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120 Threads found on edaboard.com: **Calculate Fft**

hello
i was simulating of a first order adc using code given in book of richard scherier. for calculating SNR he uses (page 265)
snr = **calculate**SNR(spec(1:ceil(N**fft**/(2*OSR))+1), tone_bin)...
where spec is spec = **fft**(v.*ds_hann(N**fft**))/(N**fft***(nLev-1)/4);
well i don't understand this.if i (...)

Digital Signal Processing :: 12-05-2014 01:05 :: sona_ :: Replies: **1** :: Views: **473**

Hi everyone.
Hoping someone has the time to explain this to me.
After taking an N-point **fft**, I'm left with the Fourier Coeff's of each frequency bin and can **calculate** the fequency with a little math. No problem. But if I try to reconstruct the original signal, it always seems to be shifted in frequency. Will someone please help me understand?

Digital Signal Processing :: 03-19-2014 07:59 :: youngguns21 :: Replies: **0** :: Views: **295**

I am trying to calculat the energy spectrum of a signal in MATLAB.
for example I want **calculate** this ratio :
(low frequency energy (1 hz to 2 hz)) / (high frequency energy (4 hz to 5 hz)) in the spectrum of the discrete signal .
But, I have no idea how to get energy-Hz for each frequency components.
Any help is much appreciated !

Digital Signal Processing :: 02-22-2014 12:30 :: Adnan86 :: Replies: **6** :: Views: **444**

That is just your sampling window. So you may be simulating your ADC in a time interval but dft is going to **calculate** ft for the time interval specified by from-to parameters. Please refer to cadence documentation, most of the special functions are really well documented.
Also to give you a straight answer, let's say that the number of samples you

Analog Integrated Circuit (IC) Design, Layout and Fabrication :: 01-26-2014 19:27 :: kemiyun :: Replies: **3** :: Views: **510**

Hello
I have analysed a CMOS PLL with HSPICE. I have tried transient analysis and printed the output data in a txt file.
Then I have used MATLAB for **fft** analysis of this txt file. Now, I want to **calculate** phase noise of the PLL. How I can do this? Is there any MATLAB function or SIMULINK block to do this?
Tnx

Analog Circuit Design :: 10-21-2013 09:48 :: april1975 :: Replies: **1** :: Views: **533**

I tested my inverter experimentally and I obtained the THD of the inverter output voltage by using power analyzer YOKOGAWA WT1800 and it gave me a certain value. then i wanted to verify this value by the simulation results. where, i use a matlab simulink as a simulator. i used **fft** tools of the powergui to **calculate** the THD. but it gave me

Power Electronics :: 10-03-2013 10:58 :: maha.eg :: Replies: **0** :: Views: **438**

Hi,
i am trying to use 3gsps adc of e2v's ev10as152a, the datasheet is claiming that this adc can give upto 5GHz bandwidth (better SFDR even in 2nd and 3rd Nyquist zones). but when i **calculate** **fft** for this digital data(after down sampling) i can only get Fs/2 bandwidth i.e i can only get upto 1.5Ghz frequency calculation. How can i (...)

Digital Signal Processing :: 08-06-2013 09:20 :: appalanaidu :: Replies: **0** :: Views: **636**

Matlab comand dftmtx(N) (in this case N=3) gives the fourier matrix W. Then multiply as Mityan said X=W x. Where x is your input vector. and X the DFT coefficients vector.
Also with only 3 points you can **calculate** it even by hand. Using the analysis equations (for N=3):
Re X(k)= sum x cos(2 pi k i / N) for i=0 to N-1
Im X(k)= sum x sin(2 p

Digital Signal Processing :: 04-15-2013 22:38 :: albert22 :: Replies: **3** :: Views: **746**

i've done some simulations on sigma delta ADC. but i think my output is not so correct..anyone can help me out attacedh are my design and waveforms
mainly the decimation design im not sure of.
matlab simulink
1st order sigma delta adc
input: 2V Fb=1kHz , OSR=16 times88922
the 1 bit DAC simply is matlab m functio

