Rohde & Schwarz SMBV100B, User Manual

Page: 93 / 1030

Configuring the Internal Baseband Source
R&S
®
SMBV100B
91 User Manual 1178.4460.02 ─ 03
The pseudo-random sequence from a PRBS generator is uniquely defined by the
register number and the feedback. The
Table 3-1 describes the available PRBS
generators.
For PRBS15 and PRBS23, a CCITT V.52-compliant data inversion is performed in
the feedback path automatically.
Table 3-1: 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 3-1: A 9-bit PRBS generator
Related settings:
●
Chapter 3.5.3.3, "Data Source" , on page 119
●
Chapter 3.5.3.7, "Data List Editor" , on page 128
●
Chapter 3.5.3.8, "Control and Marker Lists Editor" , on page 130
●
"Data Source" selection in the dialogs of the firmware options
Clock Signals
The instrument requires a clock reference for generating the timing pulse and uses its
internal clock reference for that purpose.
The internally generated symbol clock signal can be output at the User x connectors.
The
Table 3-2 gives an overview.
Common Functions and Settings in the Baseband Domain