MA REV A
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PRODUCT DESCRIPTION
Cellular Specialties, Inc. developed the Model 310
Plus
In-Building Amplifier (IBA) for use in enclosed
structures where sufficient signal from local cell sites to operate cell phones was unavailable within the
building. It is, of course, necessary that sufficient signal be available on the roof of the structure. The
IBA 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" however an omni-directional antenna
may be used when the building is located in close proximity to one or more cell sites. Internal antennas
are usually omni-directional although various other types may be used for certain installations. The IBA
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 four amplification stages on the downlink and four on the uplink
for a total of +57dB nominal
gain for each link. (see Figure 2.1) Both links have manual gain control settings accessed through DIP
switches on the back panel plus an AGC control for both the uplink and downlink. There are LED
indicators on the front panel for power on, transmitter on, uplink overload and downlink overload.
An automatic amplifier safety shutdown circuit is also present which will disable the transmitters for ten
seconds should the uplink and downlink overloads be reached simultaneously to prevent excessive
intermodulation and oscillation.
FIGURE 2.1 Functional Block Diagram
2.0
