182 Chapter 7
Custom Real Time I/Q Baseband
Working with Data Patterns
Deselecting a Predefined Real Time Modulation Setup
To deselect any predefined mode that has been previously selected, and return to the top–level
custom modulation menu:
1. Press
Preset.
2. Press
Mode > Custom > Real Time I/Q Baseband.
3. Press
More (1 of 3) > More (2 of 3) > Predefined Mode > None.
4. Press
More (3 of 3).
Working with Data Patterns
This section provides information on the following:
• “Using a Predefined Data Pattern” on page 183
• “Using a User–Defined Data Pattern” on page 183
• “Using an Externally Supplied Data Pattern” on page 187
The Data menu enables you to select from predefined and user defined data patterns. Data Patterns
are used for transmitting continuous streams of unframed data. When the Custom Off On softkey is
on, the real–time custom I/Q symbol builder creates I/Q symbols based on the data pattern and
modulation type that has been selected. Refer to “Working with Modulation Types” on page 171 for
information on selecting a modulation type.
The following data patterns are available:
• PN sequence allows you to access a menu (PN9, PN11, PN15, PN20, PN23) for internal data
generation of pseudorandom sequences (pseudorandom noise sequences); a pseudorandom noise
sequence is a periodic binary sequence approximating, in some sense, a Bernoulli “coin tossing”
process with equiprobable outcomes.
• FIX4 0000 allows you to define a 4–bit repeating sequence data pattern and make it the active
function. The selected 4–bit pattern will be repeated as necessary to provide a continuous stream
of data.
• Other Patterns allows you to access a menu of choices (4 1’s & 4 0’s, 8 1’s & 8 0’s, 16 1’s & 16
0’s, 32 1’s & 32 0’s, or 64 1’s & 64 0’s) from which you can select a data pattern. Each pattern
contains an equal number of ones and zeroes. The selected pattern will be repeated as necessary
to provide a continuous stream of data.
• User File allows you to access a menu of choices from which you can create a file and store it to
the Catalog of Bit Files, select from a Catalog of Bit Files and use it, or select from a Catalog of
Bit Files, edit the file, and resave the file.
• Ext allows data patterns to be fed into the I/Q symbol builder, through the DATA port, in
real–time.
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