one of the most common signals used for achieving high range resolution in radar is stepped-frequency signals. when a target is stationary in these radars, dft (discrete fourier transform) based processing is used to attain high range resolution profile (hrrp). however, in the case of moving target, due to spreading of the echo signal spectrum, dft based processing is not optimal and decreases ...

Introduction In recent years methods based on radio frequency waves have been used for detecting breast cancer. Using theses waves leads to better results in early detection of breast cancer comparing with conventional mammography which has been used during several years. Materials and Methods In this paper, a new method is introduced for detection of backscattered signals which are received by...

The Discrete Fourier Transform (DFT) is used to transform the samples in time domain into frequency domain coefficients. The Fast Fourier Transform (FFT) is a widely used algorithm that computes the Discrete Fourier Transform (DFT) using much less operations than a direct realization of the DFT. FFTs is of great significance to a wide variety of applications such as data compression, spectral a...

seismic attribute is a quantitative measure of an interested seismic characteristic. there are several seismic attributes. in recent years, time-frequency (tf) attributes have been developed which to reach them, tf analyzing of seismic data is required. a high resolution tf representation (tfr) can yield more accurate tf attributes. there are several tfr methods including short-time fourier tra...

Wavelet transforms have become one of the most important and powerful tool of signal representation. Nowadays, it has been used in image processing, data compression, and signal processing. This paper will introduce the basic concept for Wavelet Transforms, the fast algorithm of Wavelet Transform, and some applications of Wavelet Transform. The difference between conventional Fourier Transform ...

An Orthogonal Frequency Division Multiplexing (OFDM) scheme offers high spectral efficiency and better resistance to fading environments. In OFDM the data is modulated using multiple numbers of sub-carriers that are orthogonal to each other because of which the problems associated with other modulation schemes such as Inter Symbol Interference (ISI) and Inter Carrier Interference (ICI) are redu...

This paper presents a method for the derermination of the frequency response functions using thefast wavelet transform (FWT) as an alternative to the fast Fourier transform (FFT)-based method. After a brief description of underlying theory, a focus problem is used to examine the relative perjonnance between the FFT-based vs. the FWT-based procedures for noisy data. The performance evaluations i...

Nonlinearities are often encountered in the analysis and processing of real-world signals. Most existing approaches to nonlinear signal processing characterize the nonlinearity in the time domain or frequency domain. In fact, there are good reasons for characterizing nonlinearity using more general signal representations like the wavelet expansion. Wavelet expansions often provide very concise ...