310 Keysight EXG and MXG X-Series Signal Generators User’s Guide
Using Custom Digital Modulation for N5172B/82B with Option 431 and 653/655/656/657
Differential Encoding
This encodes the first symbol by adding a symbol table offset of 1. The symbol rotates forward
through the state map by 1 value when a data value of 0 is modulated.
2. Press +/– > 1 > Enter.
This encodes the second symbol by adding a symbol table offset of -1. The symbol rotates
backward through the state map by 1 value when a data value of 1 is modulated.
3. Press 2 > Enter.
This encodes the third symbol by adding a symbol table offset of 2. The symbol rotates
forward through the state map by 2 values when a data value of 10 is modulated.
4. Press 0 > Enter.
This encodes the fourth symbol by adding a symbol table offset of 0. The symbol does not
rotate through the state map when a data value of 11 is modulated.
Applying Custom Differential Encoding
Press Return > Differential Encoding Off On.
This applies the custom differential encoding to a user–defined modulation.
At this point, the modulation has one bit per symbol. For the first two data
values (00000000 and 00000001) only the last bits (the 0 and the 1,
respectively) are significant.
At this point, the modulation has two bits per symbol. For the data values
00000000, 00000001, 00000010, 00000011, the symbol values are 00, 01,
10, and 11 respectively.
Notice that (UNSTORED) appears next to Differential State Map on the signal
generator’s display. Differential state maps are associated with the user–defined modulation for
which they were created.
In order to save a custom differential state map, you must store the user–defined modulation for
which it was designed. Otherwise the symbol table offset data is purged when you press the
Confirm Exit From Table Without Saving softkey when exiting from the I/Q or FSK
table editor.
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