| 摘要 |
A digital radio paging communication system has a transmitter and a plurality of receivers. The receivers are energized intermittently to save battery power. The transmitter generates a preamble signal, a synchronization signal, a plurality of calling signals and a stabilization signal, which are arranged into a sequence of signals including two of the preamble signals separated by a measured time interval and at least one batch signal including the synchronization signal and the plurality of calling signals which are divided into a plurality of groups. Each group of calling signals have a stabilization signal at the leading portion thereof followed by a receiver identifying code. A carrier wave is modulated with the sequence of signals and then transmitted. Each of the receivers receives and demodulates the carrier wave. Responsive to the receipt of a first preamble signal, the receiver switches from intermittent to continuous power at an intermediate stand-by level. If a second preamble signal is received within a predetermined time period, the receiver switches to full power. From there, it either receives its own code and gives a paging signal or it times out. Either way, it returns to the intermittent battery saver mode. The two step raise in the power supply (i.e. from intermittent to full power), eliminates a clipping of initially received paging signals which sometimes occurs in the prior art before the receiver got up to full power. |
