Continuously armed high reliability pulse train processor
First Claim
1. A continuously armed pulse train processor for a field disturbance sensor, comprising:
- means for providing a pulse train of constitutive consecutive pulses in response to a magnetic tag being present in an interrogation zone of the field disturbance sensor;
resetable means coupled to the pulse train providing means for sequentially determining whether the several constitutive pulses serially meet predetermined minimum and maximum temporal duration criteria established therefor; and
means cooperative with the resetable means and responsive to a failure of any pulse of the pulse train to meet the corresponding criteria for resetting the resetable means such that the resetable means is again able to sequentially determine ab initio whether sequentially received pulse train pulses serially received after the resetting of the resetable means meet the predetermined pulse train criteria therefor.
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Accused Products
Abstract
A pulse train processor includes a plurality of parallel input, serially coupled pulse discriminating modules one for each of the consecutive pulses of a pulse train characteristic of a magnetic strip or resonant tag target signal produced in a magnetic interrogation zone such as found in retail clothing or library theft prevention applications. Each module is tailored to the particular expected characteristics of the corresponding pulse of the pulse train, and the modules are serially enabled and an alarm is triggered if and only if the expected characteristics of the several pulses are sequentially present from the initial pulse to the last pulse of the received pulse train. The modules are self-resetting in the event that the pulse characteristics of any of the pulses are other than the expected pulse characteristics whereby the pulse train processor is substantially continuously armed. The modules are responsive to pulse sequence, pulse polarity, pulse height, and minimum and maximum duration of the several constitutive pulses of the pulse train whereby an ultra-high detection reliability is provided.
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Citations
27 Claims
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1. A continuously armed pulse train processor for a field disturbance sensor, comprising:
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means for providing a pulse train of constitutive consecutive pulses in response to a magnetic tag being present in an interrogation zone of the field disturbance sensor; resetable means coupled to the pulse train providing means for sequentially determining whether the several constitutive pulses serially meet predetermined minimum and maximum temporal duration criteria established therefor; and means cooperative with the resetable means and responsive to a failure of any pulse of the pulse train to meet the corresponding criteria for resetting the resetable means such that the resetable means is again able to sequentially determine ab initio whether sequentially received pulse train pulses serially received after the resetting of the resetable means meet the predetermined pulse train criteria therefor. - View Dependent Claims (2, 3, 4, 5)
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6. A continuously armed pulse train processor for a swept radio frequency sensor, comprising:
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means for providing a pulse train of constitutive consecutive pulses in response to a resonant tag being present in an interrogation zone of the swept radio frequency sensor; resetable means coupled to the pulse train providing means for sequentially determining whether the several constitutive pulses serially meet predetermined minimum and maximum temporal duration criteria established therefor; and means cooperative with the resetable means and responsive to a failure of any pulse of the pulse train to meet the corresponding criteria for resetting the resetable means such that the resetable means is again able to sequentially determine ab initio whether sequentially received pulse train pulses serially received after the resetting of the resetable means meet the predetermined pulse train criteria therefor. - View Dependent Claims (7, 8, 9, 10)
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11. A pulse-train processor for discriminating a pulse-train provided by a true target from noise provided by a false target, comprising:
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receiver means having a field of view for providing a pulse-train signal having n constitutive pulses in response to a target being in the field of view, where n is an integer greater than or equal to 2; a like plurality of n resetable pulse processing module means coupled in parallel to the receiver means respectively for discriminating corresponding pulses of said n pulses constituting said pulse train signal with respect to whether or not individual constitutive pulses of said pulse-train signal satisfy predetermined expected first criteria associated with each of the pulses of the pulse-train signal; sequencing means coupled to said plural pulse processing modules for enabling a kth module means of said n pulse processing module means to discriminate a kth pulse corresponding thereto in response to the k-1 module means having already discriminated that the corresponding k-1 pulse satisfied its associated first criteria and for disabling the enabled kth module in response to decay of the kth pulse for every module means except a first module means which is always enabled, where k is an integer greater than 1 and less than or equal to n; and means cooperative with the sequencing means and coupled to said pulse processing module means for resetting the kth module means if the k-1 pulse of the pulse-train signal satisfies a second predetermined criteria different from the first predetermined criteria for each module means. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. For use in an electronic theft prevention system which includes transmitter means for providing a field within a predetermined interrogation zone, receiving means for monitoring the field of the interrogation zone and for detecting the presence of a target in the interrogation zone and for providing a pulse train representative of target presence in the interrogation zone, a pulse train processor for discriminating a pulse train provided by a true target from noise provided by a false target, said processor comprising;
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a plurality of pulse detection modules each operative to simultaneously receive the pulse train, the plurality of pulse detection modules including a first module, one or more intermediate modules and a last module; the first module being operative to receive the first pulse of the pulse train and upon recognition of predetermined valid characteristics of that first pulse to enable the next intermediate module; each of the intermediate modules being operative to receive respective successive pulses of the pulse train and each being operative upon recognition of predetermined valid characteristics of the successive received pulses to enable the next intermediate or the last module; the final module being operative to receive the next successive pulse of the pulse train and upon recognition of predetermined valid characteristics of that received pulse to provide a trigger pulse output signal; means of accumulating the trigger pulses from the last module; means for providing an output alarm signal in response to the accumulation of a predetermined number of trigger pulses. - View Dependent Claims (22, 23, 24, 25, 26, 27)
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Specification