Accuracy Calculation of Digital Multimeter
The accuracy of the multimeter is also called uncertainty by some manufacturers, which generally says "measured under the condition of operating temperature 18°C~28°C (64°F~82°F) and relative humidity less than 80[%] within one year after leaving the factory. , ±(0.8[%] reading + 2 characters)." Many buyers or users are not very clear about this and often ask. I am assuming here that there is a meter, in a certain range, such as DC 200V, it is written like this, and the measured value shows 100.0 on the meter, so what should be the correct value at this time. I think that for general users, you can completely ignore the calculation of accuracy, and just think that it is 100V DC. Calculated according to the manufacturer's accuracy, when measuring 100V (display 100.0), the error is ±(0.8[%]*1000+2)=±10, that is, the error is 1.0V. When you substitute the reading, don't consider the decimal point. Substitute the displayed value into the calculation, add a decimal point to the calculated value, and then use the original reading to calculate the shipping cost. Like this example, the correct value is 100.0±1.0, which should be between DC 99.0~101.0V.
The difference between three and a half digits and four and a half digits of a digital multimeter
Three and a half digits are also called 31/2 digits (pronounced as three and one-half digits), and four and a half digits are also called 41/2 digits (pronounced as four and one-half digits). We know that after an analog quantity is quantized and converted into a number, the precision it represents is related to the number of digits of the number. The more digits, the closer to the original value, the more accurate (this is generally speaking , regardless of other circumstances, if the quantized value is 1.00000V, it is the same to represent it with one bit and N bits (:). So in general, the more digits, the more accurate, that is, four digits Half is more precise than three and a half digits.
