Integrated Pulse Measurements

How to start the Pulse Setup dialog

Using Hardkey/SoftTab/Softkey

Using a mouse

1. Press Sweep > Source Control >  Pulse Setup....

1. Click Stimulus

2. Select Sweep

3. Select Sweep Control

4. Select Pulse Setup...

Pulse Setup dialog box help

Note: The M937xA does not support this function.

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 VNA 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 VNA 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. select Stimulus, then Sweep, then Sweep type = CW in the VNA menu.

Pulse Profile - Pulse profile measurements provides 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 VNA 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.

• In SW Gating mode, software gating sensitivity is improved. When unchecked, all data outside the measurement band is zeroed. SW Gating mode is used for troubleshooting purposes.

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 VNA 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 press Sweep > Main, then change the Start Time and Stop Time.

Sweep Time - Sets the time the analyzer takes to complete one sweep.

Number of Points - Sets the number of data points for the measurement.

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.

Measurement Timing

Port n, Rcvr  - 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 VNA 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.

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:

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.

Plot Pulse...  Accesses the Pulse Timing dialog, which displays an interactive screen for evaluating the pulse timing setup.

Plot Pulse is enabled for Pulse Profile measurements in N524xB and N522xB models, but disabled in all other models.

Plot Pulse is disabled for all NarrowBand pulse measurements.

Right-click in the display area to access the following menu:

Autoscale - Automatically scales the data to fit vertically within the display grid area.

Display marker annotation - Select to display marker annotation in the top-right of the display.

Show graticule - Select to display graticules.

Add marker to: - Select to add a marker to a displayed pulse trace. When a selection is made, the mouse pointer changes to a "+". Click in the display area and the marker will appear. Drag the marker to the desired position. Each time this selection is made, a new marker will be added.

Copy to Clipboard - Copies a bitmap of the trace control (Display) to the clipboard. It can then be pasted into any document that accepts bitmaps.

Print... - Prints the displayed data.

Scale properties... - Accesses the following dialog:

Stimulus - Sets the Begin and End displayed on the X-axis in seconds.

Response - Sets the Reference level in the center of the Y-axis and sets the scale per division.

Pulse Setup (Modulation Distortion Channel) dialog box help

Note: The does not support this function.

Pulse Measurement

Off - Source and Receivers are NOT pulsed

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

Pulse Timing

RF Pulse Width - Sets the width of the RF Source pulse.

Pulse Period pulldown- Allows the selection of the following:

Pulse Period - The time to make one complete pulse.

Pulse Frequency - The reciprocal of Period (1/ Period).

Pulse Duty Cycle - Pulse Width divided by the Pulse Period.

Labels

• Sweep - Complete cycle time of measurement including background sweeps.

• Acquire - The ADC acquisition time required to measure the data for a single FFT.

• Pulse/Swp - Number of pulses which will occur during the sweep, including pulses used for background sweeps.

Pulse Details

Generator - Pulse generator outputs in numerical order.

Device -  Indicates the device being controlled by the pulse generator output.

• Pulse0 - Always set to Receiver. Sets the amount of time to wait before triggering the ADC to begin acquisition and is always selected for Pulse0 and cannot be changed. Pulse0 adds (ADC Delay) + (Modulator Delay). The ADC will begin measuring data 250 ns before the rising edge of Pulse0. This delay is indicated in the Fixed ADC Delay = 250 ns annotation.

• Pulse1 through Pulse4 - Pulse outputs can be set to the following:

• RF - Selecting RF indicates that the pulse signal is used to drive the RF modulator. Only one pulse generator output can be used to drive an RF source. If you try to set more than one pulse generator output to RF, then the other one will be set to User N (where "N" is the pulse generator number).

• User 1, User 2, User 3, User 4 - Labels for user convenience. These labels do not connect the pulse generator to any specific hardware. These selections may be used to control a DUT, DC biases, or other signals.

• Pulse4 ADC Activity - (Pulse4 only) Pulse4 can also be set to ADC. This selection outputs a signal on Pulse4 when the ADC is active. This is the same as Pulse4 Output Indicates ADC Activity on the Pulse Generators Setup dialog. If ADC is selected for Pulse4, then the pulse width and delay entries are grayed out because Pulse4 is no longer a pulse output.

Width - RF Source pulse width. This setting is the same as Pulse Width under RF Pulse.

Delay - If the Offset Pulses using ADC Delay check box is disabled, then the delays are the pulse delays relative to the trigger. If the Offset Pulses using ADC Delay check box is enabled, then the delays are defined for the pulses relative to each other. In this case, you can enter negative delays, and the delay from the trigger will be adjusted to correct for these values.

