Problem with Xdata and Ydata scaling
I have a little problem with the use of XData. I am plotting and imagesc, for example for the matrix:
A=[ 5 6 4 8; 8 12 23 31;15 9 27 5];
The default Xdata scaling would be: 0.5 1 1.5 2 2.5 3 3.5 4 4.5
If I want to have (for example): 3 6 9 12, (only in with tick in the center of the squares, ie avoid the intermediate ticks and labels) how can I do?
I tried with:
but that doesn't work well, the ticks are not placed where I want.
Please, any help will be very appreciated!
"Camille Couzi" <camil...find the index of fft
i'm working on a project and i actually have an audio signal.
After applying to it the fft() function,how can i find the index
of the maximum fft value ,and transform it to (Hz) units?
I'm a new user so...
Thanks a lot.
"Dimitris Valapetrou" <email@example.com> wrote in message <firstname.lastname@example.org>...
> i'm working on a project and i actually have an audio signal.
> After applying to it the fft() function,how can i find the index
> of the maximum fft value ,and transform it to (Hz) units?
> I'm a new user...Please verify my "solution" to FFT scale factors
Dear DSP masters!!
I'm using the FFTW C library to evaluate some signal processing ideas. As I have Richard Lyons Understanding ... book I first tried his DFT example of paragraph 3.1.1 in order to check if the FFT results are matching. They did.
But I would like to use the FFT to get a correct frequency domain representation, so the outputs must be properly scaled.
Note: I'm using the FFTW library with a complex input and a complex output.
After the forward FFT operation I divide each individual real and imaginary part by N / 2. And after the inverse FFT operation I divide...Help with Signal Processing
I need some guidance on the following issue
Problem : I have a clipped signal
Objective ; To reconstruct original value
Approach : 1. Make it band limited
2. Apply reconstruction technique
Obstacles : 1.I can make the clipped value zeros, and take those as missing values
.can any one give me example of band limiting the say between 0 to 50 Hz,
2. Say sampling frequency is 1000 Hz that is sampling interval .001
"kk KKsingh" <email@example.com> wrote in message <firstname.lastname@example.org....To FFT or not to FFT
i am working on mc-cdma and in most of the papers that i read, the
recieved signal vector is written as Y = HCA + N, where H is a channel
matrix (rayleigh fading diagonal matrix),C is an orthogonal code
matrix and A is the bit vector. N is the noise vector. My doubt is
that is there no need to ifft . I mean that is how we transmit it, so
is that step not required in the simulations. if yes, then why is it
not used in these papers and if no then why not
thanks a lot,
"Prateek" <email@example.com> wrote in message
news:72a694e0.0312070319.208d489f@posting....US-TX-Austin: Design Eng., Mixed signal integrated circuit design, Analog Circui (45320957609)
US-TX-Austin: Design Eng., Mixed signal integrated circuit design, Analog Circui (45320957609)
Position: Design Eng.
Location: Austin TX
Skills: MSEE or MSCE or BSEE plus 5 years of experience.
0-5yrs design experience in mixed-signal integrated
Strong emphasis on analog design.
Exp in one or more of the following:
Analog Circuit Design:
...FFT problem #6
I have a amplitude 2 level sine wave signal, for which i have
camputed it`s FFT. i have also calculated it`s magnitude. Kindly let
me know now how i can obtain amplitude value back from the magnitude
Gaurav khandre wrote:
> I have a amplitude 2 level sine wave signal, for which i have
> camputed it`s FFT. i have also calculated it`s magnitude. Kindly
> me know now how i can obtain amplitude value back from the
s=(s1+s2);...US-TX-Austin: Digital or Mixed Signal Design Eng.; 3-8yrs exp., Verilog, DSP, Au (45341757632)
US-TX-Austin: Digital or Mixed Signal Design Eng.; 3-8yrs exp., Verilog, DSP, Au (45341757632)
Position: Digital or Mixed Signal Design Eng.
Location: Austin TX
Skills: BSEE (MSEE preferred) with experience ranging from 3-8
Applicants should have skills in the following areas:
Mixed-signal design and simulation tools
DSP architectures, synthesis t...linprog error messages and the difference between large and medium scale
I m using matlab optimization toolbox, namely the function linprog.
