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

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

Digital Signal Processing :: 02-16-2017 03:41 :: arve9066 :: Replies: **6** :: Views: **458**

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

Digital Signal Processing :: 02-13-2017 14:00 :: KBR27 :: Replies: **1** :: Views: **382**

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 (...)

Digital Signal Processing :: 01-05-2017 20:09 :: nateduong :: Replies: **0** :: Views: **580**

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 (...)

Analog Circuit Design :: 10-27-2016 04:27 :: Pavlanto :: Replies: **0** :: Views: **458**

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

Electromagnetic Design and Simulation :: 07-23-2016 14:04 :: rrumpf :: Replies: **3** :: Views: **538**

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 (...)

PLD, SPLD, GAL, CPLD, FPGA Design :: 04-26-2016 11:10 :: Mansoor1364 :: Replies: **2** :: Views: **417**

Hi,
How did you **calculate** both **fft**s from the above diagram?
Klaus

Digital Signal Processing :: 03-13-2016 13:59 :: KlausST :: Replies: **7** :: Views: **3322**

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

RF, Microwave, Antennas and Optics :: 02-28-2016 12:29 :: Dominik Przyborowski :: Replies: **3** :: Views: **881**

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.

Digital Signal Processing :: 12-20-2015 10:53 :: hamid.abbaszadeh :: Replies: **4** :: Views: **769**

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

Digital Signal Processing :: 07-28-2015 01:53 :: Biruntha :: Replies: **0** :: Views: **526**

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 06:05 :: sona_ :: Replies: **1** :: Views: **829**

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 11:59 :: youngguns21 :: Replies: **0** :: Views: **472**

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 17:30 :: Adnan86 :: Replies: **6** :: Views: **775**

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 :: 01-27-2014 00:27 :: kemiyun :: Replies: **3** :: Views: **849**

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 13:48 :: april1975 :: Replies: **1** :: Views: **1010**

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 14:58 :: maha.eg :: Replies: **0** :: Views: **765**

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 13:20 :: appalanaidu :: Replies: **0** :: Views: **1179**

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 :: 04-16-2013 02:38 :: albert22 :: Replies: **3** :: Views: **1378**

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.

Digital Signal Processing :: 05-04-2013 05:13 :: phongphanp :: Replies: **6** :: Views: **1140**

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 16:48 :: fasto2008 :: Replies: **4** :: Views: **2356**

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 12:20 :: lhlblue :: Replies: **1** :: Views: **497**

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 18:51 :: aminshafie :: Replies: **1** :: Views: **400**

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 15:12 :: nishagajare :: Replies: **0** :: Views: **567**

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 09:06 :: Terminator3 :: Replies: **0** :: Views: **1103**

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 07:41 :: aida.p :: Replies: **0** :: Views: **584**

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 17:39 :: keith1200rs :: Replies: **1** :: Views: **802**

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 11:03 :: karanbanthia :: Replies: **0** :: Views: **1614**

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 10:34 :: volker_muehlhaus :: Replies: **14** :: Views: **955**

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 14:22 :: caledonia :: Replies: **1** :: Views: **1118**

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 06:23 :: jaya krishna :: Replies: **0** :: Views: **580**

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 14:49 :: shivani04 :: Replies: **2** :: Views: **883**

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 :: 05-02-2012 03:49 :: shivani04 :: Replies: **7** :: Views: **910**

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 09:52 :: snehalg :: Replies: **0** :: Views: **712**

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 22:45 :: ark5230 :: Replies: **3** :: Views: **1676**

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 11:01 :: klystron :: Replies: **3** :: Views: **2148**

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 19:23 :: youngguns21 :: Replies: **0** :: Views: **1100**

Digital Signal Processing :: 03-20-2012 21:32 :: klystron :: Replies: **2** :: Views: **616**

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 17:13 :: sab_sab :: Replies: **0** :: Views: **1603**

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 18:15 :: singhji0000 :: Replies: **0** :: Views: **943**

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 07:08 :: ashumtech :: Replies: **3** :: Views: **920**

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

Analog Circuit Design :: 11-27-2011 04:10 :: JoannesPaulus :: Replies: **3** :: Views: **583**

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 :: 10-17-2011 01:41 :: acbalbason :: Replies: **0** :: Views: **899**

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 20:37 :: Syswip :: Replies: **0** :: Views: **706**

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 :: 09-10-2011 03:09 :: yakex :: Replies: **3** :: Views: **705**

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 08:18 :: hajar ghotb :: Replies: **0** :: Views: **2904**

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 13:44 :: bibhukalyan :: Replies: **0** :: Views: **832**

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 Linux and Real-Time Operating Systems (RTOS) :: 05-17-2011 03:05 :: happylbd :: Replies: **2** :: Views: **2283**

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 10:08 :: ReComm :: Replies: **0** :: Views: **683**

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 16:48 :: elias63 :: Replies: **1** :: Views: **2292**

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 15:33 :: Syswip :: Replies: **2** :: Views: **1970**

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