| 摘要 |
<p>A communication system includes a common receiver unit and a plurality of satellite transmitter units remote from the receiver unit. Each transmitter unit has a logic section and a transmitter section, and each transmitter unit is switchable between a standby mode in which no message is to be sent to the receiver unit and an active mode in which a message is to be sent to the receiver unit. The logic section generates status messages and data messages, the format of the status message including an address portion identifying the transmitter unit and an indicator portion shiftable between first and second values. During a standby mode, the transmitter unit periodically and repetitively generates status messages in which the indicator portion is set to the first value, and only during an active mode of the transmitter unit when the transmitter section is sending a message to the receiver unit, the indicator portion of the status message is switched to the second value.</p> |
