Integrated Pulse Measurements


The Pulse Setup dialogs shown in this topic are now integrated in the PNA firmware and are available with Opt 008 or Opt H08.

Previously, setup was performed with the Narrowband or Wideband pulse programs. With the appropriate hardware options (Opt 021, 022, 025) these commands are still available without Opt 008 or H08. Learn more about PNA Options.

Beginning with A.09.50, external pulse generators can be used along with the PNA internal pulse generators. Learn more.

In this topic

See Also (separate topics)

App Note: Active-Device Characterization in Pulsed Operation Using the PNA-X (1408-21)

How to start the Pulse Setup dialog

To provide quicker access, use the Setup softkey. Learn how.  

Using front-panel
hardkey
[softkey] buttons

Using Menus

  1. Press Sweep

  2. then [Pulse Setup]

  1. Click Stimulus

  2. then Sweep
  3. then Pulse Setup

 

Pulse Setup dialog box help

The Basic controls allow simple pulse measurements using the default (Autoselect) settings in the Advanced section of the dialog.

Pulsed measurements are performed in a Standard channel. See Measurement Class. However, several PNA measurement settings are controlled by the Pulse setup, such as sweep type, number of points, and so forth.

Pulse Measurement

Off - Source and Receivers are NOT pulsed

Standard Pulse - With pulsed RF, the PNA can be configured to sweep in frequency, power sweep, and CW time.

  • To make 'Point-in-Pulse' measurements, narrow the receiver pulse width and enter delay.

  • To make 'Pulse-to-Pulse' measurements, disable Autoselect Pulse Detection Method, then select Wideband. In the PNA menu, select Stimulus, then Sweep, then Sweep type = CW.

Pulse Profile - Pulse profile measurements provide a time domain (CW frequency) view of the pulse envelope. Profiling is performed using a measurement technique that "walks" a narrow receiver "snapshot" across the width of the pulse. This is analogous to using a camera to take many small snapshots of a wide image, then piecing them together to form a single, panoramic view.

Pulse Profile measurement using default settings and R1 receiver.

  • Pulse Profiling can be performed using ratioed or unratioed measurements. You can preview the pulse on port 1 by using an R1 receiver measurement.

  • Pulse Profiling is performed at a single CW frequency in either Narrowband or Wideband mode.

  • To select the CW Frequency, click Stimulus, then Sweep Type.

  • In Narrowband mode, the delay increment value, which is responsible for "walking" the receiver snapshot across the pulse, is selected by the PNA and is accessible only with a programming command.

  • In Wideband mode, the receiver is walked across the pulse by making a sequence of closely-spaced measurements in real-time.

Pulse Timing

Pulse Width - Sets the width of the source pulse. See measurement timing to learn how to control the receiver width and delay.

Pulse Period  The time to make one complete pulse.

Pulse Frequency (PRF) The reciprocal of Period (1/ Period). See Internal Pulse Generators to learn more.

By default, these settings configure Pulse Gen 1 to drive Source Modulators 1 and 2. This can be changed from the Advanced Settings Pulse Generator Setup dialog.

-------- Advanced Settings ----------

The following settings allow maximum control of a Pulse measurement.

Note: When the "Auto" check boxes are cleared, it is possible to configure settings to make an invalid measurement.

Properties

Autoselect pulse detection method - check to automatically switch between Narrowband and Wideband based on the Pulse Width.

In Standard Pulse:

  • Wideband - used when the (source) Pulse Width is WIDER than the fastest receiver acquisition time.  This allows the receiver to measure all pulse ON time - no pulse OFF time.  The PNA will select Wideband whenever possible.

  • Narrowband - used when the (source) Pulse Width is NARROWER than the fastest receiver acquisition time (267 ns). This measurement requires a spectral nulling technique to measure the pulse response through the DUT.

In Pulse Profile:

  • Wideband - used when the (source) Pulse Width is greater than 1.600 us. This allows the receiver make several sequential measurements to measure the entire pulse.

  • Narrowband - used when the (source) Pulse Width is less than or equal to 1.600 us.

Autoselect IF Path Gain and Loss - For future use.

IF Path - Click to launch the IF Path dialog.

Optimize Pulse Frequency - Automatically selects the Pulse Frequency and Pulse Period.

  • In Narrowband, the pulse frequency is adjusted slightly to get the best spectral-nulling filtering possible.

  • In Wideband, this checkbox is ignored.

Autoselect Profile Sweep Time - In Pulse Profile mode, adjusts the default X-axis start time to zero and the stop time double the Pulse Width. This allows you to see one complete pulse. If unchecked, the Sweep Time will not be changed.

To adjust the X-axis manually, click OK to close the dialog. Then click Stimulus, then Sweep, then Sweep Time, then change the Start Time and Stop Time.

