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What is the difference between analogue and digital acquisition?

There are a couple of differences between analogue and digital acquisition:

  • In analogue way there is the following chain in modern detectors: analogue detector unit, detector A/D converter, detector processing unit, detector D/A converter, analogue cable, Clarity A/D converter (Colibrick, U-PAD2, INT9, etc.).
  • The digital chain is much simpler: analogue detector unit, detector A/D converter, detector processing unit, digital cable (USB, RS232, etc.), Clarity Control Module.

You can see at least three source of problem in analogue way:

  • Detector D/A converter
  • Analogue cable
  • Clarity A/D converter (Colibrick, U-PAD2, INT9, etc.)

So there might be a significant difference between analogue and digital signal quality. It depends on many factors like:

  • Quality of detector D/A converter (analog output resolution may be worse than digital).
  • Length and quality of analogue cable.
  • Proper cable connection (symmetrical, non-symmetrical).
  • Absolute level of analogue signal (lower signal is more influenced by interferences from other laboratory devices).
  • Proper A/D converted voltage range set (most typical problem is that a detector maximum signal is 10-100 mV only and Colibrick voltage range is set to 10 V. This leads to decrease of the voltage step resolution by 100-1000x!)
  • Proper sample rate frequency set at all three converters, see FAQ How to set proper Sampling Rate?.
  • Proper peak width parameter, see FAQ How to set proper Peak Width parameter?.
Send comment30.11.2010
 

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Last updated: 2019-05-14 | webmaster