Notes:
The default pulse shape is ‘Gaussian’.
The filter types ‘None’ and ‘Rectangular’ define the pulse shape in time
domain. These filter types can only be applied for integer oversampling.
Examples: Filter type ‘None’ with 4 times oversampling generates one
sample with the actual value followed by 3 samples with a value of zero
(Dirac-Pulse). The filter type ‘Rectangular’ with 4 times oversampling
generates 4 identical sample values.
The filter types ‘Root Raised Cosine’, ‘Raised Cosine’, ‘Gaussian’, ‘EDGE’,
and ‘Half Sine’ describe the filter shape in frequency domain.
Alpha / BT
The meaning and labeling of this edition field depends on the selected pulse
shaping. For “Nyquist” filters (Raised Cosine and Square Root of Raised
Cosine) it is the ‘Alpha’ parameter (or roll-off factor) of the filter. For Gaussian
filters it is the BT (Bandwidth/symbol period product) parameter. Some filter
types do not require an additional filter parameter.
Data Source
This drop-down list allows the selection of different pseudo random binary
sequences as data sources for modulation. Choices are PRBS7 (Polynomial
x
7
+x
6
+1), PRBS10 (Polynomial x
10
+x
7
+1), PRBS11 (Polynomial x
11
+x
9
+1),
PRBS15 (Polynomial x
15
+x
14
+1), PRBS23 (Polynomial x
23
+x
18
+1), PRBS23p
(Polynomial x
23
+x
21
+x
18
+x
15
+x
7
+x
2
+1), and PRB31 (Polynomial x
31
+x
28
+1).
Data Length
This edition field may be used to set a given data length to be implemented by
the modulated signal. This field defaults to the maximum non-repeating length
of the selected PRBS. It also defaults to this value if the user types ‘0’ (Zero).
Otherwise, the sequence will be truncated when the number of bits set by this
control is reached. If this number is longer than the PRBS maximum length,
the sequence will be re-started as many times as necessary.
I/Q Delay
This numeric edition field allows for the definition of the time skew between
the I and the Q baseband components. It can be used to compensate or
emulate timing misalignments caused by cabling, external modulators and
other devices. This control is activated only when the Generate I/Q Data
checkbox is selected. Delay is applied differentially to both components.
Gray Coding
This checkbox enables gray coding for the applicable modulation modes.
Corrections Section
File…
Opens a correction file selection dialog box. Default file extension is CSV
(Comma-Separated Values). The name of the successfully loaded correction
factors file is shown in the field located at the left of this button. The accepted
format for correction files may be found in the Correction File Format section.
Channel Specific Frequency and Phase Response
This checkbox activates the application of corrections based on frequency-
domain calibration data stored in the target instrument in non-volatile
memory. It improves flatness and linear phase distortions.
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