1、精選優質文檔-傾情為你奉上1.In most cases, these signals originate as sensory data from the real world: seismic vibrations visual images, sound waves, etc.DSP isthe mathematics, the algorithms, and the techniques used to manipulate these signals after they have been converted into a digital form.在大多數情況下，這些信號來源于人

2、對真實世界的感覺，比如地震的震動，視覺圖像，聲音波形等。數字信號處理是一種數學工具，是一種用來處理那些將上述信號轉換成數字形式后的信號的算法和技術。2.Fouriers representation of functionsas a superposition of sines and cosines has become Ubiquitous for both the analytic and numerical solution of differential equations and for the analysis and treatment of communication sig

3、nals函數的傅里葉表示，即將函數表示成正弦和余弦信號的疊加，這種方法已經廣泛用于微分方程的解析法和數值法求解過程以及通信信號的分析和處理。3.If f (t ) is a nonperiodic signal, the summation of the periodic functions ,such as sine and cosine, does not accurately represent the signal. You could artificially extend the signal to make it periodic but it would require add

4、itional continuity at the end points .如果f(t)是非周期信號，那么用周期函數例如正弦和余弦的和，并不能精確的表示該信號f(t)。你可以人為的拓展這個信號使其具有周期性，但是這要求在端點處附加連續性4.A digital filter is a mathematical algorithm implemented in hardware, firmware, and software that operates on a digital input signal to produce a digital output signal for achievin

5、g filtering objectives.數字濾波器是一種數學算法，它可以用硬件，固件和軟件來實現。它作用于數字輸入信號產生數字輸出信號從而達到濾波目標。5.The basic idea of Fourier series method is to design an FIR filter that approximates the desired frequency response of filter by calculating its impulse response.用傅里葉級數設計FIR濾波器的基本的理念是計算出此濾波器的單位沖激響應來逼近所期望的濾波器的頻率響應。6.If t

6、he signal has sharp transitions, it is necessary to window the input data, so that the sections converge to zero at the endpoints如果信號有急劇的過渡，就有必有對輸入信號加窗，這樣信號在端點處就會收斂于零。7.Theconceptsofsignalsandsystemsariseinawidevarietyoffields,andtheideasandtechniquesassociatedwiththeseconceptsplayanimportantroleins

7、uchdiverseareasofscienceandtechnologyascommunication,aeronauticsandastronautics,circuitdesign,acoustics,seismology,biomedicalengineering,energygenerationdistributionsystems,chemicalprocesscontrol,andspeechprocessing.信號與系統的概念出現在廣闊的范圍內，在科學技術的不同領域，如通信、航空航天、電路設計、聲學、地震學、生物學、生物醫學工程、發電和輸電系統、化學過程控制和語音處理中都離不

8、開這個概念的思想與技術。它在科學技術中發揮了重要作用。8.Withoutsomerestrictions,whenthecharacterizationofasystemrequiresacompleteinput-out-putrelationship,knowingtheoutputofasystemtoacertainsetofinputdoenotallowustodeterminetheoutputofthesystemtoothersetsofinputs.當系統的特性描述要求完整的輸入輸出關系時，如果沒有約束條件，即使知道了系統對某 些特定輸入產生的輸出時，我們也并不知道系統對其

9、他輸入產生的輸出。9.Anexampleofafinite-energysignalisasignalthattakesonthevalue1for0t1and0otherwise.舉一個有限能量信號的例子：信號在0t1，而在其他時間范圍取值為0。10.This,ofcourse,makessense,sinceifthereisanonzeroaverageenergyperunittime,thenintegratingorsummingthisoveraninfinitetimeintervalyieldsaninfiniteamountofenergy.當然這是有意義的，因為如果單位時

