// create firpfb from external coefficients
// _M : number of filters in the bank
// _h : coefficients [size: _M*_h_len x 1]
// _h_len : filter delay (symbols)
FIRPFB() FIRPFB(_create)(unsigned int _M,
TC * _h,
unsigned int _h_len)
{
// validate input
if (_M == 0) {
fprintf(stderr,"error: firpfb_%s_create(), number of filters must be greater than zero\n",
EXTENSION_FULL);
exit(1);
} else if (_h_len == 0) {
fprintf(stderr,"error: firpfb_%s_create(), filter length must be greater than zero\n",
EXTENSION_FULL);
exit(1);
}
// create main filter object
FIRPFB() q = (FIRPFB()) malloc(sizeof(struct FIRPFB(_s)));
// set user-defined parameters
q->num_filters = _M;
q->h_len = _h_len;
// each filter is realized as a dotprod object
q->dp = (DOTPROD()*) malloc((q->num_filters)*sizeof(DOTPROD()));
// generate bank of sub-samped filters
// length of each sub-sampled filter
unsigned int h_sub_len = _h_len / q->num_filters;
TC h_sub[h_sub_len];
unsigned int i, n;
for (i=0; i<q->num_filters; i++) {
for (n=0; n<h_sub_len; n++) {
// load filter in reverse order
h_sub[h_sub_len-n-1] = _h[i + n*(q->num_filters)];
}
// create dot product object
q->dp[i] = DOTPROD(_create)(h_sub,h_sub_len);
}
// save sub-sampled filter length
q->h_sub_len = h_sub_len;
// create window buffer
q->w = WINDOW(_create)(q->h_sub_len);
// set default scaling
q->scale = 1;
// reset object and return
FIRPFB(_reset)(q);
return q;
}
// create square-root Nyquist filterbank
// _type : filter type (e.g. LIQUID_RNYQUIST_RRC)
// _M : number of filters in the bank
// _k : samples/symbol _k > 1
// _m : filter delay (symbols), _m > 0
// _beta : excess bandwidth factor, 0 < _beta < 1
FIRPFB() FIRPFB(_create_rnyquist)(int _type,
unsigned int _M,
unsigned int _k,
unsigned int _m,
float _beta)
{
// validate input
if (_M == 0) {
fprintf(stderr,"error: firpfb_%s_create_rnyquist(), number of filters must be greater than zero\n", EXTENSION_FULL);
exit(1);
} else if (_k < 2) {
fprintf(stderr,"error: firpfb_%s_create_rnyquist(), filter samples/symbol must be greater than 1\n", EXTENSION_FULL);
exit(1);
} else if (_m == 0) {
fprintf(stderr,"error: firpfb_%s_create_rnyquist(), filter delay must be greater than 0\n", EXTENSION_FULL);
exit(1);
} else if (_beta < 0.0f || _beta > 1.0f) {
fprintf(stderr,"error: firpfb_%s_create_rnyquist(), filter excess bandwidth factor must be in [0,1]\n", EXTENSION_FULL);
exit(1);
}
// generate square-root Nyquist filter
unsigned int H_len = 2*_M*_k*_m + 1;
float Hf[H_len];
liquid_firdes_rnyquist(_type,_M*_k,_m,_beta,0,Hf);
// copy coefficients to type-specific array (e.g. float complex)
unsigned int i;
TC Hc[H_len];
for (i=0; i<H_len; i++)
Hc[i] = Hf[i];
// return filterbank object
return FIRPFB(_create)(_M, Hc, H_len);
}
// create arbitrary resampler
// _rate : resampling rate
// _m : prototype filter semi-length
// _fc : prototype filter cutoff frequency, fc in (0, 0.5)
// _As : prototype filter stop-band attenuation [dB] (e.g. 60)
