1、精選優質文檔-傾情為你奉上數據采集 數據采集是對現實世界抽樣產生出可以由計算機操縱的數據，有時也把它縮寫為DAS或者DAQ，數據采集和信號通常涉及到的信號波形采集和處理，以獲得所需的信息。數據采集系統的組成部分包括的任何測量參數轉換為電信號，然后調節電信號，然后再通過數據采集硬件獲取相應數據的傳感器。 使用廠商提供的軟件，或自定義顯示和控制，開發利用如BASIC，C，Fortran，Java，Lisp，Pascal各種通用編程語言把獲得的數據顯示，分析和存儲在計算機中。為了構建大規模數據采集系統，使用了包括EPICS等專業的編程語言進行的數據采集。LabVIEW，內置了圖形化工具和數據的采集和

2、分析，它提供了圖形化編程環境數據采集優化，并使用MATLAB作為其編程語言。 數據是如何取得 (1)來源 根據調查，數據采集是和物理現象或物體的物理性質一起開始的。這物理性質或現象，可能是根據溫度或房間溫度，強度或光源的強度變化而變化，內部的壓力，迫使應用到一個對象，或許多其他事情。一個有效的數據采集系統可以測量這些不同性質或現象。 換能器是一種可以將電壓，電流，電阻或電容值的變化等轉換成相應的可測量的電信號的裝置，數據采集系統衡量不同的物理現象的能力，取決于換能器把數據采集硬件采集到的可測量的物理現象轉換成可測量信號。在DAQ系統中，傳感器是感應器的代名詞。不同的傳感器有許多不同的應用，如測

3、量溫度，壓力，或液體流動。數據采集還進行各種信號調理技術，將充分修改各種不同的電壓，使之變為可以使用ADC測量的數字化電信號。 (2)信號 信號可能是數字信號（有時也稱為邏輯信號）或使用不同的傳感器進行模擬分析的結果。 如果從傳感器得到的信號與數據采集硬件不兼容，信號調理就是非常必要的了。該信號可以被放大，或者可能需要過濾，或鎖定放大器解調列入執行。模擬信號容忍幾乎沒有串音等轉換為數字數據，然后才接近一臺PC或之前沿長電纜。對于模擬數據，具有很高的信噪比，信號需要非常高，同時派遣一個50歐姆的終端快速信號路徑+ -10伏特，需要強大的驅動程序。(3)數據采集硬件 數據采集硬件通常是與信號和PC

4、接口。它可以從母板連接到計算機的端口（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。 數據采集卡通常包含復用器，模數轉換，數模轉換，與TTL印務局，高速定時器，RAM等多個組件。這些都可以通過由一個可以運行小程序的總線的微控制器進行控制。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是沒有問題。例如：等待一個觸發，啟動ADC時，查找的時間，等待完成的ADC，移動值到RAM，切換多路，得到TTL輸入，

5、讓數模轉換器進行電壓斜坡。由于16位模數轉換器，數模轉換器，運算放大器和樣品，并作為2007年只有1兆赫運行等精度認為，即使像成本低為AVR32數字控制器有簿記之間約100個時鐘周期。 可重構計算可提供高速數字信號。數字信號處理器算法花費大量的硅，并允許嚴格控制回路或過濾器。與個人電腦連接允許舒適固定編制和調試。使用外部住房在1總線插槽模塊化設計，可以增加與用戶的需求。高速二進制數據需要特殊用途的硬件要求時向數字轉換器和高速8位ADC稱為數字存儲示波器示波器，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，并非所有的數據采集硬件的運行永久連接到電腦上，例如智能獨立伐木者和控制

6、器，可以從電腦操作，但他們可以經營完全獨立的個人電腦。 (4)數據采集軟件 數據采集軟件，是為了對數據采集硬件與PC的工作。這樣可能會至少在三個方面：應用程序直接從硬件寄存器，低層次的軟件驅動程序（通常包裝與數據采集硬件），讓開發更高級別的應用程序注冊資料從硬件和越野的現成應用程序來 驅動軟件，通常與數據采集硬件或其他廠商來了，讓操作系統識別的數據采集硬件和程序訪問的信號正由數據采集硬件閱讀。一個優秀的車手提供了高，低級別的訪問。所以，一開始時會與高級別提供的解決辦法，提高到組裝說明在時間關鍵的或外來的申請。 場外的現成應用程序編程接口的手段包括記錄，分析和顯示所獲得的數據。這種軟件的例子是M

7、ATLAB和LabVIEW中，既提供一個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