10、間內存在一個非零的平均能量，那么在一個無限的時間間隔范圍內，對其積分或者求和就會產生一個無限的能量總和。11.Wecanbringcontinuous-timeanddiscrete-timesystemstogetherthroughtheconceptofsampling,andwecandevelopsomeinsightsintotheuseofdiscrete-timesystemstoprocesscontinuous-timesignalsthathavebeensampled.我們可以在抽樣的概念下將連續時間和離散時間系統放在一起考慮。我們可以將一些離散時間系統的概念推廣，用以

11、處理抽樣后的連續時間系統。12.Oneofthemostimportantmotivationsforthedevelopmentofgeneraltoolsforanalyzinganddesigningsystemsisthat systemsfrommanydifferentapplicationshaveverysimilar mathematicaldescriptions.許多具有不同應用的系統都有相類似的數學描述，這是開發系統分析和設計通用工具軟件的最重要的動機之一。13.Electronic amplifiers are often symbolized by a simple

12、 triangle shape ,where the internal components are not individually represented.電子放大器一般都表示成三角形形狀，內部器件并不分別表示出來。14.An increasingly positive voltage on the(+)input tends to drive the output voltage more positive,and an increasingly positive voltage on the(-)input tends to drive the output voltage more

13、negative.增大同向輸入端的電壓，會使輸出電壓增大；增大反向輸入端的電壓，會使輸出電壓減小。15.Because we know that both inputs of the op-amp have extremely high impedance,we can safely assume they wont add or subtract any current through the divider.因為我們知道，運算放大器的兩個輸入端之間有無窮大的電阻，所以我們完全可以假設他們沒有增加或分擔任何電流。16.In other words,we can treat R1 and R2

14、 as being in series with each other:all of the electrons flowing through R1 must flow through R2.換句話說，我們可以認為R1和R2串聯，即通過R1的電流一定會通過R2。17.FPGAs,which do not use operating sytems,minimize reliability cincerns with true parallel execution and deterministic hardware dedicated to every task.FPGA不使用操作系統，減少了

15、對每項任務并行操作和確定的硬件分配的依賴性。18.Digital communication protocols,for example,have specifications that can chang over time,and ASIC-based interfaces may cause maintenance and forward compatibility challenges.例如，數字通信協議規范可能隨時改變，基于ASIC的接口則保持穩定且兼容。19.VHDL is an acronym for Very high speed intergrated circuit(VHS

16、IC)Hardware Description Language which is a programming Language that describes a logic cir cuit by function,data flow behavior,and/or structure.VHDL是甚高速集成電路硬件描述語言的縮寫，它是一種通過函數、數據流和（或）結構描述邏輯電路的可編程語言。20.The data flow model makes use of concurrent statements that are executed in parallel as soon as dat

17、a arrives at the input.數據流模式在數據到達輸入端的同事就給出相同的說明。2.傅里葉分析Fouriers epresentation of functions as a superposition of sines and cosines has become ubiquitous for both the analytic and numerical solution of differential equations and for the analysis and treatment of communication signals.函數的傅里葉表示，即將函數表示成

18、正弦和余弦信號的疊加，這種方法已經廣泛用于微分方程的解析法和數值法求解過程以及通信信號的分析和處理。The Fourier transforms utility lies in its ability to analyze a signal in the time domain for its frequency content. The transform works by first translating a function in the time domain into a function in the frequency domain. The signal can then b

19、e analyzed for its frequency content because the Fourier coefficients of the transformed function represent the contribution of each sine and cosine function at each frequency. An inverse Fourier transform dose just what youd expect, transform data from the frequency domain into the time domain.傅里葉變

20、換的效用在于它能夠在時域范圍內分析它的頻率內容。變換的第一步是將時域上的函數轉換為時域表示。然后就可以分析信號的頻率內容了。因為變換函數的傅里葉系數代表各個正弦和余弦函數在各自對應頻率區間的分配。傅里葉逆變換就會按你剛才設想的那樣，將頻域數據轉換為時域的。The discrete Fourier transform (DFT) estimates the Fourier transform of a function from a finite number of its sampled points. The sampled points are supposed to be typical

