Circuit frequency following technique transponder resonant
First Claim
1. A method of transferring information to a transponder, comprising the steps of:
- selecting a first frequency associated with data bits of information having a binary zero level state;
selecting a second frequency associated with data bits of information having a binary one level state;
transmitting information corresponding to the digital data with a transmit frequency signal, said transmitting step including the step of changing a frequency of the transmit frequency signal between the first and second frequencies according to a binary level state of the information;
detecting the change in the frequency of the transmit frequency signal at the transponder; and
tuning said transponder resonant circuit to approximately said first frequency when the frequency of said transmit frequency signal is said first frequency, and tuning said transponder resonant circuit to approximately said second frequency when the frequency of said transmit frequency signal is said second frequency.
1 Assignment
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Accused Products
Abstract
A transponder system (10) includes an interrogation unit (12) that transmits a first frequency F1 representing a binary zero, and a second frequency F2, representing a binary one. These signals are transmitted from an interrogator resonant circuit (22) within a radio frequency module (16). The transponder system (10) also includes a transponder unit (14) that receives a transmit frequency signal (51) from the interrogation unit (12) at a transponder resonant circuit (42). The transponder resonant circuit (42) is tuned to the first frequency F1 and the second frequency F2. A transponder control module (44) detects a change in the transmit frequency signal (51) from the interrogation unit (12) by a decrease in the voltage amplitude with the transponder resonant circuit (42). The transponder control module (44) repositions a switch circuit (48) that connects and disconnects capacitors within the transponder resonant circuit (42) to match the frequency of the transponder resonant circuit (42) with the new transmit frequency signal (51).
211 Citations
17 Claims
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1. A method of transferring information to a transponder, comprising the steps of:
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selecting a first frequency associated with data bits of information having a binary zero level state; selecting a second frequency associated with data bits of information having a binary one level state; transmitting information corresponding to the digital data with a transmit frequency signal, said transmitting step including the step of changing a frequency of the transmit frequency signal between the first and second frequencies according to a binary level state of the information; detecting the change in the frequency of the transmit frequency signal at the transponder; and tuning said transponder resonant circuit to approximately said first frequency when the frequency of said transmit frequency signal is said first frequency, and tuning said transponder resonant circuit to approximately said second frequency when the frequency of said transmit frequency signal is said second frequency. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A transponder unit operable to receive information, comprising:
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a transponder resonant circuit operable to receive a transmit frequency signal, said transponder resonant circuit being tuned to a first frequency and a second frequency, said transmit frequency signal being one of said first and second frequencies, said first and second frequencies representing information in binary zero and binary one level states respectively, said transmit frequency signal further operable to supply power to the transponder unit; and a transponder control module coupled to said transponder resonant circuit and operable to detect a change in a frequency of said transmit frequency signal between said first and second frequencies, and to tune said transponder resonant circuit to approximately said first frequency when the frequency of said transmit frequency signal is said first frequency, and to tune said transponder resonant circuit to approximately said second frequency when the frequency of said transmit frequency signal is said second frequency. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17)
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Specification