Agilent Technologies FieldFox N9923A User Manual page 44

DTF Units
By default, X-axis units for DTF measurement settings are displayed in Meters.
How to change DTF units
 With a DTF measurement present, press Freq/Dist .
 Then
 The current selection is underlined
Frequency Mode
All DTF measurements are made with frequency settings and, using Inverse Fast
Fourier Transform (IFFT), the time and distance to faults are calculated.
How to set Frequency Mode
With a DTF measurement present,
 Press Meas Setup 4
 Then
 Choose one of the following:
Typically, you will set the frequency range of the measurement to the passband
of the filter. However, you may also want to test the ability of the filter to reject
unwanted frequencies. In this case, set the frequency range to include those
frequencies which the filter may not be adequately rejecting.
When the DTF frequencies are set manually, they may not be the optimum
frequencies for measuring the distance to fault. The distance may no longer be
alias-free. Learn more about alias-free range on page 49.
How to manually set Frequencies in Bandpass Mode
 Press Freq/Dist
 Then
 Then
OR
 Press
 Then
44
DTF Units.
Frequency Mode
The frequency range of a DTF measurement is set
Lowpass Mode
o
automatically based on the Start and Stop Distances. Use Lowpass mode
when the DUT is a cable ONLY.
(Default setting) The frequency range of a DTF
Bandpass Mode
o
measurement is set manually. Use Bandpass mode when the DUT contains a
diplexer or other filtering device which does not pass some frequencies.
Min Start Freq and type the start of the frequency range to use for the
DTF measurement.
Max Stop Freq and type the stop frequency to use for the DTF
measurement.
More
and type the frequency range to use for the DTF
Max Freq Span
measurement.
m (meters) Feet.
N9923A FieldFox User's Guide