電子信息類專業(yè)英語-翻譯

1、Unit 9 Digital Signal Processing,Passage C Comparison of DSP and ASP,9單元 數(shù)字信號處理,C篇 比較DSP和ASP,學(xué)號：20107600 姓名：章太元,Passage C Comparison of DSP and ASP Signals may be processed using analog techniques (analog signal processing, or ASP), digital techniques(digital signal processing, or DSP), or a combina

2、tion of analog and digital techniques(mixed signal processing, or MSP). In some cases, the choice of techniques is clear; in others, there is no clear cut choice, and second-order considerations may be used to make the final decision. With respect to DSP, the factor that distinguishes it from tradit

3、ional computer analysis of data is its speed and efficiency in performing sophisticated digital processing functions such as filtering, FFT analysis, and data compression in real time.,信號可以用模擬技術(shù)處理（模擬信號處理，數(shù)字技術(shù)（或ASP），數(shù)字信號處理，或DSP），或一個組合的模擬和數(shù)字技術(shù)（混合信號處理，或MSP）。在某些情況下，技術(shù)的選擇是明確的；在其他情況下，沒有明確的選擇，和二階考慮可以用來做最后的

4、決定。 對于DSP，使得它與傳統(tǒng)計算機(jī)數(shù)據(jù)分析是它的速度和效率，進(jìn)行復(fù)雜的數(shù)字處理功能，如濾波，F(xiàn)FT分析，數(shù)據(jù)的實時壓縮,The term mixed signal processing implies that both analog and digital processing is done as part of the system. The system may be implemented in the form of a printed circuit board or a single integrated circuit chip. In the context of th

5、is broad definition, ADCs and DACs are considered to be mixed signal processors, since both analog and digital functions are implemented in each. Recent advances in Very Large Scale Integration (VLSI) processing technology allow complex digital processing as well as analog processing to be performed

6、 on the same chip. The very nature of DSP itself implies that these functions can be performed in real-time.,術(shù)語混合信號處理意味著，模擬和數(shù)字處理系統(tǒng)的一部分。該系統(tǒng)可在印刷電路板或一個單一的集成電路芯片的形式實現(xiàn)。在這個廣泛的定義下，ADC和DAC被認(rèn)為是混合信號處理器，由于模擬和數(shù)字功能的實現(xiàn)在每個。在超大規(guī)模集成電路（VLSI）處理技術(shù)的進(jìn)展使得復(fù)雜的數(shù)字信號處理和模擬處理的是在同一芯片上進(jìn)行。DSP本身的性質(zhì)意味著，這些功能可以在實時執(zhí)行。,ASP vs. DSP Todays

7、 engineer faces a challenge in selecting the proper mix of analog and digital techniques to solve the signal processing task at hand. It is impossible to process real-world analog signals using purely digital techniques, since all sensors (microphones, thermocouples, strain gages, piezoelectric crys

8、tals, disk drive heads, etc.) are analog sensors. Therefore, some sort of signal conditioning circuitry is required in order to prepare the sensor output for further signal processing, whether it be analog or digital. Signal conditioning circuits are, in reality, analog signal processors, performing

9、 such functions as multiplication (gain), isolation (instrumentation amplifiers and isolation amplifiers),detection in the presence of noise (high common-mode instrumentation amplifiers etc.), dynamic range compression (log amps, LOGDACs, and programmable gain amplifiers), and filtering (both passiv

10、e and active). Several methods of accomplishing signal processing are shown in Figure 9.5. The top portion of the figure shows the purely analog approach. The latter parts of the figure show the DSP approach. Note that once the decision has been made to use DSP techniques, the next decision must be

11、where to place the ADC in the signal path.,ASP與DSP今天的工程師在選擇適當(dāng)?shù)幕旌夏M和數(shù)字技術(shù)來解決手頭的信號處理任務(wù)所面臨的挑戰(zhàn)。這是不可能的真實世界的模擬信號處理采用純數(shù)字技術(shù)，因為所有的傳感器（麥克風(fēng)，熱電偶，應(yīng)變計，壓電晶體，磁盤驅(qū)動器的磁頭，等）是模擬傳感器。因此，某種形式的信號調(diào)理電路是為了準(zhǔn)備傳感器輸出信號進(jìn)一步處理，無論是模擬或數(shù)字。信號調(diào)理電路，在現(xiàn)實中，模擬信號處理器，如乘法執(zhí)行這些功能（增益），隔離（儀表放大器和隔離放大器），在存在噪聲檢測（高共模儀表放大器等），動態(tài)范圍壓縮（對數(shù)放大器，logdacs，和可編程增益放大器）

12、，和過濾（包括被動和主動的）。完成信號處理的幾種方法，如圖9.5所示。圖中的頂部顯示純模擬方法。圖中的一部分顯示的數(shù)字信號處理方法。請注意，一旦決定已經(jīng)做出，采用DSP技術(shù)，未來的決定必須在什么地方ADC的信號路徑。,Figure 9.5 Some Methods of Accomplishing Signal Processing,In general, as the ADC is moved closer to the actual sensor, more of the analog signal conditioning burden is now placed on the ADC.

