Microhard Systems 09P29 L400 Narrowband Wireless Module User Manual L400manualREV0 20 FCC
Microhard Systems Inc L400 Narrowband Wireless Module L400manualREV0 20 FCC
User Manual
Operating Manual
L400
400–480 MHz Narrowband Modem
Revision 0.20, June 4, 2009
#17, 2135 – 32nd Ave N.E.
Calgary, Alberta T3K 4Z4
Phone: (403) 248-0028
Fax: (403) 248-2762
www.microhardcorp.com
Model: L400
Microhard S
y
stems Inc.
ii L400 Operating Manual
Warranty
Microhard Systems Inc. warrants that each product will be free of defects in material and workmanship for a period of one (1)
year for its products. The warranty commences on the date the product is shipped by Microhard Systems Inc. Microhard Systems
Inc.’s sole liability and responsibility under this warranty is to repair or replace any product which is returned to it by the Buyer
and which Microhard Systems Inc. determines does not conform to the warranty. Product returned to Microhard Systems Inc. for
warranty service will be shipped to Microhard Systems Inc. at Buyer’s expense and will be returned to Buyer at Microhard
Systems Inc.’s expense. In no event shall Microhard Systems Inc. be responsible under this warranty for any defect which is
caused by negligence, misuse or mistreatment of a product or for any unit which has been altered or modified in any way. The
warranty of replacement shall terminate with the warranty of the product.
Warranty Disclaims
Microhard Systems Inc. makes no warranties of any nature of kind, expressed or implied, with respect to the hardware, software,
and/or products and hereby disclaims any and all such warranties, including but not limited to warranty of non-infringement,
implied warranties of merchantability for a particular purpose, any interruption or loss of the hardware, software, and/or product,
any delay in providing the hardware, software, and/or product or correcting any defect in the hardware, software, and/or product,
or any other warranty. The Purchaser represents and warrants that Microhard Systems Inc. has not made any such warranties to
the Purchaser or its agents MICROHARD SYSTEMS INC. EXPRESS WARRANTY TO BUYER CONSTITUTES
MICROHARD SYSTEMS INC. SOLE LIABILITY AND THE BUYER’S SOLE REMEDIES. EXCEPT AS THUS
PROVIDED, MICROHARD SYSTEMS INC. DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
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MICROHARD SYSTEMS INC. PRODUCTS ARE NOT DESIGNED OR INTENDED TO BE USED IN
ANY LIFE SUPPORT RELATED DEVICE OR SYSTEM RELATED FUNCTIONS NOR AS PART OF
ANY OTHER CRITICAL SYSTEM AND ARE GRANTED NO FUNCTIONAL WARRANTY.
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POSSIBILITY OF SUCH DAMAGES AND TAKES NO ACTION TO PREVENT OR MINIMIZE SUCH
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LIABLE OR RESPONSIBLE FOR ANY DAMAGE OR INJURY, MICROHARD SYSTEMS INC.'S LIABILITY
FOR ANYDAMAGES SHALL NOT EXCEED THE PROFIT REALIZED BY MICROHARD SYSTEMS INC.
ON THE SALE OR PROVISION OF THE HARDWARE TO THE CUSTOMER.
Proprietary Rights
The Buyer hereby acknowledges that Microhard Systems Inc. has a proprietary interest and intellectual property rights in the
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with this Agreement.
L400 Operating Manual: Contents iii
L400 Regulatory Requirements
PLEASE READ THIS SECTION CAREFULLY
WARNING:
To satisfy FCC RF exposure requirements for mobile transmitting devices, a separation distance is based on
the above them ranging from 39 cm to 305 cm between the antenna of this device and persons during device
operation. To ensure compliance, operations at closer than this distance is not recommended. The antenna
used for this transmitter must not be co-located in conjunction with any other antenna or transmitter.
Antenna Impedance
(ohms) Antenna Gain (dBi) Minimum Separation
Distance (cm)
Minimum Gain 50 0 39
Maximum Gain 50 18 305
WARNING:
EQUIPMENT LABELING
The FCC and IC numbers depend on the model of the radio module. Do NOT use the Marketing
Name of the product but the Model to distinguish the Certifications Numbers. This device has
been modularly approved. The manufacturer, product name, and FCC and Industry Canada
identifiers of this product must appear on the outside label of the end-user equipment.
