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Hi Will,
i am maybe a bit rusty and probly missing something at the equation 5.21
What it looks to me is that the result should be sqrt( 0.25 - 0.25j^2 )
what are the passages to get to sqrt( 0.25 + 0.25 ) ? maybe considering j = sqrt(-1) ?
Thanks !
multiplying out you get:
|H(jw)| = 0.25 +j025 - j0.25 -j^20.25
= 0.25 -j^20.25
and j^2 = -1
so 0.25 + j0.25
- Will
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thanks !
but this gave me another doubt... sorry 
in equation 5.65 / 5.66
so j^2 = -1
we have 0.19 + j0.27
so we should have sqrt( 0.19^2 (-) 1.27^2 ) ? that gives me 1.25
what i am missing ?
thanks again !
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Hi Will,
i didn't know if i had to answer or not... anyway..
maybe i didn't explain very well....
B^2 should not be = J^2*1.27^2 ?
so if J^2 = -1
from 0.19 + J0.27
A^2+B^2 = 0.19^2 + J^2*1.27^2 we have 0.19^2 - 1.27^2 not 0.19^2 + 1.27^2
i just wanted to understand the step that i didn't get....
- Vito
Hi Vito
Sorry for the delayed response - I got off on another tangent.
When you use the equation sqrt(a^2 + b^2) you don't square the j term. You only square the coefficient, b. So, j does not get squared, just b.
However, when multiplying out the polynomials for reduction, you very often will run into a j^2 term, which will evaluate to -1.
- Will
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