// _npfb : number of filters in polyphase filterbank
RESAMP() RESAMP(_create)(float _rate,
unsigned int _m,
float _fc,
float _As,
unsigned int _npfb)
{
// validate input
if (_rate <= 0) {
fprintf(stderr,"error: resamp_%s_create(), resampling rate must be greater than zero\n", EXTENSION_FULL);
exit(1);
} else if (_m == 0) {
fprintf(stderr,"error: resamp_%s_create(), filter semi-length must be greater than zero\n", EXTENSION_FULL);
exit(1);
} else if (_fc <= 0.0f || _fc >= 0.5f) {
fprintf(stderr,"error: resamp_%s_create(), filter cutoff must be in (0,0.5)\n", EXTENSION_FULL);
exit(1);
} else if (_As <= 0.0f) {
fprintf(stderr,"error: resamp_%s_create(), filter stop-band suppression must be greater than zero\n", EXTENSION_FULL);
exit(1);
} else if (_npfb == 0) {
fprintf(stderr,"error: resamp_%s_create(), number of filter banks must be greater than zero\n", EXTENSION_FULL);
exit(1);
}
// allocate memory for resampler
RESAMP() q = (RESAMP()) malloc(sizeof(struct RESAMP(_s)));
// set rate using formal method (specifies output stride
// value 'del')
RESAMP(_set_rate)(q, _rate);
// set properties
q->m = _m; // prototype filter semi-length
q->fc = _fc; // prototype filter cutoff frequency
q->As = _As; // prototype filter stop-band attenuation
q->npfb = _npfb; // number of filters in bank
// design filter
unsigned int n = 2*q->m*q->npfb+1;
float hf[n];
TC h[n];
liquid_firdes_kaiser(n,q->fc/((float)(q->npfb)),q->As,0.0f,hf);
// normalize filter coefficients by DC gain
unsigned int i;
float gain=0.0f;
for (i=0; i<n; i++)
gain += hf[i];
gain = (q->npfb)/(gain);
// copy to type-specific array, applying gain
for (i=0; i<n; i++)
h[i] = hf[i]*gain;
q->f = FIRPFB(_create)(q->npfb,h,n-1);
// reset object and return
RESAMP(_reset)(q);
return q;
}
// create firpfb derivative square-root Nyquist filterbank
// _type : filter type (e.g. LIQUID_RNYQUIST_RRC)
// _M : number of filters in the bank
// _k : samples/symbol _k > 1
// _m : filter delay (symbols), _m > 0
// _beta : excess bandwidth factor, 0 < _beta < 1
FIRPFB() FIRPFB(_create_drnyquist)(int _type,
unsigned int _M,
unsigned int _k,
unsigned int _m,
float _beta)
{
// validate input
if (_M == 0) {
fprintf(stderr,"error: firpfb_%s_create_drnyquist(), number of filters must be greater than zero\n", EXTENSION_FULL);
exit(1);
} else if (_k < 2) {
fprintf(stderr,"error: firpfb_%s_create_drnyquist(), filter samples/symbol must be greater than 1\n", EXTENSION_FULL);
exit(1);
} else if (_m == 0) {
fprintf(stderr,"error: firpfb_%s_create_drnyquist(), filter delay must be greater than 0\n", EXTENSION_FULL);
exit(1);
} else if (_beta < 0.0f || _beta > 1.0f) {
fprintf(stderr,"error: firpfb_%s_create_drnyquist(), filter excess bandwidth factor must be in [0,1]\n", EXTENSION_FULL);
exit(1);
}
// generate square-root Nyquist filter
unsigned int H_len = 2*_M*_k*_m + 1;
float Hf[H_len];
liquid_firdes_rnyquist(_type,_M*_k,_m,_beta,0,Hf);
// compute derivative filter
float dHf[H_len];
