I have an input signal that is generated using the following statements. Fs = 1.4287e6 (Sampling Frequency) Fbin = 32 (FFT Bin Number) N =...

I have an input signal that is generated using the following statements. Fs = 1.4287e6 (Sampling Frequency) Fbin = 32 (FFT Bin Number) N = 2^17 (FFT points) t = 0:N-1 input = A*Sin(2*pi*(Fbin/N)*t) I send this input through a Delta Sigma modulator. And then decimate it by 100 using a CIC decimation filter. Now the question is 1. I thought that the equation I use to generate the input,...

Hi guys, I have a very basic problem. I am able to calculate FFT of an input vector. But now what i want is, to subdivide the input vector ...

Hi guys, I have a very basic problem. I am able to calculate FFT of an input vector. But now what i want is, to subdivide the input vector into blocks, each having equal number of elements. An FFT needs to be performed on each individual block. The results of these FFTs are then averaged to give the final result. How to accomplish this ? Please pour in.

Hi, I have a doubt. May be, someone on this list can help me out here... In IEEE 802.11a (OFDM system), packet data given at end of...

Hi, I have a doubt. May be, someone on this list can help me out here... In IEEE 802.11a (OFDM system), packet data given at end of the standard document (for verification, i assume) can be generated if IFFT-FFT vectors are NOT normalized. unnormalized IFFT vectors have energy = 1/Nfft (Used in transmitter). unnormalized FFT vectors have energy = Nfft (used in receiver). (Nfft-> FFT leng

Hi, Not long ago a friend of mine who works with digital amplifiers asked me I knew of a special FFT (less demanding computation wise) that...

Hi, Not long ago a friend of mine who works with digital amplifiers asked me I knew of a special FFT (less demanding computation wise) that can analyze a stream containing only ones and zeros. I guess he want's to analyze a sampled PWM signal and as the amplifiers are working in the Ghz "area" of sampling frequency, he needs to process heavy data. Does such a FFT exits? Thomas S. ...

One of the properties of the FT is f(-t) F(-w) Does this mean that if we take the FFT of a signal and compute F(-w) then inverse FFT...

One of the properties of the FT is f(-t) F(-w) Does this mean that if we take the FFT of a signal and compute F(-w) then inverse FFT we have a reverse-time representation? K

Hello I have found this 2 FFT algorithm. The first seem to work good. The second seem to NOT work good but should be more fast than the...

Hello I have found this 2 FFT algorithm. The first seem to work good. The second seem to NOT work good but should be more fast than the first. There is some brave man that could verify if they work good and if really the second is more fast? Thanks '----------------------------------------------------------------------- Public Sub fft() PI = 3.14159265 'Set constants 100...

Hi all.. I would be grateful if more info on the above could be provided with regards the equations to precompute the twiddle factors for...

Hi all.. I would be grateful if more info on the above could be provided with regards the equations to precompute the twiddle factors for each stage/butterfly in the FFT. This is to enable me write a piece of code to generate this ( i have not found much on this on the net). I am aware that for a DIF radix-2 FFT the total number of butterflies is (N/2 LogN). The total number of twiddle fac...

Hi all, I am using dsPIC33F from microchips to do FFT. The code for FFT is downloaded from microchip.com and it's for...

Hi all, I am using dsPIC33F from microchips to do FFT. The code for FFT is downloaded from microchip.com and it's for dsPIC30F(CE018: http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=2620) I have been trying to modify the project to make it compliance with dspIC33F but still have several problems. When building the code the errors said "Link Error: Could not allocate sec...

Dear Sir.. I'm trying to implement a fft program with TI 320f2812. I'm using Ti FFT library. I can't get the correct amplitude of...

Dear Sir.. I'm trying to implement a fft program with TI 320f2812. I'm using Ti FFT library. I can't get the correct amplitude of result. 1. If the input value is small than 100000, the output is "0", Is this right? 2. In my opinion, Question 1 has relation to this question. some sample code use bit shift command( <

Hi folks, Im working on developing a Matlab version of pruned FFT/IFFT algorithm. But although i think that the implementation is correct, the...

Hi folks, Im working on developing a Matlab version of pruned FFT/IFFT algorithm. But although i think that the implementation is correct, the reults are not equal to full FFT. So, in a fast x-correlation problem this mismatch arises out of the maximum (the time delay) is somtimes shifted. I am at pains to search about this accuracy/mismatch but i have not found the point. I need your knowle...

I get different results using Kiss FFT and Octave/Matlab fft. Here's the input/output of my...