IFBW - Select the IFBW for the measurement.

  • In Narrowband, an IFBW as close as possible to the entered value will be used.

  • In Wideband, this setting determines the receiver acquisition time - approximately 1/ IFBW.

Pulse mode OFF sets ALC - Sets the ALC mode that the Pulse Setup will use when the pulse is turned off.

The ALC’s cannot use their Internal Leveling circuits when the source is being pulse modulated. When pulse is turned ON via the GUI, COM, or SPCI, the Pulse Setup software sets the modulated source ALC’s into Open Loop Mode.

When pulse is turned OFF, the default behavior is to set the ALC’s back to Internal Leveling. This behavior can cause problems in some situations. Source power levels can shift slightly (a few dB) in normal conditions, to more dramatic shifts for less common conditions.

Here is an example of a dramatic power shift. The instrument has no source attenuators, and the power level has been set to -40 dBm in pulse mode (-40 dBm is allowed when Open Loop Leveling is selected). When the pulse is turned OFF, the power level will jump to -30 dBm, which is the lower power limit when the ALC is in Internal Leveling mode. This behavior can be avoided by setting the Pulse mode OFF sets ALC to Open Loop. When pulse is turned OFF, the ALC mode does not change and the power levels do not shift.

  • Internal - Set ALC to internal when the pulse is turned off.

  • Open Loop - Set ALC to open loop to use no ALC when the pulse is turned off.

Pulse Setup ALC Mode Warning

When the pulse is turned OFF, and sensing that an ALC mode will change, a warning dialog is displayed indicating the ALC changes about to be made. Choose a new setting or keep the current setting. Either selection will NOT affect the channel setting for the pulse OFF behavior.

  • Do not show this warning again - Check to not show this warning again.

  • Select Yes to change ALC modes or No to prevent the changes.

Measurement Timing

Source1 and Source2 - Used as RF Source Modulation Drive.

  • Width - source pulse width.

  • Delay - source pulse delay relative to the pulse generator clock.

  • Pulse Gen - Pulse generator used to modulate the source. Select CW to have NO source modulation.

The receiver settings in this table change depending on whether the PNA is in Narrowband or Wideband mode.

  • In Narrowband, for each IF receiver path, configure the Pulse Width, Delay, and Pulse Generator to be used to drive the receiver gate.

  • In Wideband, all receiver paths are the same.

Master Pulse Trigger  Refer to Block Diagram  Choose from:

  • Internal - Default setting. The pulse generator is triggered by an internal pulse clock.

  • External - The pulse generator is triggered by an external pulse clock.

  • <External Pulse Gen name> - Available when a 81110A is configured as an External Device and Master Mode is checked on the pulse generator properties dialog.  See how to make this setting using SCPI and COM.  

Primary Clock

The Primary Clock is controlled by the internal or external pulse generator and is the primary pulse clock. The Internal and External selections are not the same as the Trigger Source Internal and External selections found in the Pulse Trigger tab of the Trigger dialog. However, they are inter-related as follows:

 

 

Primary Clock

Trigger Source (from Pulse Trigger tab of Trigger dialog)

 

Primary pulse clock controlled by selected pulse generator.

Trigger source for the internal pulse generator.

Internal

  • Primary pulse clock is controlled by the internal pulse generator.

  • PRF setting is applied to the internal pulse generator.

  • Trigger is self-generated in the internal pulse generator.

  • The trigger source for the internal pulse generator trigger is set to Internal and is reflected in the Trigger Source selection in the Pulse Trigger tab of the Trigger dialog.

External

  • The primary pulse clock is an uncontrolled external pulse generator.

  • PRF settings are determined by the external pulse generator, which the VNA firmware does not control. The user must set up the external system clock. Entries for frequency and period in the VNA GUI dialogs will have no effect.

  • Trigger comes from the PULSE I/O connector (PulseSyncIn) on the rear panel.

  • The trigger source for the internal pulse generator trigger is set to External and is reflected in the Trigger Source selection in the Pulse Trigger tab of the Trigger dialog.

 

Other selections

If there is a defined pulse generator in the external devices list, its name will be displayed in the Pulse Setup dialog Primary Clock control and it will also be an accepted choice for the SENSe:SWEep:PULSe:PRIMary:CLOCk SCPI command.

 

 

 

Autoselect Width and Delay - When checked, for Wideband mode and Pulse Gen = Pulse Trigger, the default setting for the receiver is adjusted to approximately 75% of the source pulse width, with 20% delay. This leaves approximately 5% of the source pulse ON after acquisition is complete.

When checked for Narrowband mode and Pulse Gen <> CW, then Delay and Width matches the RF Source.

Autoselect Pulse Generators - When checked:

  • Pulse1 is selected for Modulator Drive.

