Instrument Function > Modulation > Pulse Modulation (PM) > Pulse Modulation Settings
Pulse Modulation Settings
 

To access the "Pulse Modulation" settings, select "Modulation > config... > Pulse Modulation".

 

The dialog contains all parameters for configuring a pulse modulation signal, comprising the signal source, pulse generator and trigger settings.

Depending on the selected modulation source, the provided parameters vary:
  • "Source Pulse Generator"
    Displays the parameters for configuring the pulse generator signal, which in turn vary according to the selected "Mode > Single / Double ...".
    Note: Extended features as the generation of double pulse signals or selectable trigger mode require option R&S SMA-K23.
  • "External"
    Enables you to configure the polarity of an externally supplied pulse modulation signal.

Note: The pulse generator settings in this dialog are mirrored from the actual "Pulse Generator" dialog of the "Mod Gen" block. Therefore find the description on the access and the corresponding parameters under in "Pulse Generator Settings".

Option R&S SMA-K27 enables the generation of pulse trains. For description of the pulse train dialog, see "Pulse Train Generation".

State

Activates pulse modulation.

Activation of pulse modulation deactivates ALC and power ramping.

Note: Automatic Level Control is deactivated with pulse modulation!.

When pulse modulation is activated, the R&S SMA deactivates ALC automatically ("ALC OFF", i.e. switches to "Sample & Hold" state).

The "Sample&Hold" state opens the ALC loop, and disables the automatic control of the output level. The level modulator is set directly.

However, to correct the output level, the R&S SMA executes a "Sample & Hold" measurement after each change of frequency or level settings.

The nominal level is ON for typically 3 ms to 5 ms after level or frequency setting, if:
  • No attenuator is fitted (frequency option R&S SMA-B103L/B106L)
  • "High Power" mode is enabled
  • "Auto" mode is enabled, and if the level is in the range of the high power, i.e. the mechanical relay bypass is switched.

The level is decreased by 30 dB during "Sample & Hold" measurement.

When the internal modulation source (pulse generator) is selected, the pulse generator is switched on automatically and the video/sync signal is output at the PULSE VIDEO output at the rear of the instrument. Signal output can be switched off in the "Pulse Generator" dialog (see "Pulse Generator").

Remote command: 
 
Source

Selects the modulation signal source for pulse modulation.

"Pulse Generator"

Uses the pulse generator as modulation signal source.

The settings for the pulse characteristics and the trigger are offered in the "Pulse Generator" section of the "Pulse Modulation" menu.

The internal pulse generator signal is provided at the PULSE VIDEO output, the sync signal at the PULSE SYNC output.

  • Without option R&S SMA-K23:
    The internally generated rectangular signal is used for the pulse modulation. The frequency of the internal signal can be set in the LF Output menu.
  • With option R&S SMA-K23:
    If option R&S SMA-K23 is installed, the characteristics of the generated pulse can be set in a wide range, and double pulse generation is possible. The settings are made in the "Pulse Generator" section of the menu.

"External"

Uses an externally applied modulation signal.

The external modulation signal is input via the PULSE EXT connector.

The external modulation is provided at the PULSE VIDEO output.

Remote command: 
 
Polarity

(External Source only)

Selects the polarity of the modulation signal.

"Normal"

The RF signal is On while the level is high at the modulation input.

"Inverted"

The RF signal is Off while the level is high at the modulation input.

Remote command: 
 

 


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