Apparatus and methods for estimating an unknown frequency error of a tone signal

An apparatus for estimating an unknown frequency error of a tone signal, the apparatus comprising:

• a sampler for sampling, within an error bandwidth, wireless signals including the tone signal that occupy the error bandwidth to generate signal samples;
• and
• signal processing circuitry configured to:
• apply a frequency offset to the signal samples to produce offset values that represent the signals occupying an offset bandwidth equal to the error bandwidth offset by an offset frequency, wherein applying the frequency offset to produce the offset values comprises the signal processing circuitry being configured to:
• auto-correlate the signal samples to produce correlation values;
• and
• rotate the phase of each correlation value by a phase representing the frequency offset;
• estimate, within a frequency estimation range less than the error bandwidth, a tone frequency error using the offset values;
• measure a signal-to-noise ratio of the tone signal using the signal samples and the estimated tone frequency error;
• repeat the applying, estimating, and measuring for different frequency offsets upon determining that the measured signal-to-noise ratio does not satisfy a threshold;
• and
• determine that the unknown frequency error of the tone signal is equal to the particular estimated tone frequency error upon determining that the measured signal-to-noise ratio satisfies the threshold.

An apparatus for estimating an unknown frequency error of a tone signal, the apparatus comprising:

• means for sampling, within an error bandwidth, wireless signals including the tone signal that occupy the error bandwidth to generate signal samples;
• means for applying a frequency offset to the signal samples to produce offset values that represent the signals occupying an offset bandwidth equal to the error bandwidth offset by an offset frequency, wherein the means for applying the frequency offset to produce the offset values comprises:
• means for auto- correlating the signal samples to produce correlation values;
• and
• means for rotating the phase of each correlation value by a phase representing the frequency offset;
• means for estimating, within a frequency estimation range less than the error bandwidth, a tone frequency error using the offset values;
• means for measuring a signal-to-noise ratio of the tone signal using the signal samples and the estimated tone frequency error;
• means for repeating the applying, estimating, and measuring for different frequency offsets upon determining that the measured signal-to-noise ratio does not satisfy a threshold;
• and
• means for determining that the unknown frequency error of the tone signal is equal to the particular estimated tone frequency error upon determining that the measured signal-to-noise ratio satisfies the threshold.

A computer-readable storage device comprising code, which, when executed by a processor, cause the processor to perform operations for estimating an unknown frequency error of a tone signal, the computer-readable storage device comprising:

• code for sampling, within an error bandwidth, wireless signals including the tone signal that occupy the error bandwidth to generate signal samples;
• code for applying a frequency offset to the signal samples to produce offset values that represent the signals occupying an offset bandwidth equal to the error bandwidth offset by an offset frequency, wherein the code for applying the frequency offset to produce the offset values comprises:
• code for auto-correlating the signal samples to produce correlation values;
• and
• code for rotating the phase of each correlation value by a phase representing the frequency offset;
• code for estimating, within a frequency estimation range less than the error bandwidth, a tone frequency error using the offset values;
• code for measuring a signal-to-noise ratio of the tone signal using the signal samples and the estimated tone frequency error;
• code for repeating the applying, estimating, and measuring for different frequency offsets upon determining that the measured signal-to-noise ratio does not satisfy a threshold;
• and
• code for determining that the unknown frequency error of the tone signal is equal to the particular estimated tone frequency error upon determining that the measured signal-to-noise ratio satisfies the threshold.