CLOCK CALIBRATION IN SLEEP MODE
First Claim
1. A method for calibrating a second clock based on a first clock, the method comprising:
- (a) measuring a number L of counts of the first clock during a first interval;
(b) measuring a number M(n) of counts of the second clock during a second interval, wherein the second interval corresponds in length to N counts of the first clock;
(c) applying filtering to the number M(n) of counts of the second clock to generate a filtered count F(n); and
(d) updating the second clock based on L, N, and F(n).
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Accused Products
Abstract
In one embodiment, an improvement is described for synchronization between devices in, e.g., a wireless network, wherein at least one device includes both a slow clock and a fast clock for different modes of operation. The fast clock for an active mode of operation is calibrated after a sleep mode of operation during which the slow clock is employed for device timing. Calibration employs a filter-based technique. Counts for the slow clock and for the fast clock are measured over a first interval, and the number of slow-clock counts is measured over a second interval. An estimate for the number of fast counts over the second interval is generated, filtered to reduce noise and error effects, and then employed to update the fast clock in the active mode of operation.
26 Citations
20 Claims
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1. A method for calibrating a second clock based on a first clock, the method comprising:
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(a) measuring a number L of counts of the first clock during a first interval; (b) measuring a number M(n) of counts of the second clock during a second interval, wherein the second interval corresponds in length to N counts of the first clock; (c) applying filtering to the number M(n) of counts of the second clock to generate a filtered count F(n); and (d) updating the second clock based on L, N, and F(n). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An apparatus for calibrating a second clock based on a first clock, the apparatus comprising:
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a measurement generator adapted to; (i) measure a number L of counts of the first clock during a first interval; (ii) measure a number M(n) of counts of the second clock during a second interval, wherein the second interval corresponds in length to N counts of the first clock; a filter adapted to apply filtering to the number M(n) of counts of the second clock to generate a filtered count F(n); and an update generator adapted to update the second clock based on L, N, and F(n). - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
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Specification