



Baldwin illustrates and explains forward and inverse Fourier transforms using both DFT and FFT algorithms. He also illustrates and explains the implementation of frequency filtering by modifying the complex spectrum in the frequency domain and transforming the modified complex spectrum back into the time domain.
Revised: Sat Oct 17 17:00:21 CDT 2015
This page is included in the following book:
Digital Signal Processing  DSP
Table of contents
Preface
A previous module titled
Fun with Java, How and Why Spectral Analysis Works explained some of the
fundamentals regarding spectral analysis.
The module titled
Spectrum Analysis using Java, Sampling Frequency, Folding Frequency, and the FFT
Algorithm presented and explained several Java programs for doing spectral
analysis, including both DFT programs and FFT programs. That module illustratedthe fundamental aspects of spectral analysis that center around the sampling
frequency and the Nyquist folding frequency.
The module titled
Spectrum Analysis using Java, Frequency Resolution versus Data Length used
similar Java programs to explain spectral frequency resolution.
The module titled
Spectrum Analysis using Java, Complex Spectrum and Phase Angle explained
issues involving the complex spectrum, the phase angle, and shifts in the timedomain.
This module will illustrate and explain
forward and
inverse Fourier transforms using both DFT and FFT algorithms. I will also illustrate andexplain the implementation of frequency filtering by modifying the complex
spectrum in the frequency domain and then transforming the modified complexspectra back into the time domain.
Viewing tip
I recommend that you open another copy of this module in a separate
browser window and use the following links to easily find and view the Figuresand Listings while you are reading about them.

Figure 1. Forward and inverse transform of a time series using DFT algorithm.

Figure 2. Forward and inverse transform of a time series using FFT algorithm.

Figure 3. The signature of the complexToComplex method.

Figure 4. Filtering in the frequency domain.

Figure 5. Filtering in the frequency domain.
Questions & Answers
find the 15th term of the geometric sequince whose first is 18 and last term of 387
The given of f(x=x2. then what is the value of this f(3) 5f(x+1)
hmm well what is the answer
Abhi
how do they get the third part x = (32)5/4
can someone help me with some logarithmic and exponential equations.
sure. what is your question?
ninjadapaul
okay, so you have 6 raised to the power of 2. what is that part of your answer
ninjadapaul
I don't understand what the A with approx sign and the boxed x mean
ninjadapaul
it think it's written 20/(X6)^2
so it's 20 divided by X6 squared
Salomon
I'm not sure why it wrote it the other way
Salomon
ok. so take the square root of both sides, now you have plus or minus the square root of 20= x6
ninjadapaul
oops. ignore that.
ninjadapaul
so you not have an equal sign anywhere in the original equation?
ninjadapaul
is it a question of log
Abhi
im all ears I need to learn
Sherica
right! what he said ⤴⤴⤴
Tamia
what is a good calculator for all algebra; would a Casio fx 260 work with all algebra equations? please name the cheapest, thanks.
algebra 2 Inequalities:If equation 2 = 0 it is an open set?
or infinite solutions?
Kim
The answer is neither. The function, 2 = 0 cannot exist. Hence, the function is undefined.
Al
if A not equal to 0 and order of A is n prove that adj (adj A = A
rolling four fair dice and getting an even number an all four dice
Differences Between Laspeyres and Paasche Indices
No. 7x 4y is simplified from 4x + (3y + 3x) 7y
how do you translate this in Algebraic Expressions
Need to simplify the expresin. 3/7 (x+y)1/7 (x1)=
. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
what's the easiest and fastest way to the synthesize AgNP?
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials and their applications of sensors.
what is system testing?
AMJAD
preparation of nanomaterial
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
good afternoon madam
AMJAD
what is system testing
AMJAD
what is the application of nanotechnology?
Stotaw
In this morden time nanotechnology used in many field .
1Electronicsmanufacturad IC ,RAM,MRAM,solar panel etc
2Helth and MedicalNanomedicine,Drug Dilivery for cancer treatment etc
3 Atomobile MEMS, Coating on car etc.
and may other field for details you can check at Google
Azam
anybody can imagine what will be happen after 100 years from now in nano tech world
Prasenjit
after 100 year this will be not nanotechnology maybe this technology name will be change .
maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
Azam
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
Prasenjit
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
Damian
silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
Azam
I'm interested in Nanotube
Uday
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^15
Prasenjit
can nanotechnology change the direction of the face of the world
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
the Beer law works very well for dilute solutions but fails for very high concentrations. why?
how did you get the value of 2000N.What calculations are needed to arrive at it
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