Westell BA15X-01 Bidirectional Amplifier User Manual Cellular Specialties Inc
Westell, Inc. Bidirectional Amplifier Cellular Specialties Inc
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Exhibit D Users Manual per 2 1033 c3
Cellular Specialties, Inc.
Model 150 Miniature In-Building Amplifier
Operation and Users Manual
1 150 BDA Rev. 1
5/29/03
Table of Contents
1. Product Description
Background
Functional Description
Circuit Description
2. General Specifications
3. Inspection and Installation
Inspection of Contents
Package Contents
Installation
Safety
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1. Product Description
Background
The performance of a cell phone can be easily degraded when in enclosed
structures where signals from a local cell site are not sufficient for reliable
phone operation. The Model 150 In-Building Amplifier (Mini-IBA) was
developed to enhance wireless network performance within these enclosed
structures. Specifically, the Model 150 is intended to cover relatively small
areas such as home offices, workshops, offices etc.
Functional Description
The Model 150 amplifier boosts the wireless network’s performance by
providing amplification of both transmit and receive signals. The unit
receives the portable phone’s signal through an inside antenna, amplifies it
and then sends it to an outside antenna. This signal is referred to as the
“Uplink”. The amplifier also receives signals from the Cell Site base station
through the outside antenna. This signal is amplified and re-radiated to the
portable phone and is referred to as the “Downlink”. It is necessary that
sufficient signal be available at the outside antenna.
The outside antenna is usually a directional type such as a “Yagi”, however
an Omni-directional antenna may be used when the structure is located in
close proximity to one or more cell sites. Inside antennas are usually Omni-
directional although other types, such as low profile wall or ceiling mount,
may be used for special installations.
As shown in Figure 1, there are four stages of gain in the Downlink and four
stages in the Uplink for maximum gain of 50 dB in each link. The
maximum linear output power is 125 milliwatts for the Uplink and 80
milliwatts for the Downlink. These levels are factory set and are maintained
by an internal Automatic Gain Control (AGC) circuit.
Four LED indicators on the unit indicate:
• Green “Power” LED indicates that power is applied and the unit is
operating.
• Yellow “AGC” LED indicates that the gain of the Uplink and/or
Downlink is being reduced to maintain the maximum power
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output, which prevents spurious radio-frequency emissions from
the amplifier.
• Yellow “Isolation” LED indicates that the microcontroller in the
unit has sensed instability due to insufficient isolation between the
inside antenna and the outside antenna, and has reduced the gain of
the amplifier. This is done to prevent oscillation, which can
interfere with the handsets in the covered area and/or the wireless
service provider’s base station. This “degraded mode” will be
maintained until the amplifier power is disconnected and
reconnected. The outside antenna should be placed as far as
practical from the internal antenna, and should not be pointed
toward the inside antenna.
• Red “Shutdown” LED indicates that the gain of the unit has been
reduced to minimum to prevent very strong input signals from
overloading the amplifier. The amplifier will attempt to recover
from this condition, initially at fifteen intervals and then at four-
minute intervals.
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Circuit Description
Uplink Amplifier
The uplink amplifier circuit consists of four stages of gain. Each gain stage
is a monolithic integrated circuit (MMIC) mounted to a printed circuit board
(PCB). The signal received by the inside antenna is directed to the 1st
MMIC stage by a frequency diplexer, which separates the uplink frequency
band (1850 - 1910 MHz) from the downlink frequency band (1930 - 1990
MHz). This signal is amplified by three additional MMIC stages and filtered
by a ceramic bandpass filter, then directed to an identical diplexer at the
output of the fourth stage. A variable attenuator is provided to implement
Automatic Gain Control (AGC) in the Model 150, and is controlled by the
Control circuit (described below). All stages are biased for linear operation.
The overall gain from the inside antenna terminal to the outside antenna
terminal is nominally 50 dB. Each diplexer / filter combination provides
more than 65 dB of rejection between the uplink amplifier chain and the
downlink.
Downlink Amplifier
The downlink circuit is identical in operation to the uplink, providing four
stages of MMIC amplification. The major differences are the downlink
frequency (1930 – 1990 MHz.) and signal flow in the opposite direction.
Controller
Operation of the Model 150 amplifier is monitored and controlled by a
microcontroller. The primary functions of the microcontroller are: maintain
linear operation by controlling the gain of the unit to prevent spurious radio-
frequency emissions; shut down the amplifier in the event of a severe
overload condition which exceeds the range of the AGC circuit; and to
detect and reduce the amplifier’s gain to prevent instability of the unit in the
event that the isolation between the outside antenna and the inside antenna is
insufficient.
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Power Supply
All of the MMIC amplification stages, in both the uplink and downlink,
operate from a single supply voltage of +5 Vdc. All internal dc circuits are
filtered and de-coupled from the RF circuits. A high-efficiency 115 Volt AC
to 5 Volt DC “Wall” supply is provided with the unit. The current
requirement at 5 Volts DC is less than 1.2 Amperes.
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2. General Specifications
All specifications stated as typical unless otherwise noted. Cellular Specialties, Inc.
reserves the right to change these specifications at any time without prior notice.
Downlink Uplink
Frequency Band 1930 – 1990 MHz 1850 – 1910 MHz
Linear Gain (dB) 50 50
Typical Power Out (max)
Linear * ** +19 dBm (80 mW) +21 dBm (125 mW)
Noise Figure 6 dB 6 dB
Propagation Delay < 150 nsec. < 150 nsec.
