The invention relates to a real-time oscilloscope with a built-in time domain reflectometry (TDR) and/or time-domain transmission (TDT) function for measurements of a device under test (DUT). The real-time oscilloscope comprises at least one built-in generator and at least one real-time measurement channel. The built-in generator is in communication with the real-time measurement channel and the device under test (DUT) and is configured to generate incident signals. The real-time measurement channel is configured to capture incident signals transmitted to and reflected by and/or transmitted by the device under test (DUT).