Method, apparatus and article for detection of transponder tagged objects, for example during surgery
First Claim
Patent Images
1. A method of operation of a transponder detection device, the method comprising:
- during each of a plurality of detection cycles,receiving electromagnetic signals during a noise detection portion of the detection cycle;
determining a value indicative of a noise level based at least in part on the electromagnetic signals received during the noise detection portion of the detection cycle;
adjusting a detection threshold based at least in part on at least one determined value indicative of the noise level;
emitting at least one electromagnetic interrogation signal during a transmit portion of the detection cycle;
receiving electromagnetic signals during a receive response portion of the detection cycle that follows the transmit portion of the detection cycle; and
determining the presence or absence of a transponder based at least in part on the electromagnetic signals received during the detection cycle and the adjusted detection threshold, wherein determining a value indicative of a noise level based at least in part on the electromagnetic signals received during the noise detection portion of the detection cycle includes averaging the values indicative of the noise level over each of the detection cycles, andwherein adjusting a detection threshold based at least in part on the determined value indicative of the noise level includes adjusting the detection threshold based at least in part on an average of the values indicative of the noise levels over multiple samples or measurements of at least one of the detection cycles, wherein averaging a sufficient number of the values indicative of the noise level over each of the detection cycles includes averaging the values indicative of the noise level over each of the detection cycles sufficient to provide a signal to noise ratio greater than approximately 1.93.
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Accused Products
Abstract
The presence or absence of objects is determined by interrogating or exciting transponders coupled to the objects using pulsed wide band frequency signals. Ambient or background noise is evaluated and a threshold adjusted based on the level of noise. Adjustment may be based on multiple noise measurements or samples. Noise detection may be limited, with emphasis placed on interrogation to increase the signal to noise ratio. Match filtering may be employed. Appropriate acts may be taken if detected noise is out of defined limits of operation, for example shutting down interrogation and/or providing an appropriate indication.
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Citations
31 Claims
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1. A method of operation of a transponder detection device, the method comprising:
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during each of a plurality of detection cycles, receiving electromagnetic signals during a noise detection portion of the detection cycle; determining a value indicative of a noise level based at least in part on the electromagnetic signals received during the noise detection portion of the detection cycle; adjusting a detection threshold based at least in part on at least one determined value indicative of the noise level; emitting at least one electromagnetic interrogation signal during a transmit portion of the detection cycle; receiving electromagnetic signals during a receive response portion of the detection cycle that follows the transmit portion of the detection cycle; and determining the presence or absence of a transponder based at least in part on the electromagnetic signals received during the detection cycle and the adjusted detection threshold, wherein determining a value indicative of a noise level based at least in part on the electromagnetic signals received during the noise detection portion of the detection cycle includes averaging the values indicative of the noise level over each of the detection cycles, and wherein adjusting a detection threshold based at least in part on the determined value indicative of the noise level includes adjusting the detection threshold based at least in part on an average of the values indicative of the noise levels over multiple samples or measurements of at least one of the detection cycles, wherein averaging a sufficient number of the values indicative of the noise level over each of the detection cycles includes averaging the values indicative of the noise level over each of the detection cycles sufficient to provide a signal to noise ratio greater than approximately 1.93. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 12, 14)
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10. A method of operation of a transponder detection device, the method comprising:
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during each of a plurality of detection cycles, receiving electromagnetic signals during a noise detection portion of the detection cycle; determining a value indicative of a noise level based at least in part on the electromagnetic signals received during the noise detection portion of the detection cycle; adjusting a detection threshold based at least in part on at least one determined value indicative of the noise level; emitting at least one electromagnetic interrogation signal during a transmit portion of the detection cycle; receiving electromagnetic signals during a receive response portion of the detection cycle that follows the transmit portion of the detection cycle; and determining the presence or absence of a transponder based at least in part on the electromagnetic signals received during the detection cycle and the adjusted detection threshold, wherein determining a value indicative of a noise level based at least in part on the electromagnetic signals received during the noise detection portion of the detection cycle includes averaging the values indicative of the noise level over each of the detection cycles, and wherein adjusting a detection threshold based at least in part on at least one determined value indicative of the noise level includes adjusting the detection threshold based at least in part on a number N of noise measurements or samples, and determining the presence or absence of a transponder based at least in part on the electromagnetic signals received during the detection cycle and the adjusted detection threshold includes determining the presence or absence of the transponder based at least in part on a number M of response measurements or samples received an interrogation portion of the detection cycle, wherein a square root of a ratio of M/N is equal or greater than approximately 1.93.
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11. A method of operation of a transponder detection device, the method comprising:
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during each of a plurality of detection cycles, receiving electromagnetic signals during a noise detection portion of the detection cycle; determining a value indicative of a noise level based at least in part on the electromagnetic signals received during the noise detection portion of the detection cycle; adjusting a detection threshold based at least in part on at least one determined value indicative of the noise level; emitting at least one electromagnetic interrogation signal during a transmit portion of the detection cycle; receiving electromagnetic signals during a receive response portion of the detection cycle that follows the transmit portion of the detection cycle; and determining the presence or absence of a transponder based at least in part on the electromagnetic signals received during the detection cycle and the adjusted detection threshold, wherein determining a value indicative of a noise level based at least in part on the electromagnetic signals received during the noise detection portion of the detection cycle includes averaging the values indicative of the noise level over each of the detection cycles, and wherein adjusting a detection threshold based at least in part on at least one determined value indicative of the noise level includes adjusting the detection threshold based at least in part on a number N of noise measurements or samples, and determining the presence or absence of a transponder based at least in part on the electromagnetic signals received during the detection cycle and the adjusted detection threshold includes determining the presence or absence of the transponder based at least in part on a number M of response measurements or samples received an interrogation portion of the detection cycle, wherein a square root of a ratio of M is equal or greater than approximately 1.1.
