Analogue to digital converter

Thread Starter

helloeveryone

Joined Apr 8, 2011
64
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
 

tshuck

Joined Oct 18, 2012
3,534
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
Being that this is homework help, what is your reasoning for/against each option?
 

Thread Starter

helloeveryone

Joined Apr 8, 2011
64
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
 

3v0

Joined Mar 26, 2009
14
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.
 

3v0

Joined Mar 26, 2009
14
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.
 

Mark IV

Joined Oct 1, 2013
15
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.
I agree, but I think it doesn't adjust to any answer in helloeveryone homework which relates to signal.
 

tshuck

Joined Oct 18, 2012
3,534
So much for getting help...
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.
 

3v0

Joined Mar 26, 2009
14
I agree, but I think it doesn't adjust to any answer in helloeveryone homework which relates to signal.
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.
 

WBahn

Joined Mar 31, 2012
29,978
I agree, but I think it doesn't adjust to any answer in helloeveryone homework which relates to signal.
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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