Measurement of cable quality by power over ethernet

A power sourcing equipment operative to determine an impedance between the power sourcing equipment and a powered device, the power sourcing equipment comprising:

• a voltage measuring means;
• a control circuitry responsive to said voltage measuring means;
• and
• at least one current limiter responsive to said control circuitry,
• said control circuitry operative to:
• supply power to a powered device over a communication cabling at a first current limited level, Ilim1, said Ilim1 being responsive to said at least one current limiter;
• measure, via said voltage measuring means, at a plurality of times in relation to the beginning of said power being supplied at said Ilim1, a voltage associated with the output of the power sourcing equipment;
• determine a minimum voltage, Vmin1, of said measured plurality of voltages;
• determine an associated time, tmin, of said determined Vmin1 in relation to said beginning of said power being supplied at said Ilim1;
• remove, subsequent to said power being supplied at said Ilim1, said supplied power from the powered device;
• subsequent to said removal of power, supply power to the powered device over the communication cabling at a second current limited level, Ilim2, said Ilim2 being different than said Ilim1, said Ilim2 being responsive to said at least one current limiter;
• measure, via said voltage measuring means, at said determined associated time tmin in relation to the beginning of said power being supplied at said Ilim2, a voltage associated with the output of the power sourcing equipment, Vmin2;
• and
• determine an impedance responsive to said Vmin1, Vmin2, Ilim1 and Ilim2.