SAMPLE LABEL REQUIREMENT for Model: L400:
Contains:
FCCID: NS909P29 IC : 3143A-09P29
This device complies 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.
iv L400 Operating Manual
Contents
Warranty ....................................................................................................................................................................... ii
Warranty Diclaims ........................................................................................................................................................ ii
Indemnification ............................................................................................................................................................. ii
Proprietary Rights ......................................................................................................................................................... ii
L400 Regulatory Requirements ................................................................................................................................... iii
CONTENTS .............................................................................................................................................................. IV
2. GENERAL ........................................................................................................................................................... 1
2.0 PRODUCT OVERVIEW ........................................................................................................................................................ 1
2.1 OUTPUT POWER LEVEL ..................................................................................................................................................... 2
3. INSTALLATION ................................................................................................................................................. 4
3.0 OVERVIEW ....................................................................................................................................................................... 4
3.1 ESTIMATING THE GAIN MARGIN ....................................................................................................................................... 4
3.2 ANTENNAS AND CABLING ................................................................................................................................................. 6
3.2.1 ........................................................................................................................ Internal Cabling
............................................................................................................................................................................... 6
3.2.2 ............................................................ Installing External Cables, Antennas and Lightning Arrestors
............................................................................................................................................................................... 7
L400 Operating Manual: Chapter2 General 1
2. General
2.0 Product Overview
The L400 is a high-performance embedded wireless data transceiver.
Operating in the 400 - 480 MHz band, this narrowband module is capable
of providing reliable wireless data transfer between almost any type of
equipment which uses an asynchronous serial interface. The small-size and
superior RF performance of this module make it ideal for many
applications.
While a pair of L400 modules can link two terminal devices (“point-to-
point” operation); multiple modules can be used together to create a
network of various topologies, including “point-to-multipoint” and
“repeater” operation. Multiple independent networks can operate
concurrently, so it is possible for unrelated communications to take place in
the same or a nearby area without sacrificing privacy or reliability.
1.1 Features
Key features of the L400 include:
a serial I/O data port with handshaking and hardware flow
control, allowing the L400 to interface directly to any
equipment with an asynchronous serial interface.
ease of installation and use – the L400 module uses a subset of
standard AT style commands, very similar to those used by
traditional telephone line modems.
all units in a system are physically identical, and can be
configured as a master, repeater or slave using the AT
command set. No hardware modifications are required
32-bit of CRC error detection and auto re-transmit to provide
accuracy and reliability of data.
2 L400 Operating Manual: Chapter 2 General
TDMA (time division multiple access) support, allowing
multi-slave access in point-to-point mode.
roaming ability, allowing repeaters and slaves to re-
synchronize with a new master if the synchronization pulse
from the original master is lost.
While the typical application for the L400 is to provide a short- to mid-
range wireless communications link between DTEs, it can be adapted to
almost any situation where an asynchronous serial interface is used and data
intercommunication is required.
2.1 Output Power Level
The Output Power Level determines at what power the L400 transmits. The
L400’s sensitive receiver can operate with very low power levels, so it is
recommended that the lowest power necessary is used; using excessive
power contributes to unnecessary “RF pollution”.
Ideally, you should test the communications performance between units
starting from a low power level and working upward until the RSSI is
sufficiently high and a reliable link is established. The conditions will vary
widely between applications, the output power settings can be calculated
based on following information.
• Transmitter antenna gain
• Cable loss
• Effective radiated power (ERP) requirement by FCC Regulations
Power Setting = 36 – Antenna Gain – Cable Loss
The power setting must be no more than the above calculation value. Any
higher is a violation of FCC rules. See IMPORTANT warning below.
Table 1 Output Power
Power Setting
(dBm) Approx. Output Power
(mW)
0 1
20 100
21 125
22 160
23 200
24 250
25 320
26 400
27 500
28 630
29 800
30 1000
33 2000
35 3162
37 5000
L400 Operating Manual: Chapter2 General 3
4 L400 Operating Manual: Chapter 3 Installation
3. Installation
3.0 Overview
Qualified and experienced personnel must carry out the
installation, removal or maintenance of all antenna
components.
The L400 complies with FCC part 15 at the modular level for operation in
the license-free 400 to 480MHz depending on the country of operation there
maybe some band restrictions. This chapter provides guidelines for
installing and deploying equipment which incorporates the L400 module.
