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Why should we choose suitable scale on T&M EQUIPMENT?
- 2017-6-12 -

 To enhance the measurement ability, most of T&M equipment set various scale to meet the demand on different signal measurement. What if using a large scale to measure a small signal? Many people know it will cause deviation, but cannot explain the reason. Let us see how different scale influence the result.

Engineers believe that large scale can measure more range of object signal. Means both small and large signal can be observed by instrument. For this reason, some of them often choose large scale to implement the measurement. And some others even keep the scale at default position. Measurement result seems accurate by this way. But where is the problem inside the measurement?

 

ADC Quantification Deviation

The quantification deviation inside the instrument can influence the accuracy of result. Take the oscilloscope for example, we assume it’s with 9-bits ADC. It has 29= 512 valid bits. When it is under 1000V scale (Peak-Peak), considering the input maximum ±1000V to share 512 valid bits. The quantification deviation would reach 2000V/512=3.9V

If using this scale to measure the signal like 11V, it’s obvious that the minimum resolution of single ADC sampling cannot tell 1V reading change. Comes to a deviate result at last.

It seems that high ADC bits will bring the lower quantification deviation. However, it’s pity that high ADC resolution is contrast with high sample rate. High bandwidth brings high noise. Meanwhile, ADC manufacture process and framework limits the compatibility of high sample rate.

 

OWON breaks this technical difficulty, release XDS series 12-bits oscilloscope. At the same condition with 1000V scale, the deviation only reaches 2000V/4096=0.5V. Highly lower down the deviation. What’s more, it can run at 1GS/s sample rate, which will satisfy normal measurement process.

 

Proper scale to measure the signal is important. If not necessary, don’t choose the large scale to measure small signal. Instead of which, select the close scale assure the accurate result. OWON XDS offers user more options to select the scale. Help you complete the accurate measurement easily.