Ambulatory medical apparatus and method using a telemetry system with predefined reception listening
First Claim
1. An apparatus for synchronizing a first clock with a second clock, comprising:
- an oscillator for producing a first pulse stream that oscillates at an initial frequency; and
a circuit for calculating a drift rate based on a difference in time between the first clock and the second clock, and for removing selected pulses from the first pulse stream based on the drift rate to produce a second pulse stream that is used to control at least one of the first clock and the second clock.
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Abstract
An implanted medical device (e.g. infusion pump) and an external device communicate with one another via telemetry messages that are receivable only during windows or listening periods. Each listening period is open for a prescribed period of time and is spaced from successive listening periods by an interval. The prescribed period of time is typically kept small to minimize power consumption. To increase likelihood of successful communication, the window may be forced to an open state, by use of an attention signal, in anticipation of an incoming message. To further minimize power consumption, it is desirable to minimize use of extended attention signals, which is accomplished by the transmitter maintaining an estimate of listening period start times and attempting to send messages only during listening periods. In the communication device, the estimate is updated as a result of information obtained with the reception of each message from the medical device.
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Citations
40 Claims
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1. An apparatus for synchronizing a first clock with a second clock, comprising:
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an oscillator for producing a first pulse stream that oscillates at an initial frequency; and
a circuit for calculating a drift rate based on a difference in time between the first clock and the second clock, and for removing selected pulses from the first pulse stream based on the drift rate to produce a second pulse stream that is used to control at least one of the first clock and the second clock. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An apparatus for synchronizing a first clock with a second clock, comprising:
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means for producing a first pulse stream that oscillates at an initial frequency;
means for calculating a drift rate based on a difference in time between the first clock and the second clock; and
means for removing selected pulses from the first pulse stream based on the drift rate to produce a second pulse stream that is used to control at least one of the first clock and the second clock. - View Dependent Claims (10, 11)
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12. A method of synchronizing a first clock with a second clock, the method comprising:
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producing a first pulse stream that oscillates at an initial frequency;
determining a drift rate based on a difference in time between the first clock and the second clock;
removing selected pulses from the first pulse stream based on the drift rate to produce a second pulse stream; and
controlling at least one of the first clock and the second clock based on the second pulse stream. - View Dependent Claims (13, 14, 15, 16)
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17. A method of generating a system timing signal, the method comprising:
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producing a first pulse stream that oscillates at an initial frequency that is greater than a desired frequency; and
removing selected pulses from the first pulse stream to produce a second pulse stream that oscillates with an average frequency closer to a desired frequency than the initial frequency;
wherein the second pulse stream generates a system timing signal that has a frequency less than that of the second pulse stream; and
wherein the timing signal has a frequency less than about 1/100 of an average frequency of the second pulse stream.
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18. A method of generating a system timing signal, the method comprising:
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producing a first pulse stream that oscillates at an initial frequency that is greater than a desired frequency; and
removing selected pulses from the first pulse stream to produce a second pulse stream that oscillates with an average frequency closer to a desired frequency than the initial frequency;
wherein the average frequency of the second pulse stream is no less than 90% of the initial frequency.
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19. A method of generating a system timing signal, the method comprising:
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producing a first pulse stream that oscillates at an initial frequency that is greater than a desired frequency; and
removing selected pulses from the first pulse stream to produce a second pulse stream that oscillates with an average frequency closer to a desired frequency than the initial frequency;
wherein the average frequency of the second pulse stream is no less than 99% of the initial frequency.
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20. A method of generating a system timing signal, the method comprising:
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producing a first pulse stream that oscillates at an initial frequency that is greater than a desired frequency; and
removing selected pulses from the first pulse stream to produce a second pulse stream that oscillates with an average frequency closer to a desired frequency than the initial frequency;
wherein removing selected pulses from the first pulse stream includes repetitively counting to a first predefined value and then removing a pulse from the first pulse stream to produce the second pulse stream. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35)
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36. A method of generating a system timing signal the method comprising:
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producing a first pulse stream that oscillates at an initial frequency that is greater than a desired frequency; and
removing selected pulses from the first pulse stream to produce a second pulse stream that oscillates with an average frequency closer to a desired frequency than the initial frequency;
wherein the second pulse stream generates a system timing signal that has a frequency less than that of the second pulse stream; and
wherein the selected pulses are removed upon receipt of a pulse from at least one counter programmed to begin counting from a predefined value.
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37. A method of generating a system timing signal, the method comprising:
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producing a first pulse stream that oscillates at an initial frequency that is greater than a desired frequency;
removing selected pulses from the first pulse stream to produce a second pulse stream that oscillates with an average frequency closer to a desired frequency than the initial frequency, wherein the second pulse stream generates a system timing signal that has a frequency less than that of the second pulse stream;
measuring at least one predetermined parameter in a system for which the system timing signal is generating; and
removing the selected pulses from the first pulse stream at times determined at least in part based on the measured predetermined parameter. - View Dependent Claims (38)
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39. An apparatus for generating a timing signal, comprising:
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an oscillator for producing a first pulse stream that oscillates at an initial frequency that is greater than a desired frequency;
a counter for repetitively counting to a first value; and
a circuit for removing at least one pulse from the first pulse stream each time the counter counts to the first value to produce a second pulse stream that oscillates with an average frequency closer to a desired frequency than the initial frequency. - View Dependent Claims (40)
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Specification