# Overview of multirate signal processing

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Digital transformation of the sampling rate of signals, or signal processing with different sampling rates in the system.

## Applications

1. CD to DAT format change, for example.
2. oversampling converters; which reduce performance requirements onanti-aliasing or reconstruction filters
3. bandwidth of individual channels is much less than theoverall bandwidth
4. Eyes and ears are not as sensitive to errors in higher frequencybands, so many coding schemes split signals into different frequency bands and quantize higher-frequency bands withmuch less precision.

## General rate-changing procedure

This procedure is motivated by an analog-based method: one conceptually simple method to change the sampling rate is tosimply convert a digital signal to an analog signal and resample it! ( [link] )

${H}_{\mathrm{aa}}(\Omega )=\begin{cases}1 & \text{if \left|\Omega \right|< \frac{\pi }{{T}_{1}}}\\ 0 & \text{otherwise}\end{cases}$ ${h}_{\mathrm{aa}}(t)=\frac{\sin (\frac{\pi }{{T}_{1}}t)}{\frac{\pi }{{T}_{1}}t}$ Recall the ideal D/A:
${x}_{a}^{\prime }(t)=\sum_{n=()}$ x 0 n t n T 0 T 0 t n T 0 T 0
The problems with this scheme are:
1. A/D, D/A,filters cost money
2. imperfections in these devices introduce errors

Digital implementation of rate-changing according to this formula has three problems:

1. Infinite sum: The solution is to truncate. Consider $sinc(t)\approx 0$ for $t< {t}_{1}$ , $t> {t}_{2}$ : Then $m{T}_{1}-n{T}_{0}< {t}_{1}$ and $m{T}_{1}-n{T}_{0}> {t}_{2}$ which implies ${N}_{1}=\lceil \frac{m{T}_{1}-{t}_{2}}{{T}_{0}}\rceil$ ${N}_{2}=\lfloor \frac{m{T}_{1}-{t}_{1}}{{T}_{0}}\rfloor$ ${x}_{1}(m)=\sum_{n={N}_{1}}^{{N}_{2}} {x}_{0}(n){sinc}_{{T}^{\prime }}(m{T}_{1}-n{T}_{0})$
This is essentially lowpass filter design using a boxcar window: other finite-length filter design methods could beused for this.
2. Lack of causality : The solution is to delay by $\max\{\left|N\right|\}$ samples. The mathematics of the analog portions of this system can be implemented digitally.
${x}_{1}(m)=(t, , ({h}_{\mathrm{aa}}(t), {x}_{a}^{\prime }(t)))=\int_{()} \,d \tau$ n x 0 n m T 1 τ n T 0 T 0 m T 1 τ n T 0 T 0 τ T 1 τ T 1
${x}_{1}(m)=({T}^{\prime }, , \sum_{n=()} )$ x 0 n T m T 1 n T 0 T m T 1 n T 0 n x 0 n sinc T m T 1 n T 0
So we have an all-digital formula for exact digital-to-digital rate changing!
3. Cost of computing ${sinc}_{{T}^{\prime }}(m{T}_{1}-n{T}_{0})$ : The solution is to precompute the table of $\mathrm{sinc}(t)$ values. However, if $\frac{{T}_{1}}{{T}_{0}}$ is not a rational fraction, an infinite number of samples will be needed, so some approximation will have tobe tolerated.
Rate transformation of any rate to any other rate can be accomplished digitally with arbitrary precision (if somedelay is acceptable). This method is used in practice in many cases. We will examine a number of special cases andcomputational improvements, but in some sense everything that follows are details; the above idea is the centralidea in multirate signal processing.

Useful references for the traditional material (everything except PRFBs) are Crochiere and Rabiner, 1981 and Crochiere and Rabiner, 1983 . A more recent tutorial is Vaidyanathan ; see also Rioul and Vetterli . References to most of the original papers can be found in these tutorials.

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
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
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