-void iceFsk(int * data, const size_t len){
-
- //34359738 == 125khz (2^32 / 125) =
-
- // parameters
- float phase_offset = 0.00f; // carrier phase offset
- float frequency_offset = 0.30f; // carrier frequency offset
- float wn = 0.01f; // pll bandwidth
- float zeta = 0.707f; // pll damping factor
- float K = 1000; // pll loop gain
- size_t n = len; // number of samples
-
- // generate loop filter parameters (active PI design)
- float t1 = K/(wn*wn); // tau_1
- float t2 = 2*zeta/wn; // tau_2
-
- // feed-forward coefficients (numerator)
- float b0 = (4*K/t1)*(1.+t2/2.0f);
- float b1 = (8*K/t1);
- float b2 = (4*K/t1)*(1.-t2/2.0f);
-
- // feed-back coefficients (denominator)
- // a0 = 1.0 is implied
- float a1 = -2.0f;
- float a2 = 1.0f;
-
- // filter buffer
- float v0=0.0f, v1=0.0f, v2=0.0f;
-
- // initialize states
- float phi = phase_offset; // input signal's initial phase
- float phi_hat = 0.0f; // PLL's initial phase
-
- unsigned int i;
- float complex x,y;
- float complex output[n];
-
- for (i=0; i<n; i++) {
- // INPUT SIGNAL
- x = data[i];
- phi += frequency_offset;
-
- // generate complex sinusoid
- y = cosf(phi_hat) + _Complex_I*sinf(phi_hat);
-
- output[i] = y;
-
- // compute error estimate
- float delta_phi = cargf( x * conjf(y) );
-
-
- // print results to standard output
- printf(" %6u %12.8f %12.8f %12.8f %12.8f %12.8f\n",
- i,
- crealf(x), cimagf(x),
- crealf(y), cimagf(y),
- delta_phi);
-
- // push result through loop filter, updating phase estimate
-
- // advance buffer
- v2 = v1; // shift center register to upper register
- v1 = v0; // shift lower register to center register
-
- // compute new lower register
- v0 = delta_phi - v1*a1 - v2*a2;
-
- // compute new output
- phi_hat = v0*b0 + v1*b1 + v2*b2;
-
- }
-
- for (i=0; i<len; ++i){
- data[i] = (int)crealf(output[i]);
- }
-}
-
projects / proxmark3-svn / commitdiff