Crosstalk injection when testing transmission systems

One of the key performance requirements specified for local loop transmission systems is that of performance in the presence of crosstalk. Objective testing requires the injection of known levels of synthetic crosstalk into test copper pair loops with variable and frequency dependent impedances. It has been shown that a transformer with multiple secondaries in combination with a high performance buffer amplifier can be used to inject controlled levels of synthetic crosstalk without the use of complicated calibration procedures.