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Product Description
Cellular Specialties, Inc. (CSI) developed the LCD Model Bi-Directional Amplifier
(BDA) for use in enclosed structures where sufficient signal from local cell sites to
operate cell phones was unavailable within the building. It is necessary that sufficient
signal be available on the roof of the structure. The BDA is connected to an external
antenna, usually on the roof, and to one or more internal antennas placed strategically
throughout the area where phone service is desired.
The external antenna is usually a directional type such as a “yagi”. Internal antennas
are usually omnidirectional, although various other types may be used for certain
installations. The BDA amplifies both the “uplink” (phone to tower) and “downlink”
(tower to phone) signals thus facilitating communications to and from the local cell
site.
There are seven amplification stages on the downlink and seven on the uplink
for a
total of +65 to +80 dB nominal gain for each link. Gain can be set using the LCD
display and select/up/down switches. There are also LED indicators on the top
cover for power overload and gain reduction to prevent oscillation.
LED Indicators
Warning:
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 oscilla-
tion, which can interfere with the handsets in the covered area
and/or the wireless service provider’s base station.
Fault:
The gain of the unit has been reduced to a minimum in order
(Red) to prevent very strong input signals from overloading the
amplifier. The amplifier will attempt to recover from this condi-
tion, initially at fifteen second intervals and then at four-minute
intervals.
Pin-Out Chart
Pin
Description
1
5 Volts
2
Center Contact Alarm Relay
3
Alarm Contact-Open
4
Alarm Contact-Closed
5
Shut Down
6
Ground
