Tips to Improve Oscilloscope Measurement Accuracy

In the process of using an oscilloscope, we often ignore some details, resulting in measurement errors. Therefore, we should pay attention to the correct method when using it. There is a brief introduction in the article "Precautions for using an oscilloscope". Even so, there are inevitably some errors in the measurement of the oscilloscope.
For engineers, on the one hand, it is necessary to understand these factors that affect the accuracy in order to better understand the indicators and measurement results of various parameters of the oscilloscope; on the other hand, for the inherent and uneliminable influencing factors of the instrument itself, the error can be reduced by correctly operating the oscilloscope and using measurement techniques. The following introduces to you the more practical principles and techniques for improving the measurement accuracy of the oscilloscope.
1. Minimize the quantization error based on the existing conditions, that is, try to make the measured waveform fill the grid, and make full use of the ADC range in the motor test.
2. Always be vigilant about the sampling rate, and oversample rather than undersample. For example, if the sampling rate is too low when measuring the waveform frequency, aliasing will occur, and the measurement result will be wrong.
3. Use the measurement statistics function. Because the shape of the waveform is unstable, the waveform measurement results captured by the oscilloscope are different each time. By using measurement statistics, you can find the worst case circuit performance and the parameter values ​​of some intermittent signals. This is a good way to determine whether the key signal characteristics are within the specification range.
4. Use averaging algorithms and filtering functions. For periodic repetitive signals, after stable triggering, use multiple measurements to find the average value to reduce the error caused by signal noise. The averaging algorithm will also reduce the noise introduced by the oscilloscope analog front end and probe. It should be noted that when making such measurements, the waveform must be stably triggered, and the storage depth and sampling rate must be sufficient.
5. Using FIR filters can also reduce noise. There is no need to capture multiple waveforms for averaging evaluation, a single capture is sufficient, so it can be used for the measurement of non-periodic repetitive waveforms that cannot be stably triggered.
6. To reduce the influence of the probe on the measurement accuracy, it is mainly necessary to pay attention to the following points:
1) Minimize the loop between probes as much as possible;
2) Place the probe in a suitable position (for example, keep the probe cable as far away from the radiation source as possible, and avoid entanglement of the cable to prevent it from forming a loop and picking up greater spatial radiation noise;
3) For differential probes, try to couple the positive and negative cables of the probe together so that the positive and negative cables are subjected to balanced spatial radiation, which is conducive to the elimination of common-mode noise.