數(shù)據(jù)采集中英文文獻(xiàn)(共5頁)

1、精選優(yōu)質(zhì)文檔-傾情為你奉上數(shù)據(jù)采集 數(shù)據(jù)采集是對現(xiàn)實(shí)世界抽樣產(chǎn)生出可以由計(jì)算機(jī)操縱的數(shù)據(jù)，有時(shí)也把它縮寫為DAS或者DAQ，數(shù)據(jù)采集和信號(hào)通常涉及到的信號(hào)波形采集和處理，以獲得所需的信息。數(shù)據(jù)采集系統(tǒng)的組成部分包括的任何測量參數(shù)轉(zhuǎn)換為電信號(hào)，然后調(diào)節(jié)電信號(hào)，然后再通過數(shù)據(jù)采集硬件獲取相應(yīng)數(shù)據(jù)的傳感器。 使用廠商提供的軟件，或自定義顯示和控制，開發(fā)利用如BASIC，C，F(xiàn)ortran，Java，Lisp，Pascal各種通用編程語言把獲得的數(shù)據(jù)顯示，分析和存儲(chǔ)在計(jì)算機(jī)中。為了構(gòu)建大規(guī)模數(shù)據(jù)采集系統(tǒng)，使用了包括EPICS等專業(yè)的編程語言進(jìn)行的數(shù)據(jù)采集。LabVIEW，內(nèi)置了圖形化工具和數(shù)據(jù)的采集和

2、分析，它提供了圖形化編程環(huán)境數(shù)據(jù)采集優(yōu)化，并使用MATLAB作為其編程語言。 數(shù)據(jù)是如何取得 (1)來源 根據(jù)調(diào)查，數(shù)據(jù)采集是和物理現(xiàn)象或物體的物理性質(zhì)一起開始的。這物理性質(zhì)或現(xiàn)象，可能是根據(jù)溫度或房間溫度，強(qiáng)度或光源的強(qiáng)度變化而變化，內(nèi)部的壓力，迫使應(yīng)用到一個(gè)對象，或許多其他事情。一個(gè)有效的數(shù)據(jù)采集系統(tǒng)可以測量這些不同性質(zhì)或現(xiàn)象。 換能器是一種可以將電壓，電流，電阻或電容值的變化等轉(zhuǎn)換成相應(yīng)的可測量的電信號(hào)的裝置，數(shù)據(jù)采集系統(tǒng)衡量不同的物理現(xiàn)象的能力，取決于換能器把數(shù)據(jù)采集硬件采集到的可測量的物理現(xiàn)象轉(zhuǎn)換成可測量信號(hào)。在DAQ系統(tǒng)中，傳感器是感應(yīng)器的代名詞。不同的傳感器有許多不同的應(yīng)用，如測

3、量溫度，壓力，或液體流動(dòng)。數(shù)據(jù)采集還進(jìn)行各種信號(hào)調(diào)理技術(shù)，將充分修改各種不同的電壓，使之變?yōu)榭梢允褂肁DC測量的數(shù)字化電信號(hào)。 (2)信號(hào) 信號(hào)可能是數(shù)字信號(hào)（有時(shí)也稱為邏輯信號(hào)）或使用不同的傳感器進(jìn)行模擬分析的結(jié)果。 如果從傳感器得到的信號(hào)與數(shù)據(jù)采集硬件不兼容，信號(hào)調(diào)理就是非常必要的了。該信號(hào)可以被放大，或者可能需要過濾，或鎖定放大器解調(diào)列入執(zhí)行。模擬信號(hào)容忍幾乎沒有串音等轉(zhuǎn)換為數(shù)字?jǐn)?shù)據(jù)，然后才接近一臺(tái)PC或之前沿長電纜。對于模擬數(shù)據(jù)，具有很高的信噪比，信號(hào)需要非常高，同時(shí)派遣一個(gè)50歐姆的終端快速信號(hào)路徑+ -10伏特，需要強(qiáng)大的驅(qū)動(dòng)程序。(3)數(shù)據(jù)采集硬件 數(shù)據(jù)采集硬件通常是與信號(hào)和PC

