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What's negative frequency in analysis of s domain and w domain

  1. Feb 13, 2013 #1
    what's negative frequency???

    can we say s=-3 in example bode plot !!!!!
    or we can say it's unstable at w=-3 rad/s

    that's I mean is there negative frequency????????????
     
  2. jcsd
  3. Feb 13, 2013 #2

    Simon Bridge

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    Re: what's negaive frequency in analysis of s domain and w domain

    Where have you seen a negative frequency occur?
    Something like this?
     
  4. Feb 13, 2013 #3
    Re: what's negaive frequency in analysis of s domain and w domain

    yes.
     
  5. Feb 14, 2013 #4

    Simon Bridge

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    Re: what's negaive frequency in analysis of s domain and w domain

    The link explains them.
     
  6. Feb 14, 2013 #5
    Re: what's negaive frequency in analysis of s domain and w domain

    Negative frequency is nothing but phase reversal.

    eg. sin(2pi(-f)t)=-sin(2pi(f)t)
     
    Last edited: Feb 14, 2013
  7. Feb 14, 2013 #6

    marcusl

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    Re: what's negaive frequency in analysis of s domain and w domain

    That's not even close to correct.
     
  8. Feb 14, 2013 #7
    Re: what's negaive frequency in analysis of s domain and w domain

    Im sorry its sine not cosine.
     
  9. Feb 15, 2013 #8

    marcusl

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    Re: what's negaive frequency in analysis of s domain and w domain

    The concept of negative frequencies makes sense for complex or quadrature data, that is, when you consider both sine and cosine components impressed on a carrier according to
    [tex]V(t)=\Re\{[\cos(\omega t)+j\sin(\omega t)]\exp(j\omega_0 t)\}[/tex]versus
    [tex]V(t)=\Re\{\cos(\omega t)-j\sin(\omega t)]\exp(j\omega_0 t)\}[/tex]
     
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