Object identification system using an RF roll-call technique
First Claim
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1. A system for identifying each object in a multitude of objects comprising:
- transmitter means for illuminating each object with a first electromagnetic signal which contains a sequence of codes and wherein each object is associated with a code in the sequence;
transponder means associated with each of the objects comprising first antenna means for receiving the first electromagnetic signal containing the sequence of codes;
first resonant circuit means coupled to the first antenna means and responsive to the carrier frequency of the first electromagnetic signal;
demodulating means coupled to the first resonant circuit means for separating the sequence of codes from the carrier frequency;
memory means for storing a preselected internal code;
means, coupled to said memory means and to said demodulating means for comparing the preselected internal code with each code in the sequence and for generating a signal when a match is detected between the preselected internal code and the associated code in the sequence; and
signal generator means, coupled to an output antenna means for transmitting an acknowledge signal in response to the signal from said comparing means;
receiving means responsive to the acknowledge signals for detecting coincidence between an acknowledge signal and the code in the sequency whose transmission immediately preceded receipt of the acknowledge signal, thereby identifying each object in the multitude of objects.
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Abstract
An object identification system using an RF roll-call technique wherein an interrogator illuminates a multitude of cooperating objects with a sequence of codes and receives from each such cooperating object an acknowledge signal immediately following the transmission of the code associated with that object and which terminates prior to completion of transmission of the next code in the sequence.
52 Citations
13 Claims
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1. A system for identifying each object in a multitude of objects comprising:
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transmitter means for illuminating each object with a first electromagnetic signal which contains a sequence of codes and wherein each object is associated with a code in the sequence; transponder means associated with each of the objects comprising first antenna means for receiving the first electromagnetic signal containing the sequence of codes;
first resonant circuit means coupled to the first antenna means and responsive to the carrier frequency of the first electromagnetic signal;
demodulating means coupled to the first resonant circuit means for separating the sequence of codes from the carrier frequency;
memory means for storing a preselected internal code;
means, coupled to said memory means and to said demodulating means for comparing the preselected internal code with each code in the sequence and for generating a signal when a match is detected between the preselected internal code and the associated code in the sequence; and
signal generator means, coupled to an output antenna means for transmitting an acknowledge signal in response to the signal from said comparing means;receiving means responsive to the acknowledge signals for detecting coincidence between an acknowledge signal and the code in the sequency whose transmission immediately preceded receipt of the acknowledge signal, thereby identifying each object in the multitude of objects. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A system for identifying each object in a multitude of objects comprising:
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transmitter means for illuminating each object with the first electromagnetic signal which contains a sequence of codes and wherein each object is associated with a code in a sequence; transponder means associated with each of the objects and comprising transponder first receiving means for receiving said first electromagnetic signal;
a body having an active surface layer and for propagating acoustic surface waves, said active surface layer having piezoelectric properties;
launching transducer means coupled between said transponder receiver means and the active layer surface of said body for converting the sequence of codes to acoustic surface waves and launching the same along said active surface layer means;
a plurality of electrode finger pair means disposed on the active surface layer wherein the fingers of each electrode finger pair means are positioned to form a preselected internal code and wherein potential is developed across the electrode finger means in response to the acoustic waves propagating along the active surface layer;
means for summing the total potential developed across the plurality of electrode finger pair means wherein the total potential is indicative of the comparison between the internal code and the sequence of codes and wherein the magnitude of the total potential substantially increases at the point when a match is detected, that is, when the corresponding code in the sequence propagating along the active surface layer properly aligns with the plurality of electrode finger pair means; and
first resonant circuit means coupled to an output antenna means for generating an acknowledge signal in response to the total potential from said summing means at the point when the corresponding code in the sequence is detected thereby; andreceiving means responsive to the acknowledge signals for detecting coincidence between an acknowledge signal and the code in the sequence whose transmission immediately preceded receipt of the acknowledge signal, thereby identifying each object in a multitude of objects. - View Dependent Claims (9, 10, 11, 12, 13)
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Specification