Deviser S7200 User Manual page 88

Part II: Settings and Measurements
Sweep Speed
There are two ways to set the sweep speed: manual and automatic. In manual mode, an asterisk (*)
appears near the sweep speed parameter at the top of the screen.
In the bandwidth menu, tap Sweep. Select Auto to allow the S7200 to choose a suitable sweep time
according to the active Span, VBW, and RBW settings; or Manual to enter a new value. Press Enter to
confirm.
Note that Spectrum analyzers normally couple sweep time, span, and resolution bandwidth automatically.
This allows the measured signal enough time to achieve full amplitude within the RBW for an accurate &
calibrated measurement.
If any of the parameters are manually set, "UNCAL" appears in the status bar at the bottom of the screen.
Spectrum calculation mode
The S7200 has two spectrum calculation modes: FFT and DFT (fast / discrete Fourier transform, respectively).
Tap [DFT]/[FFT] in the bandwidth menu to toggle between them.
DFT is the foundation of FFT, and FFT is the fast algorithm of DFT. Every result calculated with DFT represents a
pixel point of the spectrum trace, while every result calculated with FFT represents a limited segment of the
spectrum trace. In general, FFT is better suited for high sweep speeds.
Spectrum hold
In the BW/SWP menu, tap Hold to pause the trace for detailed analysis. Press Hold again to resume normal
operation.
Auto Sweep Time
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Manual Sweep Time, causing UNCAL warning