Analogue to digital converter

Discussion in 'Homework Help' started by helloeveryone, Jan 18, 2014.

  1. helloeveryone

    Thread Starter Active Member

    Apr 8, 2011
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    Hello, which of the following is it necessary to do before bringing a signal to the input of an analogue to digital converter? Using an AVR 8 bit micro-controller.

    i) convert into digital form
    ii) connect to a multiplexor(mandatory)
    iii) write the signal in its largest resolution
    iv) adjust/condition the signal
    v) none of the above
     
  2. tshuck

    Well-Known Member

    Oct 18, 2012
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    Being that this is homework help, what is your reasoning for/against each option?
     
  3. helloeveryone

    Thread Starter Active Member

    Apr 8, 2011
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    i) convert into digital form
    Makes no sense because the whole idea of an analogue to digital converter is to take an analogue signal and convert it into a digital signa.

    ii) connect to a multiplexor(mandatory)
    I'm not sure why you would nee to multiplex the signal.

    iii) write the signal in its largest resolution
    How can an analogue signal have a resolution?

    iv) adjust/condition the signal
    This might be it, but have no idea how you condition a signal. For example using a LM35 temp sensor. Does conditioning mean just putting a capacitor on vref to smooth out the voltage?

    v) none of the above
     
  4. 3v0

    Member

    Mar 26, 2009
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    If you can't answer that question go back and read your lesson or review your notes. Then power up an AVR and start playing with the ADC. You will be glad you did. If you run into problems doing that you can get help here.
     
  5. MrChips

    Moderator

    Oct 2, 2009
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    Look up Nyquist Theorem.
     
  6. helloeveryone

    Thread Starter Active Member

    Apr 8, 2011
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    So much for getting help...
     
  7. MrChips

    Moderator

    Oct 2, 2009
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    Is that sarcasm? Too bad because you just missed an important lesson and the answer to your question.
     
  8. t06afre

    AAC Fanatic!

    May 11, 2009
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    I for my own part have problems then I try to decode what your teacher is asking for here. The answers seams to be taken out of some context. But without that context it is not possible to give much help
     
  9. 3v0

    Member

    Mar 26, 2009
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    We see enough people going through higher education with no real dedication. If and when the manage to land a job they are mostly clueless. Go figure.

    I expect that in the west they would never land a job. Elsewhere there are mom and pop operations that need high tech help but have no way to tell good from bad and in some cases pay so poorly their engineers need second jobs to make the rent. They are also unwilling to buy anything but the most basic of tools. I guess it is not much to look forward to.
     
  10. Mark IV

    New Member

    Oct 1, 2013
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    I think Nyquist is important for the converter, not for the raw signal, isn't it?
     
  11. WBahn

    Moderator

    Mar 31, 2012
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    The implications of Nyquist must be taken into account prior to applying the signal to the converter because, in general, the converter can't do it.
     
  12. Mark IV

    New Member

    Oct 1, 2013
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    I agree, but I think it doesn't adjust to any answer in helloeveryone homework which relates to signal.
     
  13. tshuck

    Well-Known Member

    Oct 18, 2012
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    You require an answer within 4 hours of responding!?

    This is an international forum. As for me, I have things to do aside from checking to see if you have responded and those often take priority.

    Understand that the world does not work in instant gratification and that you must sometimes put in work and wait before something will come of it.

    To the question in general, I would have to agree with your inclination. You must condition the signal (which could include considering the sampling rate, were it continuously sampled - again, I am answering in general) before the ADC can process the signal. This includes attenuating/amplifying the signal for maximum resolution, re-sampling, filtering, etc.

    Now, calm down and don't be so sarcastic to those trying to help you.
     
  14. 3v0

    Member

    Mar 26, 2009
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    I think the important thing here is not to give the asked for answer but to convince helloeveryone that he needs to understand the stuff he is studying.
     
  15. shteii01

    AAC Fanatic!

    Feb 19, 2010
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    I am voting for 4.
     
  16. helloeveryone

    Thread Starter Active Member

    Apr 8, 2011
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    I apologize, I am in the process of calming down.
     
  17. WBahn

    Moderator

    Mar 31, 2012
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    The question is basically the following:

    We have a signal that contains some information on it and we want to get at the information via an A2D converter. From a practical standpoint, there is one thing (two, if we break it up functionally a bit) that we pretty much always have to do in order to make the signal compatible with the A2D (unless whatever is producing the signal was designed to be compatible with that A2D (or basic class of A2D) from the beginning, in which this was still done but it was simply done at the output of whatever is producing the signal).
     
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