Frequency Sweep

Start Frequency and Stop Frequency

The start frequency and stop frequency set the sweep’s upper and lower frequency bounds. The sweep begins at the start frequency, sweeps to the stop frequency, and then resets back to the start frequency.

• Start and Stop frequencies: 1 µHz to maximum frequency for the waveform. The sweep is phase continuous over the full frequency range. The default start frequency is 100 Hz. The default stop frequency is 1 kHz.
• To sweep up in frequency, set the start frequency less than the stop frequency. To sweep down in frequency, set the opposite relationship.
• Sync setting Normal: Sync pulse is high throughout the sweep.
• Sync setting Carrier: Sync pulse has a 50% duty cycle for every waveform cycle.
• Sync setting Marker: Sync pulse goes high at the beginning and goes low at the marker frequency. You can change this with OUTPut[1|2]:SYNC:MODE MARKER.
• Front Panel:
  
  
  
• SCPI:
  [SOURce[1|2]:]FREQuency:STARt {<frequency>|MINimum|MAXimum|DEFault}
  
  [SOURce[1|2]:]FREQuency:STOP {<frequency>|MINimum|MAXimum|DEFault}

Center Frequency and Frequency Span

You can also set the sweep frequency boundaries of the sweep using a center frequency and frequency span. These parameters are similar to the start frequency and stop frequency (above) and they provide added flexibility.

• Center frequency: 1 µHz to maximum frequency for the waveform. The default is 550 Hz.
• Frequency span: Any value between ±maximum frequency for the waveform. The default is 900 Hz.
• To sweep up in frequency, set a positive frequency span; to sweep down, set a negative frequency span.
• Sync setting Normal: Sync pulse is high throughout the sweep.
• Sync setting Carrier: Sync pulse has a 50% duty cycle for every waveform cycle.
• Sync setting Marker: Sync pulse goes high at the beginning and goes low at the marker frequency. You can change this with OUTPut[1|2]:SYNC:MODE MARKER.
• Front Panel:
  
  
  

• SCPI:
  [SOURce[1|2]:]FREQuency:CENTer {<frequency>|MINimum|MAXimum|DEFault}
  
  [SOURce[1|2]:]FREQuency:SPAN {<frequency>|MINimum|MAXimum|DEFault}

Sweep Mode

You can sweep with linear or logarithmic spacing, or with a list of sweep frequencies. For a linear sweep, the instrument varies the output frequency linearly during the sweep. A logarithmic sweep varies the output frequency logarithmically.

The selected mode does not affect the sweep return (from stop to start, if one is set). The sweep return is always linear.

• Front Panel:
  
  
• SCPI: [SOURce[1|2]:]SWEep:SPACing {LINear|LOGarithmic}

Sweep Time

Sweep time specifies the number of seconds required to sweep from the start frequency to the stop frequency. The instrument calculates the number of points in the sweep based on the sweep time.

• Sweep time: 1 ms to 250,000 seconds, default 1 s. For a linear sweep in immediate trigger mode, the maximum total sweep time (including hold time and return time) is 8,000 s. The maximum total sweep time for linear sweeps using other trigger modes is 250,000 s; the maximum total sweep time for logarithmic sweeps is 500 s.
• Front Panel:
     
• SCPI: [SOURce[1|2]:]SWEep:TIME {<seconds>|MINimum|MAXimum|DEFault}

Hold/Return Time

Hold time specifies time (in seconds) to remain at the stop frequency, and return time specifies the number of seconds to return from the stop frequency to the start frequency.

• Hold time and return time: 0 to 3600 seconds (default 0).
• Front Panel:
     
  
  
     
  
• SCPI:
  [SOURce[1|2]:]SWEep:HTIMe {<hold_time>|MINimum|MAXimum|DEFault}
  
  [SOURce[1|2]:]SWEep:RTIMe {<return_time>|MINimum|MAXimum|DEFault}

Marker Frequency

If desired, you can set the frequency at which the signal on the front panel Sync connector goes to a logic low during the sweep. The Sync signal always goes from low to high at the beginning of the sweep.

