Interpreting Measurement Results; Baseband Filtering Errors - Agilent Technologies ESA-E Series User And Programming Manual

Interpreting Measurement Results

The power of the Modulation Analysis Personality is its ability to
characterize the radio signal for transmitter troubleshooting. This
section illustrates how to interpret the data to indicate symptoms of
problems in radio signals.
The following radio signal errors are investigated in this section:

Baseband Filtering Errors

I/Q Gain Imbalance
I/Q Quadrature (Skew) Error
I/Q DC Offset Error
Symbol Rate Error
I/Q DC Offset Error
In-Channel Phase Modulation Interference
In-Channel Amplitude Modulation Interference
In-Channel Spurious Signal Interference
Baseband Filtering Errors
Filtering errors are among the most common in digital communication
design. Typical filter errors can be due to errors in filter alpha, wrong
filter shape, or incorrect filter coefficients. The result is increased
intersymbol interference. Lower peak overshoot is also caused by signal
compression, which can indicate that an amplifier stage is being
overdriven.
1. The vector diagram gives the first indication of baseband filtering
errors. Press
I/Q Measured Polar Vector
similar to that shown in
CDMA signal shown with a filter α of 0.22.
Chapter 4
Making Modulation Analysis Measurements
Interpreting Measurement Results
. The display should look
Figure 4-9. This is a normal Wideband
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