Instrument Function > Modulation Generator and LF Output > LF Frequency Sweep
LF Frequency Sweep

The "LF Frequency Sweep" dialog is used to configure and activate an LF frequency sweep signal.

To open the "LF Frequency Sweep" dialog, select "Mod Gen > Configure > LF Frequency Sweep" or use the MENU key under "Mod Gen".

The LF sweep mode is activated and the sweep mode is selected. The buttons are used to reset the LF sweep (all sweep modes) or to execute the LF sweep ("Single" mode).

The sweep range, sweep spacing and dwell time are set in the bottom of the section.

State

Activates the LF frequency sweep signal generation.

Note: Activating the LF sweep automatically deactivates other sweeps.

Remote command: 
 
Mode

Selects the LF frequency sweep mode.

If you change the sweep mode during the execution, the signal generator stops the sweep and starts with the next trigger event at the initial value.

The "Reset Sweep" button sets the sweep to the start value.

"Auto"

Generates a continuously repeating sweep signal immediately after activating the sweep mode.

The sweep steps are performed atomatically, controlled by the dwell time, see "Dwell Time - LF Sweep".

Example: 

SOUR:LFO:SWE:FREQ:MODE AUTO

TRIG0:SWE:SOUR AUTO

SOUR:LFO:FREQ:MODE SWE

"Single"

Generates a single sweep cycle after a trigger event.

The sweep steps within the cycle are performed automatically, controlled by the dwell time. If one cycle is completed, the instrument waits for the next trigger event.

To trigger the sweep, use "Execute Single Sweep" button, or the corresponding remote control commands, for example *TRG.

Example: 

SOUR:LFO:SWE:FREQ:MODE AUTO

TRIG0:SWE:SOUR SING

SOUR:LFO:FREQ:MODE SWE

SOUR:LFO:SWE:FREQ:EXEC

"Step"

Generates the sweep signal step-by-step, manually triggered.

To perform the sweep steps, enter the frequency value under "Current Freq".

Example: 

SOUR:LFO:SWE:FREQ:MODE MAN

SOUR:LFO:FREQ:MODE SWE

SOUR:LFO:SWE:FREQ:SPAC LIN

SOUR:LFO:SWE:FREQ:STEP:LIN 1E34

SOUR:LFO:FREQ:MAN 12 kHz

The value entered with command SOUR:LFO:SWE:FREQ:STEP:LIN|LOG sets the step width.

The value entered with command SOUR:LFO:FREQ:MAN has no effect, the command only sets the next sweep step. In remote control only a step-by-step sweep from start to stop frequency is possible.

"Extern Single"

Generates a single sweep cycle when an a external trigger event occurs.

The sweep steps within the cycle are performed automatically, controlled by the dwell time. If one cycle is completed, the instrument waits for the next trigger event.

To trigger the sweep, apply an external trigger signal.

Refer to the description of the rear panel for information on the connectors for external trigger signal input (see "Rear Panel Tour").

Example: 

SOUR:LFO:SWE:FREQ:MODE AUTO

TRIG0:SWE:SOUR EXT

SOUR:LFO:FREQ:MODE SWE (External trigger)

"Extern Step"

Generates the sweep signal step-by-step, manually triggered.

To trigger a sweep step, apply an external trigger signal. The step width corresponds to the step width set for the rotary knob.

Example: 

SOUR:LFO:SWE:FREQ:MODE AUTO

TRIG0:SWE:SOUR EXT

SOUR:LFO:FREQ:MODE SWE (External trigger)

"Extern Start/Stop"

Generates a continuously repeating sweep signal that is started, stopped and restarted by subseqeunt external trigger events. The sweep steps are performed automatically, controlled by the dwell time.

Refer to the description of the rear panel for information on the connectors for the external trigger signal input (see "Rear Panel Tour").

Example: 

SOUR:LFO:SWE:FREQ:MODE AUTO

TRIG0:SWE:SOUR EAUT

SOUR:LFO:FREQ:MODE SWE (External trigger)

Remote command: 
 
Execute Single Sweep

Starts a sweep manually. This trigger button is displayed in "Single" mode.

Example: 

SOUR:LFO:SWE:FREQ:MODE AUTO

TRIG:LFFS:SWE:SOUR SING

TRIG:LFFS

Remote command: 
 
Reset Sweep

Resets a sweep.

With the next trigger event, the sweep starts with at the initial value.

Remote command: 
 
Start Freq

Sets the start frequency.

Remote command: 
 
Stop Freq

Sets the stop frequency.

Remote command: 
 
Current Freq

Displays the current frequency.

In sweep "Step" mode, the parameter is editable and you can enter frequency for the next step.

Remote command: 
 
Spacing

Selects the mode for the calculation of the frequency sweep intervals.

"Linear"

Takes the frequency value entered as an absolute value in Hz

"Logarithmic"

Takes the value entered as a lograithmic value, that means as a constant fraction of teh current frequency in %.

Remote command: 
 
Shape

Selects the waveform shape of the sweep signal.

"Sawtooth"

The sweep runs from the start to the stop frequency. Each subsequent sweep starts at the start frequency, that means the shape of the sweep sequence resembles a sawtooth.

"Triangle"

The sweep runs from start to stop frequency and back, that means the shape of the sweep resembles a triangle. A subsequent sweep starts at the start frequency.

Remote command: 
 
Retrace - LF Frequency Sweep

Activates that the signal changes to the start frequency value while it is waiting for the next trigger event.

You can enable this feature, when you are working with sawtooth shapes in sweep mode "Single" or "External Single", see "Mode".

Remote command: 
 
Step Lin/Log - LF Sweep

Sets the step width for the individual frequency sweep steps.

At each step this value is added to the current frequency.

Depending on the "Spacing" mode you have set, the corresponding parameter is displayed.

"Step Lin"

The step width is a constant value in Hz.

Remote command: 

 

"Step Log"

The step width is determined logarithmically in %, that means as a constant fraction of the current frequency.

Remote command: 

 

Dwell Time - LF Sweep

Defines the duration of the individual sweep steps.

The "Dwell Time" set by the user is used as the step time of the sweep. The effective net dwell time is shorter, reduced by the setting time. This setting time may be greater than the time specified in the data sheet.

Note:

It is recommended to switch off the display update for optimum sweep performance especially with short dwell times (see "Display Update").

Remote command: 
 
Ext. Trigger Input Slope

Sets the polarity of the active slope of an externally applied instrument trigger.

This setting affects the PULSE EXT/INST TRIG input (BNC connector at the rear of the instrument).

"Positive"

activates the rising edge of the trigger signal.

"Negative"

activates the falling edge of the trigger signal.

Remote command: 
 

 


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