Measure the Length of Cable by an Oscilloscope

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As the above screenshot shows, the time difference between the transmitted signal and the reflected

the signal is 61.2 nanoseconds, which is calculated using the formula as below.

The calculated cable length is 5.504 meters, and the actual length of the cable is 5.5 meters.

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If the speed factor of a certain cable is unknown, you can calculate the VF by a cable of a known length.

VF = cable speed factor, constant, without unit.

L = cable length, unit: meter.

Δt = the time difference between the transmitted signal and reflected signal, unit: second.

C = speed of light, unit: meters per second.