Rohde & Schwarz SMW200A - External Modulation Data

Configuring the Internal Baseband Source
R&S
®
SMW200A
229User Manual 1175.6632.02 ─ 16
Table 4-2: Overview of PRBS generators
PRBS generator Length in bits Feedback to GUI selection
9-bit
2
9
-1 = 511
Registers 4, 0 PRBS 9/PN9
11-bit
2
11
-1 = 2047
Registers 2, 0 PRBS 11/PN11
15-bit
2
15
-1 = 32767
Registers 1, 0 PRBS 15/PN15
16-bit
2
16
-1 = 65535
Registers 5, 3, 2, 0 PRBS 16/PN16
20-bit
2
20
-1 = 1048575
Registers 3, 0 PRBS 20/PN20
21-bit
2
21
-1 = 2097151
Registers 2, 0 PRBS 21/PN21
23-bit
2
23
-1 = 8388607
Registers 5, 0 PRBS 23/PN23
Example:
By way of example, the diagram on A 9-bit PRBS generator shows a 9-bit generator
with feedback to registers 4 and 0 (output). The generated serial data is converted
internally, e.g 2 Bit/Symbol if QPSK is used.
Figure 4-1: A 9-bit PRBS generator
Related settings:
●
Chapter 4.6.3.3, "Data Source", on page 268
●
Chapter 4.6.3.7, "Data List Editor", on page 280
●
Chapter 4.6.3.8, "Control and Marker Lists Editor", on page 282
●
"Data Source" selection in the dialogs of the firmware options
External Modulation Data
The R&S SMW equipped with standard baseband generator can generate custom digi-
tally modulated signal form external serial data source.
For proper synchronization, the R&S SMW requires a reference (external) symbol
clock signal to generate a bit clock out of it. The active edge of both, the symbol clock
and the bit clock, is configurable. Positive and negative timing deviations between the
clock and the data signals are indicated and automatically corrected.
Common Functions and Settings in the Baseband Domain