I get different results using Kiss FFT and Octave/Matlab fft. Here's the input/output of my code: ========================================================= xtmp[2][4] 0 1 2 3 0 (0.2348,-0.5121) (-0.2745,0.0647)(-0.06092,-0.4704) (-0.04771,0.1112) 1 (-0.14,-0.04515)(-0.5469,0.4785) (-0.3687,-0.2009)(-0.04413,0.1298) Input: Output: 0.234797 -0.512116 -0.1706950.026731 -0.27448...

Hi, here A basic problem of DSP make me confused. When we want to the spectrum character of a signal sequence, we can use the function "fft(...

Hi, here A basic problem of DSP make me confused. When we want to the spectrum character of a signal sequence, we can use the function "fft( )" of Matlab. fft(X,n) returns the n-point DFT. 1) If the length of X is less than n, X is padded with trailing zeros to length n. 2) If the length of X is greater than n, the sequence X is truncated. If we want to do a DFT of a sequence of disc...

All This might have been discussed multiple times. However, I am new comer to the site. My question is given below. I wanted to put plots...

All This might have been discussed multiple times. However, I am new comer to the site. My question is given below. I wanted to put plots but could not find the way to do it. I took a sine curve from 0-1 s( 1Hz)and 'fft'ed it in MATLAB. I get unit magnitude at 1 Hz as expected. Sampling rate 1024. Then I zero padded it till 2 sec. So, total lines = 2048. The fft then showed major p...

First order ODE, it's of the form y'(t)=c1*y(t) + c2 + c3*exp(f(y(t)), y(0)=0, where f(.) may be a nonlinear function, How to use...

First order ODE, it's of the form y'(t)=c1*y(t) + c2 + c3*exp(f(y(t)), y(0)=0, where f(.) may be a nonlinear function, How to use FFT to do it? Thanks a lot!

Hi, I am puzzled at Bit-Reversed FFT algorithm and not very certain if my understanding is correct. For example, for an 8 point Radix-2...

Hi, I am puzzled at Bit-Reversed FFT algorithm and not very certain if my understanding is correct. For example, for an 8 point Radix-2 FFT, the input to the first stage is {0, 4, 2, 6, 1, 5, 3, 7}, a Bit-Reversed form, so the Bit-Reverse addressing mode is very useful. And the output is from 0 to 7, a very nice form too! But what happen to the following two stages? For example, the s...

Hello, Im new to dsp related stuff and fft. My problem is that i have low frequency data that i want to analyze. Assume a time signal like...

Hello, Im new to dsp related stuff and fft. My problem is that i have low frequency data that i want to analyze. Assume a time signal like this which has time length of 1 sec. /----------\ / \ ---/ \--- Normaly my fft gives me results that my fundamental frequencies are below 1 Hz. My question is now how can i get those low frequencies, lets say in the...

Hello!!!!!! I would like to know how can i get more resolution in phase without increase the samples or the number of points in FFT, I've...

Hello!!!!!! I would like to know how can i get more resolution in phase without increase the samples or the number of points in FFT, I've work with fft matlab function and it is very well without so many points but in my fft program i cant get better resolution. Thanks!!!!!!!

Hello, I am implementing a 128 point real Radix-2 fft, data and coefficient widths are 16 bit. I am synthezising it for use in an FPGA....

Hello, I am implementing a 128 point real Radix-2 fft, data and coefficient widths are 16 bit. I am synthezising it for use in an FPGA. However, it is taking a very long time to synthesize. (approx 3 days using Leonardo on a 2 GHz machine with 512 MByte RAM) I am using a 20K1000 Altera FPGA. The ram required by the fft will be internal to the FPGA Will this design take up all the space ...

Hi, I'm working with a Analog Devices 21161 EZKIT board. I'm a beginner on the dsp subject and having problems with fft / inverse fft. I...

Hi, I'm working with a Analog Devices 21161 EZKIT board. I'm a beginner on the dsp subject and having problems with fft / inverse fft. I used the talkthrough - example provided with the visual dsp environment to fill a buffer with the audio signal coming from line-in input. After filling it, it will be repeated infinite. My idea now was to fft this buffer after it has been filled an...

Hi folks. Suppose a data set was 'syncopated' sampled, like x[n] = {x(T_0), x(T_1),x(T_2),...,x(T_(N-1))} where T_n = n(A+B) n...

Hi folks. Suppose a data set was 'syncopated' sampled, like x[n] = {x(T_0), x(T_1),x(T_2),...,x(T_(N-1))} where T_n = n(A+B) n even T_n = n(A+B)+A n odd and A and B are integers. Is there a way to use the FFT to directly compute the spectrum of such a signal? The alternative right now is to interpolate to a regularly sampled grid, and then use the FFT. Rune