1-I obtain these messages using the interior point method:
Exiting: One or more of the residuals, duality gap, or total relative
the primal appears to be infeasible (and the dual unbounded).
(The dual residual < TolFun=1.00e-08.)
2-using simplex method I obtain for the same example :
Exiting: Maximum number of iterations exceeded in Phase 1;
what does it mean, and what should I do to solve my problem ?
Can someone help me to make the diagnostic ...US-TX-Austin: DSP Eng., Digital Signal Processing Exp., DSP/Algoritm bckgrnd; DH (45320532404)
US-TX-Austin: DSP Eng., Digital Signal Processing Exp., DSP/Algoritm bckgrnd; DH (45320532404)
Position: DSP Eng.
Location: Austin TX
Skills: Digital Signal Processing Experience.
Solid DSP/Algorithm/Communication theory background.
Firmware implementation knowledge preferred.
BSEE, Master's Preferred - GPA 3.75 or better.
Please send your current resume in confidence to <staf...FFT resolution lines
The FFT function returns Nyquist (half) of input points. How do I get
400 lines of resolution out of 1024 points? Do I just disregard other
In an ideal world, a 1024-point FFT results in 512 valid values, at
frequencies from 0/N * Fsamp up to (N/2-1) / N * Fsamp.
Of course, an ideal world would also have a filter with 100% pass at
the nyquist frequency, and 0% at any frequency above it.
T'ain't no such beast.
The usual reason for using 400 lines instead of 512 (or 800 instead of
1024, etc.) is the imprecision of the input filters - you don't really
know if their cuto...symbolic fft #3
is it possible to compute symbolic fft by matlab or other sw?
Where can i find fft outputs for inputs at each stage of fft radix-2
On 15.01.12 01:42, ahmad salehi wrote:
> is it possible to compute symbolic fft by matlab or other sw?
See the same question posted two hours earlier by �daryoosh�.
...mri signal intensity values differ in efilm ge-centrcity osirix philips
My hospital has a Philips 3T scanner. We did an abdominal MRI and I
wanted to compare adrenal and spleen SI values on a pair of images (in
and out of phase T1 weighted images).
I compared the numbers reported on the
1) original philips scanner console
2) ge-centricty pacs
3) efilm 1.5.3
4) osirix 1.6.2
only on osirix 1.6.2 were the numbers similar to the philips scanner
I use a similar size ROI measurement tool on same image, approximate
Here is a table of results
ip = in phase op = out-of-phase
measure device ip-adrenal ip-spleen op-ad...signal integration #2
I can't seem to figure out how to continuiously integrate an
accelerometer signal twice to view the displacement. Ive used all of
the different integration VI's and i can't seem to get the result i
need. i don't want to see a waveform, i just the value of the
displacement. Any one help? been at this a long time now.
kungfucrazy <firstname.lastname@example.org> wrote in message news:<5065000000080000006FAF0000email@example.com>...
> I can't seem to figure out how to continuiously integrate an
> accelerometer signal twice to view the displacement. Ive used al...scaling FFT problem
I'm trying to scale FFT's to give desireable units. Searching the
archives, I cam across this which is very helpful:
but not exactly what I want. So here's the question: If I have a
signal (pure sine wave of freq. f) with an amplitude of, let's say 2,
I would like to do an FFT and scale it such that the magnitude (i.e.,
sqrt(power spectrum)) gives a value of 2 at frequency f. Any ideas
on how to this for arbitrary amplitudes and frequencies (i.e.
BTW, the above procedure (from the TMW l...FFT and ESD from Literature Definition [Matlab]
I am complete beginner in DSP and FFT in matlab. Thanks for helping guys !
I have a vector of signal x(t) with its time vector. I want to obtain a frequency representation of the signal, in particular the energy spectrum of x(t) in the following definition:
I stumbled on this explanation to obtain the energy spectrum, which spells out my intention, from an IEEE paper(Open Circuit Fault Diagnosis in 3 phase uncontrolled rectifiers, 2012, Rahiminejad, Diduch, Stevenson, Chang).
