| 摘要 |
A watchman's clock system comprises a time clock unit capable of interrogating and receiving a coded response from a passive radio frequency responder (20), typically an identification coded radio frequency tag, located at a site to be visited. The time clock unit comprises a radio frequency transponder (30) and associated aerial (32) under the control of a microprocessor (34), which also controls the other functions of the time clock. Site identity coded information incoming to the radio frequency transceiver (30) from tag (20) is stored in memory (38). A timer (36) generates timing information. The time clock is further provided with a visual display (40) and a power supply (42) and power management system (42). Stored information representing a site or sites visited in the course of a duty may be transferred to an associated computer, local or remote, using dial tone multi-frequency (DTMF) signals produced by a tone generator (46) and a transducer (48). In the case of a remote computer the signals are transmitted by telephone line or radio link, a modem only being required at the receive end. The time clock may be provided with a complementary mount which receives it and a telephone handset. The mount may also incorporate a power supply for charging time clock battery (42). |
