Rohde & Schwarz RTP Series - Page 409

Spectrum analysis
R&S
®
RTP
409User Manual 1337.9952.02 ─ 12
● To couple the used record length to the required RBW, select the "RBW con-
trolled" option. This option is only available if no gate is being used ("Use Gate"
disabled).
The required acquisition time for the defined RBW value is indicated.
● To restrict the basis of the FFT calculation to a certain time base, configure a
time gate, that is: an extract of the time base in the original diagram. To do so,
enable the "Use Gate" option, then do one of the following:
– Select the "Absolute" mode and enter the "Start" and "Stop" times that
define the gate area.
– Select the "Relative" mode and enter the percentages of the total time base
that define the "Relative Start" and "Relative Stop" times.
– If a zoom area has already been defined in the original diagram and you
want to use the same time base for FFT analysis, select "Zoom coupling".
The spectrum waveform displays the spectrum for the specified time span.
To configure magnitude results
1. Open [FFT] > "FFT setup" > "Setup" tab.
2. Set "Type" = "Magnitude".
3. In the "Scale" tab of the "Math" dialog, select the "Unit". Use logarithmic scaling
only for input values in Volt or Watt.
4. Select the "Vertical scale mode" to configure the value range manually or use the
automatic settings.
5. For "Vertical scale mode" > "Manual", define the size of the "Vertical range" and the
"Vertical maximum" to be displayed.
For "Vertical scale mode" > "Auto", define the size of the "Vertical range" to be dis-
played.
For logarithmic scaling ("Unit = dB"), also define the "Reference level" to be used.
To configure phase results
1. Open [FFT] > "FFT setup" > "Setup" tab.
2. Set "Type" = "Phase".
3. In the "Scale" tab of the "Math" dialog, select the "Unit".
4. To eliminate phase shifts due to a limitation of the value range, enable the
"Unwrap" function.
5. To suppress small phase values due to noise, enable the "Suppression" function
and enter a "Threshold" value.
FFT analysis