Circuit for acoustic distance measuring
First Claim
1. An acoustic distance measuring circuit, comprising:
- a transmitter amplifier having an output adapted to be coupled to an acoustic transducer for providing an acoustic signal thereto;
a receiver amplifier having an input adapted to be coupled to the acoustic transducer and an output; and
a sensing circuit having an input coupled to the output of the receiver amplifier, and an output for providing a close proximity indication flag signal, for defining a start and an end of a close proximity indication zone window, detecting an obstacle at a first time in the close proximity indication zone window if a magnitude of a first pulse received from the acoustic transducer in a proximity indication zone window at a second time is less than a first threshold but greater than a second threshold for a debounce time, and a magnitude of a second pulse received from the acoustic transducer in the proximity indication zone window at a third time is less than the second threshold but greater than a third threshold for the debounce time, wherein the third time is equal to one and one-half of a difference between the second time and the first time and providing the close proximity indication flag signal in response to detecting the obstacle in the close proximity indication zone window.
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Accused Products
Abstract
In one form, an acoustic signal is generated for an acoustic transducer, where the acoustic transducer is susceptible to reverberation that defines a close proximity indication zone. The start of a close proximity indication zone window is defined after the generation of the acoustic signal at a first time. During the close proximity indication zone window, a signal is received from the acoustic transducer. When the signal is received, an obstacle is detected in the close proximity indication zone if the magnitude of a first pulse received from the transducer at a second time is less than a first threshold but greater than a second threshold for a debounce time. Additionally, a magnitude of a second pulse received from the transducer outside the close proximity indication zone window at a third time should be less than the second threshold but greater than a third threshold for the debounce time. In this form, the third time is equal to the first time plus two times the difference between the second time and the first time.
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Citations
15 Claims
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1. An acoustic distance measuring circuit, comprising:
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a transmitter amplifier having an output adapted to be coupled to an acoustic transducer for providing an acoustic signal thereto; a receiver amplifier having an input adapted to be coupled to the acoustic transducer and an output; and a sensing circuit having an input coupled to the output of the receiver amplifier, and an output for providing a close proximity indication flag signal, for defining a start and an end of a close proximity indication zone window, detecting an obstacle at a first time in the close proximity indication zone window if a magnitude of a first pulse received from the acoustic transducer in a proximity indication zone window at a second time is less than a first threshold but greater than a second threshold for a debounce time, and a magnitude of a second pulse received from the acoustic transducer in the proximity indication zone window at a third time is less than the second threshold but greater than a third threshold for the debounce time, wherein the third time is equal to one and one-half of a difference between the second time and the first time and providing the close proximity indication flag signal in response to detecting the obstacle in the close proximity indication zone window. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method comprising:
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generating an acoustic signal for an acoustic transducer at a first time, wherein the acoustic transducer is susceptible to reverberation that defines a close proximity indication zone; defining a start of a close proximity indication zone window after generating the acoustic signal; defining an end of the close proximity indication zone window; receiving a signal from the acoustic transducer during the close proximity indication zone window; and detecting an obstacle in the close proximity indication zone window if a magnitude of a first pulse received from the acoustic transducer outside the close proximity indication zone window at a second time is less than a first threshold but greater than a second threshold for a debounce time, and a magnitude of a second pulse received from the acoustic transducer in the close proximity indication zone window at a third time is less than the second threshold but greater than a third threshold for the debounce time, wherein the third time is equal to the first time plus two times a difference between the second time and the first time. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15)
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Specification