Có 20+ tài liệu thuộc chủ đề "DSP"
000000104466.pdf
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1 1.1.1 Các công cụ phân tích thời gian-tần số. 3 1.1.2 ðộ phân giải thời gian và tần số. 6 2.2 Biến ñổi Fourier và biến ñổi Wavelet. 9 2.2.1 Biến ñổi Fourier. 9 2.2.2 Khái niệm biến ñổi Wavelet. 12 2.2.3 Sự giống nhau giữa biến ñổi Wavelet và biến ñổi Fourier. 14 2.2.4 Sự khác biệt giữa...
000000104466-TT.pdf
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TÓM TẮT LUẬN VĂN Trong luận văn này, phân tích Wavelet ñược sử dụng ñể khử nhiễu tín hiệu và ứng dụng trên DSP. Mục tiêu thứ nhất của luận văn là giới thiệu và trình bày chi tiết về lý thuyết Wavelet, ñưa ra các ñặc ñiểm chi tiết của Wavelet và ứng dụng của Wavelet. Mục tiêu thứ...
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We are all remarkably complex signal processing systems, adap- tively processing intricate audio and video signals every moment of our lives.. While awake we input intricate signals from our environment, extract high- level representations of information carried by these signals, make decisions based on this information, record some of the information for later recall and processing, and produce new signals...
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We present some of the simplest signals, and discover that arbitrary signals can be represented in terms of simple ones. The first question we must ask when approaching the subject of signal anal- ysis is ‘What exactly do we mean by signal?’ The reader may understand intuitively that a signal is some function of time that is derived from the...
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Spectroscopy and X-ray crystallography rely on Fourier analysis to analyze the chemical composition and physical structure from minute quantities of materials, and spectral analysis of light from stars tells us of the composition and temperature of bodies separated from us by light years. Although he was completely sure of the outcome, he had been waiting to complete this experiment for...
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Looking back at the steps in proving the existence of the Fourier series we see that the periodicity of the signals was not really crucial. There we saw how increasing the period of the signal to be analyzed required decreasing the fundamental frequency of the HRSs. The conditions for the convergence of the Fourier transform are almost the same as...
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Extracting a signal from noise can rely on knowledge of the clean signal and/or knowledge of the noise. The point of the joke is that most people take. The ratio of the energy of the deterministic signal to that of the pure noise component is called the Signal to Noise Ratio (SNR), usually specified in dB. Being ignorant of the...
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We now turn to signal processing, which requires adding a new concept, that of the signal processing system.. 6.1.1 Which of the following are signal processing systems (we shall use 2 for inputs and y for outputs)? Explain.. We can generalize the concept of the amplifier/attenuator by allowing deviations from linearity. Figure 6.1: The effect of clipping amplifiers with different...
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In electronics the word ‘filter’ evokes thoughts of a system that removes components of the input signal based on frequency. This delay consists of the time it takes to fill the buffer (the buffer delay) plus the time it takes to perform the FFT, multiplication, and iFFT (the computation delay). 7.1.4 The squared frequency response of the ideal low-pass filter...
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In the previous chapter we have seen that they are simple to design, describe and implement. First, no system in the real world is ever perfectly linear. a small change in the input signal will always lead to a bounded change in the output signal. Nonlinear systems, however, may behave chaot- ically, that is, very small changes in the input...
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In order to be able to reliably detect the presence of the return signal we employ a signal detector whose output is maximized when a true reflection appears. This can be accomplished by building signal detectors for each of the basic signals and choosing the signal whose respective detector’s output is the highest. Were the error signal to be identically...
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10.1 Adaptive Noise Cancellation. Figure 10.1: Cancelling delayed and attenuated noise by subtracting.. This attempt is depicted in Figure 10.1, using a self-explanatory graphical technique to be presented more fully in Chapter 12. It is clear from the conservation of energy that the energy of the spot is the sum of each flashlight’s energy. signal is the sum of the...
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The majority of the signals we acquire from the outside world and pro- cess in our brains are visual, and much interesting signal processing takes place in our visual system. Ernst Weber was professor of physiology and anatomy at the university of Leipzig in the first half of the nineteenth century. His investigations involved the sensitivity of the senses. One...
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12.1 Graph Theory. A diagram obviously does not capture all the features of the original.. Maps of the entire world are even more abstract representations since the world is spherical and the map is flat. The distances between nodes, the lengths or thicknesses of the arcs, and the geometric orientations are meaningless in graph theory. In Figure 12.1 we see...
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13.1 Zero Crossings. Figure 13.1: Zero crossing detector for clean sinusoid with no DC offset. 13.1.2 Assume that we have located a rising zero crossing between times n and n+ 1.. 13.2 Bank of Filters. Figure 13.2: A bank of filters dividing the frequency band from 0 to F into N subbands, each containing a band-pass signal. Figure 13.3: Two...
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It is difficult to overstate the importance of the FFT algorithm for DSP. The discovery of the first FFT algorithm predated the availability of hardware capable of actually exploiting it. The basic principle of the FFT ensues from the search for such time-saving mechanisms, but its discovery also encouraged the development of DSP hardware. Today’s DSP chips and special-purpose FFT...
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15.1 Computation of Convolutions. (15.1) which is eminently suitable for real-time implementation. In this case the place shifting of the elements in the buffer occurs as part of the overall convolution, in parallel with the computation.. In equation (15.1) the index of summation runs over the filter coefficients.. (15.2) where the index i runs over the inputs, assuming these exist....
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As a simple but important example, consider a complex mixer of the type used to shift a signal in frequency (see Section 8.5). Lack of accuracy in the calculations will cause phase instabilities in the mixed signal, while loss of precision will cause its frequency to drift. Accurate values can be quickly retrieved from lookup tables, but such tables require...
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DSP processors are characterized by having at least some of the fol- lowing special features: DSP-specific instructions (most notably the MAC), special address registers, zero-overhead loops, multiple memory buses and banks, instruction pipelines, fast interrupt servicing (fast context switch), specialized ports for input and output, and special addressing modes (e.g., bit reversal).. 17.1 Multiply-and-Accumulate (MAC). First consider the outside of...
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18.1 History of Communications. 18.2 Analog Modulation Types. Now equation (18.2) is strongly reminiscent of the instantaneous representation of a signal of equation (4.66). 18.3 AM. Figure 18.3: The basic analog AM transmitter built from an oscillator and a variable gain amplifier. Figure 18.4: The basic hybrid digital-analog AM transmitter. Figure 18.5: The basic analog envelope detector for the demodulation...