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Техническое руководство по пейджинговому передатчику MOTOROLA NUCLEUS

SECTION 2: MOTOROLA`S NUCLEUS ADVANCED CONTROL PAGING SYSTEM
Types of Nucleus Advanced Control Stations
 
Non-Simulcast Paging Transmitters Non-Simulcast Paging Transmitters are primarily for single transmitter systems or systems where coverage is not required to be continuous over a large geographic area.

Simulcast Paging Transmitters Simulcast Paging Transmitters place entirely different requirements upon a paging transmitter. In a simulcast system, a pager can receive signals from two or more paging transmitters. The geographical area where a pager receives this type of transmission is referred to as an overlap area. In this overlap area, there are several characteristics of the transmission that need to be carefully controlled. These characteristics include: power, delay, phase, deviation, and frequency. The power needs to be balanced so that the pager will capture the signal from all the transmitters. If one transmitter is putting out significantly more power in the overlap area, the pager will capture the signal from it. The phase and delay of the signal are also important. It is essential that the pager receives the signal at the same time from each transmitter. In voice pages, it is also important that the signals are in phase also. If these two conditions are not met, there will be destructive cancellation of the signals and the correct information will not be received by the pagers. Finally, it is important that the frequency and deviation of the signal be closely aligned to each other so the pager re¬ceives the correct information. As mentioned before, these characteris¬tics place additional requirements upon the station. The Nucleus Ad¬vanced Control Station can allow you to meet these requirements. A delay line is built into the station so signals can be equalized. It also has electron¬ic control of power and deviation so these settings can easily be set. The High Stability Oscillator (HSO) included in the station allows transmit¬ting on the correct frequency. The station comes equipped with an HSO with 30 ppB accuracy for VHF bands and a UHSO with 5 ppB accuracy for 900 MHz bands.
 
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