Instrument Function
R&S
®
SMU200A
173Operating Manual 1007.9845.32 ─ 15
5.3.3.6 Power Spectrum
With the spectrum display, the signal spectrum is calculated from the I/Q signal by means
of Fast Fourier Transform (FFT).
The power density over frequency is displayed. The power density is plotted on the Y
axis, and the frequency is plotted symmetrically on the X axis (-sampling rate/2 to +sam-
pling rate/2). FFT Points indicates the number of I/Q value pairs which are used for cal-
culating a (part-)FFT. AVG indicates the number of subspectra used for averaging. The
recording depth is 8kSamples.
This signal is picked off at the output of the baseband main module ("Impairment" function
block), i.e. contained in the displayed signal is:
●
impairment of the signal as defined by the user and the addition of noise.
●
Fading of the signal as defined by the user
●
an added external (Baseband Input)
●
an added internal signal (from the second path).
The spectrum display of the output signal is particularly suitable for checking multi carrier
signals.
Graphical Display - Graphics
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