Trace and Waveform Data are analyzed using tools in the Tektronix MDO3104 oscilloscope.
Greetings and welcome to our 53rd Test & Measurement video. Our topic is Analyzing Waveform or Trace Data in the amazing Tektronix MDO 3000 Series oscilloscope.
The first task in using an oscilloscope is displaying the signal. For an individual who is new to the fascinating world of waveform acquisition, it is sometimes a challenge to make a signal display. The waveform is either unstable or it does not appear at all. A good proportion of these problems, not all of them to be sure, can be resolved simply by pressing Default setup, then reloading the signal and pressing Autoset.
Next on the agenda, going beyond initial acquisition and display, is using tools that are built into the instrument to highlight, measure and record information pertaining to the waveform under investigation.
These tools include, among others, cursors, automatic measurements, statistics, waveform histograms, math and Fast Fourier Transform, or FFT.
We have connected the Arbitrary Function Generator (AFG) to Channel One and activated the Sine wave. Then, going to Math, we press FFT in order to display a frequency domain graph of this function. The object is to demonstrate the use of markers.
Press Markers to bring up the Markers side menu. Then press Peak Markers and turn Multipurpose Knob a to select the number of peaks to be labeled in the display.
Next, in the red triangle, press R to Center. This sets the center frequency to the location relative to the X-axis indicated by the Reference Marker, which is automatically placed on the highest amplitude peak. For many waveforms rendered in the frequency domain, this will have the effect of moving the fundamental to the center of the display so that power distribution on either side of it can be viewed.
Press Threshold and turn Multipurpose Knob a to define the threshold of the peak markers. Their excursion level is set by Multipurpose Knob b.
Manual Markers may be turned On or Off. When On, they measure non-peak areas of interest in the spectrum as displayed.
Finally, the object of the exercise: Press Readout to select absolute or delta readouts. Delta readouts are relative to the reference marker.
Automatic Measurements can also be taken in the time domain. If the oscilloscope has been working in the frequency domain, it must be reconfigured. Press Default Setup to bring up a display with the X-axis corresponding to time. Then, press measure. In the menu bar below the display, press Add Measurement. If necessary, use Multipurpose Knob a to establish the source. Previously, we have connected the AFG output to Channel One. The default waveform is Sine, but for variation we will move it to Square Wave.
Multipurpose Knob b establishes the measurement type. The default is Snapshot All Measurements. To activate this mode, it is necessary additionally to press OK Snapshot All Measurements. When this is done, a list of 28 parameters appears with current values. Of particular interest in regard to Square Wave are rise time, 178.7 nanoseconds, and fall time, 6.466 microseconds.
The information is shown in the snapshot of the square wave, as synthesized in the instrument’s internal arbitrary function generator.
Returning to Multipurpose Knob b, we can select each of the parameters one at a time. As always, we have to follow up by pressing OK Add Measurement.
A bar appears across the bottom with details pertaining to the selected parameter.
DVM, which stands for Digital Volt Meter, is very frequently used. To bring up this instrument, press the soft key associated with DVM. Then, in the side menu, the DVM can be moved using Multipurpose Knob a from the Off state so as to read AC plus DC RMS, DC, AC RMS or frequency. Notice the nice clear numbers at the top, making for a very user-friendly instrument.
Another type of time-domain measurement is the histogram, which we will treat by itself in a future Test and Measurement video. Thanks for watching. New videos are added periodically, so check back frequently.