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Homework Help: Sampling frequencies

  1. Jan 27, 2015 #1
    1. The problem statement, all variables and given/known data

    We have the following signal frequencies:

    f1=18 Hz, f2=510 Hz, f3=1100 Hz

    when using the sampling frequency fs=1000 Hz.

    how would these signals be like?

    my question is if I could use the same formula stated below for all the frequencies f1,f2,f3.. because the second and third ones are above the Nyquist Frequency fc=fs/2=500 Hz so there would be aliasing in this case.

    and what about the graphs for these samplings?

    2. Relevant equations

    when using another sampling frequency fs=1002 Hz

    and here also would be the same questions.

    3. The attempt at a solution

    I used the formula:

    $$ S_{\Delta }(v)= f_{s}\sum_{n=-\infty}^{+\infty}(S(v-n*f_{s})) $$

    for the first frequency f1= 18 Hz I had:

    $$ S_{\Delta}(18)=1000\sum(S(18-n*1000)) $$

    where $$ n=-\infty $$ to $$ +\infty $$
  2. jcsd
  3. Jan 27, 2015 #2


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    Do you mean, for each actual frequency, what is the lowest frequency that could yield the same sampling results?
  4. Jan 28, 2015 #3
    No i mean for each actual frequency wha are the sampling results for fs=1000 Hz and then for fs=1002 Hz.
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