Instrument Function
R&S
®
SMU200A
170Operating Manual 1007.9845.32 ─ 15
5.3.3.3 Constellation Diagram
In the constellation diagram, the Q component is also displayed over the I component.
However, only the values at the constellation points (signal value at the ideal scanning
instant of the symbol) are displayed, i.e. for each symbol only 1 value in the form of a
circle is shown for the I and Q component.
The amplitudes of the signal components scaled to the peak envelope power (PEP) are
plotted on the X and Y axis (minimum scaled amplitude = -1; maximum scaled amplitude
= +1). The recording depth is 2kSamples.
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).
This display shows the various states of modulation mapping which occur in the signal.
The example shows the constellation diagram of a QPSK modulation signal.
Graphical Display - Graphics
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