| 摘要 |
A method and apparatus for a telephone line interface or data access arrangement (DAA) which includes a shunt regulator in series with a line modulator. A first sense resistor is placed in series between the shunt regulator and the line modulator to provide a measurement of the amount of current distortion in the DAA shunt regulator. The voltage across the first sense resistor is fed back to the line modulator. A second sense resistor is inserted into the line modulator circuitry to provide a measurement of the system current distortion that is outside of the path containing the sense resistor used to monitor the current distortion in the DAA shunt regulator. The voltage across the second sense resistor is also fed back to the line modulator. The line modulator is capable of adjusting the AC modulation and the DC termination presented to the telephone line. The method includes drawing power from the telephone line using a shunt regulator, modulating the telephone line in series with the shunt regulator, sensing a level of distortion in the shunt regulator, sensing a level of distortion outside the shunt regulator, and feeding the sensed levels of distortion to the line modulator.
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