Using an Oscilloscope to Measure Wire Length

Method Core: Time Domain Reflectometry (TDR) Principle

By sending a fast pulse signal into one end of the wire, the signal reflects back after reaching the other end. The oscilloscope captures the time difference between the transmitted and reflected signals. Combined with the signal propagation speed in the wire, the length of the wire can be accurately calculated (length = signal propagation speed × time).

 

Validation through Actual Measurement:

Equipment Connection: The signal source, the network cable under test (actual length 2 meters), and the oscilloscope were connected via adapters.
Waveform Capture: The oscilloscope automatically displayed the transmitted and reflected signals.
Time Difference Measurement: The cursor function was used to precisely measure the time interval between the edges of the two signals.
Automatic Calculation: By substituting the values into the formula (Length = Speed of Light × Velocity Factor × Time Difference / 2), the result was calculated as 1.98 meters. The error was extremely small, fully meeting the needs of daily engineering and experimental applications.

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