Line impedance

The impedance seen when looking toward the power source from the end of a power line, such as a commercial power outlet. When measuring conducted noise that travels along a power line, if the line impedance is low, the noise is displayed lower than its actual level; conversely, if it is high, the noise is displayed higher than its actual level. Therefore, it is a factor that causes errors in noise measurement. To eliminate errors in noise measurement caused by line impedance, a Line Impedance Stabilization Network (LISN) is used.