To become an expert at capturing pulses, you should learn how to use trigger holdoff and how to set the digitizing oscilloscope to capture pretrigger data, as described earlier in the Controls section. Horizontal magnification is another useful feature for measuring pulses, since it allows you to see fine details of a fast pulse. The horizontal control section may have an XY mode that lets you display an input signal rather than the time base on the horizontal axis. This mode of operation opens up a whole new area of phase shift measurement techniques. The phase of a wave is the amount of time that passes from the beginning of a cycle to the beginning of the next cycle, measured in degrees.
Phase shift describes the difference in timing between two otherwise identical periodic signals.
One method for measuring phase shift is to use XY mode. This involves inputting one signal into the vertical system as usual and then another signal into the horizontal system. This set up is called an XY measurement because both the X and Y axis are tracing voltages. From the shape of the Lissajous pattern, you can tell the phase difference between the two signals. You can also tell their frequency ratio.