<< Chapter < Page Chapter >> Page >
d = I 0 0 U 0 H x .

Next consider switching from an M -channel filter bank to a one-channel filter bank. Until n = - 1 , the M -channel filter bank is operational. From n = 0 onwards the inputs leaks to the output. In this case, there are exit filterscorresponding to flushing the states in the first filter bank implementation at n = 0 .

d = H 0 W 0 0 I x .

Finally, switching from an M 1 -band filter bank to an M 2 -band filter bank can be accomplished as follows:

d = H 1 0 W 1 0 0 U 2 0 H 2 x .

The transition region is given by the exit filters of the first filter bank and the entry filters of the second. Clearly the transition filters areabrupt (they do not overlap). One can obtain overlapping transition filters as follows: replace them by any orthogonal basis for the row space ofthe matrix W 1 0 0 U 2 . For example, consider switching between two-channel filter banks with length-4and length-6 Daubechies' filters. In this case, there is one exit filter ( W 1 ) and two entry filters ( U 2 ).

Growing a filter bank tree

Consider growing a filter bank tree at n = 0 by replacing a certain output channel in the tree (point of tree growth) by an M channel filter bank. This is equivalent to switching from a one-channel to an M -channel filter bank at the point of tree growth. The transition filters associated with this change are related to the entry filters of the M -channel filter bank. In fact, every transition filter is the net effect of an entry filterat the point of tree growth seen from the perspective of the input rather than the output point at which the treeis grown. Let the mapping from the input to the output “growth” channel be as shown in [link] . The transition filters are given by the system in [link] , which is driven by the entry filters of the newly added filter bank. Every transition filter is obtained byrunning the corresponding time-reversed entry filter through the synthesis bank of the corresponding branch of the extant tree.

Pruning a filter bank tree

In the more general case of tree pruning, if the map from the input to the point of pruning is given as in [link] , then the transition filters are given by [link] .

A Branch of an Existing Tree
A Branch of an Existing Tree

Wavelet bases for the interval

By taking the effective input/output map of an arbitrary unitary time-varying filter bank tree, one readily obtains time-varying discrete-timewavelet packet bases. Clearly we have such bases for one-sided and finite signals also. These bases are orthonormal because they are built from unitary building blocks.We now describe the construction of continuous-time time-varying wavelet bases. What follows is the most economical (in terms of number of entry/exit functions)continuous-time time-varying wavelet bases.

Transition Filter For Tree Growth
Transition Filter For Tree Growth

Wavelet bases for L 2 ( [ 0 , ) )

Recall that an M channel unitary filter bank (with synthesis filters h i ) such that n h 0 ( n ) = M gives rise to an M -band wavelet tight frame for L 2 ( ) . If

W i , j = S p a n ψ i , j , k = def M j / 2 ψ i ( M j t - k ) for k Z ,

then W 0 , j forms a multiresolution analysis of L 2 ( ) with

W 0 , j = W 0 , j - 1 W 1 , j - 1 ... W M - 1 , j - 1 j Z .

In [link] , Daubechies outlines an approach due to Meyer to construct a wavelet basis for L 2 ( [ 0 , ) ) . One projects W 0 , j onto W 0 , j h a l f which is the space spanned by the restrictions of ψ 0 , j , k ( t ) to t > 0 . We give a different construction based on the following idea. For k I N , support of ψ i , j , k ( t ) is in [ 0 , ) . With this restriction (in [link] ) define the spaces W i , j + . As j (since W 0 , j L 2 ( ) ) W 0 , j + L 2 ( [ 0 , ) ) . Hence it suffices to have a multiresolution

Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
Privacy Information Security Software Version 1.1a
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get the best Algebra and trigonometry course in your pocket!

Source:  OpenStax, Wavelets and wavelet transforms. OpenStax CNX. Aug 06, 2015 Download for free at https://legacy.cnx.org/content/col11454/1.6
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Wavelets and wavelet transforms' conversation and receive update notifications?