YOKOGAWA FG420, User Manual

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77 IM FG410-01EN
The internal modulation frequency cannot be set if the internal modulation waveform is noise.
If the modulation type is FSK or PSK, the internal modulation waveform is fixed to a 50% duty
square wave, and the internal modulation waveform cannot be selected.
When an arbitrary waveform is selected for the internal modulation waveform, waveform data simply
decimated to 4096 points from the start is used as the modulation waveform in case of the array
format. When [RAW] is shown in the [Type] field in the arbitrary waveform selection screen, the
arbitrary waveform is in the array format. If the value in the [Size] field is 17 KB or more, the original
waveform size is larger than 4096 points. On the other hand, when [Point] is shown in the [Type]
field, the arbitrary waveform is in the control point format. The arbitrary waveform in this format,
the waveform is developed using 4096 points to maintain the waveform characteristics as much as
possible. For details on the arbitrary waveforms,

“2. CREATING ARBITRARY WAVEFORMS”
in the Application Instruction Manual.
f) To perform modulation with an external signal source
Set [Source] (modulation source) on the 2nd page of the setting screen to [Ext] (external).
The external modulation signal input terminal differs as follows according to the modulation type.
When the modulation type is FM, PM, AM, AM(SC), OSFM, or PWM
Input the modulation signal to the external modulation/addition input terminal. The modulation
width setting is the value when the signal level is ±1 V. If the input level is lower than ±1 V,
keep it mind that the modulation width may become below the specified modulation width.
When the external modulation/addition input terminal is used for external addition input, the
external modulation function cannot be used.
When the modulation type is FSK or PSK
Input the modulation signal (TTL level) to the external trigger input terminal.
The polarity can be set on the screen.
g) To start modulation → Modulation starts automatically. Resume with the [Start] soft
key.
When the modulated oscillation mode is set, modulated oscillation starts automatically.
However, if the modulation setting is improper, modulated oscillation will not start. ([Conflict!] is
displayed in the top right part of the screen in this case.) When the [?] soft key appearing at the left
end is pressed, a message about the inappropriate setting is displayed. Once the setting has been
changed to an appropriate setting, modulated oscillation starts.
When modulation has been paused, it can be resumed by pressing the [Start] soft key.
h) To stop modulation → [Stop] soft key
Modulation can be paused.
When the [Stop] soft key is pressed during modulation, modulation stops and the carrier signal is
output without being modulated. The oscillation mode remains the modulated oscillation mode.
4.7 Modulation Setting and Manipulation