Stack Overflow
Stack Overflow

Questions tagged [frequency-analysis]

393 questions
3
votes
1 answer

Pandas: Find end frequency spectrum above a defined threshold

long time reader, first time posting. I am working with x,y data for frequency response plots in Pandas DataFrames. Here is an example of the data and the plots (see full .csv file at end of post): fbc['x'],fbc['y'] (0 [89.25, 89.543, 89.719,…
Brady Volpe
  • 31
  • 4
3
votes
4 answers

convert frequency to keyboard note

I'm trying to write an audio application. I can play a cin wave from a frequency of 20 to 20K to hear sounds. my question is how can i convert frequencies to keyboard notes in order to create a virtual keyboard (or piano) ? is there some kind of…
ufk
  • 30,912
  • 70
  • 235
  • 386
3
votes
3 answers

How to get the fundamental frequency from FFT?

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…
Lucas Speranza
  • 149
  • 1
  • 3
  • 5
3
votes
1 answer

FFT pitch detection for guitar string

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…
cartoon_20
  • 303
  • 1
  • 4
  • 7
3
votes
2 answers

Getting frequency response of my microphone

I'm trying to get a frequency response curve from a microphone that I have connected to my pc, using matlab. I think I'm pretty close of getting the final code, but i think I'm missing something. This is what I have right now: close all, clear…
Eric_W
  • 43
  • 3
3
votes
0 answers

Frequency Detection on iOS

I want to be able to detect a high frequency (60 - 70 kHz) on a iOS application written in Swift. However, I don't know where I should start. I know that on a typical iPhone the sampling rate is about 44 kHz and by the Nyquist Theorem, I can only…
DevbyArlindo
  • 31
  • 2
3
votes
4 answers

How to implement smoothing in frequency domain?

I want to do smoothing to an image in the frequency domain. when i use google to see any articles it gave some Matlab codes which i don't need. i could do FFT to an image but i don't know how to implement any smoothing techniques(ILPF, BLPF, IHPF,…
Keshan
  • 14,251
  • 10
  • 48
  • 72
3
votes
3 answers

R- Count of Specific values and Print in R

I have created data frame "df" Age Sex Income 45 Female 3000 25 Female 5000 34 Male 4500 Now I want to count no of females in sex column and Print it like " No of Females = 2" without using any special package I could see number of male and…
Ani
  • 61
  • 2
  • 9
3
votes
1 answer

Simple and efficient algorithm to detect frequency and phase of a sine signal

I need an algorithm to detect frequency and phase of a pure sine signal. The frequency of the input signal changes between 0 and 100 Hz. The value of the signal gets captured with a frequency of 20kHz (so I get 20.000 values per second) - this is…
jurij
  • 383
  • 3
  • 7
  • 21
3
votes
2 answers

Frequency detection for guitar tuning

I am planning to implement a mobile guitar tuner app. I did an initial research and found out some commonly used methods for pitch detection such as fast Fourier transformation , autocorrelation ,etc. I have also found out that FFT is not a very…
Troller
  • 1,108
  • 8
  • 29
  • 47
3
votes
3 answers

Why Ideal band pass filter not working as expected?

Here is latest version that produce effect close to the desired void DeleteFrequencies(short *audioDataBuffer, const int bufferSize, int lowestFrequency, int highestFrequency, int sampleRate ) { int frequencyInHzPerSample = sampleRate /…
spin_eight
  • 3,925
  • 10
  • 39
  • 61
3
votes
1 answer

wxMaxima + gnuplot = Mathematica-like densitymap with a twist

I would like to plot the frequency-domain response of a filter in a similar manner to how the pole-zero plots are on the Wikipedia's "Chebyshev filter" page: http://en.wikipedia.org/wiki/File:Chebyshev_Type_I_Filter_s-Plane_Response_(8th_Order).svg…
Vlad
  • 75
  • 5
3
votes
2 answers

Randomly selecting a key based on the frequency of a value

I have the following Hashmap: Map > map = new HashMap>(); I want to pick a group of countries at random, with the following condition: Countries with a lower number of cities should have a higher…
MTA
  • 739
  • 2
  • 9
  • 29
3
votes
1 answer

Matlab: How to apply low-pass filter on tf-system for faster evaluation in simulink

I have a mechanical oscillation system defined by a n x n matrix with transfer functions tf( ... ). W = minreal( [ tf( ... ) ... tf(...) ; ... ; tf( ... ) ... tf(...) ]; In the following picture you can see some selected frequency responses. It…
Robert Seifert
  • 25,078
  • 11
  • 68
  • 113
3
votes
2 answers

Frequency resolution issue using FFT in numpy

I use Tektronix oscilloscope to perform some signal acquisition. I get 10.000 measurement points (few signal periods) and I have to do a frequency analysis on that set of data. My signal is 8MHz sine wave. When I use either SciPy or NumPy I get the…
akson128
  • 59
  • 1
  • 5
1 2 3
…
26 27