The 80E10 is a dual channel Time Domain Reflectometry (TDR) sampling module, providing up to 12 ps incident and 15 ps reflected rise time. Each channel of the module is capable of generating a fast step for use in TDR mode and the acquisition portion of the sampling module monitors the incident step and any reflected energy. The polarity of each channel's step can be selected independently. This allows for differential or common-mode TDR or S-parameters testing of two coupled lines, in addition to the independent testing of isolated lines. The independent step generation for each channel allows true differential measurements, which ensures measurement accuracy for differential devices.