void updateFFT() {
//kiss_fft_scalar pt;
int timespend = 0;
int timestamp = millis();
for(int i=0; i < FFT_SIZE; i++) {
fft_in[i] = (windowfunction(i)*(((float)analogRead(MICROPHONE))-2048)/16.f); // decrease the signal input number so that u can process it with fft
/*float anIN = ((float)analogRead(MICROPHONE))/32.f;
fft_in[i] = windowfunction(i)*anIN;
Serial.print(anIN);
Serial.print(" \t");
Serial.print(windowfunction(i));
Serial.print(" \t");
Serial.println(fft_in[i]);
//testing with artificial sinus signal */
//fft_in[i] = sin(2*3.14*5/FFT_SIZE*i)+sin(2*3.14*0.45*i);
delayMicroseconds(SAMPLEDELAY); // Define the sample rate: 280us are about 3500Hz samplerate,
// frequency analysis works up to the half of this frequency
}
timespend = millis() - timestamp;
frequency = FFT_SIZE*1000/timespend;
Serial.print(FFT_SIZE);
Serial.print("analog reads at ");
Serial.print(frequency);
Serial.print(" Hz needed");
Serial.print(timespend);
Serial.println(" ms");
kiss_fftr(fft_cfg, fft_in, fft_out);
}
int main(int argc, char *argv[])
{
/* Important definitions */
// Lengths
size_t N = 0; // Length of time series
size_t M = 0; // Length of sampling vector (number of frequencies)
// Filenames
char inname[100];
char outname[100];
// Sampling
double low, high, rate;
// Frequency of window function
double winfreq = 0;
// Options
int quiet = 0;
int unit = 1;
int prep = 1;
int autosamp = 0;
int fast = 0;
int useweight = 0;
int windowmode = 0;
int Nclean = 0;
int filter = 0;
/* Process command line arguments and return line count of the input file */
N = cmdarg(argc, argv, inname, outname, &quiet, &unit, &prep, &low, &high,\
&rate, &autosamp, &fast, &useweight, &windowmode, &winfreq,\
&Nclean, &filter, NULL, NULL);
// Pretty print
if ( quiet == 0 || fast == 1 ){
if ( windowmode == 0 && useweight != 0 )
printf("\nCalculating the weighted power spectrum of \"%s\" ...\n",\
inname);
else if ( windowmode == 0 )
printf("\nCalculating the power spectrum of \"%s\" ...\n", inname);
else
printf("\nCalculating the window function of \"%s\" ...\n", inname);
}
/* Read data (and weights) from the input file */
if ( quiet == 0 ) printf(" - Reading input\n");
double* time = malloc(N * sizeof(double));
double* flux = malloc(N * sizeof(double));
double* weight = malloc(N * sizeof(double));
readcols(inname, time, flux, weight, N, useweight, unit, quiet);
// Do if fast-mode and window-mode is not activated
if ( fast == 0 && windowmode == 0 ) {
// Calculate Nyquist frequency
double* dt = malloc(N-1 * sizeof(double));
double nyquist;
arr_diff(time, dt, N);
nyquist = 1.0 / (2.0 * arr_median(dt, N-1)) * 1e6; // microHz !
free(dt);
// Calculate suggested sampling (4 times oversampling)
double minsamp;
minsamp = 1.0e6 / (4 * (time[N-1] - time[0])); // microHz !
// Display info?
if ( quiet == 0 ){
printf(" -- INFO: Length of time series = %li\n", N);
printf(" -- INFO: Nyquist frequency = %.2lf microHz\n", nyquist);
printf(" -- INFO: Suggested minimum sampling = %.3lf microHz\n",\
minsamp);
}
// Apply automatic sampling?
if ( autosamp != 0 ) {
low = 5.0;
high = nyquist;
rate = minsamp;
}
}
/* Prepare for power spectrum */
// Calculate proper frequency range for window-function-mode
double limit = 0;
if ( windowmode != 0 ) {
limit = low;
low = winfreq - limit;
high = winfreq + limit;
}
// Get length of sampling vector
M = arr_util_getstep(low, high, rate);
// Fill sampling vector with cyclic frequencies
double* freq = malloc(M * sizeof(double));
arr_init_linspace(freq, low, rate, M);
// Initialise arrays for data storage
double* power = malloc(M * sizeof(double));
double* alpha = malloc(M * sizeof(double));
double* beta = malloc(M * sizeof(double));
/* Calculate power spectrum OR window function */
if ( windowmode == 0 ) {
// Subtract the mean to avoid "zero-frequency" problems
if ( prep != 0 ) {
if ( quiet == 0 ){
printf(" - Subtracting the mean from time series\n");
}
arr_sca_add(flux, -arr_mean(flux, N), N);
}
else {
if ( quiet == 0 )
printf(" - Time series used *without* mean subtraction!\n");
}
// Display info
if ( quiet == 0 ){
printf(" - Calculating fourier transform\n");
if ( autosamp != 0 ) {
printf(" -- NB: Using automatic sampling!\n");
printf(" -- INFO: Auto-sampling (in microHz): %.2lf to %.2lf"\
" in steps of %.4lf\n", low, high, rate);
}
else {
printf(" -- INFO: Sampling (in microHz): %.2lf to %.2lf in"\
" steps of %.4lf\n", low, high, rate);
}
printf(" -- INFO: Number of sampling frequencies = %li\n", M);
}
// Calculate power spectrum with or without weights
fourier(time, flux, weight, freq, N, M, power, alpha, beta, useweight);
}
else {
if ( quiet == 0 ){
printf(" - Calculating window function\n");
printf(" -- INFO: Window frequency = %.2lf microHz\n", winfreq);
printf(" -- INFO: Sampling in the range +/- %.2lf microHz in" \
" steps of %.4lf microHz\n", limit, rate);
printf(" -- INFO: Number of sampling frequencies = %li\n", M);
}
// Calculate spectral window with or without weights
windowfunction(time, freq, weight, N, M, winfreq, power, useweight);
if ( quiet == 0 )
printf(" - Sum of spectral window = %.4lf\n", arr_sum(power, M));
// Move frequencies to the origin
arr_sca_add(freq, -winfreq, M);
}
/* Write data to file */
if ( quiet == 0 ) printf(" - Saving to file \"%s\"\n", outname);
writecols(outname, freq, power, M);
/* Free data */
free(time);
free(flux);
free(weight);
free(freq);
free(power);
free(alpha);
free(beta);
/* Done! */
if ( quiet == 0 || fast ==1 ) printf("Done!\n\n");
return 0;
}
