An apparatus for acquiring waveform data from a metallic transmission cable under test includes a transmitter for generating interrogating pulses for examining a segment or segment lengths of the transmission cable under test. A variable gain receiver receives a return signal from the segment or segment lengths of the cable and generates at least two gain segment acquisitions of waveform data representative of the signal from each segment or segment lengths with each gain segment acquisition of waveform data being generated with a different receiver gain. A controller operating under program control initiates the generation of interrogating pulses, establishes the receiver gain for each gain segment acquisition of waveform data, and controls the gain segment acquisitions of waveform data over the segment or segment lengths. An event table is created containing event characterization data for each gain segment. A congruent event filter passes events having optimum characterization data for display on a display device.