| 摘要 |
<p>A method and apparatus for synchronizing a timepiece to a reference time includes the preparation (10) of an encoded and/or encrypted signal for transmission from a paging network (12) transmitter (14, 16). The signal, which contains a time message and information on Daylight Saving changes and corrections to UTC time, is transmitted a number of times in a twenty-four hour period, with brief intervals between each transmission. A timepiece (18, 22) has a receiver and control circuitry (34) which receive and decode the signal. The decoded time information is used to automatically set the time of the timepiece (18, 22) to the correct time for a predetermined time zone. A locality switch is provided on the timepiece (18, 22) to determine which time zone time is to be displayed (20, 24). To correct for delays which may be encountered in queuing and transmission, a second signal may be transmitted as a result of the first signal being received by a monitor, the second signal including information about the time of receipt of the first signal by the monitor, such that the timepiece, upon receipt of the second signal, is able to correct for any delays, and to then display accurate time. To correct for the possibility that data may be corrupted, updates may not take place until a third signal is transmitted. A master unit located in the paging network coverage area, which has a source of accurate time, receives the time update and determines that the updated time is correct or incorrect. If it is correct, the third signal will be a 'confirmation' signal. If the updated time is incorrect, the third signal will be an 'ignore' signal.</p> |
