Implementation of goertzel algorithm in C I am implementing BFSK frequency hopping communication system on a DSP processor. It was suggested by some of the forum members to use Goertzel algorithm for the demodulation of frequency hopping at specific frequncies. I have tried implementing  the goertzel alorithm in C. the code is follows :

float goertzel(int numSamples,int TARGET_FREQUENCY,int SAMPLING_RATE, float* data)
{
int k,i;
float   floatnumSamples;
float   omega,sine,cosine,coeff,q0,q1,q2,result,real,imag;

floatnumSamples = (float) numSamples;
k = (int) (0.5 + ((floatnumSamples * TARGET_FREQUENCY) / SAMPLING_RATE));
omega = (2.0 * M_PI * k) / floatnumSamples;
sine = sin(omega);
cosine = cos(omega);
coeff = 2.0 * cosine;
q0=0;
q1=0;
q2=0;

for(i=0; i&lt;numSamples; i++)
{
    q0 = coeff * q1 - q2 + data[i];
    q2 = q1;
    q1 = q0;
}
real = (q1 - q2 * cosine);
imag = (q2 * sine);
result = sqrtf(real*real + imag*imag);
return result;
}


When I use the function to calculate the result at specific frequencies for a given dataset, I am not getting the correct results. However, if I use the same dataset and calculate the goertzel result using MATLAB, then I get the results perfectly. I am implemented the algorithm using C, with the help of some online tutorials that I found over the internet. I just want to get the view of you guys if the function is implmenting the goertzel algorithm correctly.

Thanks,
Anshu
It's been a while, but if anyone would like a working fixed-point implementation (no floats/doubles) in C you might take a look at: http://www.ti.com/ww/cn/uprogram/share/ppt/c6000/Chapter17.ppt‎
– Slide 14.

It looks like it will work beautifully and efficiently in even a low-powered micro-controller.
(In which case some of the ‘int’ variables in that TI C code may need to become ‘longs’ to be 32-bit.)