Introduction to What Technical Parameters and Measurement Methods a Digital Multimeter Has
Resolution, Number of Digits and Bits
Resolution refers to the ability of a multimeter to distinguish small signals during measurement. Knowing the resolution of a multimeter allows you to determine whether it can detect very small changes in the measured signal. For example, if a digital multimeter has a resolution of 1 mV in the 4 V range, it means that when reading 1 V, it can observe a change of 1 mV (1/1000 V).
If you have to measure a length as small as 1/4 inch (or 1 millimeter), you won't buy a ruler with the smallest scale of 1 inch (or 1 centimeter). If the normal temperature is 98.6 degrees Fahrenheit, a thermometer that can only measure whole degrees is not very useful. You need a thermometer with a resolution of 0.1 degree.
The terms "bit" and "digit" are used to describe the resolution of a multimeter. Multimeters can be grouped according to the number of digits or bits displayed on a digital multimeter.
A 3½-digit multimeter can display three full digits (0 to 9) and a "half digit" (which can only display a "1" or be left blank). The display resolution of a 3½-digit multimeter is up to 1,999 digits. The display resolution of a 4½-digit multimeter is up to 19,999 digits. Compared with "bit", using "digit" can more accurately describe the resolution of a multimeter. Nowadays, the resolution of a 3½-digit multimeter may be as high as 3,200, 4,000 or 6,000 digits.
For some measurements, a 3,200-digit multimeter can provide better resolution. For example, if you want to measure a voltage of 200 V or higher, a 1,999-digit multimeter cannot measure to 0.1 V. However, a 3,200-digit multimeter can display up to 0.1 V when measuring a voltage of up to 320 V. Before the voltage exceeds 320 V, this resolution is the same as that of a more expensive 20,000-digit multimeter.
