3 Displaying Waveforms
66 InfiniiVision 7000B Series Oscilloscopes User’s Guide
In Roll mode there is no trigger. The fixed reference point on the
screen is the right edge of the screen and refers to the current
moment in time. Events that have occurred are scrolled to the left of
the reference point. Since there is no trigger, no pre- trigger
information is available.
If you would like to pause the display in Roll mode press the [Single]
key. To clear the display and restart an acquisition in Roll mode,
press the [Single] key again.
Use Roll mode on low-frequency waveforms to yield a display much
like a strip chart recorder. It allows the waveform to roll across the
display.
XY Time Mode
The XY time mode converts the oscilloscope from a volts- versus- time
display to a volts-versus- volts display using two input channels. Channel 1
is the X- axis input, channel 2 is the Y-axis input. You can use various
transducers so the display could show strain versus displacement, flow
versus pressure, volts versus current, or voltage versus frequency. This
exercise shows a common use of the XY display mode by measuring the
phase difference between two signals of the same frequency with the
Lissajous method.
1 Connect a sine wave signal to channel 1, and a sine wave signal of the
same frequency but out of phase to channel 2.
2 Press the [AutoScale] key, press the [Horiz] key; then, press Time Mode
and select “XY”.
3 Center the signal on the display with the channel 1 and 2 position ( )
knobs. Use the channel 1 and 2 volts/div knobs and the channel 1
and 2 Fine softkeys to expand the signal for convenient viewing.
The phase difference angle () can be calculated using the following
formula (assuming the amplitude is the same on both channels):
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