# Sub-band processing

 Page 1 / 1
This module covers the fundamentals of Filterbanks and explains why the are very useful in filter design.

## Sub-band processing

There exist many applications in modern signal processing where it is advantageous to separate a signal into differentfrequency ranges called sub-bands . The spectrum might be partitioned in the uniform mannerillustrated in , where the sub-band width ${\Delta }_{k}=\frac{2\pi }{M}$ is identical for each sub-band and the band centers areuniformly spaced at intervals of $\frac{2\pi }{M}$ .

Alternatively, the sub-bands might have a logarithmic spacing like that shown in .

For most of our discussion, we will focus on uniformly spaced sub-bands.

The separation into sub-band components is intended to make further processing more convenient. Some of the mostpopular applications for sub-band decomposition are audio and video source coding (with the goal of efficient storageand/or transmission).

illustrates the use of sub-band processing in MPEG audio coding. There apsychoacoustic model is used to decide how much quantization error can be tolerated in each sub-band while remainingbelow the hearing threshold of a human listener. In the sub-bands that can tolerate more error, less bits are usedfor coding. The quantized sub-band signals can then be decoded and recombined to reconstruct (an approximateversion of) the input signal. Such processing allows, on average, a 12-to-1 reduction in bit rate while stillmaintaining "CD quality" audio. The psychoacoustic model takes into account the spectral masking phenomenon of the human ear, which says that high energy in one spectral region will limit the ear's ability to heardetails in nearby spectral regions. Therefore, when the energy in one sub-band is high, nearby sub-bands can becoded with less bits without degrading the perceived quality of the audio signal. The MPEG standard specifies32-channels of sub-band filtering. Some psychoacoustic models also take into account "temporal masking" propertiesof the human ear, which say that a loud burst of sound will temporarily overload the ear for short time durations,making it possible to hide quantization noise in the time interval after a loud sound burst.

In typical applications, non-trivial signal processing takes place between the bank of analysis filters and the bank ofsynthesis filters, as shown in . We will focus, however, on filterbank design rather than on the processing that occurs between thefilterbanks.

Our goals in filter design are:

• Good sub-band frequency separation ( i.e. , good "frequency selectivity").
• Good reconstruction ( i.e. , $y(n)\approx x(n-d)$ for some integer delay $d$ ) when the sub-band processing is lossless.

The first goal is driven by the assumption that the sub-band processing works best when it is given access to cleanly separated sub-band signals, while thesecond goal is motivated by the idea that the sub-band filtering should not limit the reconstruction performancewhen the sub-band processing ( e.g. , the coding/decoding) is lossless or nearly lossless.

where we get a research paper on Nano chemistry....?
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
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
Got questions? Join the online conversation and get instant answers!