4、接口。它可以從母板連接到計(jì)算機(jī)的端口（并行，串行，USB等.）或連接到插槽卡（PCI，ISA和PCI - E等.）。通常在一個(gè)PCI卡背面的空間太小，不能滿足所有需要的連接的血藥，所以外部的盒式是必需的。這之間的電纜盒和PC是昂貴的原因是許多的電線需屏蔽。 數(shù)據(jù)采集卡通常包含復(fù)用器，模數(shù)轉(zhuǎn)換，數(shù)模轉(zhuǎn)換，與TTL印務(wù)局，高速定時(shí)器，RAM等多個(gè)組件。這些都可以通過由一個(gè)可以運(yùn)行小程序的總線的微控制器進(jìn)行控制。該控制器比硬布線邏輯靈活，但比CPU便宜，所以用它阻止它用簡單的投票循環(huán)是沒有問題。例如：等待一個(gè)觸發(fā)，啟動(dòng)ADC時(shí)，查找的時(shí)間，等待完成的ADC，移動(dòng)值到RAM，切換多路，得到TTL輸入，

5、讓數(shù)模轉(zhuǎn)換器進(jìn)行電壓斜坡。由于16位模數(shù)轉(zhuǎn)換器，數(shù)模轉(zhuǎn)換器，運(yùn)算放大器和樣品，并作為2007年只有1兆赫運(yùn)行等精度認(rèn)為，即使像成本低為AVR32數(shù)字控制器有簿記之間約100個(gè)時(shí)鐘周期。 可重構(gòu)計(jì)算可提供高速數(shù)字信號(hào)。數(shù)字信號(hào)處理器算法花費(fèi)大量的硅，并允許嚴(yán)格控制回路或過濾器。與個(gè)人電腦連接允許舒適固定編制和調(diào)試。使用外部住房在1總線插槽模塊化設(shè)計(jì)，可以增加與用戶的需求。高速二進(jìn)制數(shù)據(jù)需要特殊用途的硬件要求時(shí)向數(shù)字轉(zhuǎn)換器和高速8位ADC稱為數(shù)字存儲(chǔ)示波器示波器，這是典型的未連接到DAQ硬件，而是直接到PC。 另外值得注意的是，并非所有的數(shù)據(jù)采集硬件的運(yùn)行永久連接到電腦上，例如智能獨(dú)立伐木者和控制

6、器，可以從電腦操作，但他們可以經(jīng)營完全獨(dú)立的個(gè)人電腦。 (4)數(shù)據(jù)采集軟件 數(shù)據(jù)采集軟件，是為了對數(shù)據(jù)采集硬件與PC的工作。這樣可能會(huì)至少在三個(gè)方面：應(yīng)用程序直接從硬件寄存器，低層次的軟件驅(qū)動(dòng)程序（通常包裝與數(shù)據(jù)采集硬件），讓開發(fā)更高級(jí)別的應(yīng)用程序注冊資料從硬件和越野的現(xiàn)成應(yīng)用程序來 驅(qū)動(dòng)軟件，通常與數(shù)據(jù)采集硬件或其他廠商來了，讓操作系統(tǒng)識(shí)別的數(shù)據(jù)采集硬件和程序訪問的信號(hào)正由數(shù)據(jù)采集硬件閱讀。一個(gè)優(yōu)秀的車手提供了高，低級(jí)別的訪問。所以，一開始時(shí)會(huì)與高級(jí)別提供的解決辦法，提高到組裝說明在時(shí)間關(guān)鍵的或外來的申請。 場外的現(xiàn)成應(yīng)用程序編程接口的手段包括記錄，分析和顯示所獲得的數(shù)據(jù)。這種軟件的例子是M

7、ATLAB和LabVIEW中，既提供一個(gè)高層次的圖形化編程語言。Data acquisition Data acquisition is the sampling of the real world to generate data that can be manipulated by a computer. Sometimes abbreviated DAQ or DAS, data acquisition typically involves acquisition of signals and waveforms and processing the signals to obtain

