
Chapter 3 133
Basic Digital Operation
Differential Encoding
Configuring User-Defined I/Q Modulation
1. Press
Preset.
2. Perform the following keypress sequence required for your format type.
For Custom Format
Press
Mode > Custom > Real Time I/Q Base Band > Modulation Type > Define User I/Q >
More (1 of 2) > Load Default I/Q Map > QAM > 4QAM
For TMDA Formats
Press
Mode > Real Time TDMA > desired format > More (1 of 2) > Modify Standard >
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 and displays it in the I/Q table editor.
The default 4QAM I/Q modulation contains data that represent 4 symbols (00, 01, 10, and
11) mapped into the I/Q plane using 2 distinct values (1.000000 and −1.000000). These 4
symbols will be traversed during the modulation process by the symbol table offset values
associated with each symbol of data. Refer to Figure 3-31.
Figure 3-31
Accessing the Differential State Map Table Editor
Press
Configure Differential Encoding.
This opens the Differential State Map table editor, as shown. At this point, you see the
data for the 1st symbol (00000000) and the cursor prepared to accept an offset value.You are
now prepared to create a custom differential encoding for the user-defined default 4QAM I/Q
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