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

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

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, 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 Wideband mode.

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

• 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.

Properties

Autoselect pulse detection method - .

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.

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.

Autoselect IF Path Gain and Loss - For future use.

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

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 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.

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.

Autoselect Pulse Generators - When checked:

• Pulse1 is selected for Modulator Drive.

Pulse Generators...  Click to launch the Pulse Generators Setup dialog.

Pulse Generators Setup dialog box help

This dialog is available with Option S96325B (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.

Modulator Drive - Choose the pulse generator to modulate the specified source. Choose from CW (NO pulse), Pulse 1, 2, 3, 4, External.  

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 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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Trigger Level/Edge

Sets the edge 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.

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.