Method and apparatus for measuring attenuation and crosstalk in data and communication channels

A circuit for measuring crosstalk in transmission channels, comprising:

• a cable having a characteristic impedance, a near end and a far end;
• an impedance matching circuit coupled to the far end of the cable, the impedance matching circuit including a resistor having a resistance substantially equal to the characteristic impedance of the cable and a switching device coupled to the resistor;
• an actuation circuit coupled at the near end of the cable comprising a power supply for selectively switching the switching device on and off from the near end of the cable selectively coupling the resistor across the far end of the cable for operating the cable as an antenna, the cable receiving the crosstalk signals transmitted from surrounding transmission channels;
• and
• a receiver coupled to the near end of the cable for measuring the crosstalk signals.

A method for measuring attenuation and crosstalk in a channel, comprising:

• transmitting a test signal and a control signal from a near end to a far end of the channel, the test signal and control signal each having an associated frequency and amplitude;
• mixing the test signal and the control signal at the far end of the channel together forming a measurement signal, the measurement signal having a frequency component different than the frequencies of the test signal and the control signal and having an amplitude attenuated amount substantially equal to an amount of attenuation in the test signal;
• reflecting the measurement signal back to the near end of the channel;
• filtering the measurement signal from both the test signal and the control signal;
• measuring the amount of attenuation in the measurement signal thereby determining an amount of attenuation in the test signal;
• operating the channel as an antenna for receiving external crosstalk signals transmitted by surrounding devices;
• and
• measuring the external crosstalk signals received on the channel at the near end of the channel.