Data acquisition

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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 desired information. The components of data acquisition systems include appropriate sensors that convert any measurement parameter to an electrical signal, which is acquired by data acquisition hardware.

Acquired data is displayed, analyzed, and stored on a computer, either using vendor supplied software, or custom displays and control can be developed using various text-based programming languages such as BASIC, C, Fortran, Java, Lisp, Pascal. EPICS is used to build large scale data acquisition systems. LabVIEW offers a graphical programming environment optimized for data acquisition. MATLAB provides a programming language but also built-in graphical tools and libraries for data acquisition and analysis. Measure Foundry is also optimized for data acquisition but uses a drag-and-drop system for creating applications without programming.

Contents

[edit] How Data is acquired

Data acquisition begins 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 applied 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 or current. 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 transducers for many different applications, such as measuring temperature, pressure, or fluid flow.

Signals may be digital (also called logic signals sometimes) or analog depending on the tranducer 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 deamplified, or may require filtering.

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) in the mother board. DAQ-cards often contain 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 allright to block it with simple polling loops. 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 proceede with voltage ramp.

Driver Software that usually comes with the DAQ hardware or from other vendors, allows the operating system to recognize the DAQ hardware and programs to access the signals being read by the DAQ hardware.

[edit] History

Scientific Solutions[1] invented the PC based data acquisition in 1981 with the introduction of the LabMaster, BaseBoard,DADIO,LabTender, IEEE-488 hardware and LabPac software. [2] [3] [4] [5] [6]

[edit] See also

[edit] References

  1. ^ http://www.scientificsolutions.com/
  2. ^ COMDEX FALL 1981, BYTE VOL7 NO.1
  3. ^ PC Magazine Vol1 No.1
  4. ^ PC World Issue1 No.1
  5. ^ PC TechJournal, Vol1 No.1
  6. ^ Test&Meausrement World Vol11 No 10 Decade of Progress Award: Scientific Solutions - LabMaster

[edit] Books on Data Acquisition

  • Charles D. Spencer (1990). Digital Design for Computer Data Acquisition. Cambridge University Press. ISBN 0-521-37199-6. 
  • B.G. Thompson & A. F. Kuckes (1989). IBM-PC in the laboratory. Cambridge University Press. ISBN 0-521-32199-9. 
  • W. R. Leo: "Techniques for Nuclear and Particle Physics Experiments", Springer, 1994, ISBN 3-540-57280-5

[edit] Articles on Data Acquisition

[edit] Articles about generic data acquisition systems

  • E. T. Subramaniam, Kusum Rani, B. P. Ajith Kumar, and R. K. Bhowmik (Sept 2006). "Ethernet based list processing controller for high speed data acquisition systems". Review of Scientific Instruments 77: 096102. DOI:10.1063/1.2338300. 
  • Robson CCW, Bousselham A, Bohm C (Aug 2006). "An FPGA-based general-purpose data acquisition controller". IEEE Transactions on Nuclear Science 53 (4): 2092-2096. DOI:10.1109/TNS.2006.878698. 
  • Mason G (Nov 2002). "A handheld data acquisition system for use in an undergraduate data acquisition course". IEEE Transactions on Education 45 (4): 388 - 393. DOI:10.1109/TE.2002.804402. 

[edit] Articles about how to teach a course on data acquisition

[edit] Articles about data acquisition systems for specific applications

  • Ochoa OR, Kolp NF (Nov 1997). "The computer mouse as a data acquisition interface: Application to harmonic oscillators". American Journal of Physics 65 (11): 1115-1118. DOI:10.1119/1.18732. 
  • Spencer CD, Paul SR (Jan 1997). "Hardware and software for a pulse height analyzer linked to a personal computer". Computers in Physics 11 (1): 101-109. DOI:10.1063/1.168598. 

[edit] External links

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