Agilent Technologies E8247C PSG CW - Manual (Page 149)

Chapter 6 139
Custom Arb Waveform Generator
Working with Modulation Types
Creating a QPSK I/Q Modulation Type User File with the I/Q Values Editor
In I/Q modulation schemes, symbols appear in default positions in the I/Q plane. Using the I/Q Values
editor, you can define your own symbol map by changing the position of one or more symbols. Use the
following procedure to create and store a 4-symbol unbalanced QPSK modulation.
1. Press
Preset
.
2. Press
Mode
>
Custom
>
Real Time I/Q Baseband
>
Modulation Type
>
Define User I/Q
>
More (1 of 2)
>
Delete All Rows
>
Confirm Delete All Rows
.
This loads a default 4QAM I/Q modulation and clears the I/Q Values editor.
3. Enter the I and Q values listed in the following table:
a. Press
0.5
>
Enter
.
b. Press
1
>
Enter
.
c. Enter the remaining I and Q values.
As the I value updates, the highlight moves to the first Q entry (and provides a default value of 0) and an
empty row of data appears below the first row. As the Q value updates, the highlight moves to the next I
value. As you press the numeric keys, the numbers display in the active entry area. If you make a
mistake, use the backspace key and retype.
Also note that 0.000000 appears as the first entry in the list of Distinct Values , and that
0.500000 and 1.000000 are listed as the distinct values.
4. Press
More (2 of 2)
>
Display I/Q Map
.
An I/Q State Map is displayed from the current values in the I/Q Values table.
The I/Q State Map in this example has four symbols. The I/Q State Map uses the following four unique
values: 0.5, 1.0,
−
0.5, and
−
1.0 to create the four symbols. It is not the number of values that defines how
many symbols a map has, but how those values are combined.
5. Press
Return
.
When the contents of an I/Q Values table have not been stored, I/Q Values (UNSTORED) appears
on the display.
Symbol Data I Value Q Value
0
0000 0.500000 1.000000
1
0001 −0.500000 1.000000
2
0010 0.500000 −1.000000
3
0011 −0.500000 −1.000000