Line impedance matching using dynamically generated transfer functions

A system for determining a transfer function for a transmission line comprising:

• means for generating a test signal;
• line interface means connecting said test signal generating means and said transmission line;
• means for transmitting said test signal through said interface means to said transmission line;
• means for monitoring an echo signal from said transmission line after said echo signal passes through said line interface means, wherein said echo signal corresponds to said transmitted test signal;
• means for correlating said test signal and said echo signal to generate a system impulse response;
• means for generating a system transfer function from said system impulse response;
• means for calculating a transmission line transfer function using said system transfer function and a line interface means transfer function.

A system for determining the impedance of a telephone transmission line comprising:

• a switch connecting a local telephone system to a telephone transmission line, wherein said switch provides a conversion between analog signals on said telephone transmission line and digital signals on said local telephone system;
• and
• a digital signal processor for generating a test signal and for transmitting said test signal over said transmission line, wherein said digital signal processor monitors an echo signal corresponding to said transmitted test signal, and wherein said digital signal processor correlates said transmitted test signal and said echo signal to generate an impulse response;
• wherein a system transfer function is derived from said impulse response, said transfer function representing the frequency domain transfer function of said switch in combination with said transmission line;
• a transmission line transfer function is derived from said system transfer function and a transfer function of said switch;
• and a transmission line impedance is calculated from said transmission line transfer function.