Keysight N9923-90001 User’s Guide63Time Domain – Option 010OverviewOverviewIn normal NA Mode operation, the FieldFox measures the characteristics of atest device as a function of frequency. With Time Domain (opt 010), frequencyinformation is used to calculate the inverse Fourier transform and displaymeasurements with time on the horizontal display axis. The response valuesappear separated in time, allowing a different perspective of the test device'sperformance and limitations.The graphic below compares the same cable reflection measurement data inboth the frequency and time domain. The cable has two bends. Each bendcreates a mismatch or change in the line impedance.The frequency domain of an S11 measurement shows reflections caused bymismatches in the cable. It is impossible to determine where the mismatchesphysically occur in the cable.The Time Domain response shows both the location and the magnitude of eachmismatch. The responses indicate that the second cable bend is the location ofa significant mismatch. This mismatch can be gated out, allowing you to viewthe frequency domain response as if the mismatch were not present. Learnmore about gating in “Gating” on page 72.Markers that are created on a Time Domain trace can be used to pinpoint thedistance of the mismatch from the reference plane.For more information on Time Domain theory, seehttp://literature.cdn.keysight.com/litweb/pdf/5989-5723EN.pdf
