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Notes for using FFT
Use the default
dB
scale for details of multiple frequencies, even if they have very different
amplitudes. Use the
Vrms
scale to compare frequencies.
DC component or offset can cause incorrect magnitude values of FFT waveform. To minimize
the DC component, choose AC Coupling on the source signal.
To reduce random noise and aliased components in repetitive or single-shot events, set the
oscilloscope acquisition mode to average.
What is Nyquist frequency?
The Nyquist frequency is the highest frequency that any real-time digitizing oscilloscope can
acquire without aliasing. This frequency is half of the sample rate. Frequencies above the Nyquist
frequency will be under sampled, which causes aliasing. So, pay more attention to the relation
between the frequency being sampled and measured.
9.8 XY Mode
XY mode is used to display the amplitude of one waveform versus the amplitude of another. The
data point from the first waveform defines the horizontal position, while the corresponding data
point from the second waveform shows the vertical position for each point.
The oscilloscope is in the untriggered sampling mode: the data are displayed as bright points.
Operating the buttons:
When the HOR button is lit, the upper and lower buttons are used to adjust the horizontal scale
and position
If one of the channel buttons is lit, the vertical scaling and position are set with the upper and
lower buttons
The following functions are not available in the XY mode:
Reference or digital waveforms
Cursor
Trigger controll
FFT
Operating steps:
1. Click
to call up the menu panel. Click the
XY
softkey on panel to switch to the ON state
2. To make the XY view full screen, select
Full Screen
as
ON
in the bottom menu
9.9 Pass/Fail
The
Pass/Fail
function monitors changes of signals and output pass or fail signals by comparing
the input signal that is within the pre-defined mask.
Click
to call up the menu panel. Click the
P/F
softkey on panel to switch to the ON state.
