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first version of amplitude and frequency estimation

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This commit is contained in:
Manuel Pitz 2021-06-16 15:23:55 +00:00
parent afe88fcf45
commit aef08fc289
1 changed files with 18 additions and 2 deletions
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20
lib/hooks/dft.cpp
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@ -1158,7 +1158,8 @@ static HookPlugin<DftHook, n, d, (int) Hook::Flags::NODE_READ | (int) Hook::Flag
*
* This function is based on the following paper:
* https://mgasior.web.cern.ch/pap/biw2004.pdf
*
* https://dspguru.com/dsp/howtos/how-to-interpolate-fft-peak/
* *
* In particular equation 10
*
*/
@ -1189,7 +1190,22 @@ static HookPlugin<DftHook, n, d, (int) Hook::Flags::NODE_READ | (int) Hook::Flag
y_Fmax = startFreqency + maxBinEst * frequencyResolution;
Point ret = {y_Fmax, 0};
//calc amplitude
//double h = (y2 - ( (y1 * x2^2) / x1^2)) / (1 - x2^2 / x1^2 )
//double h = (y2 - ( (y1 * pow(x2, 2)) / pow(x1, 2))) / (1 - pow(x2, 2) / pow(x1, 2));
//double h = ( - y3 + ( (y1 * pow(x3, 2)) / pow(x1, 2))) / (pow(x3, 2) / pow(x1, 2) - 1 );
double a = (x1 * (y2-y3)+x2 * (y3-y1)+x3 * (y1-y2))/((x1-x2) * (x1-x3) * (x3-x2));
double b = (pow(x1,2)*(y2-y3)+pow(x2,2)*(y3-y1)+pow(x3,2) * (y1-y2))/((x1-x2) * (x1-x3) * (x2-x3));
double c = (pow(x1,2) * (x2 * y3 - x3 *y2)+x1 * (pow(x3,2) * y2 - pow(x2,2) * y3)+ x2 * x3 * y1 * (x2-x3))/((x1-x2) * (x1-x3) * (x2-x3));
double h = a * pow(y_Fmax,2) + b * y_Fmax + c;
Point ret = {y_Fmax, h};
return ret;
}