3.1 Estimating the Gain Margin
Successful communication between L400 modules is dependent on three
main factors:
• System Gain
• Path Loss
• Interference
System gain is a calculation in dB describing the performance to be
expected between a transmitter-receiver pair. The number can be calculated
based on knowledge of the equipment being deployed. The following four
factors make up a system gain calculation:
1. Transmitter power (user selectable)
2. Transmitter gain (transmitting antenna gain minus cabling loss between
the transmitting antenna and the L400 module)
3. Receiver gain (Receiving antenna gain minus cabling loss between the
receiving antenna and the module)
4. Receiver sensitivity (Specified as -108dBm on the L400 module)
In the following illustration, the transmitting antenna has a gain of 6 dB,
and the receiving antenna has a gain of 3 dB. The cable loss between the
module and the antenna is 2 dB on both the transmitting and receiving side.
Transmitter
30 dBm
Output Power
Receiver
Sensitivity =
-105 dBm
Cable Loss = 2 dBCable Loss = 2 dB
Antenna Gain = 6 dB Antenna Gain = 3 dB
MHX-920 Operating Manual:Glossary 5
Figure 1 Gain Calculation
The power level has been set to 30dBm (1W) on the transmitter, and the
receiver sensitivity for the L400 is -108dBm.
System gain would be calculated to be:
30 - 2 + 6 + 3 - 2 + 108 = 143 dB.
Figure 2 System Deploying
When deploying your system, care must be taken to ensure the path loss
(reduction of signal strength from transmitter to receiver in dB) between
equipment does not exceed the system gain (140 dB in the above example).
It is recommended to design for a gain margin of at least 20 dB to ensure
reliable communication. Gain margin is the difference between system gain
and path loss. Referring to the same example, suppose the path loss is 100
dB, the gain margin would be 40 dB, which is more than adequate for
reliable communication.
Path loss is a very complicated calculation which mainly depends on the
terrain profile, and the height of the antennas off the ground.
The following table provides path loss numbers for varying antenna heights
and antenna separation: These numbers are real averages taken from rural
environments. They do not apply to urban, non-line-of-sight environments.
Table 2 Path Loss
Distance
(km) Base Height
(m) Mobile Height
(m) Path Loss
(dB)
5 15 2.5 116.5
5 30 2.5 110.9
8 15 2.5 124.1
8 15 5 117.7
8 15 10 105
16 15 2.5 135.3
16 15 5 128.9
16 15 10 116.2
16 30 10 109.6
16 30 5 122.4
16 30 2.5 128.8
Base Height (m)
Mobile
Heigh
t
(m)
Distance (km)
6 MHX-920 Operating Manual: Glossary
WARNING:
Qualified and experienced
personnel must carry out the
installation, removal or
maintenance of all antenna
components.
Once the equipment is deployed, you can verify the signal strength by
entering into Command Mode and reading Register S123. This register
provides the average signal strength in dBm. The minimum strength for
communication is roughly -108dBm. For consistent reliable
communication, you should try to deploy the equipment such that signal
strength exceeds -95dBm.
3.2 Antennas and Cabling
This section describes the recommended procedure for installing cabling
and antennas for use with the L400 module.
3.2.1 Internal Cabling
The most common method for installing the module is to run a cable from
the module’s MCX connector to a reverse TNC, N-female, or SMA
bulkhead connector on the chassis of the equipment as shown in Figure 3.
This cable can be purchased from Microhard Systems.
Figure 3 Suggested Internal Cabling
Cable losses are negligible for the short piece used within the chassis.
Additional losses up to 0.5 dB may be present in the MCX and Reverse
TNC connections.
RG316 Cable
with MCX male
connecto
r
and Reverse TNC
b
ulkhea
d
connecto
r
External Antenna Connector
MCX female connector
L400
MHX-920 Operating Manual:Glossary 7
WARNING:
Direct human contact with the
antenna is potentially unhealthy
when the L400 is generating RF
energy. Always ensure that the
L400 equipment is powered down
during installation.
WARNING:
Never work on an antenna
system when there is lightning in
the area.
3.2.2 Installing External Cables, Antennas and Lightning
Arrestors
Qualified and experienced personnel must carry out the installation,
removal or maintenance of all antenna components. Never work on an
antenna system when there is lightning in the area.
Direct human contact with the antenna is potentially unhealthy when the
L400 is generating RF energy. Always ensure that the L400 equipment is
powered down during installation. At all times a distance of shown below
should be maintained between the antenna and any person when the device
is in operation.
