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US 7,443,924 B2Granted
Residual carrier and side band processing system and method
AssigneeViaSat, Inc.
InventorsMark Dale, William H. Thesling
Life of this patent
Estimating the term…
Abstract
In a communication device, the LO leakage and opposite side band signals are measured at an output signal. Input processing signals to a modulator are adjusted in response to the measured values to minimize the LO leakage and maximize side band suppression.
Claims18
A communication device-implemented method of processing communication signals, comprising:
- generating an in-phase baseband signal at a test frequency;
- generating a quadrature baseband signal at the test frequency;
- modulating a carrier signal by the in-phase and quadrature baseband signals to generate a modulated carrier signal;
- measuring a LO leakage signal in the modulated carrier signal, the measuring step comprising:
- generating sums and differences of frequency components in the modulated carrier signal;
- low pass filtering the generated sums and differences;
- and
- utilizing the filtered sums and differences to generate a digital value proportional to the magnitude of a spectral component at the test frequency, the digital value comprising a LO leakage signal value;
- adjusting at least one of an in-phase DC offset or a quadrature DC offset in response to the LO leakage signal value;
- determining if the magnitude of the LO leakage signal value as adjusted is below a leakage threshold;
- and
- if the magnitude of the LO leakage signal value as adjusted is not below the leakage threshold, continuing to adaptively adjust at least one of the in-phase DC offset or the quadrature DC offset in response to the LO leakage signal value until the LO leakage value is below the leakage threshold.
9 more elements
A communication device-implemented method of processing communication signals, comprising:
- generating a in-phase baseband signal at a test frequency;
- generating a quadrature baseband signal at the test frequency;
- modulating a carrier signal by the in-phase and quadrature baseband signals to generate a modulated carrier signal;
- measuring a side band signal in the modulated carrier signal, the measuring step comprising:
- generating sums and differences of frequency components in the modulated carrier signal;
- low pass filtering the generated sums and differences;
- and
- utilizing the filtered sums and differences to generate a digital value proportional to the magnitude of a spectral component at the multiple of the test frequency, the digital value comprising a side band signal value;
- adjusting at least one of an in-phase gain, a quadrature gain, or a channel correlation in response to the side band signal value;
- determining if the magnitude of the side band signal value as adjusted is below a side band threshold;
- and
- if the magnitude of the side band signal value as adjusted is not below the side band threshold, continuing to adaptively adjust at least one of the in-phase gain, the quadrature gain, or the channel correlation in response to the side band signal value until the side band signal value is below the side band threshold.
9 more elements
A communication device, comprising:
- means for generating a in-phase baseband signal and a quadrature baseband signal at a test frequency;
- means for modulating a carrier signal by the in-phase and quadrature baseband signals;
- means for measuring at least one of a LO leakage signal or a side band signal in the modulated carrier signal, the measuring step comprising:
- generating sums and differences of frequency components in the modulated carrier signal;
- low pass filtering the generated sums and differences;
- and
- utilizing the filtered sums and differences to generate a digital value proportional to the magnitude of a spectral component at the test frequency, the digital value comprising a LO leakage signal value or a side band signal value, respectively;
- means for adjusting at least one of the LO leakage signal or side band signal in response to the LO leakage signal value or the side band signal value, respectively;
- means for determining if the magnitude of at least one of the LO leakage signal value is below a leakage threshold or the side band signal value is below a side band threshold;
- if the magnitude of the LO leakage signal value is not below the LO leakage Threshold, means for continuing to adaptively adjust at least one of an in-phase DC offset or a quadrature DC offset in response to the leakage signal value until the leakage signal value is below the leakage threshold;
- and
- if the magnitude of the side band signal value is not below the side band threshold, means for continuing to adaptively adjust at least one of an in-phase gain, a quadrature gain, or a channel correlation in response to the side band signal value until the side band signal value is below the side band threshold.
9 more elements
A communication system, comprising:
- a modulator configured to generate a modulated carrier signal modulated by an in-phase baseband signal and a quadrature baseband signal at a baseband signal frequency;
- a signal processor configured to detect at least one of a LO leakage signal or a side band signal in the modulated carrier signal, the signal processor comprising:
- a sum-and-difference signal generator configured to generate a plurality of signals based on the sum and differences of a carrier frequency and baseband signal frequency;
- a filter configured to pass at least one of the plurality signals having a frequency proportional to the baseband frequency signal;
- an analog-to-digital converter configured to generate a digital output value proportional to the magnitude of the at least one of the plurality signals;
- and
- a processor configured to receive the digital output value and generate a DC offset control signal in response to a spectral component at the baseband signal frequency or a gain control signal in response to a spectral component at a multiple of the baseband signal frequency;
- and
- a baseband signal controller configured to receive the at least one of the gain control signal or the DC offset control signal and generate at least one of a gain signal or an offset signal to adjust at least one of the LO leakage signal or side band signal, respectively,
- wherein the signal processor and baseband signal controller are operatively associated to adaptively lower the LO leakage signal by adjusting at least one of an in-phase DC offset or a quadrature DC offset in response to the LO leakage signal value until the LO leakage value is below a LO leakage value threshold or to adaptively lower the side band signal by adjusting at least one of an in-phase gain, a quadrature gain, or a channel correlation in response to the side band signal value until the side band signal value is below a side band signal value threshold.
7 more elements
Dependencies are inferred from the claim text.