Patent ID: 7405574

Claim:
A signal detector comprising: a power input terminal supplied with power voltage from a power supply source; a power output terminal connected to a device to be measured, and outputting the power voltage inputted from the power input terminal to the device to be measured; a signal blocking circuit provided on first and second conductive lines connected to the power input terminal, and blocking transmission of a signal between the power input terminal and the power output terminal; a common-mode signal detection circuit extracting a common mode signal from signals contained in the power voltage between the power output terminal and the signal blocking circuit; a normal-mode signal detection circuit extracting a normal mode signal from the signals contained in the power voltage between the power output terminal and the signal blocking circuit; a common-mode signal output terminal provided at an output end of the common-mode signal detection circuit; and a normal-mode signal output terminal provided at an output end of the normal-mode signal detection circuit.