void autotest_iirfiltsos_impulse_n2()
{
// initialize filter with 2nd-order low-pass butterworth filter
float a[3] = {
1.000000000000000,
-0.942809041582063,
0.333333333333333};
float b[3] = {
0.0976310729378175,
0.1952621458756350,
0.0976310729378175};
iirfiltsos_rrrf f = iirfiltsos_rrrf_create(b,a);
// initialize oracle; expected output (generated with octave)
float test[15] = {
9.76310729378175e-02,
2.87309604180767e-01,
3.35965474513536e-01,
2.20981418970514e-01,
9.63547883225231e-02,
1.71836926400291e-02,
-1.59173219853878e-02,
-2.07348926322729e-02,
-1.42432702548109e-02,
-6.51705310050832e-03,
-1.39657983602602e-03,
8.55642936806248e-04,
1.27223450919543e-03,
9.14259886013424e-04,
4.37894317157432e-04};
unsigned int i;
float v, y;
float tol=1e-4f;
// hit filter with impulse, compare output
for (i=0; i<15; i++) {
v = (i==0) ? 1.0f : 0.0f;
iirfiltsos_rrrf_execute(f, v, &y);
CONTEND_DELTA(test[i], y, tol);
}
iirfiltsos_rrrf_destroy(f);
}
void autotest_iirfiltsos_step_n2()
{
// initialize filter with 2nd-order low-pass butterworth filter
float a[3] = {
1.000000000000000,
-0.942809041582063,
0.333333333333333};
float b[3] = {
0.0976310729378175,
0.1952621458756350,
0.0976310729378175};
iirfiltsos_rrrf f = iirfiltsos_rrrf_create(b,a);
float test[15] = {
0.0976310729378175,
0.3849406771185847,
0.7209061516321208,
0.9418875706026352,
1.0382423589251584,
1.0554260515651877,
1.0395087295798000,
1.0187738369475272,
1.0045305666927162,
0.9980135135922078,
0.9966169337561817,
0.9974725766929878,
0.9987448112021832,
0.9996590710881966,
1.0000969654053542};
unsigned int i;
float y;
float tol=1e-4f;
// hit filter with step, compare output
for (i=0; i<15; i++) {
iirfiltsos_rrrf_execute(f, 1.0f, &y);
CONTEND_DELTA(test[i], y, tol );
}
iirfiltsos_rrrf_destroy(f);
}
// create synchronizer object from external coefficients
// _k : samples per symbol
// _M : number of filters in the bank
// _h : matched filter coefficients
// _h_len : length of matched filter
SYMSYNC() SYMSYNC(_create)(unsigned int _k,
unsigned int _M,
TC * _h,
unsigned int _h_len)
{
// validate input
if (_k < 2) {
fprintf(stderr,"error: symsync_%s_create(), input sample rate must be at least 2\n", EXTENSION_FULL);
exit(1);
} else if (_h_len == 0) {
fprintf(stderr,"error: symsync_%s_create(), filter length must be greater than zero\n", EXTENSION_FULL);
exit(1);
} else if (_M == 0) {
fprintf(stderr,"error: symsync_%s_create(), number of filter banks must be greater than zero\n", EXTENSION_FULL);
exit(1);
}
SYMSYNC() q = (SYMSYNC()) malloc(sizeof(struct SYMSYNC(_s)));
q->k = _k;
q->M = _M;
q->tau = 0.0f;
q->bf = 0.0f;
q->b = 0;
// set output rate (nominally 1, full decimation)
SYMSYNC(_set_output_rate)(q, 1);
// TODO: validate length
q->h_len = (_h_len-1)/q->M;
// compute derivative filter
TC dh[_h_len];
float hdh_max = 0.0f;
unsigned int i;
for (i=0; i<_h_len; i++) {
if (i==0) {
dh[i] = _h[i+1] - _h[_h_len-1];
} else if (i==_h_len-1) {
dh[i] = _h[0] - _h[i-1];
} else {
dh[i] = _h[i+1] - _h[i-1];
}
// find maximum of h*dh
if ( fabsf(_h[i]*dh[i]) > hdh_max || i==0 )
hdh_max = fabsf(_h[i]*dh[i]);
}
// apply scaling factor for normalized response
// TODO: scale to 1.0 for consistency
for (i=0; i<_h_len; i++)
dh[i] *= 0.06f / hdh_max;
q->mf = FIRPFB(_create)(q->M, _h, _h_len);
q->dmf = FIRPFB(_create)(q->M, dh, _h_len);
// reset state and initialize loop filter
q->A[0] = 1.0f; q->B[0] = 0.0f;
q->A[1] = 0.0f; q->B[1] = 0.0f;
q->A[2] = 0.0f; q->B[2] = 0.0f;
q->pll = iirfiltsos_rrrf_create(q->B, q->A);
SYMSYNC(_reset)(q);
SYMSYNC(_set_lf_bw)(q, 0.01f);
// set output rate nominally at 1 sample/symbol (full decimation)
SYMSYNC(_set_output_rate)(q, 1);
// unlock loop control
SYMSYNC(_unlock)(q);
#if DEBUG_SYMSYNC
q->debug_del = windowf_create(DEBUG_BUFFER_LEN);
q->debug_tau = windowf_create(DEBUG_BUFFER_LEN);
q->debug_bsoft = windowf_create(DEBUG_BUFFER_LEN);
q->debug_b = windowf_create(DEBUG_BUFFER_LEN);
q->debug_q_hat = windowf_create(DEBUG_BUFFER_LEN);
#endif
// return main object
return q;
}