Rubidium™ MG362x1A SeriesLow-Noise RF/Microwave SignalGenerators : Instrument Operation : Setting the ALC Control : ALC Menu
ALC Menu
You can select the ALC mode of operation—internal or fixed gain (ALC off). In addition, the signal generator provides a decouple function that allows decoupling of the step attenuator (if equipped) from the level setting. The ALC LOOP CONTROL settings menu is shown in Figure: ALC Loop Control Menu.
ALC Level Modes
Press the ALC Loop Control SOURCE button shown in Figure: ALC Loop Control Menu to access the ALC leveling modes.
ALC Loop Control Menu
Provides the following leveling settings:
Internal: Leveling source is Internal. LEVEL DAC is not available. See Setting Internal Leveling.
External: Leveling source is External, LEVEL DAC is available. See Setting External Leveling.
Fixed Gain: Leveling source is Fixed. See Setting Fixed Gain. LEVEL DAC control is available in when SOURCE Fixed Gain is selected.
Enabled In Fixed Gain Mode Only. Range is 0 to 65535.
Manual setting of the ALC Range for External Closed and Open Fixed Loops. Not available
when SOURCE is set to Internal.
Setting Internal Leveling
This is the normal default leveling mode. Output power is sensed by the MG362x1A’s internal detector. The detector output signal is fed back to the ALC circuitry to adjust the output power level. Internal ALC is selected from the leveling menu.
To select internal ALC, press Internal. Pressing one of the other leveling menu soft keys External Detector or Fixed Gain will turn off internal leveling.
Setting External Leveling
In external leveling, the output power from the MG362x1A is detected by an external detector or power meter. The signal from the detector or power meter is returned to the ALC circuitry via the rear panel EXT ALC IN connector. The ALC adjusts the output power to keep the power level constant at the point of detection. To select the external ALC input from an external detector, press ALC | SOURCE External.
Setting Fixed Gain
In the fixed gain mode, the ALC is disabled. The RF level DAC and step attenuator (if installed) are used to control the relative power level. Power is not detected at any point and the absolute power level is uncalibrated. After fixed gain mode is selected, the attenuator (if installed) is decoupled and the RF level DAC value is displayed.
Manual setting of the LEVEL DAC. This setting is used in conjunction with the manual attenuation setting to allow user control of the output power when in ALC Fixed Gain selection. The RF level DAC adjustable range is from a minimum output of 0 to a maximum output of 65535. To select the Fixed Gain ALC input from an external detector:
Press: ALC | SOURCE | Fixed Gain
Edit the level DAC by pressing LEVEL DAC, and use the control keys, rotary data knob, or enter a new power level DAC value using the keypad and press ENTER.
Setting Level Range
Used when the SOURCE is set to External or Fixed Gain. Sets all the Digital Step Attenuators in the Digital Down Converter, Switched Filter Module, and Frequency Extension Module to 0 for High Range and 10 for Low Range. Can be used when the RF step attenuation is manually set to 0 dB, allowing for a 10dB extension of range in high level range.