substantial obstruction in the communications path
could compromise the performance of the system, or block communications
entirely.
Muchdepends on the minimum signal strengththatcanbetolerated in a given
system. Although the exact figure will differ from one system to another, a
Received Signal Strength Indication (RSSI) of –85 dBm or stronger will
provide acceptable performance in many cases. While the equipment will
work at lower signal strengths, this provides a “fade margin” to account for
variations in signal strength which may occur from time-to-time.
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 earlier, 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 master station site and then visiting each remote site with a
transceiver and a hand-held antenna.
With the hand-held antenna positioned near the proposed mounting spot, a
technician can check for synchronization with the master station (shown by a
lit
SYNC
lamp on the front panel) and measure the reported RSSI value. 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. 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 given in Section 5.0, beginning on Page 19.
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.

MDS 05-2708A01, Rev. B MDS TransNET 900 I&O Guide 9
3.3 A Word About Radio Interference
The MDS TransNET shares the frequency spectrum with other services and
other Part 15 (unlicensed) devices in the USA. As such, near 100% error free
communications may not be achieved in a given location, 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, configuration of radio parameters and
software/protocol techniques.
In general, keep the following points in mind when setting up your
communications 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 confine the
transmission and reception pattern to a comparatively narrow 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 vertical
polarization in this band, an additional 20 dB of attenuation to
interference can be achieved by using horizontal polarization.
4. Multiple MDS TransNET 900 systems can co-exist in proximity to each
other with only very minor interference as long as they are each assigned
a unique network address. Each network address has a different hop
pattern.
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 tools to help users remove blocked frequency
zones. Refer to the discussion of the
SKIP
command (Page 36) for more
information. In the USA, a maximum of four zones may be skipped, per
FCC rules. Check the regulatory requirements for your region.
6. Interference can also come from out-of-band RF sources such as paging
systems. Installation of a bandpass filter in the antenna system may bring
relief. (Recommended: MDS P/N 20-2822A02)
7. Proper use of the RETRY and REPEAT commands may be helpful in areas
with heavy interference.
The
RETRY
command sets the maximum number of times (1 to 10) that a
radio will re-transmit upstream data over the air. Values greater than 1
successively improve the chances of a message getting through when
interference is a problem.
The REPEAT command sets a fixed number of unconditional
retransmissions for downstream data.

10 MDSTransNET 900 I&O Guide MDS 05-2708A01, Rev. B
8. The RF power output of all radios in a system should be set for the lowest
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 8 and Figure 9) is used at the
master station site in an MAS system. This provides equal coverage to all of
the remote sites.
NOTE:
Antenna polarization is important. If the wrong polarization is used, a signal re-
duction of 20 dB or more will result. Most systems using a gain-type omnidirec-
tional antenna at the master station employ vertical polarization of the signal;
therefore, the remote antenna(s) must also be vertically polarized (elements
oriented perpendicular to the horizon).
When required, horizontally polarized omnidirectional antennas are also avail-
able. Contact your MDS representative for details.
At remote sites and point-to-point systems, a directional Yagi antenna
(Figure 9), is generally recommended to minimize interference to and from
other users. Antennas are available from a number of manufacturers.
Figure 8.
Omnidirectional antenna
(mounted to mast)

MDS 05-2708A01, Rev. B MDS TransNET 900 I&O Guide 11
Invisibleplaceholder
Figure 9. Typical Yagi antenna (mounted to mast)
Feedlines
The choice of feedline used with the antenna should be carefully considered.
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 transmission,
an inexpensive type such as Type RG-8A/U may be acceptable. Otherwise,
we recommend using a low-loss cable type suited for 900 MHz, such as
Times Microwave LMR 400
®
or Andrew Heliax
®
.
Table 2 lists several types of feedlines and indicates the signal losses (in dB)
that result when using various lengths of each 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.
Table 2. 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) 300 Feet (91.44 Meters)
LMR 400 0.39 dB 1.95 dB 3.9 dB 11.7 dB
(not recommended)
1/2 inch
HELIAX
0.23 dB 1.15 dB 2.29 dB 6.87 dB
7/8 inch
HELIAX
0.13 dB 0.64 dB 1.28 dB 3.84 dB
1 1/4 inch
HELIAX
0.10 dB 0.48 dB 0.95 dB 2.85 dB
1 5/8 inch
HELIAX
0.08 dB 0.40 dB 0.80 dB 2.4 dB

12 MDSTransNET 900 I&O Guide MDS 05-2708A01, Rev. B
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 transmitter
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
dependentontheantenna gain, feedline loss, and the transmitter output power
setting. Power considerations for the MDS TransNET 900 are discussed
below.
NOTE:
In some countries, the maximum allowable RF output may be
limited to less than 1 watt (e.g., 100 mW / +20 dBm). Be sure to
check for and comply with the requirements for your area.
To determine the maximum allowable power setting of the radio, perform 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 in your region is less than 30
dBm, use the
PWR
command (described on Page 34) to set the power
accordingly.
For convenience, Table 3 lists several antenna system gains and shows the
maximum allowable power setting of the radio. Note that a gain of 6 dB or
less entitles you to operate the radio at full power output—30 dBm (1 watt).
* MostantennamanufacturersrateantennagainindBdin theirliterature. 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 2 on Page 11.
Table 3. 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