21、 of what the signal looks like at all other times離散型傅里葉變換是通過他有限的采樣點來評估函數的傅里葉變換。采樣點代表了其他時間的信號。The DFT has symmetry properties almost exactly the same as the continuous Fourier transform. In addition, the formula for the inverse discrete Fourier transform is easily calculated using the one for the dis

22、crete Fourier transform because the two formulas are almost identical.離散型傅里葉變換具有和連續型傅里葉變換幾乎完全相同的對稱特性。此外，通過離散型傅里葉變換的公式，我們可以輕易推出離散型傅里葉變換的公式。因為這兩個公式幾乎相同。If f (t ) is a nonperiodic signal, the summation of the periodic functions (such as sine and cosine)does not accurately represent the signal.You could

23、 artificially extend the signal to make it periodic but it would reqiure addition continuity at the endpoints.The window Fourier transform(WFT )is one solution to the problem of better representing the nonperiodic signal. The WFT can be used to give information about signals simultaneously in the ti

24、me domain and in the frequency domain 如果f(t)是非周期信號，那么用周期函數例如正弦和余弦的和，并不能精確的表示該信號f(t)。你可以人為的拓展這個信號使其具有周期性，但是這要求在端點處附加連續性。窗口傅里葉變換能夠更好的解決關于非周期信號的表示問題。窗口傅里葉變換同樣適用于時域和頻域上信號信息的提供。With the WFT, the input signal f(t) is chopped up into sections, and each section is analyzed for its frequency content separate

25、ly, If the signal has sharp transitions, it is necessary to window the input data, so that the sections converge to zero at the endpoints. This windowing is accomplished via a weight function that places less emphasis near the intervals endpoints than in the middle. The effect of the window is to lo

26、calize the signal in time.通過窗口傅里葉變換，輸入信號f(t)被分成許多小部分，每個部分都能分別分析它的頻率內容。如果信號有急劇的過度，就有必要對輸入信號加窗，這樣信號在端點處就會收斂于零。通過加權函數，即著眼于與中間部分而不是區間端點附近，這樣就完成了加窗。加窗效應是將信號集中在同一個時間段。To approximate a function by samples, and to approximate the Fourier integral by the discrete Fourier transform, requires applying a matrix

27、 whose order is the number sample points n. Since multiplying an n*n matrix by a vector costs on the order of arithmetic operations, the problem gets quickly worse as the number of sample points increases. However, if the samples are uniformly spaced, then the Fourier matrix can be factored into a p

28、roduct of just a few sparse matrices, and the resulting factors can be applied to a vector in a total of order arithmetic operations. This is the so-called fast Fourier transform or FFT 通過樣本來近似函數，及通過離散傅立葉傅立葉變換去逼近傅里葉積分，需要使用一個矩陣，其順序是全樣本點的數量。通過一個按n2算術運算順序的向量乘以一個n*n的矩陣，當采樣點的增多的時候，問題就迅速惡化。但是，如果樣本是均勻分布的，那

29、么傅立葉矩陣可以被分解成一個只有幾個稀疏矩陣的乘積，以及由此產生的因素可廣泛應用在算術運算順序共向量。這就是所謂的快速傅里葉變換或FFT。3. 2. Continuous-time and discrete-time systems Physical systems in the broadest sense are an interconnection of components, devices, or subsystems. In context ranging from signal processing and communications to electromechanical

30、motors, automotive vehicles, and chemical-processing plants, a system can be viewed as a process in which input signals are transformed by the system or cause the system to respond in some way, resulting in other signals as outputs. For example, a high-fidelity system takes a recorded audio signal a

31、nd generates a reproduction of that signal. If the hi-fi system has tone controls, we can change the tonal quality of the reproduced signal.Similarly, the circuit in Fig.3-1 can be viewed as a system with input voltage Vs(t) and output voltage Vc(t). An image-enhancement system transforms an input i

