Tektronix CSA8000B - Manual (Page 117)

Triggering
CSA8000B & TDS8000B User Manual 3- 43
Use a trigger source that is synchronized with the signal you are sampling and
displaying. Selection of your trigger source depends on your application, as
shown in Table 3--1.
Table 3- 1: Application-based triggering
Application Source to use
Communications (optical)
serial NRZ data signals Set source to Clock Recovery, set the clock-recovery type, and
use an optical sampling module equipped with a clock-recovery
option supporting the specific data rate of the serial optical
signal.
A custom clock recovery rate can be defined by the user if the
optical module supports a continuous-rate clock recovery. Refer
to Sampling Modules Supported on page 1--4 to see those
modules that support continuous-rate clock recovery.
TDR measurement using an
electrical sampling module
equipped with TDR Set source to Internal Clock to use the internal clock of the
instrument (TDR clock), and select the appropriate clock
frequency. Disconnect any signal connected to the External
10MHz Reference Input when using the Internal clock.
Measurements on systems
with a synchronized pretrigger
signal Set source to External Direct or External Prescaler as
appropriate (see Trigger Source Connectors) and connect the
pretrigger signal.
Any application requiring that
the input signal provide the
trigger Set source to External Direct or External Prescaler as
appropriate (see Trigger Source Connectors). Use a signal
splitter or power divider to couple to both the Ext Direct or
Prescaler input and the input channel, so that the sampled
signal is also the trigger signal.
Any application requiring that
you probe the trigger source Set source to External Direct, and use a Tektronix probe as
described in Probe-to-Trigger Source Connection on
page 3--44.
Any application requiring that
you perform special measure-
ments using gated trigger. Set source to External Direct, and use a TTL connection to
trigger gate as described in To Use Gated Trigger on
page 3--50.
Trigger Source and ESD. Observe static precautions when coupling trigger
sources to this instrument.
CAUTION. Electrostatic-static damage can permanently degrade and damage the
inputs to this instrument, its sampling modules, and accessory probes. You must
take proper precautions; please read your sampling module user manual for
more information.