Identification system interrogator
First Claim
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1. A radio frequency identification system, interrogator, comprising:
- a first antenna adapted to generate a first magnetic field component having a first phase;
a second antenna adapted to generate a second magnetic field component having a second phase;
a driver circuit coupled to the first and second antennae to provide at least one signal to cause the generation of first and second magnetic field components;
whereby a first and second magnetic fields form a time varying composite magnetic field;
a detector for detecting a transponder signal modulated on said magnetic field;
a processor for processing the transponder signal; and
wherein said processor further comprises;
at least one potentiometer coupled to said detector and adapted to nullify interference on said detected signal;
an amplifier coupled to said at least one potentiometer and adapted to amplify said detected signal;
a filter coupled to said amplifier and adapted to filter said detected signal;
a demodulator coupled to said filter and adapted to demodulate said detected signal;
at least one decoder coupled to said demodulator and adapted to decode said demodulated signal; and
a signal processor coupled to said at least one decoder and adapted to process said decoded signal.
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Abstract
An improved interrogator for an inductively coupled identification system is disclosed. The interrogator provides a multidimensional electromagnetic field through a plurality of coils aligned relative to each other. The coils provide a rotating magnetic field having approximately constant amplitude regardless of orientation with respect to the transponder. An additional coil may be utilized to precess the multidimensional electromagnetic field. The interrogator may further provide an impedance matching network that includes a series drive capacitor to match the impedance of a capacitor in parallel with a coil to a driver load impedance.
90 Citations
45 Claims
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1. A radio frequency identification system, interrogator, comprising:
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a first antenna adapted to generate a first magnetic field component having a first phase;
a second antenna adapted to generate a second magnetic field component having a second phase;
a driver circuit coupled to the first and second antennae to provide at least one signal to cause the generation of first and second magnetic field components;
whereby a first and second magnetic fields form a time varying composite magnetic field;
a detector for detecting a transponder signal modulated on said magnetic field;
a processor for processing the transponder signal; and
wherein said processor further comprises;
at least one potentiometer coupled to said detector and adapted to nullify interference on said detected signal;
an amplifier coupled to said at least one potentiometer and adapted to amplify said detected signal;
a filter coupled to said amplifier and adapted to filter said detected signal;
a demodulator coupled to said filter and adapted to demodulate said detected signal;
at least one decoder coupled to said demodulator and adapted to decode said demodulated signal; and
a signal processor coupled to said at least one decoder and adapted to process said decoded signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. An interrogator for an identification system, comprising:
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a first coil;
a second coil;
a driver coupled to and driving said first coil and said second coil by providing a time varying signal to each of said first and second coils to cause said coils to generate a rotating magnetic field;
a detector for detecting transponder signal modulated on said rotating magnetic field; and
a processor for processing said transponder signal;
wherein said processor further comprises;
at least one potentiometer coupled to said detector and adapted to nullify interference on said transponder signal;
an amplifier coupled to said at least one potentiometer and adapted to amplify said transponder signal;
a filter coupled to said amplifier and adapted to filter said transponder signal;
a demodulator, coupled to said filter and adapted to demodulate said transponder signal;
at least one decoder coupled to said demodulator and adapted to decode said transponder signal; and
a signal processor coupled to said at least one decoder and adapted to process said transponder signal. - View Dependent Claims (15)
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16. A radio frequency identification system interrogator, comprising:
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a first antenna adapted to generate a first magnetic field component having a first phase;
a second antenna adapted to generate a second magnetic field component having a second phase;
a driver circuit coupled to the first and second antennae to provide at least one signal to cause the generation of first and second magnetic field components;
whereby said first and second magnetic fields form a time varying composite magnetic field; and
a third antenna adapted to generate a third magnetic field component, said driver further coupled to said third antenna and driving said third antenna with a signal to generate said third magnetic field component to precess said composite magnetic field. - View Dependent Claims (17, 18, 19)
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20. A radio frequency identification system interrogator, comprising:
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a first antenna adapted to generate a first magnetic field component having a first phase;
a second antenna adapted to generate a second magnetic field component having a second phase;
a driver circuit coupled the first and second antennae to provide at least one signal to cause the generation of first and second magnetic field components;
whereby said first and second magnetic field components form a time varying composite magnetic field; and
a third antenna which generates a third magnetic field component which precesses said composite magnetic field.
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21. A radio frequency identification system interrogator, comprising:
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a first antenna adapted to generate a first magnetic field component having a first phase;
a second antenna adapted to generate a second magnetic field component having a second phase;
a driver circuit coupled to the first and second antennae to provide at least one signal to generate first and second magnetic field components;
whereby said first and second magnetic field components form a time varying composite magnetic field; and
a series drive capacitor for each of said antennae and through which said antennae are driven, and a parallel tank capacitor for each said antenna, wherein said series drive capacitor and said parallel tank capacitor provide an impedance matching network. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31)
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32. An interrogator for an inductively-coupled identification system, comprising:
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a plurality of coil means for generating a composite rotating magnetic field having an approximately constant amplitude in all orientations relative to a transponder; and
a series drive capacitor for each of said coil means and through which said coil means are driven, and a parallel tank capacitor for each of said coil means, wherein said series drive capacitors and said parallel tank capacitors provide an impedance matching network. - View Dependent Claims (33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44)
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45. An inductively-coupled identification system interrogator, comprising:
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coil means for generating a composite rotating magnetic field having an approximately constant amplitude in all orientations relative to a transponder; and
said coil means including a series drive capacitor for each coil of said coil means and through which said coils are driven, and a parallel tank capacitor for each of said coils, wherein said series drive capacitors and said parallel tank capacitors together allow for the independent adjustment of both resonant frequency and input impedance of the interrogator.
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Specification