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Hello all, I am looking for a software to calculate fft. In order to have an idea about SFDR . Does anyone know a good one (free would be great)? Thanks a lot. fasto
Hi all, I'm new to DSP. I'm trying to calculate fft for an ADC. I captured the digital output from the ADC by using a Digital comparator and stored the output code in a file. I need to know how i can use this digital output codes(1's and 0's) to calculate fft , as fft needs real and imaginary (...)
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 (...)
How do we caluculate fft from a group of sampled values Iam interested to calculate frequency from fft.What happens to the imaginary term in the fft in real time. Thanks Any basic DSP text book can give you the equation for DFT and fft algorithms like Radix2 and Radix4. Once you (...)
Hi, I am trying to develop a function in Matlab to calculate fft using DIF RADIX 2. In order to test it , firstly I am working with a signal with length =8 x= . Unfortunatelly it is not returning the correct result, I cant find what is wrong with the algorithm. If somebody realise what is wrong in the code below, please let
Hi thanks now I want to take DFT. is it true: dft(sample("out" 2ns 22ns "linear" 100ps) 2ns 22ns 128 ...) wil this calculate fft? rehards
I am trying to calculate fft on the PIC16F877A, since the PIC can't provide enough RAM. I have store each calculation to the SRAM. Here is the sample code.. I still can't get it to work though... Any help would be great... //Source code from here: //the adc input data is
Hi I have been trying to calculate fft based on Radix-4 in Excel. Also I have been comparing my result with matlab. But I am stuck at the moment because I felt something did not seem to be correct. Please find the attached file. Any help would be appreicate MM
:D Hello! I have been implementing OFDM with fixed-point fft. I have 16 bits at Tx output for DAC, but I have only 6 bits ADC for Rx. As you can see below At Tx.....Outout from FPGA 16 bits then connected to DAC ......... At Rx....ADC with 6bits input to FPGA for fft processing. Therefore, the problem is how to process and (...)
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
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.
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 (...)
Yes,u can. u will get the various frequency component of signal included in the text file by fft. the program below will be helpful to you clear load xxx.txt; outlen=length(xxx); ain=xxx(1:outlen,2:2); plot(ain) or clear f=fopen('xxx.txt','r'); =fscanf(f,'%f',inf); in1=rot90(in1); iRet=fclose(f); plot(in1) to calculate fft
how many sample number you take to calculate fft? for a 12 bit ADC, you should take 2^13 sample at least.
Dear naresh850, I am a little confused: you wrote that you did the processing in time domain but then you wrote that velocity recognition is based on Goertzel algorithm. But this is equivalent to saying that the processing is in Frequency domain, because the Goertzel is a simplified method to calculate fft frequency bins. Please could you clari
calculate fft, then plot magnitude response as sqrt(real_part^2+imaginary_part^2). You may consult Matlab help about fft function.
I had been simulated SDM & calculated fft through MATLAB. There must be 65536/2 point when you see fft plot between 0~ fs/2 if NP=65536 I think you put your spice output data to MATLAB with the range of 0~fs instead of 0~fs/2. If i'm wrong, write more. And I want to know your MATLAB code. Regards.
In code composer studio you can use graphs by referring x y axis variables in your code. 1) Set sampling rate of ADC 2) Take samples and copy them into array. 3) calculate fft 4) Use Graph wizards in Code Composer Studio to display. You can use TI's code support library all three steps. For more information refer help of CSL. Regards, ALPER US
calculate the RMS (Root Mean Square) it is the same as the standard deviation (1/n*Sum(value-average)^2
I must tell you, MATLAB can be used for several purposes. First of all you should be clear as to what is your target application. viz: Signal processing, Antenna toolkit etc. Now, the first and foremost tutorial for everything that your MATLAB software holds can be easily located at the "HELP" optional in the menu bar of the MATLAB window. You can
Hello! Another issue: If you use fft, then all your frequency bands will have the same width. What you may consider is to use a powerful enough chip, sample to 256 samples chunks and then calculate fft. You will get 128 frequency bands that you can group as you wish. Dora.
I want to calculate SNR for sigma-delta modulator.I know that i will require to calculating fft but I don't know that how I can calculate SNR with fft.:cry: thank you
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 = (...)
Hi all, can someone explain to me how to calculate DNL/INL from fft ??
Hello; I need a program to calculate power and energy of signal EEG by fft please help me thank you
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 want to build a harmonic current meter for power supply testing,I use AD converter to sample AC input current ,but how can i calculate harmonic current ? what is the formulate? how to use fft?
Would greately appreciate some advice. If I have say 256 sample of a digitized waveform. Is it possible to calculate the frequency from these sample ? Any info wouls be much appreciated. Thanks.
hello!! Somebody can tell me !! How to calculate SNDR of ADC?? How to find Matlab program that to analysis dynmic parameter of A/D Converter ?? thanks !!!