32、mage into an output image that has some desired properties, such as improved contrast. A continuous-time system is a system in which continuous-time input signals are applied and result in continuous-time output signals. As in Figure 3-1-5(a), where x(t) is the input, y(t) is the output, and h(t) is

33、 the system impulse response.Similarly, a discrete-time systemthat is, a system that transforms discrete-time inputs into discrete-time outputsis depicted as in Figure 3-1-5 (b). Where x(n) is the input, y(n) is the output, and h(n) is the system unit sample response. We can bring continuous-time an

34、d discrete-time systems together through the concept of sampling, and we can develop some insights into the use of discrete-time systems to process continuous-time signals that have been sampled.At present, many digital signal processing methods have been widely used in science and technology fields

35、. So we take digital signal system for example, some system properties are described in next section. 2.時間連續和時間離散系統 物理系統最直觀的感覺就是，元器件、設備和子系統的互連。在信號處理和通信，機電馬達，電動車，化學加工廠中，系統可以視為一個處理，在這里，以某種方法，信號會被系統傳輸或引起系統相應，從而產生其他信號作為輸出。例如，一個高保真系統記錄音頻信號并重放這信號。如果這高保真系統有音調控制，我們可以改變所播放的聲音的質量。同樣地，圖3-1可以視為一個帶輸入電壓Vs（t）和輸出電壓

36、Vc（t）的系統。一個圖像增強系統將輸入圖像轉化成所期望的輸出圖像，例如增強對比度。 一個時間連續系統是輸入連續信號得到連續輸出信號的系統。例如圖3-5a所描繪的，在這里，x(t)是輸入，y(t)是輸出，h(t)是系統脈沖相應。同樣地，時間離散系統是一個輸入離散，得到離散輸出的系統，如圖3-5b所描繪的，在這里，x(n)是輸入，y(n)是輸出，h(n)是系統單位抽樣相應。 我們可以通過抽樣定理使時間連續和時間離散系統相結合。我們可以開發時間離散系統來處理已被抽樣的時間連續信號。目前，很多數字信號處理方法已用在科學和技術領域。所以，我們取數字信號系統為例，它的一些系統特性將在下一部分描述。4.圖

37、像 圖像解釋題圖2-1 Any source of voltage, including batteries, has two points for electrical contact. We can provide such a path for the battery by connecting a piece of wire from one end of the battery to the other. Forming a circuit with a loop of wire, we will initiate a continuous flow of electrons in

38、a clockwise direction, which is shown in Fig.2-1. So long as the battery continues to produce voltage and the continuity of the electrical path isnt broken, electrons will continue to flow in the circuit. Following the metaphor of water moving through a pipe, this continuous, uniform flow of electro

39、ns through the circuit is called a current. So long as the voltage source keeps “pushing” in the same direction, the electron flow will continue to move in the same direction in the circuit. This single-direction flow of electrons is called a Direct Current, or DC. electron circuits are explored whe

40、re the direction of current switches back and forth: Alternating Current, or AC. But for now, well just concern ourselves with DC circuits.圖2-2 We see that I is the only current flowing into the node. However, there are three paths for current to leave the node, and these current are represented by

41、I , I and I . Once charge has entered into the node, it has no place to go except to leave （this is known as conservation of charge）. The total charge flowing into a node must be the same as the total charge flowing out of the node. So IB+IC+ID=IA Bringing everything to the left side of the above eq

42、uation, we get (IB+IC+ID)-IA=0Then, the sum of all the currents is zero. This can be generalized as follows Ii=0Note the convention we have chosen here: current flowing into the node is taken to be negative, and currents flowing out of the node are positive. 圖2-12The PNP transistor is the king of the traditional bipolar analog integrated circuits world. In fact in the most basic and most cost effective analog IC process, the chip designer has at its disposal just that; a good NPN transistor. The rest, PNPs, resistor