Method and apparatus for adaptive DC level control
First Claim
1. A method for DC level control for a line card, comprising:
- receiving a digital input signal;
determining a first DC component value of the digital input signal at a first selected time;
determining a second DC component value of the digital input signal at a second selected time;
determining a difference between the first DC component value and the second DC component value; and
providing the first DC component value to a digital-to-analog converter in response to determining that the difference is less than a first selected value.
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Accused Products
Abstract
A method and apparatus is provided for DC level control in a line card. The method includes receiving a digital input signal, determining a first DC component value of the digital input signal at a first preselected time, and determining a second DC component value of the digital input signal at a second preselected time. The method further includes determining a difference between the first DC component value and the second DC component value. The method includes providing the first DC component value to a digital-to-analog converter in response to determining that the difference is less than a first preselected value. The apparatus includes a digital-to-analog converter and logic. The logic is coupled to the digital-to-analog converter, wherein the logic is capable of receiving a digital input signal, determining a first DC component value of the digital input signal at a first preselected time, and determining a second DC component value of the digital input signal at a second preselected time. The logic is farther capable of determining a difference between the first DC component value and the second DC component value, and providing the first DC component value to the digital-to-analog converter in response to determining that the difference is less than a first preselected value.
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Citations
20 Claims
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1. A method for DC level control for a line card, comprising:
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receiving a digital input signal; determining a first DC component value of the digital input signal at a first selected time; determining a second DC component value of the digital input signal at a second selected time; determining a difference between the first DC component value and the second DC component value; and providing the first DC component value to a digital-to-analog converter in response to determining that the difference is less than a first selected value. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An apparatus, comprising:
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a digital-to-analog converter; and logic coupled to the digital-to-analog converter, the logic capable of; receiving a digital input signal; determining a first DC component value of the digital input signal at a first selected time; determining a second DC component value of the digital input signal at a second selected time; determining a difference between the first DC component value and the second DC component value; and providing the first DC component value to the digital-to-analog converter in response to determining that the difference is less than a first selected value. - View Dependent Claims (8, 9, 10, 11)
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12. An apparatus, comprising:
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a digital-to-analog converter; and a DC cancellation feedback loop comprising; an analog-to-digital converter capable of receiving a signal having a DC component from a subscriber line, the analog-to-digital converter capable of converting the signal to a digital signal; DC cancellation logic capable of approximating a first DC value proportional to the DC component of the digital signal at a first selected time and a second DC value proportional to the DC component of the digital signal at a second selected time; first logic capable of determining a difference between the first DC value and the second DC value and providing the difference to the DC cancellation logic; and second logic capable of providing the first DC value to the digital-to-analog converter in response to determining that the difference is less than a first selected value. - View Dependent Claims (13, 14, 15)
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16. A line card, comprising:
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a subscriber line interface circuit capable of interfacing with a telephonic device and providing a signal; a digital-to-analog converter; and a digital signal processor configured to receive the signal from the subscriber line interface circuit, the digital signal processor capable of; determining a first DC component value of a received digital input signal at a first selected time; determining a second DC component value of the digital input signal at a second selected time; determining a difference between the first DC component value and the second DC component value; and providing the first DC component value to the digital-to-analog converter in response to determining that the difference is less than a first selected value. - View Dependent Claims (17, 18, 19)
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20. An apparatus, comprising:
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means for receiving a digital input signal; means for determining a first DC component value of the digital input signal at a first selected time; means for determining a second DC component value of the digital input signal at a second selected time; means for determining a difference between the first DC component value and the second DC component value; and means for providing the first DC component value to a digital-to-analog converter in response to determining that the difference is less than a first selected value.
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Specification