Antenna Impedance
(ohms) Antenna
Gain (dBi)
Minimum
Separation
Distance (cm)
Min Gain 50 0 39
Max Gain 50 18 305
Surge Arrestors
The most effective protection against lightning is to install two lightning
(surge) arrestors, one at the antenna, the other one at the interface with the
equipment. The surge arrestor grounding system should be fully
interconnected with the transmission tower and power grounding systems to
form a single, fully integrated ground circuit. Typically, both ports on surge
arrestors are N-female.
External Filter
Although the L400 is capable of filtering out RF noise in most
environments, there are circumstances that require external filtering.
Paging towers and cellular base stations in close proximity to the L400
antenna can desensitize the receiver. Microhard Systems’ external cavity
filter eliminates this problem. The filter has two N-female ports and should
be connected in line at the interface to the RF equipment.
Cabling
The following coax cables are recommended:
Table 3 Cable Loss
Cable Loss (dB/100ft)
LMR 195 10.7
LMR 400 3.9
LMR 600 2.5
8 MHX-920 Operating Manual: Glossary
WARNING:
The L400 can only be used with
any antennas listed in Appendix
A and this the antenna
separations shown in Appendix
A.
WARNING:
Be careful with dBi vs dBd gains
on antenna specifications.
Antenna manufactures may not
clearly indicate the gain on the
antenna if it is dBd or dBi. Note
1dBd = 2.15dBi.
Factors to take into consideration when choosing a cable are:
• price;
• bend radius limitations (the lower performance cables generally can
bend more sharply)
• performance requirements; and,
• distance between the equipment and the antenna.
When installing the cable, always begin fastening at the top near the
antenna connector/surge arrestor. The cable must be supported at the top
with a hose clamp or wrap lock, and at 5 ft intervals down the length of the
tower. Over-tightening the fasteners will dent the cable and reduce
performance. If properly grounded surge arrestors are not installed at both
the top and the bottom of the cable, then the cable should be grounded to
the tower at these locations using a cable grounding kit. If the tower is non-
conductive, then a separate conductor, physically separate from the cable,
should be run down the tower.
Antenna
Before choosing an antenna, you should have some knowledge of the path
loss and the topology of the equipment. If the equipment is in a fixed
location and is to communicate with only one other unit also in a fixed
location, then a Yagi antenna is suitable. Choose a Yagi with enough gain
to ensure adequate gain margin. When deploying the Yagi, point the
antenna towards the intended target, ensuring the antenna elements are
perpendicular to the ground for vertical polarization.
In applications where there are multiple units that you must communicate
with or units, which are in motion, you may select an Omni-directional
antenna with appropriate gain.
See appendix A for a list of approved antennas types that can be used
with the L400 radio modem. If you require another type of antenna
please contact Microhard Systems Inc.
Microhard Systems Inc. can provide you with approved antennas to ensure
FCC and Industry Canada compliance.
ERP is calculated as follows:
ERP = Tx Power(dBm) - Cable/Connector Loss(dB) + Ant Gain(dBi)
Antenna Gains must be in dBi when calculating the 36dBm ERP limit.
1dBd = 2.15dBi
Use the guidelines in the previous section for calculating cable and
connector losses. If cabling and connector losses are 2 dB, then the
maximum allowable gain of the antenna will be 8 dB.
MHX-920 Operating Manual:Glossary 9
A. Antenna / Separations
Antenna Impedance
(ohms) Antenna Gain (dBi) Minimum Separation
Distance (cm)
Minimum Gain 50 0 39
Maximum Gain 50 18 305
RF EXPOSURE DISTANCE LIMITS
S
EIRP
S
GP
r⋅⋅
=
⋅⋅
⋅
=
ππ
44
Sample calculation:
S = 406.1/1500 mW/cm2
EIRP = 42 dBm = 1042/10 mW = 15849 mW (Worst Case for Quarter Wave antenna)
(Minimum Safe Distance, r) = cm
S
EIRP 68
)1500/1.406(4
15849
4≈
⋅⋅
=
⋅⋅
ππ
WARNING:
Changes or modifications not expressly approved by Microhard Systems Inc. could void the user’s
authority to operate the equipment. Please Contact Microhard Systems Inc. if you need more information.
WARNING:
To satisfy FCC RF exposure requirements for mobile transmitting devices, a separation distance is based
on the above them ranging from 39 cm to 305 cm between the antenna of this device and persons during
device operation. To ensure compliance, operations at closer than this distance is not recommended. The
antenna used for this transmitter must not be co-located in conjunction with any other antenna or
transmitter.