Agilent Technologies Fault Location Measurements Using Low Pass

3-18
Making Time Domain Measurements
Time Domain Low Pass Mode
Fault Location Measurements Using Low Pass
As described, the low pass mode can simulate the TDR response of the test device. This
response contains information useful in determining the type of discontinuity present.
Figure 3-13 illustrates the low pass responses of known discontinuities. Each circuit
element was simulated to show the corresponding low pass time domain S11 response
waveform. The low pass mode gives the test device response either to a step or to an
impulse stimulus. Mathematically, the low pass impulse stimulus is the derivative of the
step stimulus.
Figure 3-13 Simulated Low Pass Step and Impulse Response Waveforms
(Real Format)
Figure 3-14 shows example cables with discontinuities (faults) using the low pass step
mode with the real format.