Rohde & Schwarz SMBV100A - Internal PRBS Data and Data Patterns

Instrument Function
R&S
®
SMBV100A
327Operating Manual 1176.8016.02 ─ 17
Externally computed waveform files can be loaded in the instrument using computer
interfaces or IEC bus.
Waveform files are processed with the aid of the Arbitrary Waveform Generator (ARB),
see Chapter 5.9.4, "Arbitrary Waveform Generator ARB", on page 379.
Internally the "Multi Carrier CW" menu for defining multi carrier waveforms is available
(see Chapter 5.9.5, "Multi Carrier Continuous Wave", on page 436).
5.9.2.1 Internal PRBS Data and Data Patterns
PRBS generators deliver pseudo-random binary sequences of differing length and
duration. They are known as maximum length sequences, and are generated with the
aid of ring shift registers with feedback points determined by the polynomial.
By way of example, the diagram below shows a 9-bit generator with feedback to regis-
ters 4 and 0 (output).
Figure 5-20: 9-bit PRBS generator
For PRBS15 and PRBS23, a CCITT V.52-compliant data inversion is performed in the
feedback path automatically as shown below:
The pseudo-random sequence from a PRBS generator is uniquely defined by the reg-
ister number and the feedback. The following table describes the available PRBS gen-
erators:
Table 5-1: PRBS generators
PRBS generator Length in bits Feedback to GUI selection
9-bit
2
9
-1 = 511
Registers 4, 0 PRBS 9
11-bit
2
11
-1 = 2047
Registers 2, 0 PRBS 11
16-bit
2
16
-1 = 65535
Registers 5, 3, 2, 0 PRBS 16
20-bit
2
20
-1 = 1048575
Registers 3, 0 PRBS 20
21-bit
2
21
-1 = 2097151
Registers 2, 0 PRBS 21
The "Data Source" selection for PRBS data from the dilaog is "PN11, ...".
Baseband Signal - Baseband Block