Digital Signal Processing :: 04-06-2013 14:54 :: dawson :: Replies: **6** :: Views: **723**

hello Eminent.Engineer,
I hve also designed a delta sigma ADC and i **calculate** the SNR order to caculate the SNR after the modulator you must make the fast fourier transform function (**fft**) by MATLAB after the modulator.
About the decimation,until now i have designed the complete ADC in Smulink (MATLAB) then by using CADENCE, i only designed t

Digital Signal Processing :: 04-01-2013 12:48 :: fasto2008 :: Replies: **4** :: Views: **1733**

in dynamic test code of adc parameter, there is a paragraph to **calculate** the harmonic distortion, just as follows:
numpt=1024; %sample points
spanh=2;
%Find harmonic frequencies and power components in the **fft** spectrum
for har_num=1:10
%Input tones greater than fSAMPLE are aliased back into the spectrum
[COLOR="#FF

Analog Circuit Design :: 03-17-2013 08:20 :: lhlblue :: Replies: **1** :: Views: **309**

hello friends.
I have a question:how do I can **calculate** how time does a 1000 point **fft** take?thanks.;-)

Digital Signal Processing :: 03-13-2013 14:51 :: aminshafie :: Replies: **1** :: Views: **271**

plz help me....:-?
i m working on sigma delta of DAC , i got **fft** spectrum using Hann window in MATLAB and i want help to **calculate** SNR plz tell me how to measure signal to noise ratio in this case.........(without toolbox)

Digital Signal Processing :: 03-07-2013 10:12 :: nishagajare :: Replies: **0** :: Views: **319**

Hello! I was able to do this such way:
"real" **fft** of signal 1
"real " **fft** of signal 2
do ATAN2 of each output and **calculate** difference.
It works okay, but i wonder can it be implemented using one **fft** with complex imput? There are negative frequencies, but how i can do ATAN of complex-valued signal **fft** (...)

Digital Signal Processing :: 02-15-2013 04:06 :: Terminator3 :: Replies: **0** :: Views: **691**

Hello;
I need a program to **calculate** power and energy of signal EEG by **fft**
please help me
thank you

Elementary Electronic Questions :: 11-16-2012 02:41 :: aida.p :: Replies: **0** :: Views: **378**

As you have a known waveform and so know what the **fft** should be you should easily be able to experiment with the parameters to see what works best. I don't use Eldo so don't have the same options as you are seeing.
In general, more points is better - it just takes longer to **calculate**.
Rectangular is good if the waveform you are looking at is exa

Analog Integrated Circuit (IC) Design, Layout and Fabrication :: 11-01-2012 13:39 :: keith1200rs :: Replies: **1** :: Views: **603**

Hi,
I am trying to use the **fft** library in mikroC to **calculate** the frequency of input signal. The code gets complied but I am getting wrong and random results. The **calculate**d freq does not match the input simulated sine wave. Following are the details of my code -
Sampling freq = 1KHz
Signed Fractional Data Output from ADC. Sampling (...)

Digital Signal Processing :: 08-31-2012 07:03 :: karanbanthia :: Replies: **0** :: Views: **1022**

Time domains solvers **calculate** the S-parameters from the time domain signal using an **fft**. To get accurate results, the time signal must be sampled over a long enough period so that energy in the analysis volume is down to zero. There is some setting in the software that determines the acceptable error by setting a limit on the residual energy. The

Electromagnetic Design and Simulation :: 07-29-2012 06:34 :: volker_muehlhaus :: Replies: **14** :: Views: **638**

Hi Guys,
I'm simulationg a circuit in Pspice and parallel trying to **calculate** it in Mathcad.
I have tested the **fft** in Pspice and the c**fft** in Mathcad and there is a difference in the amplitude, so the scaling.
The one in Mathcad is scaling with 1/n I think. Can you tell me what expression does Pspice use for the (...)

