System and method for modulating a frequency signal
AssigneeLear Automotive Dearborn, Inc.
InventorSteven P. Kulha
Life of this patent
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Abstract
A radio frequency transmitter circuit including a user input switch for producing an input signal, an oscillator for producing a frequency signal having a first frequency, an antenna connected to the oscillator for broadcasting the frequency signal, a coupling circuit disposed a predetermined distance from the antenna, and a microprocessor for enabling the oscillator and activating the coupling circuit in response to the input signal. When the coupling circuit is activated, a reflected impedance, derived from a change in inductance, is reflected from the coupling circuit upon the antenna thereby shifting the frequency signal to a second frequency. Sequentially activating and deactivating the coupling circuit modulates the frequency signal.
Claims7
A radio frequency transmitter circuit comprising:
- a user input switch for producing an input signal;
- an oscillator for producing a frequency signal having a first frequency;
- an antenna connected to said oscillator for broadcasting said frequency signal;
- a coupling signal disposed a predetermined distance from said antenna;
- and
- a microprocessor for enabling said oscillator and activating said coupling circuit in response to said input signal;
- said coupling circuit arranged to produce a reflected impedance when activated to alter an inductance of said antenna, thereby shifting said frequency signal to a second frequency upon activation of said coupling circuit.
A method of modulating a signal comprising:
- a) generating a signal having a first frequency from an oscillator circuit;
- and
- b) producing a reflected impedance to selectively alter an inductance of an antenna in the oscillator circuit to shift the signal to a second frequency.
Dependencies are inferred from the claim text.