What device reads the size, shape, and return time of reflected pulses?

The Time Domain Reflectometer (TDR) is designed to send pulses of electricity down a cable or transmission line and measure the time it takes for those pulses to be reflected back. By analyzing the reflected pulses, a TDR can determine various characteristics of the cable, including its size, shape, and any discontinuities that may be present.

When a pulse encounters a change in impedance—such as a fault in the cable or a connector—it reflects back to the TDR. The device measures the time it takes for the returned signal to arrive, allowing it to calculate the distance to the fault based on the speed of the signal through the medium.

In contrast, while a cable fault locator can also identify faults in cables, it may not provide the same detailed analysis of size and shape as a TDR. An oscilloscope is used to visualize electrical signals in real-time but does not inherently measure the characteristics of cables directly. An SWR meter measures the standing wave ratio to assess the efficiency of power transmission but does not analyze time or the physical attributes of the cable itself like the TDR does.