13、 The added ADC complexity may take the form of increased sampling rate, wider dynamic range, higher resolution, input noise rejection, input filtering and programmable gain amplifiers (PGAs), on-chip voltage references, etc., all of which add functionality and simplify the system. With todays high-r

14、esolution/high sampling rate data converter technology, significant progress has been made in integrating more and more of the conditioning circuitry within the ADC/DAC itself.,In the measurement area, for instance, 24-bit ADCs are available with built-in programmable gain amplifiers (PGAs) which al

15、low full-scale bridge signals of 10 mV to be digitized directly with no further conditioning. At voiceband and audio frequencies, complete coder-decoders (Codecs or Analog Front Ends) are available which have sufficient on-chip analog circuitry to minimize the requirement for external conditioning c

16、omponents. At video speeds, analog front ends are also available for such applications as CCD image processing and others.,在一般情況下，作為ADC接近實際的傳感器，更多的模擬信號調(diào)理的負(fù)擔(dān)，現(xiàn)在放在ADC。增加ADC的復(fù)雜性可以增加采樣率的形式，更寬的動態(tài)范圍，高分辨率，輸入噪聲排斥，輸入濾波和可編程增益放大器（PGA），片上的參考電壓，等等，所有這些新增功能和簡化系統(tǒng)。今天的高分辨率、高采樣率的數(shù)據(jù)轉(zhuǎn)換技術(shù)，在集成越來越多的調(diào)理電路內(nèi)的ADC / DAC本身取得了明顯的

17、進(jìn)展。在測量領(lǐng)域，例如，24位ADC提供內(nèi)置的可編程增益放大器（PGA）允許10 MV全橋被數(shù)字化的信號直接沒有進(jìn)一步的調(diào)節(jié)。在音頻和音頻解碼器（編解碼器或編碼器，完整模擬前端）可有足夠的片上模擬電路，以盡量減少對外部條件的要求。在視頻的速度，模擬前端也可用于CCD圖像處理和其他的應(yīng)用程序。,A practical example As a practical example of the power of DSP, consider the comparison between an analog and a digital lowpass filter, each with a cutof

18、f frequency of 1 kHz. The digital filter is implemented in a typical sampled data system shown in Figure 9.6. Note that thereare several implicit requirements in the diagram. First, it is assumed that an ADC/DAC combination is available with sufficient sampling frequency, resolution, and dynamic ran

19、ge to accurately process the signal. Second, the DSP must be fast enough to complete all its calculations within the sampling interval, 1/fs. Third, analog filters are still required at the ADC input and DAC output for anti-aliasing and anti-imaging, but the performance demands are not as great. Ass

20、uming these conditions have been met, the following offers a comparison between the digital and analog filters.,一個實際的例子作為一種實用的DSP的電源的例子，考慮一個模擬和數(shù)字低通濾波器之間的比較，各有一個截止頻率為1千赫。The digital filter is implemented in a typical sampled data system shown in Figure 9.6. 注意，圖中的一些隱含的要求thereare。First, it is assumed

21、that an ADC/DAC combination is available with sufficient sampling frequency, resolution, and dynamic range to accurately process the signal. 第二，DSP必須足夠快的采樣間隔內(nèi)完成所有的計算，1 / FS。第三，模擬濾波器仍在ADC的輸入和抗混疊和反成像DAC輸出所需的，但性能的要求是不一樣大。Assuming these conditions have been met, the following offers a comparison between

22、 the digital and analog filters.,Figure 9.6 A Typical Sampled Data System,The required cutoff frequency of both filters is 1 kHz. The analog filter is realized as a 6-pole Chebyshev Type 1 filter (ripple in passband, no ripple in stopband), and the response is shown in Figure 9.7. In practice, this

23、filter would probably be realized using three 2-pole stages, each of which requires an op amp, and several resistors and capacitors. Modern filter design CAD packages make the 6-pole design relatively straightforward, but maintaining the 0.5 dB ripple specification requires accurate component select

24、ion and matching.,兩個濾波器的截止頻率是1千赫的要求。模擬濾波器的實現(xiàn)為6極切比雪夫型濾波器（1通帶阻帶紋波，無紋波），和響應(yīng)如圖9.7所示。在實踐中，該過濾器可能會使用三極階段實現(xiàn)，每一個都需要一個運(yùn)算放大器，和幾個電阻和電容器?，F(xiàn)代CAD軟件包過濾器的設(shè)計使六極設(shè)計相對簡單，但保持0.5 dB的紋波規(guī)格要求準(zhǔn)確的組件選擇與匹配。,Figure 9.7 The Magnitude Response in dB,On the other hand, the 129-tap digital FIR filter shown has only 0.002 dB passband

25、ripple, linear phase, and a much sharper roll off. In fact, it could not be realized using analog techniques! Another obvious advantage is that the digital filter requires no component matching, and it is not sensitive to drift since the clock frequencies are crystal controlled. The 129-tap filter r

26、equires 129 MACs in order to compute an output sample. This processing must be completed within the sampling interval, 1/fs, in order to maintain real-time operation. In this example, the sampling frequency is 10 kSPS, therefore 100 s is available for processing, assuming no significant additional o

27、verhead requirement. Most DSPs can complete the entire multiply-accumulate process (and other functions necessary for the filter) in a single instruction cycle.,另一方面，129個抽頭的FIR數(shù)字濾波器具有0.002 dB通帶紋波，線性相位，和一個更清晰的滾。事實上，它不可能使用模擬技術(shù)的實現(xiàn)！另一個明顯的優(yōu)勢是，數(shù)字濾波器不需要匹配，它是不敏感的漂移由于時鐘頻率晶體控制。129抽頭濾波器需要129個蘋果來計算的輸出樣本。這樣的處理必須在采樣間隔內(nèi)完成，1 / FS，為了保持實時操作。在本例中，采樣頻率為10 kSPS的，