Analog Circuit Design :: 06-14-2012 10:22 :: caledonia :: Replies: **1** :: Views: **643**

hi every one the above link show block diagram to **calculate** the power using filter ,first we find two things one active power and apparent power, i already find apparent power by **fft** method, so i need to **calculate** active power any one can help me by using filter method to **calculate**

Digital Signal Processing :: 06-05-2012 02:23 :: jaya krishna :: Replies: **0** :: Views: **396**

i want to **calculate** total harmonic distortion using **fft** of supply voltage..plz can you help me out with how to use the **fft** to **calculate** magnitude of voltages at harmonic frequencies and then find out the thd.

Elementary Electronic Questions :: 05-02-2012 10:49 :: shivani04 :: Replies: **2** :: Views: **599**

i have to **calculate** harmonic distrotion using tms320c6713 in code composer studio. i want to take real time samples on a supply voltage(sine wave) and then apply **fft** to finally **calculate** THD. please if any one can help me out with a real time program.

Digital Signal Processing :: 05-01-2012 23:49 :: shivani04 :: Replies: **7** :: Views: **636**

i m using 512 point **fft** IP core in V6 FPGA to **calculate** the frequency of the input signal, i m getting the correct peak and amplitude for the same . the peak's real and imaginary value i have to give to the cordic ip core(atan) to get the phase of the input signal . the input to the **fft** is a 10 bit samples from adc in 2's complement format (...)

Elementary Electronic Questions :: 04-25-2012 05:52 :: snehalg :: Replies: **0** :: Views: **388**

While comparing two approaches to **calculate** **fft**, better to use identical data with 2^n (say 1024) points. The outcome should agree. You can do that using your own program. availability of a sample data will also help more quantitative responses. You may try math cad too.

Elementary Electronic Questions :: 04-01-2012 18:45 :: ark5230 :: Replies: **3** :: Views: **1398**

Tell us about your problem; in short clear English sentences. for example
I want to measure sound at a sample rate of 10 kHz, block size 2048 point, 10 bit resolution.
I want to then read this data into Matlab, window the data, **calculate** the **fft** and plot the power=spectrum .........

Digital Signal Processing :: 03-24-2012 07:01 :: klystron :: Replies: **3** :: Views: **1431**

Hi all,
I am doing an inverst Fourier Transform in Matlab and wanted to know how to get the correct time scale for my axis.
If I have 201 data points in the F domain and do an I**fft** using 512 points, how do I **calculate** the timescale? Does anyone have Matlab code for this?
Also, if N**fft** is different from npts, I get a complex result. (...)

Electromagnetic Design and Simulation :: 03-22-2012 15:23 :: youngguns21 :: Replies: **0** :: Views: **779**

Digital Signal Processing :: 03-20-2012 17:32 :: klystron :: Replies: **2** :: Views: **461**

Hi all,
I obtained amplitude vs frequency of my signal. After plotting the **fft** I want to **calculate** the energy of specific bands (The integral of the area under the curve.) But **fft** is discrete.. Also when I zoom in specific frequency for ins 50 Hz, I see a curve as it was continuous. That confused me. How can I **calculate** (...)

Digital Signal Processing :: 03-07-2012 12:13 :: sab_sab :: Replies: **0** :: Views: **1272**

i need to **calculate** **fft** of the sinusoidal output of incremental ADC with 16 bit resolution
In order to achieve sinusoidal output vs input samples, i gave ramp input voltage amplitude from 0 to 3V for 20000 samples in sin function with fixed frequency freq =1 and fs = 60K with ADC cycles 257 and veried the phase from 0 to 2pi.
algorithm:
fo

ASIC Design Methodologies and Tools (Digital) :: 01-06-2012 13:15 :: singhji0000 :: Replies: **0** :: Views: **718**

Hi,
I am doing work on inverse scattering of electromagnetics and i need to know , how to **calculate** the multiplying constant that we multiply while calculating the inverse **fft** of waves from wavenumber to space domain.
help plz.

