# 3.8 Zero locations of linear-phase fir filters

 Page 1 / 1
(Blank Abstract)

## Zero locations of linear-phase filters

The zeros of the transfer function $H(z)$ of a linear-phase filter lie in specific configurations.

We can write the symmetry condition $h(n)=h(N-1-n)$ in the $Z$ domain. Taking the $Z$ -transform of both sides gives

$H(z)=z^{-(N-1)}H(\frac{1}{z})$
Recall that we are assuming that $h(n)$ is real-valued. If ${z}_{0}$ is a zero of $H(z)$ , $H({z}_{0})=0$ then $H(\overline{{z}_{0}})=0$ (Because the roots of a polynomial with real coefficients exist in complex-conjugate pairs.)

Using the symmetry condition, , it follows that $H({z}_{0})=z^{-(N-1)}H(\frac{1}{{z}_{0}})=0$ and $H(\overline{{z}_{0}})=z^{-(N-1)}H(\frac{1}{\overline{{z}_{0}}})=0$ or $H(\frac{1}{{z}_{0}})=H(\frac{1}{\overline{{z}_{0}}})=0$

If ${z}_{0}$ is a zero of a (real-valued) linear-phase filter, then so are $\overline{{z}_{0}}$ , $\frac{1}{{z}_{0}}$ , and $\frac{1}{\overline{{z}_{0}}}$ .

## Zeros locations

It follows that

• generic zeros of a linear-phase filter exist in sets of 4.
• zeros on the unit circle ( ${z}_{0}=e^{i{}_{0}}$ ) exist in sets of 2. ( ${z}_{0}\neq (1)$ )
• zeros on the real line ( ${z}_{0}=a$ ) exist in sets of 2. ( ${z}_{0}\neq (1)$ )
• zeros at 1 and -1 do not imply the existence of zeros at other specific points.

## Zero locations: automatic zeros

The frequency response ${H}^{f}()$ of a Type II FIR filter always has a zero at $=\pi$ : $h(n)$

h 0 h 1 h 2 h 2 h 1 h 0
$H(z)={h}_{0}+{h}_{1}z^{-1}+{h}_{2}z^{-2}+{h}_{2}z^{-3}+{h}_{1}z^{-4}+{h}_{0}z^{-5}$ $H(-1)={h}_{0}-{h}_{1}+{h}_{2}-{h}_{2}+{h}_{1}-{h}_{0}=0$ ${H}^{f}(\pi )=H(e^{i\pi })=H(-1)=0$
${H}^{f}(\pi )=0$ always for Type II filters.
Similarly, we can derive the following rules for Type III and Type IV FIR filters.
${H}^{f}(0)={H}^{f}(\pi )=0$ always for Type III filters.
${H}^{f}(0)=0$ always for Type IV filters.
The automatic zeros can also be derived using the characteristics of the amplitude response $A()$ seen earlier.

Type automatic zeros
I
II $=\pi$
III $=0\lor \pi$
IV $=0$

## Zero locations: examples

The Matlab command zplane can be used to plot the zero locations of FIR filters.

Note that the zero locations satisfy the properties noted previously.

where we get a research paper on Nano chemistry....?
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
Ali
what are the products of Nano chemistry?
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
hey
Giriraj
Preparation and Applications of Nanomaterial for Drug Delivery
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
ya I also want to know the raman spectra
Bhagvanji
I only see partial conversation and what's the question here!
what about nanotechnology for water purification
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
why we need to study biomolecules, molecular biology in nanotechnology?
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
why?
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
how did you get the value of 2000N.What calculations are needed to arrive at it
Privacy Information Security Software Version 1.1a
Good
Got questions? Join the online conversation and get instant answers!