An overview of Wave Inspector in the Tektronix MDO3000 Oscilloscope in time and frequency domains.

Hi again and welcome to our 84th Test and Measurement Video. Today’s topic is an overview of the Wave Inspector function in the Tektronix MDO3000 Series Oscilloscope. This interesting aspect of the instrument permits the user to take a closer look at a given signal, panning through it and zooming in on a small portion. First we’ll try it out and then talk about why anyone would want to do such a thing.

First, we’ll display a sine wave, shown here in the time domain. It comes from the internal arbitrary function generator, applied to analog Channel One by means of a BNC cable run from AFG Out on the back panel.

Notice in the AFG information bar that the frequency is 100.00 kHz and the amplitude is 500.00 mVpp, in other words one-half volt.

To activate Wave Inspector, press the button identified by a magnifying glass icon.

This button toggles Wave Inspector On and Off.

Notice the split-screen format. The upper display shows the current signal as applied to the analog channel input. There is a pair of brackets, and the portion of the signal that is enclosed within the brackets is shown in the lower display. The timebase is expanded so that the enclosed waveform spans all ten divisions of the X-axis.

Where it starts to get interesting is that using the concentric knobs in the Wave Inspector section, you can move the brackets, causing them to pan or zoom the waveform in the upper display, the enclosed portion of the signal shown in the lower display. The inner knob zooms and the outer knob pans. As you zoom, notice that the time per division in the Acquisition information bar changes accordingly.

All of this is not just an amusing diversion. To see how it brings out detail, we’ll look at another signal from the AFG, this time Noise. If necessary, press AFG again to bring up the AFG menu, and then press Waveform in the submenu. Using multipurpose knob a, scroll down to Noise, so that it is displayed. Then, turn the zoom knob in Wave Inspector to reduce the time per division; Notice how this brings out the detail in the noise signal. The effect can be seen more clearly if you press Stop to freeze the acquisition.

What about the frequency domain? Currently a square wave is being applied to the RF input. Press RF and once again toggle On the Wave Inspector. Here we get an error message stating that there is a setting conflict, so we have to conclude that Wave Inspector is not available for an RF input.

There is, however, an alternate approach. Go back to Channel 1, turn on AFG and press Math, followed by FFT, which enables Fast Fourier Transform. Now we see the sine wave in both time and frequency domains. That is what a mixed domain oscilloscope does.

Retoggle Wave Inspector, and now we can zoom and pan the frequency domain together with the time domain. This is just what is needed to isolate infrequent anomalies so that metastable performance can be changed.

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