LANcat
User Manual
Page 7-22
When the reflected signal reaches the tester where the signal was
generated, the timer stops. By knowing the speed of the signal
traveling down the cable, you can determine the length of the
cable.
How do you know how fast the signal travels down the cable? All
cables have an inherent characteristic called Nominal Velocity of
Propagation (NVP
)
. This value can be determined by contacting
the cable manufacturer. NVP is the speed of signal propagation
through a cable, expressed as a percentage of the speed of light in a
vacuum (refer to Figure 7-13). Using the NVP value and the time
to receive the returned TDR pulse, the LANcat calculates the cable
length.
Figure 7-13. Cable Nominal Velocity of Propagation
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