8、desired information. The components of data acquisition systems include appropriate sensors that convert any measurement parameter to an electrical signal, then conditioning the electrical signal which can then be acquired by data acquisition hardware. Acquired data are displayed, analyzed, and stor

9、ed on a computer, either using vendor supplied software, or custom displays and control can be developed using various general purpose programming languages such as BASIC, C, Fortran, Java, Lisp, Pascal. Specialized programming languages used for data acquisition include EPICS, used to build large s

10、cale data acquisition systems, LabVIEW, which offers a graphical programming environment optimized for data acquisition, and MATLAB which provides a programming language, and also built-in graphical tools and libraries for data acquisition and analysis. How data is acquired Source Data acquisition b

11、egins with the physical phenomenon or physical property of an object (under investigation) to be measured. This physical property or phenomenon could be the temperature or temperature change of a room, the intensity or intensity change of a light source, the pressure inside a chamber, the force appl

12、ied to an object, or many other things. An effective data acquisition system can measure all of these different properties or phenomena. A transducer is a device that converts a physical property or phenomenon into a corresponding measurable electrical signal, such as voltage, current, change in res

13、istance or capacitor values, etc. The ability of a data acquisition system to measure different phenomena depends on the transducers to convert the physical phenomena into signals measurable by the data acquisition hardware. Transducers are synonymous with sensors in DAQ systems. There are specific

14、transducers for many different applications, such as measuring temperature, pressure, or fluid flow. DAQ also deploy various signal conditioning techniques to adequately modify various different electrical signals into voltage that can then be digitized using ADCs. Signals Signals may be digital (al

15、so called logic signals sometimes) or analog depending on the transducer used. Signal conditioning may be necessary if the signal from the transducer is not suitable for the DAQ hardware to be used. The signal may be amplified, or may require filtering, or a lock-in amplifier is included to perform

16、demodulation. Analog signals tolerate almost no cross talk and so are converted to digital data, before coming close to a PC or before traveling along long cables. For analog data to have a high signal to noise ratio, the signal needs to be very high, and sending +-10 Volts along a fast signal path

17、with a 50 Ohm termination requires powerful drivers. DAQ hardware DAQ hardware is what usually interfaces between the signal and a PC. It could be in the form of modules that can be connected to the computer's ports (parallel, serial, USB, etc.) or cards connected to slots (PCI, ISA, PCI-E, etc.

18、) in the mother board. Usually the space on the back of a PCI card is too small for all the connections needed, so an external breakout box is required. The cable between this Box and the PC is expensive due to the many wires and the required shielding and because it is exotic. DAQ-cards often conta

19、in multiple components (multiplexer, ADC, DAC, TTL-IO, high speed timers, RAM). These are accessible via a bus by a micro controller, which can run small programs. The controller is more flexible than a hard wired logic, yet cheaper than a CPU so that it is alright to block it with simple polling lo

20、ops. For example: Waiting for a trigger, starting the ADC, looking up the time, waiting for the ADC to finish, move value to RAM, switch multiplexer, get TTL input, let DAC proceed with voltage ramp. As 16 bit ADCs, DACs, OpAmps and sample and holds with equal precision as of 2007 only run at 1 MHz,

21、 even low cost digital controllers like the AVR32 have about 100 clock cycles for bookkeeping in between. Reconfigurable computing may deliver high speed for digital signals. Digital signal processors spend a lot of silicon on arithmetic and allow tight control loops or filters. The fixed connection

22、 with the PC allows for comfortable compilation and debugging. Using an external housing a modular design with slots in a bus can grow with the needs of the user. High speed binary data needs special purpose hardware called Time to digital converter and high speed 8 bit ADCs are called oscilloscope#

23、Digital storage oscilloscope, which are typically not connected to DAQ hardware, but directly to the PC. Also notable is that not all DAQ hardware has to run permanently connected to a PC, for example intelligent stand-alone loggers and controllers, which can be operated from a PC, yet they can operate completely independent of the PC. DAQ software DAQ software is needed in order to the DAQ Hardware to work with a PC. This can come in at least three flavors: applications that register directly from the hardware, low-level software driver (us