The resolution and accuracy of a multimeter belong to two different concepts.
The former characterizes the sensitivity of the instrument, that is, the ability to recognize small voltages; The latter reflects the accuracy of the measurement, that is, the degree of consistency between the measurement results and the true value. There is no necessary connection between the two, so they cannot be confused, and resolution (or resolution) should not be mistaken for accuracy, which depends on the comprehensive error and quantization error of the internal A/D converter and functional converter of the instrument. From a measurement perspective, resolution is the "imaginary" indicator (independent of measurement error), while accuracy is the "real" indicator (it determines the size of measurement error). Therefore, increasing the number of display digits arbitrarily to improve the resolution of the instrument is not feasible.
measuring range
In a multifunctional digital multimeter, different functions have corresponding maximum and minimum values that can be measured.
Measurement rate
The number of times a digital multimeter measures the amount of electricity being measured per second is called the measurement rate, and its unit is "times/s.". It mainly depends on the conversion rate of the A/D converter. Some handheld digital multimeters use measurement cycles to indicate the speed of measurement. The time required to complete a measurement process is called the measurement cycle.
There is a contradiction between measurement speed and accuracy indicators, usually the higher the accuracy,
The lower the measurement rate, the more difficult it is to balance the two. To solve this contradiction, different display digits or measurement speed conversion switches can be set on the same multimeter: a fast measurement gear can be added, which is used for A/D converters with faster measurement speeds; By reducing the number of display digits, the measurement rate can be significantly improved. This method is commonly used and can meet the needs of different users for measurement rate.
Input impedance
When measuring voltage, the instrument should have a high input impedance, so that the current drawn from the measured circuit during the measurement process is minimal and does not affect the working state of the measured circuit or signal source, which can reduce measurement errors.
When measuring current, the instrument should have a very low input impedance. This way, when connected to the tested circuit, the impact of the instrument on the tested circuit can be minimized as much as possible. However, when using the current range of a multimeter, due to the small input impedance, the instrument is more likely to burn out. Users should pay attention when using it.