• Marker frequency: 1 µHz to maximum frequency for the waveform. The default is 500 Hz.
• When the sweep mode is enabled, the marker frequency must be between the specified start frequency and stop frequency. If you attempt to set the marker frequency to a frequency not in this range, the instrument will set the marker frequency equal to the start frequency or stop frequency (whichever is closer).
• You cannot configure the marker frequency with the front panel menus unless the Sync source is the sweeping channel.
• Front Panel:
  
  
• SCPI: [SOURce[1|2]:]MARKer:FREQuency {<frequency>|MINimum|MAXimum|DEFault}

Sweep Trigger Source

In sweep mode, the instrument outputs a single sweep when a trigger signal is received. After one sweep from the start frequency to the stop frequency, the instrument waits for the next trigger while outputting the start frequency.

• Sweep trigger source: Immediate (default), External, Time, or Manual.
• With the Immediate (internal) source, the instrument outputs a continuous sweep at a rate determined by the total of the hold time, sweep time and return time. The sweep time for this source is limited to 8000 seconds.
• With the External source, the instrument accepts a hardware trigger on the rear-panel Ext Trig connector and initiates one sweep each time Ext Trig receives a TTL pulse with the specified polarity.
• The trigger period must be greater than or equal to the specified sweep time.
• With the Manual source, the instrument outputs one sweep each time the front panel [Trigger] key is pressed.
• Front Panel:
  
  
• To specify the slope of the trigger signal edge:
     
• SCPI:
  TRIGger[1|2]:SOURce {IMMediate|EXTernal|TIMer|BUS}
  
  TRIGger[1|2]:SLOPe {POSitive|NEGative}

See Triggering for more information.

Trigger Out Signal

A "trigger out" signal is provided on the rear-panel Ext Trig connector (used with burst and sweep only). When enabled, a pulse with either a rising edge (default) or falling edge is output from this connector at the beginning of the sweep or burst.

• When the Immediate (internal) trigger source is selected, the instrument outputs a square waveform with a 50% duty cycle from the Ext Trig connector at the beginning of the sweep or burst. The frequency of the waveform corresponds to the specified burst period or total sweep time.
• When the External trigger source is selected, the instrument disables the "trigger out" signal. The Ext Trig connector cannot be used for sweep or burst and trigger out at the same time (an externally-triggered waveform uses the same connector to trigger the sweep or burst).
• When Manual or bus (software) trigger source is selected, the instrument outputs a pulse (>1 μs pulse width on the 33500 Series and 100 ns on the 33600 Series) from the Ext Trig connector at the beginning of each sweep or burst.
• To specify whether the instrument triggers on the rising or falling edge on the Ext Trig connector, press [Trigger] > Trig Out Setup. Then select the desired edge by pressing Trig Out.
• SCPI:
  OUTPut:TRIGger:SLOPe {POSitive|NEGative}
  
  OUTPut:TRIGger {ON|1|OFF|0}

Frequency List

In frequency list mode, the instrument "steps" through a list of frequencies, dwelling on each frequency for a specified period. You may also control progress through the list with triggering.

• The instrument will not allow sweep or list mode to be enabled at the same time that burst or any modulation mode is enabled. When you enable sweep, the burst or modulation mode is turned off.
• To avoid multiple waveform changes, enable list mode after configuring its parameters.
• Front Panel: Enable list before setting any other list parameter. Press [Sweep] > Type > List.
• SCPI:
  [SOURcd[1|2]:]FREQuency:MODE LIST
  
  [SOURce[1|2]:]LIST:FREQuency <freq1>[, <freq2>, etc.]
• Progress through list is controlled by the trigger system. If trigger source is internal or immediate, the dwell time setting (LIST:DWELl) determines time spent at each frequency. For any other trigger source, dwell time is determined by trigger event spacing.