Errors in Digital Instruments

Errors in Digital Instruments Points : Errors in Digital Instruments 1. Resolution Error The change in the value to be measured by a digital voltmeter due to which the meter reading is changed by one digit is called resolutions error. For example a digital meter 199.99V instead of 200,00V. In this case the minimum resolutions is 0.01 V. 2. Quantization Error Quantization Error is represented by the smallest unit of the count. Sometimes due to small change in analog values to be measured causes a change of “Bit” in digital output. In this way in every reading a change of ± 1 digit occurs. This errors is called quantization’s error. For example meter reads 1 or 3 instead of 2. This error can not be eliminated completely. 3. Gate Time Error In some digital instruments different pulses pass during the opening and closing internal of the gate. This is possible due to the change in opening and closing time to the change in opening and closing time of the gate and is called gate time error. This error is very common in digital frequency meters, because these measures frequency by counting pulses passing during gate time. 4. Total Error Due to long usage of the errors are produced times drift and temperature errors are produced in these instruments. (i.e. the instruments are effected due to change in temperature.). Under these conditions the calibration is affected and thus some of drift error, temperature error also produced. Therefore, the error is called total error. These errors are can be judged by comparing the total error and rated errors, as described by the manufacturer, are greater than value of total errors. 5. Sample Error For rapidly changing values i.e or measurements of high frequency value, the Conversion time for analog-to- digital converter is very low, but this time is not provided at high frequencies, which causes sample error. This error can he controlled by sampling method.