Keysight Technologies N5171B EXG, Руководство пользователя

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Keysight EXG and MXG X-Series Signal Generators User’s Guide 389
Custom Digital Modulation (Option 431)
Using the Arbitrary Waveform Generator
Figure 16-26 shows the X-Series setup and the I/Q display.
Figure 16-26 Custom Modulation and I/Q Display
Hints for Constructing Modulations
— The map is limited to 16 total signal levels for I and Q combined. The readout on the right-hand
side of the table tracks the number of I and Q levels utilized. Levels are I or Q values. Figure
16-27 shows an 8PSK signal built in two different ways. The 8PSK signal in Figure 16-27 utilizes
five of the available sixteen I/Q values on the left, and utilizes four of the available sixteen I/Q
values on the right.
— Following this example, the real-time I/Q baseband generator supports a symmetric 256QAM
constellation but not an asymmetric 256QAM constellation, since the asymmetry requires more
than sixteen I/Q values.
— The levels do not have to be equally spaced or symmetric in the I/Q plane. For example, the
16QAM modulations shown in Figure 16-28 are both possible.
Figure 16-27 8PSK Signal Built Two Ways