Math setups Set up the frequency spectral controls
Behavior
The maximum frequency span is equal to half of the sample rate. If you need a higher frequency span,
set the sample rate to a larger value.
The Resolution Bandwidth determines how small of a frequency difference can be resolved in the frequency
domain output data. It defines the bandwidth of filters used to perform the frequency domai n analysis.
The resolution bandwidth is measured in hertz at the 3dBpointsoneachsideofthepeakspectrallobe.
Adjusting the resolution bandwidth controls the g ate duration to obtain the desired resolution bandwidth.
NOTE. Th
e frequency domain controls interact with the gating and acquisition controls; changing one s et
of controls may change the other control settings.
What do
you want to do next?
Learn about the Gating controls. (see page 249)
Learn about the Math Setup controls. (see page 241)
Cent
er frequency
The center frequency is the frequency at the center of the frequency span. The maximum center
fre
quency is equal to the sample rate divided by two (the Nyquist frequency) minus one half the span.
The minimum center frequency is equal to one half of the span.
If
the frequency span is set to maximum, then the center frequency will not move. To increase the
center frequency beyond the present limits, either reduce the frequency span or increase the sample
rate. To decrease the center frequency beyond the present limits, reduce the frequency span.
Frequency span
The frequency span is the range of frequencies over which the spectral analysis is performed. The
maximum span is from DC to one half of the sample rate (the Nyquist frequency). A smaller
frequency span allows a greater range of center-frequency adjustment. If a larger frequency span
is desired, increase the sample rate.
248 DSA/DPO70000D, MSO/DPO/DSA70000C, DPO7000C, and MSO/DPO5000 Series
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