4. ALC

4. ALC: ALC Trigger Source bus (M9381A)

4. ALC: ALC Mode (M9381A)

ALC

Selections: On | Off

Default: On

Enables or disables the automatic level control.

• On − The ALC circuit constantly monitors and controls the output power level.

• Off − No automatic leveling occurs.

ALC Bandwidth

Selections: Auto | 100.00 Hz | 1.00 kHz | 10.00 kHz | 100.00 kHz

Default: Auto

Sets the ALC bandwidth. For waveforms with varying amplitudes, a high crest factor, or both, set the ALC loop bandwidth to 100 Hz, which is the default bandwidth set when an ARB format is turned on. Limiting the loop bandwidth of the ALC circuit prevents the ALC from sampling the fast rising edges of high-crest pulsed waveforms.

Power Search Reference

Selections: Modulation | Fixed

Default: Modulation

Selects a fixed or modulation reference signal when doing a power search.

• Modulation − Power search uses the RMS value of the current I/Q modulation as the reference.

• Fixed − Power search uses a fixed 0.5 V reference.

Set ALC to Off to enable this parameter.

RF During Power Search

Selections: Normal | Minimum

Default: Normal

Selects the level of the output power control during a power search routine.

• Normal − Performs power searches without setting the internal step attenuator to its maximum setting. Glitches and power changes may be present during the search.

• Minimum − Sets the signal generator's step attenuator to its maximum setting during power search to protect sensitive circuits.

Set ALC to Off to enable this parameter.

ALC Trigger Source bus (M9381A)

Choice: AUTO | PXI0 | .. | PXI7

Default: None

Double-click or use the drop-down menu to select a bus for ALC hold signal path on PXI backplane. This parameter is only available when connected to the M9381A.

ALC Mode (M9381A)

Choice: : Off | HOLD | TRACK

Default: Off

Double-click or use the drop-down menu to select ALC mode. This parameter is only available when connected to the M9381A.