Rohde & Schwarz SMU200A - Synchronizing Data Signals and Clock Signals

Instrument Function
R&S
®
SMU200A
331Operating Manual 1007.9845.32 ─ 15
Connector Location Clock Mode
CLOCK OUT rear panel Choice of bit clock or symbol clock
BITCLK AUX I/O interface, rear panel Bit clock
SYMBCLK AUX I/O interface, rear panel Symbol clock
The active edge of the external clock signal on the CLOCK input is selectable (menu
"Setup > System > Global Trigger/Clock/External Inputs"). Internally the rising edge is
always taken as the active edge. The active rising edge of the internal clocks is therefore
synchronized with either the rising or the falling edge of the external clock reference. A
symbol clock can be supplied externally or, if internally generated or externally asyn-
chronous data is being fed in, a multiple of a symbol clock can be supplied.
In the case of two-path instruments the external clock signal is applied to path A.
In order for the clock synthesizer on the R&S SMU to be synchronized correctly, the
external clock reference must first be applied and the correct symbol rate must then be
set. Until this has been done the external clock source must not be selected ("Clock
Source External").
The symbol rate set must not deviate from the symbol rate of the external signal by more
than 2% (see also data sheet).
The synchronization of data signals and clock signals for the various data sources and
clock sources is described in chapter 5.8.2.5, "Synchronizing Data Signals and Clock
Signals", on page 331.
5.8.2.5 Synchronizing Data Signals and Clock Signals
When selecting data signals and clock signals, the following operating modes are pos-
sible:
●
Internal clock and internal data
●
Internal clock and external synchronous data
●
External clock and external synchronous data
●
External clock and either internal data or external asynchronous data
Internal Clock and Internal Data
When internal data is selected for path A, this data is output in serial mode on the DATA
connector or in parallel mode on the PARADATA pins of the AUX I/O interface ("Custom
Digital Modulation").
In modulation modes with fewer than 10bits/symbol, the parallel data is output LSB-jus-
tified. In the case of 8-PSK modulation for example (3bits/symbol) only data lines D0, D1
and D2 are used.
The internal data of path B is not output in two-path instruments. For synchronization
purposes, however, it is possible to output the bit clock or symbol clock from this path to
one of the USER connectors.
Baseband Signal - Baseband Block