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

Enable  Check to enable individual pulse generators.

Autoselect Receiver Timing - Computes the width to 80% of the RF Source Width and the delay will be 10% of the RF Source Width. With this setting selected, the Width and Delay columns in the table are grayed out.

Offset Pulses using ADC Delay Check Box

• If checked (default), adds delays to the Pulse Generator:

• Pulse0 adds (ADC Delay) + (Modulator Delay).

• Pulse Output used as the Modulator Drive adds no delay.

• All other Pulse Outputs add Modulator Delay.

• RF Modulator Delay

• Defines the RF delay of the source modulator. This is the time lag between the pulse drive signal and the actual RF output. This may indicate the lag for either an internal or external source.

• The default is 40 ns, which is the average delay of the internal RF modulators. The internal modulator below 3.2 GHz is slower than the internal modulator above 3.2 GHz. Therefore, the average value is chosen.

• ADC Delay

• The ADC starts on the rising edge of Pulse0. Due to the data pipeline, the ADC begins measuring data 210 ns before the rising edge of Pulse0 occurred. Since the ADC measurement leads Pulse0, Pulse0 is delayed by this amount of time. This value cannot be changed.

Timing Example

Assume Pulse1 is used to modulate the RF signal, all Pulse outputs are enabled, all are set to zero delay, and all are set to the same width. The first timing diagram below is with offset off and the second timing diagram is with offset on.

Buttons

Plot Pulse Timing - Accesses the Pulse Timing dialog, which displays an interactive screen for evaluating the pulse timing setup.

Right-click in the display area to access the following menu:

Autoscale - Automatically scales the data to fit vertically within the display grid area.

Display marker annotation - Select to display marker annotation in the top-right of the display.

Show graticule - Select to display graticules.

Add marker to: - Select to add a marker to a displayed pulse trace. When a selection is made, the mouse pointer changes to a "+". Click in the display area and the marker will appear. Drag the marker to the desired position. Each time this selection is made, a new marker will be added.

Copy to Clipboard - Copies a bitmap of the trace control (Display) to the clipboard. It can then be pasted into any document that accepts bitmaps.

Print... - Prints the displayed data.

Scale properties... - Accesses the following dialog:

Stimulus - Sets the Begin and End displayed on the X-axis in seconds.

Response - Sets the Reference level in the center of the Y-axis and sets the scale per division.

Pulse Generators - Accesses the Pulse Generators Setup dialog. See below.

Pulse Generators Setup dialog box help

This dialog is available with Option S9x025A/B and S9x024B (pulse generators).

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

Pulse Generators

Configure the Pulse Generators to be used for your measurement.  The pulse 0 is for the receiver. The pulse 1 is for source and P1 output and pulse 2 to 4 are for P2 to P4 output signal, receptively.

• 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 VNA 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 though Pulse Sync IN.

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 the required internal source ports.

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.

Offset Pulses

Offset Pulses using ADC Delay Check Box

• If checked (default), adds delays to the Pulse Generator:

• Pulse0 adds (ADC Delay) + (Modulator Delay).

• Pulse Output used as the Modulator Drive adds no delay.

• All other Pulse Outputs add Modulator Delay.

• RF Modulator Delay

• Defines the RF delay of the source modulator. This is the time lag between the pulse drive signal and the actual RF output. This may indicate the lag for either an internal or external source.

• The default is 40 ns, which is the average delay of the internal RF modulators. The internal modulator below 3.2 GHz is slower than the internal modulator above 3.2 GHz. Therefore, the average value is chosen.

• ADC Delay

• The ADC starts on the rising edge of Pulse0. Due to the data pipeline, the ADC begins measuring data 210 ns before the rising edge of Pulse0 occurred. Since the ADC measurement leads Pulse0, Pulse0 is delayed by this amount of time. This value cannot be changed.

Offset Pulse Example

Assume Pulse1 is used to modulate the RF signal, all Pulse outputs are enabled, all are set to zero delay, and all are set to the same width. The first timing diagram below is with offsets off and the second timing diagram is with offsets on.

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.

Pulse4 Output Indicates - Check to use an oscilloscope connected to the pulse 4 (pin 13 of the PULSE I/O connector on the rear panel of the VNA) to display when the ADC is making measurements. There are two selections:

All ADC Activity - When selected, all ADC activity can be monitored, including ADC activity that may not be displayed on a trace. An example is background measurements that are used for receiver leveling, but are not actually displayed on a trace.

Trace ADC Activity - When selected, Pulse4 will be active only during measurements that will be displayed on a trace.

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 VNA 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 (Pulse Sync In). All five pulse outputs have unique delay and pulse width settings.

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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.