The effects of accumulated timing jitter on some sine wave measurements

This paper investigates the effects of accumulated timing jitter on the signal-to-noise ratio (SNR) and on the phase angle measurement of real sine waves. These measurements are done via the Fast Fourier Transform (FFT) method. Accumulated timing jitter occurs when the sine wave is sampled by an unstable clock where the clock periods are randomly changing. Also, accumulated jitter is a problem in ramp-type bases that were often used in sampling oscilloscopes. Expressions for an estimate of the signal-to-noise ratio [SNR/sub (est.)/] and phase variance in terms of the jitter distribution parameters and the number of FFT points (N) are derived. The derived expressions are verified through computer simulations. Finally, a comparison between independent and accumulated jitter is presented.>