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140 Chapter 6
Custom Arb Waveform Generator
Working with Modulation Types
6. Press More (1 of 2) > Load/Store > Store To File.
If there is already a file name from the Catalog of IQ Files occupying the active entry area, press
the following keys:
Editing Keys > Clear Text
7. Enter a file name (for example, NEW4QAM) using the alpha keys and the numeric keypad.
8. Press
Enter. The user-defined I/Q State Map should now be stored in the Catalog of IQ Files and
can be recalled even after the E8267C PSG signal generator has been turned off.
Modifying a Predefined I/Q Modulation Type (I/Q Symbols) & Simulating Magnitude Errors & Phase Errors
Use the following procedure to manipulate symbol locations which simulate magnitude and phase errors. In
this example, you edit a 4QAM constellation to move one symbol closer to the origin.
1. Press
Preset.
2. Press
Mode > Custom > Real Time I/Q Baseband > Modulation Type > Define User I/Q > More (1 of 2) >
Load Default I/Q Map > QAM > 4QAM.
This loads a default 4QAM I/Q modulation into the I/Q Values editor.
3. Press
More (2 of 2).
4. In the I/Q Values editor, navigate to Data 00000000 and press
Edit Item.
5. Press
.235702 > Enter, then .235702 > Enter.
When you press
Enter the first time, the I value updates and the highlight moves to the first Q entry. The
second time, the Q value updates and the highlight moves to the following I entry.
6. Press
Display I/Q Map. Note that one symbol has moved, as shown.