To be more specific: I am measuring frequency signal something about 40kHz sampled with frequency 250kHz. With what accuracy this frequancy is measured. What are the smallest changes of input frequency that I can measured. Thank you for your help.
What device are you using? Based upon that device you can use the bit resolution to help you determine the smallest detectable change. Here is an accuracy calculator that can help you determine what the smallest detectable voltage is.
The divice is 6221. This accuracy refers to the voltage but I want to measure frequency and I,d like to know with what accuracy the frequancy I can measure.
To specifically calculate the frequency accuracy, you will need to use the timing accuracy of the 6221. For the 6221 it is 50 ppm of the sample rate. For more information see Sample Clock and Frequency Measurement Accuracy.
