Agilent Technologies MSO6012A User Manual page 222

Making Measurements 5
Figure 32 FFT measurements
FFT Measurement Hints
The number of points acquired for the FFT record is 1000
and when frequency span is at maximum, all points are
displayed. Once the FFT spectrum is displayed, the
frequency span and center frequency controls are used much
like the controls of a spectrum analyzer to examine the
frequency of interest in greater detail. Place the desired part
of the waveform at the center of the screen and decrease
frequency span to increase the display resolution. As
frequency span is decreased, the number of points shown is
reduced, and the display is magnified.
While the FFT spectrum is displayed, use the Math and
Cursors keys to switch between measurement functions and
frequency domain controls in FFT menu.
Decreasing the effective sampling rate by selecting a slower
sweep speed will increase the low frequency resolution of
the FFT display and also increase the chance that an alias
will be displayed. The resolution of the FFT is the effective
sample rate divided by the number of points in the FFT. The
actual resolution of the display will not be this fine as the
shape of the window will be the actual limiting factor in the
6000 Series Oscilloscope User's Guide 221