Essentially, the ADC oversamples the signal and averages neighboring points together. However, instead of waveform-to-waveform averaging, it is point-to-point averaging. High-resolution mode is another form of averaging. You can also use advanced triggering techniques to stabilize your trigger.Īveraging mode is a great acquisition mode for viewing or characterizing very stable periodic waveforms, but it must be used appropriately. It’s best to check and make sure that you have a stable trigger in normal mode before switching to averaging mode. If the scope doesn’t have a stable trigger, then the averaged waveforms won’t be properly aligned in time and you will see artifacts similar to that of an aperiodic signal in averaging mode. If there’s a glitch in the signal, it will be hidden by the continuous averaging.ĭebug any suspected glitches in a different mode or use advanced triggering techniques such as zone triggering. If the signal is aperiodic, the displayed signal will not be valid data-just a conglomeration of changing signals over time. Averaging acquisition mode should be used only with periodic signals and with a stable oscilloscope trigger. This mode should only be used under certain circumstances or you could get misinformation on the screen. Therefore, using averaging mode will help give you more insight into what your current waveform actually looks like. For example, clamp-on current probes are notoriously noisy. The main benefit of averaging acquisition mode is that it averages out the random noise on your signal this allows you to see just the underlying signal. Averaging mode takes multiple waveform captures and averages them together. A 100-kHz clock signal captured using normal acquisition mode.Īveraging acquisition mode is probably the second most commonly used mode. It’s a very safe mode to use, and has no significant caveats. It’s best to use normal acquisition mode for day-to-day debugging tasks because it gives a good general representation of your signal. The ADC samples and the scope decimates down to the desired number of points and plots the waveform. Normal acquisition mode is the default mode for oscilloscopes. The scope’s bandwidth is a specification that defines the front-end hardware’s ability to capture a signal’s frequency content. Sample rate is how fast the ADC acquires samples. It’s worth noting that sample rate is not the same as bandwidth. By varying the sample rate of the scope’s analog-to-digital converter (ADC) and selectively plotting or combining sample points, different characteristics of a signal can be observed. Learn how normal, averaging, and high resolution modes work, and when you should use each one.Īcquisition modes are finely tuned sampling algorithms that give you unique insights into your signal. Extracting the most confidence from your oscilloscope readings requires understanding the strengths and weaknesses of different acquisition modes. By using an ADC paired with a plotter instead of a sweep generator paired with a CRT, you can change how your signal is acquired. The movement from analog to digital oscilloscopes has opened up a new world of measurement opportunities for engineers. This file type includes high-resolution graphics and schematics when applicable.ĭaniel Bogdanoff, Oscilloscope Product Manager, Keysight Technologies
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