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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 (...)
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?
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
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
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
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 (...)
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
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
Hello Everyone I have designed a decimation filter for Delta Sigma ADC and now I want to calculate the SNR of Delta Sigma ADC after the modulator and then after Decimation. As far as Schrier and Malcovati's Toolboxes are concerned I was unable to apply them (How to use them because lot of parameters to be mentioned ? :|) to decimated data so any
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
hello friends. I have a question:how do I can calculate how time does a 1000 point fft take?thanks.;-)
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)
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 (...)
Hello; I need a program to calculate power and energy of signal EEG by fft please help me thank you
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
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 (...)
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
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 (...)
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
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.
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.
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 (...)
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.
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 .........
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. (...)
calculate the RMS (Root Mean Square) it is the same as the standard deviation (1/n*Sum(value-average)^2
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 (...)
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
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.
if X=fft(x), you need to calculate 10*log10(X*conj(X))
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
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 (...)
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
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
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
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
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
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 ,
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 (...)
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
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.
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
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
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
Hi all, can someone explain to me how to calculate DNL/INL from fft ??
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 = (...)
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!!
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.
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