BURSt Subsystem

The following code produces the oscilloscope image shown below.

APPLy:SIN 1e5,3 VPP,0
BURS:MODE TRIG
BURS:NCYC 3
BURS:INT:PER 4.4e-5
BURS:PHAS 0
TRIG:SOUR IMM
BURS:STAT ON
OUTP 1

Burst Modes

There are two burst modes, described below. The instrument enables one burst mode at a time.

• Triggered Burst Mode (default): The instrument outputs a waveform for a number of cycles (burst count) each time a trigger is received. After outputting the specified number of cycles, the instrument stops and waits for the next trigger. You can configure the instrument to use an internal trigger to initiate the burst or you can provide an external trigger by pressing the front panel [Trigger] key, by applying a trigger signal to the rear-panel Ext Trig connector, or by sending a software trigger command from the remote interface.
• External Gated Burst Mode: The instrument output is either "on" or "off" based on the level of the external signal applied to the rear-panel Ext Trig connector. When this signal is true, the instrument outputs a continuous waveform. When this signal goes false, the current waveform cycle is completed and then the instrument stops while remaining at the voltage corresponding to the starting burst phase of the waveform.

The following table shows which modes are associated with which burst features.

	Burst Mode BURSt:MODE	Burst Count BURSt:NCYCles	Burst Period BURSt:INTernal:PERiod	Burst Phase BURSt:PHASe	Trigger Source TRIGger[1|2]:SOURce
Triggered Burst Mode: Internal Trigger	TRIGgered	Available	Available	Available	IMMediate
Triggered Burst Mode: External Trigger	TRIGgered	Available	Not Used	Available	EXTernal, BUS
Gated Burst Mode: External Trigger	GATed	Not Used	Not Used	Available	Not Used

The difference between gated burst and gated output is that gated burst synchronously starts and stops using full waveform cycles, where gated output asynchronously turns instrument output on or off with an external trigger, independent of the waveform phase.

If the duty cycle is changed on a triggered bursted square wave with the trigger mode set to Timer, the current burst will finish and one more burst will be executed before the duty cycle of the burst changes.

[SOURce[1|2]:]BURSt:GATE:POLarity {NORMal|INVerted}
[SOURce[1|2]:]BURSt:GATE:POLarity?

Selects true-high (NORMal) or true-low (INVerted) logic levels on the rear-panel Ext Trig connector for an externally gated burst.

Parameter	Typical Return
{NORMal|INVerted}, default NORMal	NORM or INV
Select true-low logic for an externally gated burst: BURS:GATE:POL INV

[SOURce[1|2]:]BURSt:INTernal:PERiod {<seconds>|MINimum|MAXimum}
[SOURce[1|2]:]BURSt:INTernal:PERiod? [{MINimum|MAXimum}]

Sets the burst period for internally-triggered bursts.

Parameter	Typical Return
1 µs to 8000 s, default 10 ms	+1.200000000000000E+01
Sets the burst period to 12 seconds: BURS:INT:PER 12

• The burst period is the time between the starts of consecutive bursts.
• This is used only when IMMediate triggering is enabled (TRIGger[1|2]:SOURce IMMediate). It is ignored when manual or external triggering is enabled (or with gated burst mode).
• On the 33500 Series, burst period must satisfy the following formula:
  
       Burst Period ≥ (Burst Count / Waveform Frequency) + 1 μs.
  
  On the 33600 Series, burst period must satisfy the following formula:
  
       Burst Period ≥ (Burst Count / Waveform Frequency) + 500 ns, with a minimum Burst Period of 1 μs.
• If the burst period is too short, the instrument will increase it as needed to continuously re-trigger the burst. From the remote interface, a "Settings conflict" error will also be generated.

[SOURce[1|2]:]BURSt:MODE {TRIGgered|GATed}
[SOURce[1|2]:]BURSt:MODE?

Selects the burst mode.

Parameter	Typical Return
{TRIGgered|GATed}, default TRIGgered	TRIG or GAT
Set gated burst mode BURS:MODE GATED

• TRIGgered: the instrument outputs a waveform for a number of cycles (burst count) each time a trigger is received from the trigger source (TRIGger[1|2]:SOURce).
• In GATed burst mode, the output waveform is on or off, based on the signal at the rear-panel Ext Trig connector. Select this signal's polarity using BURSt:GATE:POLarity. When the gate signal is true, the instrument outputs a continuous waveform. When the gate signal goes false, the current waveform cycle is completed and the instrument stops and remains at the voltage level corresponding to the waveform's starting burst phase. For a noise waveform, the output stops immediately when the gate signal goes false.
• GATed: burst count, burst period, and trigger source are ignored (these are used for the triggered burst mode only). If a manual trigger is received (TRIGger[1|2] ), it is ignored and no error will be generated.

[SOURce[1|2]:]BURSt:NCYCles {<num_cycles>|INFinity|MINimum|MAXimum}
[SOURce[1|2]:]BURSt:NCYCles? [{MINimum|MAXimum}]

Sets the number of cycles to be output per burst (triggered burst mode only).

Parameter	Typical Return
Whole number from 1 (default) to 100,000,000, limited as described below	+5.000000000000000E+01
Return number of cycles per burst: BURS:NCYC 50

• With TRIGger[1|2]:SOURce IMMediate, burst count must be less than the product of the maximum burst period (8000 s) and the waveform frequency, as shown below.
  
  Burst Count < (Maximum Burst Period)(Waveform Frequency)

• The increase the burst period up to its maximum value to accommodate the burst count (but the waveform frequency will not be changed). From the remote interface, a "Settings conflict" error will also be generated.
• When gated burst mode is selected, the burst count is ignored. However, if you change the burst count while in the gated mode, the instrument remembers the new count and used it when the triggered mode is selected.

[SOURce[1|2]:]BURSt:PHASe {<angle>|MINimum|MAXimum}
[SOURce[1|2]:]BURSt:PHASe? [{MINimum|MAXimum}]

Sets the starting phase angle for the burst.

Parameter	Typical Return
-360 to +360 degrees, -2p to +2p radians, or -(period) to +(period), as specified by UNIT:ANGLe. Default 0.	+6.0000000000000E+01
Set starting burst phase to 60 degrees: UNIT:ANGLE DEG BURS:PHAS 60

• Note that BURSt:PHASe is used instead of output phase, and when burst is enabled, the output phase is set to 0.
• For sine, square, and ramp, 0 degrees is the point at which the waveform crosses 0 V (or DC offset) in a positive-going direction. For arbitrary waveforms, 0 degrees is the first waveform point. Start phase has no effect on noise.
• For arbitrary waveforms on the 33500 Series, BURSt:PHASe is only available if the waveform is 1,000,000 points or less.
• Start phase also used in gated burst mode. When the gate signal goes false, the current waveform cycle finishes, and output remains at the voltage level of the starting burst phase.

[SOURce[1|2]:]BURSt:STATe {ON|1|OFF|0}
[SOURce[1|2]:]BURSt:STATe?

Enables or disables burst mode.

Parameter	Typical Return
{ON|1|OFF|0}, default OFF	0 (OFF) or 1 (ON)
Enable burst mode: BURS:STAT ON

• Output phase is set to 0 when burst is enabled.
• To avoid multiple waveform changes, enable the burst mode after configuring the other burst parameters.
• The instrument will not allow the burst mode to be enabled at the same time that sweep or any modulation mode is enabled. When you enable burst, the sweep or modulation mode is turned off.