Method and apparatus for performing impedance measurements on a communication line

Claim 1

A device for altering the electrical condition of a communication line to allow impedance measurements to be performed on the communication line at a remote location from said device, said device comprising: first and second switches formed on a single semiconductor chip for connection in parallel to a first conductor of the communication line, each switch establishing a respective electrical path capable of altering the electrical condition of the communication line, each switch being capable of assuming an opened condition and a closed condition for controlling a state of conduction of a respective electrical path, in said opened condition each switch manifesting a high impedance to substantially prevent passage of electrical current therethrough, in said closed condition each switch manifesting a low impedance to allow passage of electrical current therethrough, said first and second switches having similar impedance characteristics; and a logic module means for a) actuating said first and second switches to either condition thereof; b) during a first time interval, maintaining said first switch in said closed condition and maintaining said second switch in said opened condition; and c) during a second time interval, maintaining said first and second switches in said closed condition, whereby successive impedance measurements of the communication line during said first and second time intervals permits a determination with relative precision of a parasitic impedance of said first and second switches.

Claim 2

A device for altering the electrical condition of a communication line to allow impedance measurements to be performed on the communication line at a remote location from said device, said device comprising: first and second switches formed on a single semiconductor chip for connection in parallel to a first conductor of the communication line, each switch establishing a respective electrical path capable of altering the electrical condition of the communication line, each switch being capable of assuming an opened condition and a closed condition for controlling a state of conduction of a respective electrical path, in said opened condition each switch manifesting a high impedance to substantially prevent passage of electrical current therethrough, in said closed condition each switch manifesting a low impedance to allow passage of electrical current therethrough, said first and second switches having similar impedance characteristics; and a logic module means for a) actuating said first and second switches to either condition thereof; b) during a first time interval, maintaining said first switch in said closed condition and maintaining said second switch in said opened condition; and c) during a second time interval, maintaining said first and second switches in said closed condition, whereby successive impedance measurements of the communication line during said first and second time intervals permits a determination with relative precision of a parasitic impedance of said first and second switches.

Claim 6

A method for measuring impedance parameters of a communication line, said method comprising the steps of: a) connecting at a certain location on the communication line first and second switches formed on a single semiconductor chip, in parallel to a first conductor of the communication line, each switch establishing a respective electrical path for altering the electrical condition of the communication line, each switch being capable of assuming an opened condition and a closed condition for controlling a state of conduction of a respective electrical path, in said opened condition each switch manifesting a high impedance to substantially prevent passage of electrical current therethrough, in said closed condition each switch manifesting a low impedance to allow passage of electrical current therethrough, said first and second switches having similar impedance characteristics; b) maintaining said first switch in said closed condition and said second switch in said opened condition for a first time period; c) measuring an impedance parameter of the communication line at a point remote from said certain location during said first time period; d) maintaining said first and second switches in said closed condition during a second time period; e) measuring an impedance parameter during said second time period; f) deriving from impedance values obtained at steps c) and e) a correction factor representative of a parasitic impedance of said first and second switches; and g) utilizing said correction factor to derive with a relative precision a value of an impedance parameter of the communication line.

Claim 7

A method for measuring impedance parameters of a communication line, said method comprising the steps of: a) connecting at a certain location on the communication line first and second switches formed on a single semiconductor chip, in parallel to a first conductor of the communication line, each switch establishing a respective electrical path for altering the electrical condition of the communication line, each switch being capable of assuming an opened condition and a closed condition for controlling a state of conduction of a respective electrical path, in said opened condition each switch manifesting a high impedance to substantially prevent passage of electrical current therethrough, in said closed condition each switch manifesting a low impedance to allow passage of electrical current therethrough, said first and second switches having similar impedance characteristics; b) maintaining said first switch in said closed condition and said second switch in said opened condition for a first time period; c) measuring an impedance parameter of the communication line at a point remote from said certain location during said first time period; d) maintaining said first and second switches in said closed condition during a second time period; e) measuring an impedance parameter during said second time period; f) deriving from impedance values obtained at steps c) and e) a correction factor representative of a parasitic impedance of said first and second switches; and g) utilizing said correction factor to derive with a relative precision a value of an impedance parameter of the communication line.