R&S FSV-K70, Руководство пользователя

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Brief Description of Vector Signal Analysis
R&S
®
FSV-K70
55 Operating Manual 1176.7578.02 ─ 09
I/Q Offset (Origin Offset)
Figure 2-51: Effect of an I/Q or origin offset after demodulation and error compensation
Figure 2-51 shows the effect of an I/Q offset in the transmitter.
The I/Q offset can be compensated for if the corresponding option is selected in the
demodulation settings. In this case, the offset does not affect the EVM.
Gain Imbalance
Figure 2-52: Effect of gain imbalance
The gain difference in the I and Q channels during signal generation in the transmitter
is referred to as gain imbalance. The effect of this error on the constellation diagram
and the unit circle are shown in
Figure 2-52 . In the example, the gain in the I channel is
slightly reduced which causes a distortion of coordinates in the I direction. The unit cir-
cle of the ideal constellation points has an elliptic shape.
The gain imbalance can be compensated for if the corresponding option is selected in
the demodulation settings. In this case, the imbalance does not affect the EVM.
Signal Model, Estimation and Modulation Errors