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US5170487A Paging system with multiple frequencies and multiple protocols 失效
具有多种频率和多种协议的寻呼系统

Paging system with multiple frequencies and multiple protocols
摘要:
The present invention provides a pager system which integrates a plurality of transmitters which operate at different frequencies. Some of the transmitters transmit paging messages using FM subcarrier signals (termed FM-SCA signals) and some transmit messages using a modulated carrier (termed RCC signals). The receiver includes two front ends. One front end receives and demodulates FM-SCA signals and one front end receives and demodulates RCC signals. Each paging message is transmitted on both FM-SCA transmitters and on RCC transmitters. The signals on each of the transmitters are slightly off set in time. When an assigned time slot occurs, one receiver turns on and attempts to receive a message, if it does not receive an appropriate signal, it tunes to another station that is in a stored list of stations. If the next station has an RCC flag associated therewith the RCC receiver rather than the FM-SCA receiver is operated. The entire process is controlled by a microprocessor which is a part of the system.
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