Sweep parameters are set using the SWEEP Menu.

When the Continuous toggle is pressed, the instrument toggles between single sweep and continuous sweep. In single sweep setting, the instrument waits until SWEEP ONCE is pressed or another setting is selected.

The number of points sets the number of display points in the trace that are generated from the measurement data.

With some spectrum analyzers, the user has control over sweep time (the elapsed time of each sweep, also referred to as scan time). An analyzer cannot be swept arbitrarily fast while maintaining its specified accuracy, but will have a sweep rate limitation depending upon the resolution bandwidth, video bandwidth, and frequency range selected. The sweep rate is not usually chosen by the user, but is determined by the frequency range swept divided by the sweep time. The limitation on sweep rate comes from the settling or response time of the resolution and video bandwidth filters. If an analyzer is swept too quickly, the filters do not have time to respond, and the measurement is inaccurate. Under such conditions, the analyzer display tends to have a “smeared” look to it, with the spectral lines being wider than normal and shifted to the right and at a lower amplitude than is correct.

Anritsu Field Master Series is designed to relieve the user from having to calculate the sweep speed or experiment to discover a sweep speed that yields accurate results. When changing the RBW and VBW, the sweep speed automatically changes to the fastest sweep speed that will yield accurate results. The sweep speed will be faster for a wide RBW or VBW and slower for a narrow RBW or VBW. Regardless of the minimum sweep time, the instrument will never sweep faster than the RBW and VBW settings will allow. The instrument is designed to ensure that no uncalibrated measurement conditions will occur.

 

 

Gated sweep is only available on instruments with Option 90 installed. Gated sweep allows you to synchronize your sweep with an event so that the analyzer collects data at the appropriate time. This is useful for measuring signals in the time domain such as pulsed RF, time multiplexed, or burst modulated signals. Field Master Series can use the GNSS (GPS) timing signal as the gating trigger event. This will allow you to synchronize measurements with GNSS (GPS) synchronized communication signals. Set up gated sweep from the GATED SWEEP Menu.

To set up the instrument for gated sweep measurements:

Below is an example of a gated sweep applied to a channel power measurement. The signal level shown varies cyclically with time and would not be measurable without gated sweep.

The channel power and gated sweep display panels at the bottom can be tapped to directly open either the Channel Power SETUP menu or the GATED SWEEP menu.

 

When power vs time is enabled, a time-domain graph is presented. This graph is a useful visual aid when setting up the GATE DELAY (1) and GATE LENGTH (2) times as you can simultaneously view the signal level within the set frame and relative to your gate delay and length. The display is enabled using the PWR VS TIME toggle setting and should be disabled after setting up the gate delay and length parameters. The gate delay and length are represented by the width of the displayed shaded area flanked with blue lines (see Figure: Power vs. Time Display).

If the blue gate delay and length setting lines are set outside of the displayed graticule scale, you will see “< Gate Start” and “Gate Stop >” messages at the edge of the display indicating where the blue setting lines are located.

Once the gate has been set up, you can apply gating to the spectrum by toggling GATED SWEEP on. Gating will continue to be applied when you access other measurements and functions of the spectrum analyzer until gated sweep is toggled off or an unsupported instrument configuration is selected.

 

When gated sweep toggle in turned ON, a time-domain graph is displayed on the bottom and frequency domain graph is shown on top of it, as shown in Figure: GATED SWEEP On Display. Note that enabling PWR VS TIME toggle will refresh the PVT trace, while disabling it will refresh the spectrum trace. The gate parameters (delay and length) can be configured with PVT enabled, and the impact on the spectrum can be observed by disabling PVT. You can also fine-tune the gate parameters without toggling PVT on and off, as it's expected that the gate period maintains a fixed relationship with the trigger event.