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

by klmnopq
Tags: analysis, domain, frequency, negative
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klmnopq
#1
Feb13-13, 08:34 AM
P: 27
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????????????
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Simon Bridge
#2
Feb13-13, 08:47 AM
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Where have you seen a negative frequency occur?
Something like this?
klmnopq
#3
Feb13-13, 09:21 AM
P: 27
yes.

Simon Bridge
#4
Feb14-13, 06:10 PM
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What's negative frequency in analysis of s domain and w domain

The link explains them.
okami11408
#5
Feb14-13, 06:52 PM
P: 15
Negative frequency is nothing but phase reversal.

eg. sin(2pi(-f)t)=-sin(2pi(f)t)
marcusl
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Feb14-13, 07:04 PM
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Quote Quote by okami11408 View Post
eg. cos(2pi(-f)t)=-cos(2pi(f)t)
That's not even close to correct.
okami11408
#7
Feb14-13, 07:06 PM
P: 15
Im sorry its sine not cosine.
marcusl
#8
Feb15-13, 01:18 PM
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Quote Quote by okami11408 View Post
Negative frequency is nothing but phase reversal.

eg. sin(2pi(-f)t)=-sin(2pi(f)t)
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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