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

Pulse modulation is available for the basic unit (R&S SMA + frequency option R&S SMA-B10x) without additional equipment options.

A standard pulse generator is available for internal modulation. Internal Pulse Modulation with extended features, for example generation of double pulse, requires option R&S SMA-K23, Pulse Generator. Option R&S SMA-K27, Pulse Train, enables generation of pulse trains.

As modulation signal, you can either use the signal of the internal pulse generator or an externally supplied signal. In case of external source, the external signal is input via the PULSE EXT connector at the rear of the instrument. In case of internal source, this connector can be used as external trigger or gate signal input for internal pulse modulation. The polarity and input impedance of the connector can be selected.

The pulse signal is output at the PULSE VIDEO connector at the rear of the instrument.

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.

 


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