"A record...Plotting Significance of FFT
Can any one comment on my below code to
plot confidence limits of spectrum calculated using matlab fft. I have
implemented following a suggestion from a book but not 100% sure if I
am correct in my implementation. Please help
In below code I use a time series form a netcdf file But it can be any
Also can any one tell me how to obtain variance preserving spectra
using matlab and how to plot significance level on it?
spec=(2./N^2)*abs(cspec)....US-TX-Austin: Product Marketing Eng.,mixed signal, engineering/design exp; DH (45329614403)
US-TX-Austin: Product Marketing Eng.,mixed signal, engineering/design exp; DH (45329614403)
Position: Product Marketing Eng.
Location: Austin TX
Skills: 3+yrs exp in mixed-signal, wireless component industry.
Engineering/design exp, combined with exposure/experience in
MS Electrical Engineering or BS Electrical Engineering with
graduate studies in business.
...convert live colour video into gray scale video
i work on project related to video processing.I do programming in MATLAB.I take video from webcam.In which i want to convert this colur video into gray scale video.i get the webcam video preview in matlab.Now i want ot convert this video into gray scale video.What can i do for this? I try but i get nothing.
> i work on project related to video processing.I do programming in MATLAB.I take video from webcam.In which i want to convert this colur video into gray scale video.i get the webcam video preview in matlab.Now i want ot convert this video into gray...CompIMAGE2006
(apology for cross posting)
Computational Modelling of Objects Represented in Images:
Fundamentals, Methods and Applications
Coimbra, Portugal, October 20-21, 2006
Please, accept our reminder related with the SUBMISSION PERIOD for the
International Symposium CompIMAGE that ENDS TOMORROW (June 30).
For more details, including invited speakers, abstracts guidelines and
submission, registration and latest news, please see...Why fft(X,n) useful?
It appears that the idea behind fft(X,N) is to save you the trouble of manually zero-padding X when higher frequency sampling is desired (and also to save memory when X is a matrix).
However, the format of the zero-padding is always wrong. Note that
>> fft([2 1 1],6)
Columns 1 through 5
4.0000 2.0000 - 1.7321i 1.0000 2.0000 1.0000
2.0000 + 1.7321i
is equivalent to
>> fft([2 1 1 0 0 0])
Columns 1 through 5
4.0000 2.0000 - 1.7321i 1.0000 2.0000 1.0000...Discrete Functions... Signal Simulation... A Study Using Mathematica
Abstract: An attempt was made to analytically describe some basic
functions which are provided with the libraries of mathematical
functions of programming languages. This study will rely on Mathematica
in calculating all numerical results. This study provides global
methods to calculate some discrete functions, which were previously
calculated by using low-level language techniques to chop digits. Using
these definitions we can simulate digital signals without the need for
IF statements and conditions.
A comparison were made between the formulas provided by this study and
some funct...FFT Structure optimization
I want to ask for your advice about a problem i have. I need to perform a
FFT every specified amount of time but the FFT calculation takes more tim
than i can afford. as an optimization step i want to throw half of th
output bins of the FFT but on the FFT structures that i know it'll onl
save half of the last stage butterflies calculation.
is there any other FFT structure that i can use so I'll save more cycle
and I'll be able to work on only half of the spectrum? (1..N samples o
the input => bins 1..(N/2-1) on the output)
> I want to ask fo...how to remove noise using fft.
i have created a signal y(t) made of a sinosoid , and i added to it white noise n(t) , so as the signal to become s(t)=y(t)+n(t).
now i want to remove the noise n(t) from the signal to get back the original signal y(t).
i want to use fft then filter the noise out then ifft however i dont really know how to do the filtering , and according to what.
does anyone know how i could do this ?
On Jul 7, 7:52 am, "roy zeghondi" <get_r...@hotmail.co...solving structural dynamic equations in frequency domain by fft
I would like to ask you to share your experiences of solving
structural dynamic equations in frequency domain by use of fft and
ifft in matlab.
My problem is like this:
say, the equation is: m a + c v + k u = p(t)
in frequency domain, we should have
U(w) = h(w)*P(w), where P(w)=fft(p), and h(w) is the frequency
then we can get the solution u(t)=ifft(U)
My question is how to perform h(w)*P(w)?
Thank you very much in advance.
I have been hoping to get some help here ...
> I would like to ask you to share your experiences of solving