Errors in synchronous data acquisition and averaging

Synchronous data acquisition and averaging are effective methods for noise reduction. However, if phase shifts are present in the synchronously acquired epochs prior to averaging, the effectiveness is greatly reduced. The errors caused by these phase shifts are examined. The desynchronization error which occurs when the acquisition repetition frequency is not an integer multiple of the signal´s frequency is discussed. Random phase shift error is discussed. An example of error correction is given. The results are useful for the analysis and design of data acquisition systems