Digital Signal Processing :: 12-02-2011 02:08 :: ashumtech :: Replies: **3** :: Views: **678**

if X=**fft**(x), you need to **calculate** 10*log10(X*conj(X))

Analog Circuit Design :: 11-26-2011 23:10 :: JoannesPaulus :: Replies: **3** :: Views: **388**

Hi All,
I have done conservative transient simulation in Cadence after doing ADC. I am trying to post process the output in Matlab using **fft**. I have a 10ns period (sampling) but in between periods I have almost 400 points of data in between. This makes it hard to **calculate** the downsampling frequency since the number can change depending on the o

Analog Integrated Circuit (IC) Design, Layout and Fabrication :: 10-16-2011 21:41 :: acbalbason :: Replies: **0** :: Views: **552**

Hello,
I'm looking a way to **calculate** my fixed point **fft** absolute error.
I don't use any scaling (increasing the word length after each stage) in my implementation. But there is still error due to a fixed point multiplication with
twiddle factor.
Is there a way to **calculate** absolute error depends on twiddle factor bit width?
Thanks (...)

Digital Signal Processing :: 09-29-2011 16:37 :: Syswip :: Replies: **0** :: Views: **462**

hi,
I have adopt the ADS5560 for sampling, and the sample sequence is expresses as X in matlab. Then I want to **calculate** the power/energy spectrum in decibel, I have a problem whether to choose 20 or 10 as the multipy coefficient, i.e.,
20*log10(abs(**fft**(X)) or
10*log10(abs(**fft**(X))
thanks to all.
--yakex

Digital Signal Processing :: 09-09-2011 23:09 :: yakex :: Replies: **3** :: Views: **536**

hello
I need m-file (matlab code):
give me my figure and **calculate** band and list harmonics (h1,h2,h3,.....) like (powergui/**fft** analysis) but
I dont use powergui and simulink ,I need a matlab code.(I need very fast answer for me).
regards
thanks
---------- Post added at 09:18 ---------- Previous post was at

Analog Circuit Design :: 08-20-2011 04:18 :: hajar ghotb :: Replies: **0** :: Views: **2369**

Hi everyone ,
I want to apply a image enhancement algorithm in c.I have a equation for this thing. ie g(x,y) = i**fft** { F(u,v) X |F(u,v)|^k} //( F(u,v) =**fft** of image)
How i will **calculate** |F(u,v)|^k ? What is the meaning of |F(u,v)|^k ?
Is there any example so that i can implement it in c ?
thanks

Digital Signal Processing :: 08-03-2011 09:44 :: bibhukalyan :: Replies: **0** :: Views: **660**

i'm working on microblaze to realize a multi_core platform on which i'm testing **fft**,in order to **calculate** the speed up ratio,i need to know how many clock cycles it takes.
C code is used in microblaze ,i'm wondering if there is some specific function in C can **calculate** the clock cycles.
waiting for your help
THX:razz

Embedded Systems and Real-Time OS :: 05-16-2011 23:05 :: happylbd :: Replies: **2** :: Views: **1526**

Dear Friends,
I simulate the I**fft** block and compare its results with the theoretical basis
but i find difference between simulation and calculation
Attached is my I**fft** Simulink model and reference to
**fft**: Fast Fourier Transform
i **calculate** the I**fft** as follows
x(0) = x(0)+x(1)+x(2)+x

Digital communication :: 04-12-2011 06:08 :: ReComm :: Replies: **0** :: Views: **557**

i have done **fft** in MATLAB to **calculate** phase noise. but it is not true, i am looking for this too. please send me if you find any information
thank you ,

Analog Circuit Design :: 03-12-2011 11:48 :: elias63 :: Replies: **1** :: Views: **1782**

Hi forum,
How to **calculate** **fft** core SQNR?
Sounds very easy but seems it is not.
I have a Verilog RTL core for **fft**.
I have a very accurate reference model for **fft**.
Let's assume that my RTL core outputs are R0, R1, R2.......Rn.
And reference model outputs are M0, M1, M2.......Mn.
Having these samples how can I (...)

