Frequency Error and Frequency Measurement and Generation Accuracy

Updated Jan 23, 2018

Issue Details

How can I determine frequency error and frequency measurement or generation accuracy?
 

Solution

Frequency accuracy (sometimes called timing accuracy) is usually given in parts per million (ppm) of the sample rate. This value depends on the device that you are using and can be found in the device's specifications. In addition to frequency accuracy (fa), frequency error (fe) is also something that you can calculate, using the equations below: 
Measured frequency (fm) = signal frequency (fs) ± frequency error (fe).
Rearranging the above equation to solve for frequency error:
Frequency error (fe) = signal frequency (fs) * frequency accuracy (fa).

Additional Information

Examples:
Consider a case in which you are measuring a precise 100kHz sine wave, using a device with a frequency accuracy of 25 ppm. The frequency error will be 100,000Hz * 25/1,000,000 = 2.5Hz. Therefore, the frequency accuracy is 100kHz ± 2.5Hz.

Consider a case in which you are generating a 1kHz sine wave, using a device with a frequency accuracy of 50 ppm. The frequency error will be 1,000Hz * 50/1,000,000 = 50mHz. Therefore, the frequency accuracy is 1kHz ± 50mHz.

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