Yeath , you are right. In the mean while , i know the step frequency (approximating delta frequency=2/(Tstop)) , by it , we can calculate the point number for frequency range estimated by fft . But the frequency step effects the time of estimation and the accauracy. How does we select the step as resonable as possible . Is there e
Hi, Is possible to calculate theorically Swtiching transients from Spectrum due to modulation by taking into account the rising and falling edge of the burst ramp? Is there any theorical calculation of Switching due to transients in GSM? Is there any paper about this subject? thank you for your help. Rafouille
you should got the final value of S/H output at each hold phase. Then perform fft to calculate the SNDR & ENOB.
I need help for my pipelined ADC. I sampled the output and used matlab to get fft. Using the program in this forum, I calculate SNR,THD,etc. But I have problem during this procedure. I sampled the single sin wave, using Matlab code, SNR is just about 100dB. But when I tried to sampled the ouput from ideal DAC(I tested the example in Baker's book(mi
Hi, I have designed a second order sigma delta for sampling frequency of 12.8MHz and OSR=256 in Hspice. I don't know how to calculate the SNDR. I mean how to set these parameters: input frequency,transiation step and N (# of fft points). Thank you in advance, tatakt
Hi, There is no differennce between DFT and fft. Both operations do the same thing, but fft is faster in computation than DFT. Actually, in fft, a divide and conquer approach is used to calculate the DFT. The algo for calculating fft is as follows: For a length N complex sequence , , the discrete (...)
The SNDR can be calculated by the calculator in spectreRF. For the SNR, you need to exclude the distortion products shown in the spectrum. Remember, it is not the distance from signal peak to noise floor -- this distance is usually called SFDR (spurious free dynamic range). Only knowing the noise floor is not sufficient, you also need to know how m
/* This computes an in-place complex-to-complex fft x and y are the real and imaginary arrays of 2^m points. dir = 1 gives forward transform dir = -1 gives reverse transform */ short fft(short int dir,long m,double *x,double *y) { long n,i,i1,j,k,i2,l,l1,l2; double c1,c2,tx,ty,t1,t2,u1,u2,z; /* calculate (...)
Hi neoflash, performing convolution using fft (so-called fast convolution) is faster than direct convolution. If you have two sequencies of length N, the complexity of direct convolution is of the order of N^2. With fast convolution, you have to perform two fft's (direct and inverse), that have complexity of the order of N*log2(N), plus spectr
Hi, all, how to calculate the SNR and SNDR of the bit stream (1-bit stream) of sigma-delta modulator, and the SNR and SNDR of the output data of the all ADC. need your helps. Thanks in advance. regards,
Hi, Currently, im designing 8-point fft. From my view, we must calculate two values within the stages of fft which is block offset and stride. Can anyone explain to me what it means by stride and block offset. Thanx
how to calculate DTFT of an analog signal using matlab?
Hi, What is the technique to calculate the frequency of an input signal which is at Ghz range. for example system1's output is given input as sys2. If I want to know the fre of sys1's output what shud be the circuit to be included? Please help me And also I want to disply this frequency in an LCD display.... help!!!
how i calculate the THD of sample and hold circuits in cadence tool actually the normal procedure as the select the net and take special function of THD and then plot . but this is ok with the continuous wave and any amp. but here the input signal is getting sampled at every clock cycle. so i need to calculate the THD this regards. and
plz help me . refer the following program, ....main aim. i want to generate 2000hz frequncy and plotting time and frequncy spectrum for the same. i have got all the result but frequncy plot result is not correct. % calculate data n1=2000; n2=500; t=0:0.1:50 x = sin(2*pi*n1*t) + sin(2*pi*n2*t); y = fft(x,512); m = y.*conj(y)/512; f
I appreciate your response about the Hilbert Transform! When I select that in the Xilinx CORE generator and build it, it gives me the I and Q parts, as you mentioned, the I part is 16 bits , but the Q part is 35 bits. I'm not sure why. It seems, however, that I am able to adjust the output width of Q somewhat based on w
i am doing the final year project about class D amplfier , use some algorithm to produce PWM , then pass to the power amplifier and low pass filter to generate sound. Since i finish to build the class D amplifier in fypga and also able to see the Power spectral of the generated PWM to measure the THD of the board. The only thing i need to do now
I wondered whether this should be in the DSP section but it involves the Xilinx Core Generator. After looking at the Core Generator fft module datasheet, I see that the fft core is expecting the data in complex format. The data I want to transform is from an ADC and will be held in an array, the sampling will be constant rate. Do I have to
I am trying to calculate the cross-spectral density for a voltage signal using Matlab. I am using the fft function to do the Fourier transform. The fft function is Y=fft(X,n). But I donot know how to pick the points n. My voltage signal Y is 2seconds long. dt is 0.0001s. so sampling frequency is 1/0.0001s=10KHz. I donot know (...)
thanks jiangxb, how can I define the range of the time-domain random number? Need I to calculate the opamp noise and transfer it to effect of digital output?
Hello there, anyone knows how to write a matlab code to calculate the discrete fourier series and its inverse given then verify the code for the following input