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US 8,559,559 B2Granted
Method and apparatus for compensating DC offsets in communication systems
AssigneeQUALCOMM Incorporated
InventorHelena Deirdre O'Shea
Life of this patent
Estimating the term…
Abstract
A communications system receiver incorporates a time-averaged DC component subtracter to subtract a time-averaged DC offset component from a received, processed signal. The time-averaged DC offset is selectably calculated from a moving average or a running average. The selection of the time-averaged DC offset can be done depending on whether the receiver operates in a frequency hop mode or not.
Claims14
An apparatus for use in a communications system, the apparatus comprising:
- a DC estimator to receive an input signal and generate estimate values of the input signal's DC level;
- a DC averager to receive the estimate values and generate a DC average, the DC average selectable from a moving average of the estimate values or a running average of the estimate values, wherein the moving average is updated whenever a new estimate value is available, and wherein the running average is updated once every predetermined time interval;
- and
- a subtracter unit to subtract the DC average from the input signal, the DC averager configured to select a running average if the receiver is in a frequency hop mode, the DC averager further configured to select a moving average if the receiver is not in a frequency hop mode;
- the input signal comprising an in-phase (I) component and a quadrature (Q) component, the DC estimator configured to generate estimate values for each of the I and Q components, the DC averager configured to generate DC averages for the estimate values generated for each of the I and Q components, and the subtracter unit configured to subtract a DC average from each of the I and Q components.
2 more elements
An apparatus for use in a communications system, the apparatus comprising:
- a DC estimator to receive an input signal and generate estimate values of the input signal's DC level;
- a DC averager to receive the estimate values and generate a DC average, the DC average selectable from a moving average of the estimate values or a running average of the estimate values, wherein the moving average is updated whenever a new estimate value is available, and wherein the running average is updated once every predetermined time interval;
- and
- a subtracter unit to subtract the DC average from the input signal, the DC averager configured to select a running average if the receiver is in a frequency hop mode, the DC averager further configured to select a moving average if the receiver is not in a frequency hop mode;
- the apparatus further comprising:
- an automatic gain correction unit to receive an uncorrected modulated composite signal, provide gain correction, and output a corresponding gain corrected modulated composite signal as the input signal;
- and
- a symbol decoder to receive the demodulated component output from the subtracter unit and output a corresponding plurality of symbol bits.
5 more elements
A method for use in a communication system, the method comprising:
- receiving an input signal and generating estimate values of the input signal's DC level using a DC estimator;
- receiving the estimate values using a DC averager to generate a DC average, the DC average selectable from a moving average of the estimate values or a running average of the estimate values, wherein the moving average is updated whenever a new estimate value is available, and wherein the running average is updated once every predetermined time interval;
- and
- subtracting the DC average from the input signal, further comprising selecting a running average if the receiver is in a frequency hop mode, and selecting a moving average if the receiver is not in a frequency hop mode;
- the input signal comprising an in-phase (I) component and a quadrature (Q) component, the DC estimator configured to generate estimate values for each of the I and Q components, the DC averager configured to generate DC averages for the estimate values generated for each of the I and Q components, and the subtracting comprising subtracting a DC average from each of the I and Q components.
2 more elements
A method for use in a communication system, the method comprising:
- receiving an input signal and generating estimate values of the input signal's DC level using a DC estimator;
- receiving the estimate values using a DC averager to generate a DC average, the DC average selectable from a moving average of the estimate values or a running average of the estimate values, wherein the moving average is updated whenever a new estimate value is available, and wherein the running average is updated once every predetermined time interval;
- and
- subtracting the DC average from the input signal, further comprising selecting a running average if the receiver is in a frequency hop mode, and selecting a moving average if the receiver is not in a frequency hop mode;
- the method further comprising:
- receiving an uncorrected modulated composite signal, providing gain correction, and outputting a corresponding gain corrected modulated composite signal as the input signal;
- and
- symbol demodulating the output of said subtracting.
5 more elements
An apparatus for use in a communications system, the apparatus comprising:
- DC estimator means for receiving an input signal and generating estimate values of the input signal's DC level;
- DC averager means for receiving the estimate values to generate a DC average, the DC average selectable from a moving average of the estimate values or a running average of the estimate values, wherein the moving average is updated whenever a new estimate value is available, and wherein the running average is updated once every predetermined time interval;
- and
- subtracter means for subtracting the DC average from the input signal, further comprising means for selecting a running average if the receiver is in a frequency hop mode, and selecting a moving average if the receiver is not in a frequency hop mode;
- the input signal comprising an in-phase (I) component and a quadrature (Q) component, the DC estimator means configured to generate estimate values for each of the I and Q components, the DC averager means configured to generate DC averages for the estimate values generated for each of the I and Q components, and the subtracter means comprising subtracting a DC average from each of the I and Q components.
2 more elements
An apparatus for use in a communications system, the apparatus comprising:
- DC estimator means for receiving an input signal and generating estimate values of the input signal's DC level;
- DC averager means for receiving the estimate values to generate a DC average, the DC average selectable from a moving average of the estimate values or a running average of the estimate values, wherein the moving average is updated whenever a new estimate value is available, and wherein the running average is updated once every predetermined time interval;
- and
- subtracter means for subtracting the DC average from the input signal, further comprising means for selecting a running average if the receiver is in a frequency hop mode, and selecting a moving average if the receiver is not in a frequency hop mode;
- the apparatus further comprising:
- means for receiving an uncorrected modulated composite signal, providing gain correction, and outputting a corresponding gain corrected modulated composite signal as the input signal;
- and
- means for symbol demodulating the output of said subtracting.
5 more elements
Dependencies are inferred from the claim text.