Agilent Technologies 7000B Series - Figure 6 Signals Are 90 out of Phase

3 Displaying Waveforms
70 InfiniiVision 7000B Series Oscilloscopes User’s Guide
Figure 6 Signals are 90 out of phase
NOTE
Z-Axis Input in XY Display Mode (Blanking)
When you select the XY display mode, the time base is turned off. Channel 1 is the X-axis
input, channel 2 is the Y-axis input, and channel 4 (or the External trigger on 2-channel
models) is the Z-axis input. If you only want to see portions of the Y versus X display, use
the Z-axis input. Z-axis turns the trace on and off (analog oscilloscopes called this Z-axis
blanking because it turned the beam on and off). When Z is low (<1.4 V), Y versus X is
displayed; when Z is high (>1.4 V), the trace is turned off.