| 摘要 |
PURPOSE: A portable wireless calling system is provided to wirelessly transmit various messages of parents to wireless paging receivers of children, or to search positions of the children, so as to alarm the parents through a wireless paging device, when the children is out of a range set by the wireless paging device. CONSTITUTION: A paging device(100) comprises as follows. The first distance signal generator compares an RSSI(Received Signal Strength Indicator) signal with a multi-step fundamental value, and generates a distance signal. The first signal processor(130) controls communication with a paging receiver(200), and finds a distance corresponding to a receiver position by the distance signal, then decides whether the receiver(200) is out of a set range to generate an alarm signal. The first display(150) displays a distance where the receiver(200) is located, and displays a message code corresponding to a functional key for being transmitted to the receiver(200). The first RF transceiver(110) converts an inputted paging signal from the first signal processor(130) into a modulated transmission signal, and demodulates a received RF propagation signal to apply binary digital data to the first signal processor(130), then supplies the RSSI signal to the distance signal generator. An alarming unit informs parents that the receiver(200) is out of the set range. The receiver(200) comprises as follows. The second signal processor(230) analyzes a message received from the paging device(100), and generates an output signal. The second display(250) displays a paging message corresponding to the functional key. A speaker(280) transmits a message corresponding to the output signal to an owner of the receiver(200). The second RF transceiver(210) converts an ACK(Acknowledge) signal into a modulated transmission signal to transmit the signal to the paging device(100), and applies the binary digital data to the second signal processor(230).
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