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Modulation Measurements Measurements
5-50 MS278XB OM
QPSK Measurement
The next class of modulation quality measurements is when you don’t have a full WCDMA transmitter,
but you want to measure the modulation quality anyway. This is a common test for RF components, for
example. These are called QPSK measurements, as you would use a QPSK-modulated signal generator
as a source.
Component measurements are similar to QAM/PSK measurements, except they are at a WCDMA chip
rate of 3.84 MHz. Signature is capable of displaying:
• Vector Diagram & Constellation
• Power vs. Time
• EVM, Magnitude Error, Phase Error, or all 3 vs. Time
• Eye Diagrams (I, Q, or both)
• Optional Summary table with any diagram
• EVM (RMS, Peak, Peak Location)
• Magnitude & Phase Error
• IQ Offset
• Frequency Error
The graph types are set up using the Graph Type setup dialog shown below by pressing the button for
the measurement you want. Each tab also has a check box that is usually in the lower left corner. This is
an option to the measurement. In the dialog shown below, the option is to include a Summary table to
each of the selected graphs.
Figure 5-27. QPSK Graph Type Setup Dialog