Keysight Technologies N9330B, Руководство пользователя

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Making Measurements
Measuring Distance to Fault (DTF)
33
Measured distance
It is not always understood how frequency range affects
measured distance and resolution, and may appears
counter-intuitive. This section is intended to help
simplify understanding the DTF measurement.
In the following equations:
Resolution refers to the number of points that are
measured and used in the displayed trace. Pressing
[MEAS/VIEW] > {Resolution}
enables you to change the
resolution setting.
• (V
t
/V
c
) refers to the velocity factor of a cable, its
transmission rate relative to light. The velocity factor
may be set by pressing
{Velo Factor}
.
• F2 and F1 refer to the stop and start frequency (MHz).
The measured distance (in meters) of a DTF
measurement is determined by the following equation:
Distance= (Resolution x 150 x V
t
/V
c
) / (F
2
–F
1
)
V
c
= 3 x 10
8
From this equation, you can adjust the measurement:
• To Increase the measured distance:
• Increase the number of points, 
or
• Reduce the frequency span.
• To decrease the measured distance:
• Reduce the number of points, 
or
• Increase the frequency span.