Question

Why is it convenient to use an uncalibrated time base on an oscilloscope to measure phase difference? Why is the actual time itself of no concern?

Answer 1

An oscilloscope plots voltage against increasing time. The main elements of the oscilloscope is a X-Y display, a voltage amplifier and a timebase. The voltage amplifier isconnected to vetical axis of the display. The time base is connected to the horizontal axis of the display.

Calibration is the comparison of a measurement device (an unknown) against an equal or better standard.

oscilloscopes seem to be basically non-precision andcalibration is needed unless the drift is massive. Basically there are two axes, time and voltage. Time is based on a crystal and is unlikely to ever drift . An oscilloscope is not considered to be a frequency counter and a drift of that amount is going to just cause a line in a waveform to move left or right probably not even an actual pixel on the screen for most measurements and since every measurement gets shifted if the time base is off.All the relative measurements are the same as if measured with a perfect time base.

Calibrating oscilloscope will maintain the integrity . Oscilloscopes need to read data accurately. If the oscilloscope is out-of-tolerance, then the product that is being measured will result in false information.

It is convenient to use uncalibrated oscilloscope because  oscilloscopes cost many times more than other types of electronic measuring instruments, such as multimeters. They are also very sophisticated, and tend to be costly to repair if damaged.