Chapter 6 175
Custom Arb Waveform Generator
Working with Modulation Types
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.
Creating an FSK Modulation Type User File with the Frequency Values Editor
Use this procedure to set the frequency deviation for data 00, 01, 10, and 11 to configure a
user–defined FSK modulation.
1. Press
Preset.
2. Press
Mode > Custom > Real Time I/Q Baseband > Modulation Type > Define User FSK > More (1 of 2) > Delete All
Rows
> Confirm Delete All Rows.
This accesses the Frequency Values editor and clears the previous values.
3. Press
600 > Hz.
4. Press
1.8 > kHz.
5. Press
–600 > Hz.
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