  • Pulse2 is CW (OFF).

  • For Wideband, Pulse Trigger is selected to gate the ADC.

  • For Narrowband, Pulse2 is selected.

Pulse Generators  Click to launch the Pulse Generators Setup dialog.

 

Pulse Generators Setup dialog box help

This dialog is available with Option 025 (pulse generators).

To see this dialog, press Pulse Gen Setup on the Pulse Setup dialog.

Pulse Generators

Configure the Pulse Generators to be used for your measurement.

When configured, external pulse generators appear in this list. Learn more.

Delay defines the delay between the pulse clock and when the receiver begins to make a measurement. Learn more.

  • D = Delay; the time before each pulse begins

  • W = Width; the time the pulse is ON

  • Duty Cycle = W/P

  • P = Period; one complete pulse cycle

  • Pulse Frequency (PRF) = 1 / Period

Important: If D + W is greater than P, then undefined PNA behavior results. There is NO error message or warning.

Invert  Check to cause the pulse ON time to be active low and OFF be active high.

Enable  Check to enable individual pulse generators.

Trigger  Choose from: (When ONE of these is changed, they ALL change. The internal Pulse Generators can NOT be triggered individually).

  • Internal - Pulse generators are triggered by the internal pulse clock.

  • External - Pulse generators are triggered by an external pulse generator.

Frequency - Set the pulse frequency of each generator.

  • Pulse Frequency (PRF) = 1 / Period

  • P = Period; one complete pulse cycle

Period - Set the period of each generator.

Learn more about the Pulse Generators.

Pulsed Sources

Check to enable one or both internal source modulators.

These are switches 8 and 9 in the Block Diagram

Important: When internally modulating the sources, source leveling is automatically set to Open-loop (ALC Open Loop box will be checked automatically).

Modulator Drive  Choose the pulse generator to modulate the specified source. Choose from CW (NO pulse), Pulse 1, 2, 3, 4, External.  This is switch 7 Block Diagram.

Pulsed Receivers

Synchronize ADCs using pulse trigger - Check to enable triggering used to gate the ADC for wideband receiver measurements. This is the same as Pulse0 Enable. The Width can NOT be configured.

ADC trigger delay - Set the amount of time to wait before triggering the ADC to begin acquisition. This is the same as Pulse0 Delay.

Pulse4 output indicates ADC activity - Check to use an oscilloscope connected to pin 13 of the PULSE I/O connector on the rear panel of the PNA to display when the ADC is making measurements.

Pulse Trigger.. - Click to start the Pulse Trigger dialog.

Trigger... - Accesses the Trigger dialog for setting up triggering. Learn more.

 

 

Pulse Trigger Tab - Trigger dialog box help

To see this dialog, press Pulse Trigger on the Pulse Generator Setup dialog or select Stimulus, then Trigger from the PNA Menu.

Trigger Source

Select Internal or External to provide sync capability for the internal pulse generators.

  • Internal - The pulse generator is internally triggered and puts out a periodic pulse train with a period defined by the Pulse Generator Setup dialog.

  • External - The internal pulse generator puts out one set of pulses (P0-P4) per external trigger. All five pulse outputs have unique delay and pulse width settings.

The external trigger input is on the Pulse I/O connector pin 7 (PulseSyncIn). The PulseSyncIn line provides a configurable trigger signal into the Pulse Generators. If the trigger mode is set to "level", and if the trigger is still valid when the first pulse set is finished, another set will be generated. Only one set of pulses is emitted when edge triggering is used.

Trigger Level/Edge

Sets the edge or level of the trigger signal to which the internal pulse generators will respond when being externally triggered at the PulseSyncIn pin.

Positive = rising edge; Negative = falling edge.

These selections are available ONLY with DSP version: 4.0 FPGA: 34 or higher. Learn more. Otherwise, the pulse generators respond only to positive, level input trigger signals.

Receiver synchronization

Synchronize ADCs using pulse trigger - Check to enable triggering used to gate the ADC for wideband receiver measurements. The Width can NOT be configured.

ADC trigger delay - Set the amount of time to wait before triggering the ADC to begin acquisition.

 

Pulse Trigger Block Diagram

See complete description at IF Path Configuration

See also Using External Pulse Generators

Using External Pulse Generators

Setup the External Pulse Generator as an External Device.

Calibration in Pulse Mode

To perform a calibration in pulse mode (option H08 / 008), first configure and apply the pulse parameters (PRF, Pulse Width, Delays, IF gating, and so forth) before calibrating the system. This will ensure the PNA is configured properly during the calibration and measurement.


Last Modified:

15-Feb-2017

Added Pulse mode off sets ALC info

19-Dec-2013

Added Pulse-to-Pulse

11-Apr-2010

MX New topic (A.09.20)