Table of Contents
Advertisement
Selecting the appropriate frequency span (= start freq – stop freq) is not as obvious as it may seem.
The resolution and maximum distance range are dependent upon the span, the number of frequency
data points and the velocity factor of the cable. Therefore, the frequency span must be chosen
carefully.
There is a constraint that limits the frequency range:
Maximum Distance (meters) =
The wider the span is, the smaller the maximum distance that can be measured. In another words, long
distance measurements require small span settings.
Meanwhile, there is also a relationship between resolution and the span.
The wider the span, the smaller the resolution; wider frequency sweeps improve the resolution of DTF
measurements.
Table 4-3 Stop Distance
Parameter
Default
Range
Unit
Knob Step
Direction Key Step
4.1.4 Unit
Set the display units for the fault point distance, including the following two units. This value is also
displayed in the status bar on the left side of the screen.
�
Meter
�
Feet
The default unit is "Meter".
4.1.5 Velocity Factor
Set the velocity factor of the cable to be measured with respect to the speed of light in a vacuum. Make
sure that the velocity factor of the cable to be measured matches the actual value. Otherwise, the
position of the positioning point obtained from the measurement does not meet the actual
requirements.
This value is also displayed in the status bar on the left side of the screen.
Resolution (meters) =
Explanation
34.00 m
0.2 m - 34.00 m
m, feet
0.1 m
In 1-2-5 sequence(Unit: m)
10
7.68 x 10
x velocity factor
Start freq - stop freq (Hz)
8
1.5 x 10
x velocity factor
Start freq - stop freq (Hz)
T3VNA User Manual 81
Advertisement
Table of Contents
