Frequency Domain Analysis of Nonuniform Sampling Rates

Topics: Signal processing, Estimation theory, Discrete Fourier transform Pages: 2 (455 words) Published: July 18, 2010
In statistical signal processing, the sampling times are most often taken to be equally spaced. However, several applications need that non-uniform sampling is important. The major work on nonuniform sampling is for when the sampling times can be specified, and the signal processing community lacks tools to deal with standard issues like identification and decimation for signals sampled at non-uniform times. With a stochastic view, this thesis aims to fill this gap, and it provides tools to deal with errors induced by nonuniform sampling. Much is gained by studying apriorie properties of frequency transforms and estimates, and the tools can be used for several signal processing problems. Nonuniform sampling is used in radar applications, medical applications, image processing and astronomical data processing. In uniform sampling , the sampling interval is fixed .Uniform sampling is also known as periodic sampling. In nonuniform sampling, the sampling time and amplitude are not predictable. Nonuniform sampling is also known as stochastic sampling. Nonuniform sampling signal spectrum plays an important role in signal detection and tracking. In many applications, much interest lies in narrow band signal detection which may be recorded in very noisy environment. Therefore signal detection and frequency estimation becomes nontrial problems that require robust, high resolution spectrum estimation techniques[2]. We first consider Fast Fourier transform method of spectrum estimation which is most often used technique in spectral analysis. By using FFT, frequency resolution of noise spectrum is decreased and variance is also reduced, but these may not be reduced to optimum level [3]. So we take nonparametric methods for spectrum estimation. The nonparametric methods emphasize on obtaining consistent estimate of the power spectrum through some average or smoothing operations performed directly on the periodogram or on the autocorrelation of the noisy data. Although...
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