System and method for automatically tuning an antenna

A method for automatically tuning an antenna, comprising:

• selecting a desired frequency;
• initializing a control signal to a start value at the beginning of the tune mode, the start value corresponding to a frequency at one end of the operating spectrum of the wireless system;
• arranging the antenna to oscillate at a resonant frequency with a tuning circuit, the tuning circuit having an adjustable tuning element that is arranged to adjust the resonant frequency in response to the control signal;
• determining a signal strength of the output signal at a selected frequency, the output signal in cooperation of the antenna and tuning circuit;
• changing the control signal to another value when the signal strength is below a predetermined threshold level;
• and
• maintaining the control signal when the signal strength is above the predetermined threshold level, whereby the resonant frequency is substantially the same as the selected frequency when the signal strength is above the predetermined threshold level such that the antenna is tuned.

A method for using a tuned antenna, comprising:

• arranging an antenna with a tuning circuit, the antenna and the tuning circuit forming a tuned antenna circuit that has a resonant frequency;
• selecting an operating mode and a desired frequency;
• coupling the tuned antenna circuit to an amplifier circuit when the operating mode is a tune mode such that the tuned antenna circuit oscillates at the resonant frequency;
• sweeping the resonant frequency over a range of values when the operating mode is the tune mode and the resonant frequency is substantially different from the desired frequency;
• and
• stopping the sweep when the resonant frequency is substantially the same as the desired frequency and the operating mode is the tune mode.

A wireless watch device including an antenna that is automatically tuned to a selected frequency, comprising:

• a means for tuning that is coupled to the antenna such that the antenna and the means for tuning have a resonant frequency;
• a means for amplifying that is arranged to provide an output signal in response to an input signal from the antenna;
• a means for oscillating that is arranged to provide feedback of the output signal to the antenna such that the antenna and the means for tuning oscillate at the resonant frequency when selected;
• a means for receiving that is arranged to receive the output signal and provide a signal strength that indicates a level of the output signal that is tuned to the selected frequency;
• a means for discriminating that is arranged to activate an enable signal when the signal strength is substantially below a predetermined threshold, and the enable signal is deactivated when the signal strength reaches or exceeds the predetermined threshold;
• and
• a means for adjusting that is arranged to adjust the resonant frequency of the means for tuning when the enable signal is active such that the resonant frequency is adjusted until tuned to the selected frequency.

An apparatus that includes an antenna that is automatically tuned, the apparatus comprising:

• a tuned circuit that includes the antenna and a tuning array, wherein the tuned circuit has a resonant frequency that is associated with a tuning control signal that is provided to the tuning array;
• an oscillator circuit that is coupled to the tuned circuit such that the tuned circuit and the oscillator circuit form a resonant circuit that provides an antenna oscillation signal that oscillates at the resonant frequency when the oscillator circuit is enabled;
• a comparator circuit that is coupled to the tuned circuit such that the comparator circuit produces a comparator output signal in response to the antenna oscillation signal when the comparator circuit is enabled;
• a counter circuit that is coupled to the comparator circuit such that the counter detects a number of oscillations associated with the comparator output signal during a time interval;
• and
• a successive approximation register that is arranged to provide the tuning control signal, wherein the tuning control signal is adjusted in response to a carryout signal from the counter at the end of the time interval when the successive approximation register is enabled.

A method for automatically tuning an antenna, comprising:

• selecting a desired frequency;
• initializing a tuning control signal to an initial value at the beginning of the tuning mode, the initial value corresponding to a frequency at one end of the operating spectrum;
• configuring the antenna to oscillate such that the antenna provides an oscillator signal with an associated resonant frequency, wherein the resonant frequency is related to the tuning control signal;
• initiating tuning cycles when the tune mode is active, wherein each tuning cycle includes:
• counting a number of oscillations in the oscillator signal over the predetermined time interval;
• and
• adjusting the tuning control signal in response to the number of oscillations counted over the predetermined time interval.

A method for using an antenna, comprising:

• coupling the antenna to a tuning array such that the antenna and the tuning array form a tuned circuit that has a resonant frequency;
• selecting an operating mode and a desired frequency;
• activating an oscillator circuit when the operating mode is a tune mode, wherein the oscillator circuit excites the tuned circuit such that the tuned circuit oscillates at the resonant frequency;
• adjusting the resonant frequency when the operating mode is the tune mode and the resonant frequency is substantially different from the desired frequency, wherein adjusting the resonant frequency includes:
• counting a number of oscillations in the tuned circuit over a time interval;
• activating additional elements in the tuning array when the number of oscillations in the tuned circuit is above a predetermined amount at the end of the time interval;
• and
• deactivating elements in the tuning array when the number of oscillations in the tuned circuit is below the predetermined amount at the end of the time interval.

An apparatus that includes an antenna for transmitting an information signal, the apparatus comprising:

• a tuning array that is coupled to the antenna, wherein the tuning array is responsive to a tuning control signal;
• a modulation tuner that is coupled to the antenna, wherein the modulation tuner includes a tuning element that is responsive to a modulation control signal, wherein the tuning array, the modulation tuner, and the antenna form a tuned circuit that has an associated resonant frequency;
• an oscillator that is coupled to the tuned circuit such that the oscillator and the tuned circuit form a resonant circuit that provides an antenna oscillation signal that oscillates at the resonant frequency when the oscillator circuit is enabled;
• and
• a phase detector that is arranged to provide the modulation control signal by comparing the phase of the antenna oscillation signal to an IF oscillation signal, wherein the IF oscillation signal corresponds to a local oscillator signal that is modulated in response to the information signal such that the resonant frequency of the tuned circuit changes in response to the information signal.

A method for transmitting an information signal with an antenna, the method comprising:

• configuring the antenna to oscillate such that the antenna provides an antenna oscillator signal with an associated resonant frequency;
• generating an IF oscillator signal, wherein the IF oscillator signal corresponds to a frequency shift keyed signal that is shifted in response to the information signal;
• comparing the phase of the antenna oscillator signal to the phase of an IF oscillation signal to provide a phase difference signal;
• and
• adjusting the resonant frequency with a modulation tuner in response to the phase difference signal such that the antenna transmits the information signal as an FM modulated signal using FSK encoding.