| 摘要 |
<p>A timekeeping system which includes a sensor for sensing a signalable event, a signalling device for transmitting an event signal representing the signalable event, a receiving device for receiving the event signal from the signalling device, a central controller device for issuing an instruction upon receipt by the receiving device of the event signal and a time clock interface device for interfacing with a time clock device which receives and implements the instruction issued by the central controller device. The event signal is preferably a radio frequency signal which is transmitted at a carrier frequency of at least about 900 megahertz, is preferably transmitted as a direct sequence broad spectrum transmission and preferably includes data which identifies the signalling device responsible for transmitting the event signal.</p> |