Passband Ripple (max) 4 dB pk-pk 4 dB pk-pk
Connectors Type N female
Power Requirements +5 Vdc, 1.2 A
Temperature -40º F to +122º C; -40º C to +50º C
Dimensions 6.1 x 3 x 1 inch; 15.4 x 7.6 x 2.5 cm.
Weight (amplifier only) 1.2 lb.; 0.55 kg.
Indicator LEDs Power, AGC, Isolation, Shutdown
Regulatory Approvals FCCID: NVRBA15X-01
IC: 4307A-BA15X19
NOTES
* The manufacturer’s rated output power of this equipment is for single carrier operation. For situations
when multiple carrier signals are present, the rating must be reduced by 3.5 dB, especially where the output
signal is re-radiated and can cause interference to adjacent band users. This power reduction is to be by
means of input power or gain reduction and not by an attenuator at the output of the device.
** Maximum total output power without exceeding the FCC allowable emissions of –13 dBm.
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3. Inspection and Installation
Inspection
Inspect the equipment as soon as possible after purchase. If any part of the
equipment has been damaged in transit, report the damage to the
transportation company and also to the company where purchased.
Contents
The unit package contains the following:
Model 150 Amplifier
Power Transformer, 110 volt to 5 volt
User Manual
Installation
Note:
The Installer should refer to the Safety Precautions, in the following section,
for proper antenna selection and installation
The installation of the Model 150 is relatively simple. If possible,
measurements of the Received Signal Strength Indicator (RSSI) should be
recorded as close as possible to the proposed outside antenna location.
Optimum performance will be obtained with RSSI readings greater than –85
dBm.
With the exact location of the outside antenna and the coordinates of the cell
sites closest to the building in which the unit is being installed, the distance
and bearings to each of the local cells can be determined. The first choice
would be the closest site unless there is blockage in the form of buildings or
terrain. If blockage exists, an alternate site may be available.
If coordinates are not available, measure the signal strength at the outside
antenna output by connecting a phone to the outside antenna and slowly
rotating the antenna until a maximum reading is obtained. NEVER
CONNECT A PHONE DIRECTLY TO THE AMPLIFIER.
The amplifier and inside antenna should be centrally located, keeping
coaxial cable runs to a minimum. A maximum length of 100 feet of low loss
cable is recommended. The actual coax used should be RG-8 type or better
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with a flame retardant rating as a minimum. If the coax is run through an
area where heating and/or cooling air is channeled, a plenum rated coax
must be used. When mounting the amplifier, take care to avoid areas of high
heat or extreme cold. In general, do not place the unit on or near the top of
high ceilings, by heaters or in cold storage areas.
During installation, care must be taken to provide the adequate isolation
between inside and outside antennas. It is good practice to install the
antennas where that there are metal and/or concrete building obstructions
between the antennas, such as concrete floors, elevator shafts, restroom
areas, chimneys, etc. The outside antenna should never be pointed in the
direction of any inside antenna unless significant metal/concrete obstructions
or significant height difference exists between the antennas.
Isolation must be at least 60 dB to prevent re-generative feedback in the
system. Feedback of this nature could cause the amplifier to emit a
continuous signal at maximum amplitude. The Model 150 amplifier’s
controller will detect inadequate isolation and will reduce the gain of the
amplifier to prevent oscillation (the yellow “Isolation” indicator indicates
this condition). Though the amplifier will continue to operate, its
performance is reduced and the inadequate isolation condition should be
corrected.
If the yellow “Isolation” LED is on, re-orient the outside and / or inside
antennas to minimize signals between the antennas and reset the amplifier by
disconnecting and reconnecting the power supply at the amplifier. The gain
of the amplifier will remain in a reduced state until adequate isolation is
achieved and it is reset.
There are no installation or user adjustments or tuning on this unit.
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Safety Precautions
CAUTION
!
For INDOOR use, an Omni-Directional Antenna with a maximum gain of 8 dBi
is authorized for use with this unit.
Inside antennas must be positioned to observe minimum separation of 20 cm.
(~ 8 in.) from all users and bystanders. For the protection of personnel working
in the vicinity of inside (downlink) antennas, the following guidelines for
minimum distances between the human body and the antenna must be
observed.
The installation of an INDOOR antenna must be such that, under normal
conditions, all personnel cannot come within 20 cm. (~ 8.0 in.) from any
inside antenna. Exceeding this minimum separation will ensure that the
employee or bystander does not receive RF-exposure beyond the
Maximum Permissible Exposure according to section 1.1310 i.e. limits for
General Population/Uncontrolled Exposure.
!
For OUTDOOR use, a Directional Antenna up to a maximum gain of 14 dBi is
authorized for use with this unit. The Outside antenna must be positioned to
observe minimum separation of 120 cm. (~ 4 ft.) from all users and bystanders.
For the protection of personnel working in the vicinity of outside (uplink)
antennas, the following guidelines for minimum distances between the human
body and the antenna must be observed.
The installation of an OUTDOOR antenna must be such that, under normal
conditions, all personnel cannot come within 120 cm. (~ 4 ft.) from the
outside antenna. In all installations, the antenna should never be mounted
such that the main beam is directed toward an area where workers or
bystanders may be present. Exceeding this minimum separation will
ensure that the worker or bystander does not receive RF-exposure beyond
the Maximum Permissible Exposure according to section 1.1310 i.e. limits
for General Population/Uncontrolled Exposure.
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