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Chapter 6 133
Custom Arb Waveform Generator
Working with Symbol Rates
Working with Symbol Rates
The Symbol Rate menu enables you to set the rate at which I/Q symbols are fed to the I/Q modulator. The
default transmission symbol rate can also be restored in this menu.
• Symbol Rate (displayed as Sym Rate) is the number of symbols per second that are transmitted using
the modulation (displayed as Mod Type) along with the filter and filter alpha (displayed as Filter).
Symbol rate directly influences the occupied signal bandwidth.
Symbol Rate is the Bit Rate divided by the number of bits that can be transmitted with each symbol; this
is also known as the Baud Rate.
• Bit Rate is the frequency of the system bit stream. The internal baseband generator (Option 002/602)
automatically streams the selected Data Pattern at the appropriate rate to accommodate the symbol rate
setting (Bit Rate = Symbols/s x Number of Bits/Symbol).
• Occupied Signal Bandwidth = Symbol Rate x (1 + Filter Alpha); therefore, the occupied signal
bandwidth is dependent on the filter alpha of the Nyquist or Root Nyquist filter being used. (To change
the filter alpha, refer to the procedure, “Adjusting the Filter Alpha of a Predefined Root Nyquist or
Nyquist Filter” on page 126.)
To Set a Symbol Rate
1. Press Preset.
2. Press
Mode > Custom > ARB Waveform Generator > Digital Mod Define > Symbol Rate
or
Mode > Custom > Real Time I/Q Baseband > Symbol Rate
3. Enter a new symbol rate and press Msps, ksps, or sps.
To Restore the Default Symbol Rate (Custom Real Time I/Q Only)
•Press Mode > Custom > Real Time I/Q Baseband > Symbol Rate > Restore Default Symbol Rate.
This replaces the current symbol rate with the default symbol rate for the selected modulation format.