Agilent Technologies 8753ET User Manual page 205

Making Time Domain Measurements
Time Domain Low Pass Mode
Interpreting the Low Pass Response Vertical Axis
The vertical axis depends on the chosen format. In the low pass mode, the frequency domain data is taken at
harmonically related frequencies and extrapolated to dc. Because this results in the inverse Fourier
transform having only a real part (the imaginary part is zero), the most useful low pass step mode format in
this application is the real format. It displays the response in reflection coefficient units. This mode is similar
to the traditional TDR response, which displays the reflected signal in a real format (volts) versus time (or
distance) on the horizontal axis.
The real format can also be used in the low pass impulse mode, but for the best dynamic range for
simultaneously viewing large and small discontinuities, use the log magnitude format.
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