Pager watch system utilizing time slot communication

DETAILED DESCRIPTION The present invention is a method and apparatus for transmitting paging and time information from a central station and receiving such information at a remote electronic timepiece and pager unit during a short time slot assigned to the pager unit.
In the pager unit, an oscillator is coupled to a timer which produces a time display.
These functions are constantly powered.
The timer periodically causes power to be supplied to the receiver and message decoding components, during a short time slot in which the transmitted data is to be received.
The receiver detects and reconstitutes the transmitted signal.
The transmitted signal is processed through a decoder which extracts paging and time update data.
If the paging data includes the pager unit's ID number, the unit audibly and/or visually indicates to the user that a page has been received.
The time update data extracted from the transmitted signal is used to synchronize the timer in the pager unit.
The timer serves the dual function of providing an accurate time indication for the watch function as well as causing power to be supplied during the time slot as described.
By transmitting time update information rather than resetting an internal counter, the watch function is accurately synchronized and will not stray.
Because the timer which is synchronized powers up the receiver during the pager unit's assigned time slot in addition to indicating the correct time, a very short time slot can be used.
In the preferred embodiment, the unit corrects its time slot alignment by comparing the transmitted time slot position to its assigned time slot position.
If they do not match, this means the timer has caused the receiver circuit to be powered at the wrong time, so the timer is adjusted by the difference in time between the received time slot and its assigned time slot.
The timer will thereafter cause the receiver circuit to be powered up during its assigned time slot.
In the preferred embodiment, if a time slot is not filled with data, an end of message signal instructs the pager unit to power down early, thereby achieving an additional reduction in power consumption beyond the reduction achieved by only powering the receiver circuit during short time slots