Method, apparatus and article for detection of transponder tagged objects, for example during surgery
First Claim
1. A method of operation of a transponder detection device, the method comprising:
- during each of a plurality of detection cycles,receiving electromagnetic signals by a receiver during a noise detection portion of the detection cycle;
determining a noise value indicative of a noise level that corresponds to a highest one of a number N of samples or measurements of the electromagnetic signals received during the noise detection portion of the detection cycle by a processor circuit, where the number N is greater than one;
adjusting a signal detection threshold by the processor circuit based at least in part on the determined noise value of at least one of the detection cycles;
emitting at least one electromagnetic interrogation signal during a transmit portion of the detection cycle by a transmitter;
receiving electromagnetic signals by the receiver 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 by the processor circuit based at least in part on a number M of samples or measurements of the electromagnetic signals received during the detection cycle and the adjusted signal detection threshold, where the number M is greater than one.
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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. Presence/absence determination may take into account frequency and/or Q value to limit false detections. 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
37 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 by a receiver during a noise detection portion of the detection cycle; determining a noise value indicative of a noise level that corresponds to a highest one of a number N of samples or measurements of the electromagnetic signals received during the noise detection portion of the detection cycle by a processor circuit, where the number N is greater than one; adjusting a signal detection threshold by the processor circuit based at least in part on the determined noise value of at least one of the detection cycles; emitting at least one electromagnetic interrogation signal during a transmit portion of the detection cycle by a transmitter; receiving electromagnetic signals by the receiver 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 by the processor circuit based at least in part on a number M of samples or measurements of the electromagnetic signals received during the detection cycle and the adjusted signal detection threshold, where the number M is greater than one. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. A transponder detection system, comprising:
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a transmitter configured to transmit electromagnetic interrogation signals during at least one transmit portion of each of a plurality of detection cycles; a receiver configured to receive electromagnetic signals during a noise detection portion and a receive response portion of each of the detection cycles; and a controller communicatively coupled to the transmitter and the receiver and that includes; a noise level determiner that determines a noise level that corresponds to a highest one of a number N of samples or measurements of the electromagnetic signals received 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; a detection threshold adjuster that adjusts 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; and a presence or absence determiner that determines a presence or absence of the transponders based at least in part on a number M of samples or measurements of the received electromagnetic signals and the adjusted detection threshold. - View Dependent Claims (27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
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Specification