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# Calculate Fft

129 Threads found on edaboard.com: Calculate Fft

## DC term in a periodogram estimate

I was trying to understand the noise in switiching regulators and took 8192 samples of a 5V DC supply at 5Khz. If I calculate the 8k point fft of this sequence, divide the absolute value by 8192 and square the expression, I will get the power right? It comes out as 14dB approximate. If I connect the dc supply then to a 50 ohm spectrum analyzer, wou

## what sampling frequency is used to calculate the frequency usimg fft

what sampling frequency is used to calculate the frequency usimg fft,either fft sampling frequency or input signal sampling frequency.

## How to calculate standard deviation from the delay?

hi guys, I am trying to calculate the unit vector and standard deviation of the signal. I hope everyone can give me ideas. Here is my scenario: I have 2 rx channels: - f is channel 1 with the length 1x256 complex, then fft. - g is channel 2 with the length 1x256 complex, then fft. - from f and g, I can calculate the (...)

Hi, I have designed an ADC in cadence virtuoso and i want to calculate the metrics such as SNR,SINAD,ENOB etc. For example i want to calculate ENOB. I read everywhere that i need to do an fft my input, or simply use the spectrumMeas function. So i am using a sinuid input of 875MHz as fin and 2GHz as flck. In the field in spectrumMeas i use (...)

## Modeling layer in RCWA simulation

I have a few resources for you. For arbitrary and strange grating cross sections, you can use an fft to calculate the Fourier coefficients. Take a look at "Lecture x -- fft" here: You will need to use many points on your array describing the grating cross section, like maybe 1000 points. If yo

## connect high frequency ADC (for example FMC160) to a FPGA

Thanks for your explain under this condition if user needs high frequency clock in FPGA for some processing(same calculate fft from signal) what is solution by no loss data? assume: ADC clk:2 GHz and 16 bit fft block:500 MHz and 256 poin is it right save data in 4, 256 cell RAMs and calculate fft from this (...)

## How to know if there is noise affecting my signal

Hi, How did you calculate both ffts from the above diagram? Klaus

Follow the IEEE Standard 1241 about ADC measurement methodology. Apply sinusoidal wave to the input and sampling it with numbers of samples≥2^N and make fft of collected samples to get SINAD. Next calculate ENOB from formula ENOB=(SINAD-1.76)/6.02 Of course the sampling frequency cannot be an integral multiplicity of input signal frequency to

## relation between micro frequancy and calculate fft time?

hi all i want to find relation between micro frequancy and calculate fft time for choosing best micro for varities of fft.for example if i have a sampling rate 1Mhz with 256 lenght of sample.what speed is optimize for choosing micro controller.? i need to some formula.

## LFCC (Linear Frequency Cepstral Coefficients)

It is used to extract the features in audio signal. It has steps Signal Normalization, Compute fft power spectrum, Compute autoregressive model analysis, Convert LPC to cepstra , Apply DCT and Convert to cepstra, Apply lifter to matrix of cepstra, calculate the deltas of a output mel sequence . Can anyone briefly explain about LFCC and it's ste

## calculating snr in delsig toolbox

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 = calculateSNR(spec(1:ceil(Nfft/(2*OSR))+1), tone_bin)... where spec is spec = fft(v.*ds_hann(Nfft))/(Nfft*(nLev-1)/4); well i don't understand this.if i (...)

## Signal Reconstruction after FFT

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?

## calculate frequency energy from spectrum signal

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 !

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

## phase noise calculation using MATLAB [hlp]

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

## Calculation THD for multilevel inverter

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

## fft in 2nd nyquist zone

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 (...)

## Hi, how to calculate 3 point fft?

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

## Sigma Delta simulation help

Can u calculate by hand before take up designing? This will be best choice I think so. Another way is using conditional opamp to shape wanted signal on Digital Signal.

## SNR calculation of Delta Sigma ADC after Modulator and After Decimation

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

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

## how do I can understand FFT speed

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

## SNR of sigma delta for DAC

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)

## Determine phase shift in quadrature signal using complex FFT and not two "real" FFTs.

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 (...)

## calculate power and energy inMatlab FFT for signal EEG

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

## FFT simulation setup

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

## Help!!! Wrong results while using FFT in MikroC Pro for dsPIC

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 calculated 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 (...)

## s21>0 for passive device!!

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

## FFT algorithm in Pspice

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 cfft 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 (...)

## to find active power calculation by using filter method

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

## calculation of harmonics

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.

## real time program in tms320c6713

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.

## fft and cordic IP ,how to pass the data from fft to cordic for finding the phase?

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 (...)

## about plotting FFT in matlab

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.

## FFT using data from Oscilloscope.--- Matlab

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 .........

## Inverse FFT Time Scale----->HELP

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 Ifft using 512 points, how do I calculate the timescale? Does anyone have Matlab code for this? Also, if Nfft is different from npts, I get a complex result. (...)

## How to get the total energy of two waveforms buried in a noise

calculate the RMS (Root Mean Square) it is the same as the standard deviation (1/n*Sum(value-average)^2

## energy calculation of a specific band of signal after fft in MATLAB

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 (...)

## sinusoidal ADC output for FFT

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

## inverse fast fourier transform

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.

## SNDR measurement issues

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

## Conservative Transient Simulation in Cadence and Matlab Post processing

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

## FFT absolute error calculation

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 (...)

## 10x or 20x in calculation the ADC sample sequence in decibel

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

## matlab code for THD(total harmonic destortion)

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

## image enhancement in c

Hi everyone , I want to apply a image enhancement algorithm in c.I have a equation for this thing. ie g(x,y) = ifft { 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

## how to count clock cycles in microblaze（using ML510-virtex_5 FX130）

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

## IFFT Problem between simulation and theory

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

## PLL phase noise simulation by matlab

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 ,

## How to calculate FFT core SQNR?

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 (...)