خلاصة:
In this paper the author considers a general method, based on time domain samples for spectral manipulation of time limited signals. First, the original signal is divided into some frames in the time domain. Then, by presenting a suitable theoretical and computational algorithm, and using a method for improving the speed of convergence, we find the local bandwidth of each frame; thereby, each frame is sampled with a new rate, so the amount of data per frame is decreased. Finally, by storing suitable information at the beginning of each frame, the original signal could be reconstructed. Therefore, by this method some redundant data is removed and the net volume of data is reduced. The reconstruction of original signal is achieved by using periodic interpolation. In this technique, a method for reduction of error (due to false interpolation) at the end of any frame is examined carefully.
ملخص الجهاز:
Data Compression, Local Bandwidth Estimation, Interpolation, Time Domain Sampling, Adaptive Non-uniform Rate Sampling, Spectral Analysis INTRODUCTION Nowadays, construction and improvement of powerful digital processors have given impetus to work and research in the fields of data, speech and image processing.
This criterion computes the sampling frequency based on the maximum frequency of the given analog signal, and we could reconstruct band limited signals by sampling values with the use of Shannon Interpolation series [2,9].
— "THE PRD CURVE To dcscribe the behavior of PRD curve, we consider the arbitrary signal X(t), and take g(t) (Figure 2) as a time limited part of X(t), with (n) original samples' value, and define the new parameter (k = n - 1.
We solve the problem of interpolation in using (h) with the following procedure: We assume that the (n) original samples of (g) are located at t, and when the number of samples become (1), thc new points are distributed in s: (View the image of this page) Iranian Journal ‹›f Information Science & Technology, Yolume 3, Number 1 d anuary/d une, 2005 Practically, deviation of reconstructed signal is occurred in the interval (s/,tfl).
If the coordinates of marginal points are (i, and , fj), among the tested two parametric nonlinear functions, we could denote the suitable form by I - fj = A(k - S (i January/4 une, 2045 Iranian 4ournnl ot Information Science & Technology, Volume 3, Number I — TH E COMBINATION OF TI M E AN D FREQUENCY COM PUTATI Ofv As said before, our aim was data comprcssion by applying a time domain error.