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External source
When using an external modulation source, modulation wave and frequency will not show in the parameter list, when an
external waveform will be used to modulate carrier waveform. Phase deviation of PM is controlled by ±5V signal level on
external analog modulation input terminal (Modulation In connector) on the back panel. For example, if phase deviation in
parameter list is set to be 180º, phase shift is 180º when external modulation signal is +5V, and lower external signal level
generates less deviation.
Set modulation wave frequency
The frequency of modulation wave can be set when using an internal modulation source. After you use PM function, the
frequency of the modulation wave is 100Hz by default. You can change it with the multi-functional control and direction key
on interface for using phase modulation or by pressing Freq. Modulation frequency range is 2mHz~200kHz. When using
an external modulation source, modulation wave and frequency will not show in parameter list, when an external
waveform will be used to modulate carrier waveform. The frequency range of modulation signal of external input is
100Hz~20kHz.
Set phase deviation
Phase deviation is the change in phase of the waveform subject to PM, relative to carrier phase. The range of PM phase
deviation is 0º~360º, set at 180º by default. You can change it with the multi-functional control and direction keys on
interface for using phase modulation or by pressing Phase Dev.
Comprehensive example
First set the instrument to phase modulation (PM) mode, and then set an internal sine wave of 200Hz as modulation signal
and a sine wave with frequency of 900Hz and amplitude of 100mVpp as carrier signal. Finally set phase deviation to be
200º.
The specific steps are as follows:
Use PM function
Press MOD, Type and PM successively (press soft key “Type” to select ) to use PM function.
Figure 4- 29 Select PM function