Apparatus and method for acquiring an operating channel
AssigneeMotorola, Inc.
InventorJheroen Pieter Dorenbosch
Life of this patent
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Abstract
A method and selective messaging unit arranged for acquiring an operating channel (123), that is divided into frames including a signal frame. The selective messaging unit after losing the operating channel provides a clock accuracy (421) based upon an elapsed time counter (243) and a known accuracy or stability of a clock (241). The clock accuracy is compared to a thresholds and the results of this comparison(s) is used to control the frequency and location of scanning in search of an operating channel.
Claims12
In a selective messaging unit having a clock and operable on one or more operating channels, each operating channel temporally divided into frames with a frame having a signal lasting for a frame time, the frame periodically repeating, a method of acquiring an operating channel after that operating channel has been lost, the method minimizing battery usage and including the steps of:
- recording an elapsed time since losing the operating channel;
- calculating a clock accuracy value equal to a product of an oscillator stability and the elapsed time;
- comparing said clock accuracy value to a first threshold determined from a temporal distance between a nearest frame boundary and a location within the frame where scanning will occur when the clock is perfectly accurate;
- scanning for the signal during a time of the frame as determined by said clock;
- and
- also scanning for the signal during the time of an adjacent frame as determined by said clock, when the clock accuracy value is not less than the first threshold.
A selective messaging unit operable on one or more operating channels, each operating channel temporally divided into frames with a frame having a signal lasting for a frame time, the frame periodically repeating, the selective messaging unit arranged to acquire, with minimal battery usage, an operating channel after that operating channel bas been lost, the selective messaging unit comprising in combination:
- a clock having a known oscillator stability;
- a processor, coupled to said clock and coupled to a receiver, wherein the processor is programmed to:
- record an elapsed time since losing the operating channel;
- calculate a clock accuracy value equal to a product of the known oscillator stability and the elapsed time;
- and
- compare said clock accuracy value to a first threshold determined from a temporal distance between a nearest frame boundary and a location within the frame where scanning will occur when the clock is perfectly accurate;
- and
- the receiver, coupled to said processor,
- for scanning for the signal during a time of the frame as determined by said clock;
- and
- also scanning for the signal during the time of an adjacent frame as determined by said clock, when the clock accuracy value is not less than the first threshold.
Dependencies are inferred from the claim text.