2. Range Basic range: The input voltage range without attenuation or amplification is determined by the dynamic range of the A/D converter. By amplifying or attenuating the input voltage (10 times), other measuring ranges can be extended. For example, the basic range of DVM is 10V, which can be extended to 0. 1V, 1V,1000V5; DVM with a basic range of 2V or 20V can extend the range of 200mV, 2V, 200V, 1000V5.
3. Resolution Resolution refers to the ability of DVM to distinguish the minimum voltage change from CY7C 136-35JI, which reflects the sensitivity of DVM. It is expressed by the voltage value corresponding to each word, that is, V/ word. The ability to distinguish the minimum voltage change on different ranges is different. Obviously, it has the highest resolution on the minimum range. For example, a 3-and-a-half-bit DVM can measure the maximum input voltage 199.9mV with a resolution of 0. 1mV/ word (that is, when the input voltage changes by 0. 1mV, the last number displayed will change "1 word").
Resolution: expressed in percentage, independent of range, more intuitive.
4. Measuring speed Measuring speed refers to the number of measurements completed per second. Mainly depends on the conversion speed of AlD converter. Generally, the measurement speed of low-speed and high-precision DVM is several times/second to dozens of times/second.
5. Measurement accuracy Measurement accuracy depends on the inherent error and additional error of DVM (such as temperature, etc.). ) in use. The inherent error consists of two parts: reading error and full-scale error.
Reading error: related to the current reading. It mainly includes calibration coefficient error and nonlinear error of digital voltmeter.
Full-scale error: irrelevant to the current reading, only related to the selected range.
Sometimes, the full-scale error is expressed as a voltage equivalent to bamboo. When the measured value (reading) is small, the full-scale error plays a major role, and when the measured value is large, the reading error plays a major role. In order to reduce the influence of full-scale error, the measuring range should be reasonably selected so that the measuring range is more than 2/3 of the full scale.
6. Input impedance The input impedance depends on the input circuit (and is related to the range). The input impedance should be as large as possible, otherwise the measurement accuracy will be affected.
For DC DVM, the input impedance is expressed as input resistance, which is generally between 10 mfl and 1000 mω. For AC DVM, the input impedance is represented by input resistance and parallel capacitance, and the capacitance value is generally between tens and hundreds of picofarads.
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