Viavi CX100 ComXpert Operation Manual page 118

5.2.4.3 External Modulation Generator Controls and Settings
The following controls and settings are used to configure the characteristics of the external
modulated signal that is being received by the CX100:
Control/Setting
Modulation Type
Rate (AM)
Deviation (FM)
Coupling
Mod Ext On/Off
Soft-key
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August 2023
Table 5-3 External Modulation Controls and Settings
Description
The external modulation parameters that must be configured
depend on the type of modulation selected.
• None: No parameters
• AM: Rate (%), Coupling
• FM: Deviation (kHz), Coupling
Defines the rate at which the waveform is varied (modulated)
when applied to the carrier frequency.
FM Deviation defines the frequency by which the modulated
waveform varies from the carrier frequency.
Coupling selects how any unwanted AC/DC components are
filtered from the received signal.
AC Coupling
AC coupling filters the DC signal component out of a signal
that contains both AC and DC components. The DC
component of a signal acts as a voltage offset so removing
the component may increase the resolution of signal
measurements.
DC Coupling
DC coupling does not filter components from the signal; both
AC and DC signal components are therefore present in the
signal. DC coupling is typically used when any offset voltage
present is <±100 mV or if the DC content of the signal is
important.
The Mod Ext soft-key turns the external modulation generator
on and off.
CX100 ComXpert Operation Manual
Chapter 5 RF Instrument Function Descriptions
RF Test
Rev 002
5 - 9