Andrew NBPCS-9002W Channelized Paging Repeater User Manual Exh D Chapter 2

Andrew Corporation Channelized Paging Repeater Exh D Chapter 2

Exh D Chapter 2

AE02B-A3659 Rev -- OVERVIEWDocument use is restricted to that described on cover 2-1CHAPTER 2OPERATIONAL OVERVIEW2.1 OVERVIEWThe SelectAmp NBPCS-900-3 Paging Repeater accepts inputs in the 928 – 942 MHz paging band, andselectively passes one discrete channel in each band while rejecting the others. This is accomplished bydownconverting the desired signals to a 45 MHz intermediate frequency and using narrowband crystal filtersto provide adjacent channel rejection. The reverse path is not channelized, passing all frequencies in the897 – 903 MHz band.2.2 RF DISTRIBUTIONThe amplifier contains two paths; forward for the base station to pager signal and reverse for the pager tobase station signal. The forward path includes a diplexer, low noise amplifier and splitter, channelizer,combiner, and power amplifier. The channelizers determine the frequencies to be amplified and providethe gain control. The reverse path includes a diplexer, broadband module (amplifier and filters), and a poweramplifier.2.3 POWER DISTRIBUTIONMain power for the amplifier is provided by a 6.7 amp power supply operating at +15 VDC. The powersupply accepts 100 - 240 VAC inputs. This +15 VDC output of the power supply is routed to theControl/Distribution board. The Control/Distribution board regulates and outputs the +15 volts, +12 volts,and +5 volts to the various modules.2.4 CONTROL/DISTRIBUTIONThe operator has control over the gain and operating frequency of the forward paths, and gain only of thereverse path. The gain setting is controlled via front panel accessible pots. The forward channelfrequencies are entered through software installed on a PC/Laptop and sent to the Control/Distributionboard. The channel setting is then sent via a three wire serial interface from the Control/Distribution to asynthesizer in each channelizer. Each active module in the amplifier outputs status line(s) to indicate theoverall condition of the active devices. If an active device fails, the module reports a fault (red indicator)on the front panel. The reference oscillator for the channelizer synthesizers is located on theControl/Distribution board as well.

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