I/Q Dc Offset Error - Agilent Technologies ESA-E Series User And Programming Manual

I/Q DC Offset Error

DC offset is characteristic of an improperly adjusted balanced
modulator. Typically, these offsets are added in the amplifier in the I
and Q paths. This type of error should be indicated in a displaced
constellation from the origin of the I/Q plane. However, any DC offset is
reported in the summary/symbol table only, since the analyzer
measures and removes this offset during demodulation.
1. Use the I/Q polar constellation diagram to identify I/Q DC offset
errors. Press
error is shown in
errors shown in the vector diagram itself. However, the I/Q offset
value in the table is about –28 dBc (item 1), and should be closer to
–52 dBc for a Wideband CDMA signal.
Figure 4-25 Polar Vector Showing I/Q DC Offset Error
Chapter 4
Making Modulation Analysis Measurements
I/Q Measured Polar Vector
Figure 4-25. Observe that there are no noticeable
Interpreting Measurement Results
. A signal with an I/Q DC offset
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