Network Analyzers using S2VNA software

---

---

In the model S5180B Analyzer, there is a synchronizer, a pulse modulator, and a set of pulse generators that realize various pulse measurement modes.

Pulse measurement modes

The Analyzer supports three main modes for measuring the S-parameters of a pulsed DUT:

•Synchronous wideband mode (Point in Pulse) — measuring the frequency response of pulsed devices using wideband detection (see below). S-parameters are measured within one RF pulse at each frequency point. Modulation pulses are time synchronized with digital IF filter measurements

•Asynchronous narrowband mode — measuring the frequency response of pulsed devices using narrowband detection (see below). S-parameters are measured within a burst of RF pulses at each frequency point. The modulation pulses are not synchronized with the digital IF filter measurements. The measurement width of a digital IF filter is determined by the set filter bandwidth. The measurement width is selected larger than the pulse burst width. Each burst must contain more than 10 pulses

•Pulse profile mode — measurement of pulse parameters (amplitude envelope and pulse phase) in the time domain over the width of one RF pulse

---

---

Wideband and Narrowband detection

Detection is wideband when most of the spectrum of the RF pulse is within the passband of the IF filter (see figure below). This relationship between the characteristics of the filter and the signal spectrum occurs when the RF pulse width is greater than or equal to the measurement width of the digital IF filter and the measurement begins and ends within the width of each RF pulse. Since S-parameters are measured inside a RF pulse during wideband detection, in order to capture short RF pulses the Analyzer must have a wide IF filter bandwidth. The S5180B analyzer has a IF bandwidth of up to 300 kHz, which allows the capture of RF pulses from 4 μs.

Wideband detection is used in the “Point in Pulse” mode.

Wideband detection

Narrowband detection is used to measure short RF pulses that have a smaller width than can be measured by the wideband detection method.

Detection is narrowband when most of the RF pulse spectrum is outside the IF filter passband (See figure below). In this case, information is available only about the central component of the spectrum. This relationship between the characteristics of the filter and the signal spectrum occurs when the width of the measured RF pulses is significantly less than the width of one analyzer measurement.

The method uses the accumulation of bursts of identical RF pulses per width of one digital IF filter measurement. It is recommended to use more than ten RF pulses in a burst.

Narrowband detection is used in the “Asynchronous Narrow Band Mode” mode.

Narrowband detection

Comparison of point-in-pulse and asynchronous pulse mode

Internal Generators

The Analyzer contains four internal generators named Pulse0 ... Pulse3. The purpose of the generators is as follows:

•Pulse0 is the modulator control.

•Pulse1, Pulse2 are output signals for controlling external devices.

•Pulse3 is an internal trigger.

Parameters of the internal pulse generators

Parameters of the internal modulator

Pulse Mode and Channels

Turning the pulse mode ON/OFF acts for all opened channels simultaneously. The following conditions are met automatically:

•All channels share the same internal generator settings and the same trigger settings.

•Channels using the point-in-pulse mode and channels using the pulse profile mode can coexist.

•Channels using the asynchronous pulse mode cannot coexist with channels using the point-in-pulse or pulse profile mode.

Trigger in synchronous pulse modes

A special pulse trigger is used in synchronous modes "Point in pulse" and "Pulse profile". This trigger should not be confused with the standard mode trigger (See Trigger Settings). The pulse trigger has separate settings in the pulse mode menu (See Pulse Trigger Settings). The pulse trigger source can be internal (Pulse 0 generator) or external. If the source is internal, the user can set the trigger repetition period, and, accordingly, RF pulses repetition period in the software interface.

Purpose of BNC connectors (rear panel of the Analyzer)