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13. A method of operation of a transponder detection device, the method comprising:
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during each of a plurality of detection cycles, receiving electromagnetic signals during a noise detection portion of the detection cycle; determining a value indicative of a noise level based at least in part on the electromagnetic signals received during the noise detection portion of the detection cycle; adjusting a detection threshold based at least in part on at least one determined value indicative of the noise level; emitting at least one electromagnetic interrogation signal during a transmit portion of the detection cycle; receiving electromagnetic signals during a receive response portion of the detection cycle that follows the transmit portion of the detection cycle; determining the presence or absence of a transponder based at least in part on the electromagnetic signals received during the detection cycle and the adjusted detection threshold, wherein determining a value indicative of a noise level based at least in part on the electromagnetic signals received during the noise detection portion of the detection cycle includes averaging the values indicative of the noise level over each of the detection cycles; accumulating the electromagnetic signals received during the noise detection portion of at least two of the detection cycles into an accumulated noise signal; comparing the accumulated noise signal against an ambient noise threshold; and taking a fault action if the accumulated noise signal exceeds the ambient noise threshold.
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15. A transponder detection system, comprising:
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transmitting means for transmitting electromagnetic interrogation signals during at least one transmit portion of each of a plurality of detection cycles; receiving means for receiving electromagnetic signals during a noise detection portion and a receive response portion of each of the detection cycles; noise level determination means for determining a noise level during the noise detection portion of the detection cycles, the noise detection portion temporally spaced from the transmit portions such that transponders are not responding to the electromagnetic interrogation signals; detection threshold adjustment means for adjusting a detection threshold of the transponder detection system based at least in part on at least one value indicative of at least one of the noise levels, wherein the at least one value is at least one of an average or an integration of the determined noise levels over multiple samples or measurements of at least one of the detection cycles; means for determining the presence or absence of the transponders based at least in part on the received electromagnetic signals and the adjusted detection threshold; recovery means for ignoring any electromagnetic signals received during a recovery portion of the detection cycle that precedes the receive response portion of the detection cycle; dumping means for dumping energy from an antenna circuit during a dump portion of the detection cycle that precedes the recovery portion of the detection cycle; and dithering means for varying a time between a start of a first one of the successive pairs of the detection cycles and a start of a next successive one of the pairs of the detection cycles. - View Dependent Claims (16, 17)
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18. A transponder detection system, comprising:
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transmitting means for transmitting electromagnetic interrogation signals during at least one transmit portion of each of a plurality of detection cycles; receiving means for receiving electromagnetic signals during a noise detection portion and a receive response portion of each of the detection cycles; noise level determination means for determining a noise level during the noise detection portion of the detection cycles, the noise detection portion temporally spaced from the transmit portions such that transponders are not responding to the electromagnetic interrogation signals; detection threshold adjustment means for adjusting a detection threshold of the transponder detection system based at least in part on at least one value indicative of at least one of the noise levels, wherein the at least one value is at least one of an average or an integration of the determined noise levels over multiple samples or measurements of at least one of the detection cycles; and means for determining the presence or absence of the transponders based at least in part on the received electromagnetic signals and the adjusted detection threshold, wherein the nose level determination means captures a number N of noise measurements or samples are captured during the noise detection portion of the detection cycles and wherein the transponder detection system captures a number M of response measurements or samples during an interrogation portion of the detection cycle and a square root of a ratio of M/N is at least equal to approximately 1.93.
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19. A transponder detection system, comprising:
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transmitting means for transmitting electromagnetic interrogation signals during at least one transmit portion of each of a plurality of detection cycles; receiving means for receiving electromagnetic signals during a noise detection portion and a receive response portion of each of the detection cycles; noise level determination means for determining a noise level during the noise detection portion of the detection cycles, the noise detection portion temporally spaced from the transmit portions such that transponders are not responding to the electromagnetic interrogation signals; detection threshold adjustment means for adjusting a detection threshold of the transponder detection system based at least in part on at least one value indicative of at least one of the noise levels, wherein the at least one value is at least one of an average or an integration of the determined noise levels over multiple samples or measurements of at least one of the detection cycles; and means for determining the presence or absence of the transponders based at least in part on the received electromagnetic signals and the adjusted detection threshold, wherein the nose level determination means captures a number N of noise measurements or samples are captured during the noise detection portion of the detection cycles and wherein the transponder detection system captures a number M of response measurements or samples during an interrogation portion of the detection cycle and a square root of a ratio of M/N is equal to or greater than approximately 1.1.
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20. A transponder detection system, comprising:
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a receiver configured to receive electromagnetic signals during a noise detection portion and at least one receive response portion of each of a plurality of detection cycles; a transmitter configured to transmit at least one electromagnetic interrogation signal during at least one transmit portion of each of the detection cycles; a controller configured to adjust a detection threshold of the transponder detection system based at least in part on at least one determined value indicative of a noise level and to determine whether the electromagnetic signals received during the at least one receive response portion of the detection cycles were received from a transponder in response to the electromagnetic interrogation signals based at least in part on the adjusted detection threshold, wherein the controller is configured to employ a number N of noise measurements or samples captured during the noise detection portion of the detection cycles and a number M of response measurements or samples captured during an interrogation portion of the detection cycle, and a square root of a ratio of M/N is at least equal to approximately 1.93. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31)
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Specification