Method and apparatus to determine the direction to a transponder in a modulated backscatter communication system
First Claim
1. A method for determining the direction to a transponder comprising:
- transmitting a first signal to an area where communications with a transponder is desired;
producing a second signal derived from the first signal;
receiving the second signal via first, second, and third antennas;
forming a difference signal from the second signal received via the first and second antennas;
delaying the difference signal; and
comparing a first polarity of the delayed difference signal with a second polarity of the second signal received via the third antenna.
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0 Petitions
Accused Products
Abstract
Methods and systems for determining the direction to a transponder are disclosed. The methods and systems include transmitting a first signal to an area where communications with a transponder is desired; producing a second signal desired from the first signal; receiving the second signal via a first and second antenna forming a difference signal from the second signal received via the first and second antennas; forming a third signal by adding the second signal received via the first antenna and the second signal received via the third antenna; delaying the difference signal; and comparing a fist polarity of the delayed difference signal with a second polarity of the third signal.
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Citations
13 Claims
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1. A method for determining the direction to a transponder comprising:
- transmitting a first signal to an area where communications with a transponder is desired;
producing a second signal derived from the first signal;
receiving the second signal via first, second, and third antennas;
forming a difference signal from the second signal received via the first and second antennas;
delaying the difference signal; and
comparing a first polarity of the delayed difference signal with a second polarity of the second signal received via the third antenna. - View Dependent Claims (2, 3, 4, 5, 6)
- transmitting a first signal to an area where communications with a transponder is desired;
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7. A method for determining the direction to a transponder comprising:
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transmitting a first signal to an area where communications with a transponder is desired;
producing a second signal desired from the first signal;
receiving the second signal via a first and second antenna forming a difference signal from the second signal received via the first and second antennas;
forming a third signal by adding the second signal received via the first antenna and the second signal receive via the third antenna;
delaying the difference signal; and
comparing a fist polarity of the delayed difference signal with a second polarity of the third signal. - View Dependent Claims (8, 9, 10)
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11. A system for determining the direction to a transponder comprising:
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a first antenna for transmitting a first signal to the transponder;
second and third antennas for receiving a second signal from the transponder;
means for adding the second signal received by the second antenna with the second signal received by the third antenna to produce a sum signal;
means for subtracting the second signal received by the second antenna from the second signal received by the third antenna to produce a difference signal;
means for delaying the difference signal; and
a comparator for comparing a first polarity of the difference signal with a second polarity of the sum signal. - View Dependent Claims (12)
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13. A system for determining the direction to a transponder comprising:
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a first and a second antenna for receiving a signal from the transponder;
means for adding the signal received by the first antenna with the signal received by the second antenna to produce a sum signal;
means for subtracting the signal received by the first antenna from the signal received by the second antenna to produce a difference signal; and
a processor for comparing the difference signal with the sum signal to determine the direction to the transponder.
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Specification