| 摘要 |
<p>A transmitter-receiver set for use by a person charged with the responsability of looking after another individual. The receiver (11), which is to be carried by the other individual, is provided with an alarm (30) and a decoder (12). The decoder (12) enables the operation of the alarm (30) when in one state and prevents the operation when in another state. The transmitter (10) has an encoder (13) operable to send out a uniquely encoded signal which effects changes between said one state and said other state of the decoder (12) and an aerial (18) operable to transmit a radio signal which activates the alarm (30) in the receiver (11) when received thereby. The receiver (11) and transmitter (10) are adapted to be directly electrically connected to allow the uniquely encoded signal to be transferred directly from the transmitter (10) to the receiver (11).</p> |
