Implementation of Goertzel algorithm in C

Question

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 demodulatio

Answer 1

Consider two input sample wave-forms:

1) a sine wave with amplitude A and frequency W

2) a cosine wave with the same amplitude and frequency A and W

Goertzel algorithm should yield the same results for two mentioned input wave-forms but the provided code results in different return values. I think the code should be revised as follows:

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

    float   scalingFactor = numSamples / 2.0;

    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