Patent ID: 7671606

Claim:
A portable system for determining power line impedance, comprising: a set of test leads to be coupled to a power line interface; an impedance measurement system coupled to the set of test leads and comprising circuitry to generate a first resonant ring and a second resonant ring in an AC waveform, to measure frequencies or periods of the first and second resonant rings, and compute an impedance based on the frequencies or periods of the resonant rings; the impedance measurement system comprising a case that includes a resistor to be coupled to the power line interface, a first capacitor, a first switch for placing the resistor in a short circuit with the power line interface and for interrupting the short circuit to cause the first resonant ring between the first capacitor and an inductive and capacitive component of the power line impedance, a second capacitor, and a second switch for coupling a second capacitor to the first capacitor and the resistor to cause the second resonant ring between the first and second capacitors and the inductive and capacitive components of the power line impedance; measurement circuitry for measuring voltages during a test sequence in which the switches are switched on and off; processing circuitry for determining inductive and capacitive components of power line impedance based upon the measured voltages; and a display coupled to the impedance measurement system to communicate the computed impedance.