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Most of the signals directly encountered in science and engineering are continuous: light intensity that changes with distance; voltage that varies over time; a chemical reaction rate that depends on temperature, etc. Analog-to-Digital Conversion (ADC) and Digital-to-Analog Conversion (DAC) are the processes that allow digital computers to interact...
32 trang | Chia sẻ: tlsuongmuoi | Ngày: 22/02/2013 | Lượt xem: 2389 | Lượt tải: 0
DSP applications are usually programmed in the same languages as other science and engineering tasks, such as: C, BASIC and assembly. The power and versatility of C makes it the language of choice for computer scientists and other professional programmers. On the other hand, the simplicity of BASIC makes it ideal for scientists and engineers who on...
20 trang | Chia sẻ: tlsuongmuoi | Ngày: 22/02/2013 | Lượt xem: 2217 | Lượt tải: 0
Most DSP techniques are based on a divide-and-conquer strategy called superposition. The signal being processed is broken into simple components, each component is processed individually, and the results reunited. This approach has the tremendous power of breaking a single complicated problem into many easy ones. Superposition can only be used with...
20 trang | Chia sẻ: tlsuongmuoi | Ngày: 22/02/2013 | Lượt xem: 2041 | Lượt tải: 0
A linear system's characteristics are completely specified by the system's impulse response, as governed by the mathematics of convolution. This is the basis of many signal processing techniques. For example: Digital filters are created by designing an appropriate impulse response. Enemy aircraft are detected with radar by analyzing a measured impu...
18 trang | Chia sẻ: tlsuongmuoi | Ngày: 22/02/2013 | Lượt xem: 2220 | Lượt tải: 0
ASP (Active Server Page) là một mở rộng ISAPI, cung cấp một khung làm việc cho các ứng dụng phía Server. Một tài liệu ASP chứa cả ngữ pháp của HTML lẫn những cấu trúc script . Khi Web Server nhận được một yêu cầu cho một file ASP, một file HTML “ảo” được sinh ra (trong bộ nhớ) để trả lời . File sử dụng những thông tin HTML tĩnh cộng với bất kì HTML...
10 trang | Chia sẻ: tlsuongmuoi | Ngày: 22/02/2013 | Lượt xem: 2345 | Lượt tải: 1
Fourier analysis is a family of mathematical techniques, all based on decomposing signals into sinusoids. The discrete Fourier transform (DFT) is the family member used with digitized signals. This is the first of four chapters on the real DFT, a version of the discrete Fourier transform that uses real numbers to represent the input and output sign...
28 trang | Chia sẻ: tlsuongmuoi | Ngày: 22/02/2013 | Lượt xem: 2174 | Lượt tải: 0
The Discrete Fourier Transform (DFT) is one of the most important tools in Digital Signal Processing. This chapter discusses three common ways it is used. First, the DFT can calculate a signal's frequency spectrum. This is a direct examination of information encoded in the frequency, phase, and amplitude of the component sinusoids. For example, hum...
16 trang | Chia sẻ: tlsuongmuoi | Ngày: 22/02/2013 | Lượt xem: 2051 | Lượt tải: 0
The time and frequency domains are alternative ways of representing signals. The Fourier transform is the mathematical relationship between these two representations. If a signal is modified in one domain, it will also be changed in the other domain, although usually not in the same way. For example, it was shown in the last chapter that convolving...
24 trang | Chia sẻ: tlsuongmuoi | Ngày: 22/02/2013 | Lượt xem: 2176 | Lượt tải: 0
There are several ways to calculate the Discrete Fourier Transform (DFT), such as solving simultaneous linear equations or the correlation method described in Chapter 8. The Fast Fourier Transform (FFT) is another method for calculating the DFT. While it produces the same result as the other approaches, it is incredibly more efficient, often reduci...
18 trang | Chia sẻ: tlsuongmuoi | Ngày: 22/02/2013 | Lượt xem: 2021 | Lượt tải: 0
Continuous signal processing is a parallel field to DSP, and most of the techniques are nearly identical. For example, both DSP and continuous signal processing are based on linearity, decomposition, convolution and Fourier analysis. Since continuous signals cannot be directly represented in digital computers, don't expect to find computer programs...
18 trang | Chia sẻ: tlsuongmuoi | Ngày: 22/02/2013 | Lượt xem: 2083 | Lượt tải: 0