frequency-analysis

I have simply pitch detection. Input (microphone) data are passed to fft routine, then I'm looking for a pitch with maximum value It means: Max(pow(data[i].getRe(), 2) + pow(data[i].getIm(), 2)) for 0<= i < SAmplesSize I need it for detection of guitar string's primary frequency. It works well for freq 440 hz (and maybe higher, i didn't check that) downto 250 hz. Below this value detected frequency is twice as high as it should be, ie. for 195 hz detected frequency is about 380 hz. It looks like it detects higher harmonics below 250 hz. For pure 195 hz tone it detects perfectly, but for quitar

I would like to take an array of bytes of roughly size 70-80k and transform them from the time domain to the frequency domain (probably using a DFT). I have been following wiki and gotten this code so far. for (int k = 0; k < windows.length; k++) { double imag = 0.0; double real = 0.0; for (int n = 0; n < data.length; n++) { double val = (data[n]) * Math.exp(-2.0 * Math.PI * n * k / data.length) / 128; imag += Math.cos(val); real += Math.sin(val); } windows[k] = Math.sqrt(imag * imag + real * real); } and as far as I know, that finds the magnitude of each frequency window/bin. I then go

I am pretty new to Matlab and I am trying to write a simple frequency based speech detection algorithm. The end goal is to run the script on a wav file, and have it output start/end times for each speech segment. If use the code: fr = 128; [ audio, fs, nbits ] = wavread(audioPath); spectrogram(audio,fr,120,fr,fs,'yaxis') I get a useful frequency intensity vs. time graph like this: By looking at it, it is very easy to see when speech occurs. I could write an algorithm to automate the detection process by looking at each x-axis frame, figuring out which frequencies are dominant (have the highest

Given a .txt files with space separated words such as: But where is Esope the holly Bastard But where is And the Awk function : cat /pathway/to/your/file.txt | tr ' ' '\n' | sort | uniq -c | awk '{print $2"@"$1}' I get the following output in my console : 1 Bastard 1 Esope 1 holly 1 the 2 But 2 is 2 where How to get into printed into myFile.txt ? I actually have 300.000 lines and near 2 millions words. Better to output the result into a file. EDIT: Used answer (by @Sudo_O): $ awk '{a[$1]++}END{for(k in a)print a[k],k}' RS=" |\n" myfile.txt | sort > myfileout.txt Your pipeline isn't very

I am developing a flash guitar, and the only apparent method to discover the frequency of the mic's data looks to be using FFT. Nevertheless, after something like 30 hours of research I could not discover the best way to do that. Should I use Harmonic Product Spectrum (HPS), Cepstrum or Maximum Likelihood? The tuner will have to show frequencys from 25 to 3000Hz. Also, if someone knows about some open source code ready to find the fundamental frequency, please tell me. I can translate it to ActionScript. Thanks! shams The simplest technique I've had success with is to use FFT and then perform

I am new to FFTs and signal processing, so hopefully this question makes sense and/or isn't stupid. I would like to perform spectrum analysis on a live audio signal. My goal is to find a good tradeoff between responsiveness and frequency resolution, such that I can take a guess at the pitch of the incoming audio in near-realtime. From what I've gathered about the math behind the Fourier transform, there is an inherent balance between sample size and frequency resolution. The bigger the sample, the better resolution. Since I am trying to minimize sample size (to attain the near-realtime