Saved Bookmarks
| 1. |
If s=jΩ and if Ω varies from -∞ to ∞, then what is the corresponding locus of points in z-plane?(a) Circle of radius 1 with centre at z=0(b) Circle of radius 1 with centre at z=1(c) Circle of radius 1/2 with centre at z=1/2(d) Circle of radius 1 with centre at z=1/2I had been asked this question at a job interview.Origin of the question is IIR Filter Design by Approximation of Derivatives in section Digital Filters Design of Digital Signal Processing |
|
Answer» RIGHT option is (c) Circle of radius 1/2 with centre at z=1/2 To explain I WOULD say: We know that s=(1-z^-1)/T => z=1/(1-sT) Given s= jΩ => z = 1/(1- jΩT) Thus from the above equation if Ω varies from -∞ to ∞, then the corresponding LOCUS of POINTS in z-plane is a circle of radius 1/2 with centre at z=1/2. |
|