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

摘要

A termination control circuit is coupled to a far end of a cable. A modulated test signal is reflected back to a near end of the cable at a different frequency but at substantially the same level of attenuation as the test signal. Signal attenuation in the reflected signal is then measured to determine the amount of attenuation in the test signal. A second embodiment of the termination control circuit measures crosstalk by enabling and disabling termination resistors at the far end of the cable. A DC bias voltage located at the near end of the cable selectively turns on switching diodes to enable the termination resistor. Alternatively, both the attenuation and crosstalk circuits are combined together allowing both signal attenuation and crosstalk measurements with the same termination control circuit.