HIGH IMPEDANCE ABSOLUTE TELEPHONE LINE VOLTAGE MEASUREMENT CIRCUIT

摘要

A TELEPHONE LINE MEASUREMENT CIRCUIT (40) IS DISCLOSED FOR DETECTING A VARIATION OF A CHARACTERISTIC BETWEEN A FIRST AND A SECOND LEADS OF A TELEPHONE LINE. THE CIRCUIT COMPRISES A FIRST CIRCUIT (41) HAVING A FIRST AND A SECOND INPUTS AND AN OUTPUT (63). THE CIRCUIT ALSO HAS A SECOND CIRCUIT HAVING (42) A FIRST AND A SECOND INPUTS AND AN OUPUT. THE FIRRST INPUT OF THE FIRST CIRCUIT AND THE SECOND INPUT OF THE SECOND CIRCUIT ARE COUPLED TO THE FIRST LEAD OF THE TELEPHONE LINE AND THE SECOND INPUT OF THE FIRST CIRCUIT AND THE FIRST INPUT OF THE SECOND CIRCUIT ARE AOUPLED TO THE SECOND LEAD THE TELEPHONE LINE. THE OUTPUTS OF THE FIRST AND THE SECOND CIRCUITS ARE THEN COUPLED TOGETHER TO PROVIDE AN OUTPUT (63) FOR THE MEASUREMENT CIRCUIT (40).(FIGURE 4)