Digital Signal Processing :: 03-01-2011 10:33 :: Syswip :: Replies: **2** :: Views: **1431**

hiiiiiiii
I'm working on sigma Delta ADC
CAN ANY1 PLEASE HELP ME ON WORKING WITH CADENCE SPECTRE FOR snr CALCULATION
HOW MANY CYCLES I SHOULD RUN THE TRANSIENT ANALYSIS??
IN ORDER TO **calculate** snr
PLEASE HELP ME IN FIGURING OUT THESE VALUES...
how to come to conclusion to **fft** fundamental frequency of input signal ,
NO. of samp

Analog Circuit Design :: 02-07-2011 12:06 :: kapil411 :: Replies: **3** :: Views: **2891**

How can I **calculate** THD (Total Harmonic Distortion) in a MATLAB file?, I have signal out put of the inverter, Please note, I know I can do this in Simulink, I am looking for a way to do this from MATLAB directly.

Analog Integrated Circuit (IC) Design, Layout and Fabrication :: 02-02-2011 02:09 :: powersolda :: Replies: **3** :: Views: **6132**

Hi,
can anyone help me to **calculate** the THD in a frequency response of a sine wave?
I know the theory behind it, but cannot find a way to write the Matlab code.
Many thanks,
Stef

Analog Circuit Design :: 12-21-2010 12:16 :: smalandr :: Replies: **4** :: Views: **3073**

Hey dudes,
I've designed a sigma delta modulator in HSpice and I wanna **calculate** its SNR in Spice Explorer.
How should I set the values for it in **fft** window that opens up for me? IS there a rule or formula?
Thanks

Analog Integrated Circuit (IC) Design, Layout and Fabrication :: 11-23-2010 16:08 :: gigalove :: Replies: **0** :: Views: **1128**

Hi!
You need to do a transient simulation and apply **fft** in your output sine wave. After this, you can **calculate** the SINAD, and consequently ENOB, based on the following relation:
You apply a input sine wave at the input of your ADC, and then, you can use an ideal DAC (for instance, d

Analog Integrated Circuit (IC) Design, Layout and Fabrication :: 11-03-2010 11:58 :: palmeiras :: Replies: **4** :: Views: **1473**

Hi all,
can someone explain to me how to **calculate** DNL/INL from **fft** ??

Analog Circuit Design :: 10-23-2010 17:31 :: zvilupu :: Replies: **2** :: Views: **804**

thank you for your reply, but i want know how to **calculate** value of the signal energy, from its **fft**, the area under the curve is equal to energy of the signal? below code is correct to **calculate** energy of signal?
fs = 10000; % Sample frequency (Hz)
load imf1.txt;
x=imf1;
t = 1:length(x);
m = (...)

Digital Signal Processing :: 09-10-2010 05:55 :: harithota20 :: Replies: **3** :: Views: **5130**

Hello everyone，i have a problem with my ADC data.
I want to **calculate** the ADC's SNR,and i 've done **fft** using MATLAB,i found some matlab program to **calculate** the SNR,but many of some can not work,so is there anyone can help me with it ,or tell me where i can find answers.
thank you very much!!

Digital Signal Processing :: 08-06-2009 12:51 :: rusty629 :: Replies: **3** :: Views: **2833**

Hai i am working with LPC2148. i need help. how Can we **calculate** the frequency of the sine wave which is given as a input to the LPC2148 from Function generator.

Microcontrollers :: 09-04-2010 00:17 :: nagarajanj21 :: Replies: **4** :: Views: **1802**

in your simulink model, add work space and stored all your points @ fs. After it, do **fft** and **calculate** SNR using signal power / noise power

Analog Integrated Circuit (IC) Design, Layout and Fabrication :: 08-11-2010 03:15 :: ee_ykhab :: Replies: **2** :: Views: **1102**

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