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Chpater 6 155
Custom Arb Waveform Generator
Working with Modulation Types
Working with Modulation Types
The Modulation Type menu enables you to specify the type of modulation applied to the carrier
signal when the
Mod On Off hardkey is on.
When the
Custom Off On softkey is on:
• For Custom Arb, the BBG (baseband generator) creates a sampled version of the I/Q waveform
based on a random data pattern and the modulation type that has been selected.
• For Custom Real Time I/Q, the real-time custom I/Q symbol builder creates I/Q symbols based on
the data pattern and modulation type that has been selected (see “Working with Data Patterns”
on page 166 for information on selecting a data pattern).
In Custom Real Time I/Q, you can also:
• Create user-defined modulation type (see page 156) that can be used immediately or saved to the
Memory Catalog.
• Restore all modulation parameters to their default state.
To Select a Predefined Modulation Type
1. Press Preset.
2. Press
Mode > Custom > ARB Waveform Generator > Digital Mod Define > Modulation Type > Select
or
Mode > Custom > Real Time I/Q Baseband > Modulation Type > Select
3. Select one of the available modulation types.
NOTE If you select QPSK and OQPSK, you must make a specific selection from the menu that displays.
QAM
Quadratu
re
Amplitud
e
Modulatio
n
4QAM 2 90 bps − 100 Mbps 45 sps − 50 Msps 45 sps − 25 Msps
16QAM 4 180 bps − 200 Mbps 45 sps − 50 Msps 45 sps − 12.5 Msps
32QAM 5 225 bps − 250 Mbps 45 sps − 50 Msps 45 sps − 10 Msps
64QAM 6 270 bps − 300 Mbps 45 sps − 50 Msps 45 sps − 8.33 Msps
128QAM
There is no preset value for this
modulation, it must be user
defined.
7 315 bps − 350 Mbps 45 sps − 50 Msps 45 sps − 7.14 Msps
256QAM 8 360 bps − 400 Mbps 45 sps − 50 Msps 45 sps − 6.25 Msps
Modulation Type
Bits
Per
Symbol
Bit Rate =
Symbols/s x Number of
Bits/Symbol
Internal Symbol Rate
(Minimum Maximum)
Custom Real Time Only
External Symbol Rate
(Minimum Maximum)