float HdH_max = 0.0f;
unsigned int i;
for (i=0; i<H_len; i++) {
if (i==0) {
dHf[i] = Hf[i+1] - Hf[H_len-1];
} else if (i==H_len-1) {
dHf[i] = Hf[0] - Hf[i-1];
} else {
dHf[i] = Hf[i+1] - Hf[i-1];
}
// find maximum of h*dh
if ( fabsf(Hf[i]*dHf[i]) > HdH_max )
HdH_max = fabsf(Hf[i]*dHf[i]);
}
// copy coefficients to type-specific array (e.g. float complex)
// and apply scaling factor for normalized response
TC Hc[H_len];
for (i=0; i<H_len; i++)
Hc[i] = dHf[i] * 0.06f / HdH_max;
// return filterbank object
return FIRPFB(_create)(_M, Hc, H_len);
}
// 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;
}
// and apply scaling factor for normalized response
TC Hc[H_len];
for (i=0; i<H_len; i++)
Hc[i] = dHf[i] * 0.06f / HdH_max;
// return filterbank object
return FIRPFB(_create)(_M, Hc, H_len);
}
// re-create filterbank object
// _q : original firpfb object
// _M : number of filters in the bank
// _h : coefficients [size: _M x _h_len]
// _h_len : length of each filter
FIRPFB() FIRPFB(_recreate)(FIRPFB() _q,
unsigned int _M,
TC * _h,
unsigned int _h_len)
{
// check to see if filter length has changed
if (_h_len != _q->h_len || _M != _q->num_filters) {
// filter length has changed: recreate entire filter
FIRPFB(_destroy)(_q);
_q = FIRPFB(_create)(_M,_h,_h_len);
return _q;
}
// re-create each dotprod object
TC h_sub[_q->h_sub_len];
unsigned int i, n;
RESAMP() RESAMP(_create)(float _r,
unsigned int _h_len,
float _fc,
float _As,
unsigned int _npfb)
{
// validate input
if (_r <= 0) {
fprintf(stderr,"error: resamp_%s_create(), resampling rate must be greater than zero\n", EXTENSION_FULL);
exit(1);
} else if (_h_len == 0) {
fprintf(stderr,"error: resamp_%s_create(), filter length must be greater than zero\n", EXTENSION_FULL);
exit(1);
} else if (_npfb == 0) {
fprintf(stderr,"error: resamp_%s_create(), number of filter banks must be greater than zero\n", EXTENSION_FULL);
exit(1);
} else if (_fc <= 0.0f || _fc >= 0.5f) {
fprintf(stderr,"error: resamp_%s_create(), filter cutoff must be in (0,0.5)\n", EXTENSION_FULL);
exit(1);
} else if (_As <= 0.0f) {
fprintf(stderr,"error: resamp_%s_create(), filter stop-band suppression must be greater than zero\n", EXTENSION_FULL);
exit(1);
}
RESAMP() q = (RESAMP()) malloc(sizeof(struct RESAMP(_s)));
q->r = _r;
q->As = _As;
q->fc = _fc;
q->h_len = _h_len;
q->b = 0;
q->del = 1.0f / q->r;
#if RESAMP_USE_FIXED_POINT_PHASE
q->num_bits_npfb = liquid_nextpow2(_npfb);
q->npfb = 1<<q->num_bits_npfb;
q->num_bits_phase = 20;
q->max_phase = 1 << q->num_bits_phase;
q->num_shift_bits = q->num_bits_phase - q->num_bits_npfb;
q->theta = 0;
q->d_theta = (unsigned int)( q->max_phase * q->del );
#else
q->npfb = _npfb;
q->tau = 0.0f;
q->bf = 0.0f;
#endif
// design filter
unsigned int n = 2*_h_len*q->npfb+1;
float hf[n];
TC h[n];
liquid_firdes_kaiser(n,q->fc/((float)(q->npfb)),q->As,0.0f,hf);
// normalize filter coefficients by DC gain
unsigned int i;
float gain=0.0f;
for (i=0; i<n; i++)
gain += hf[i];
gain = (q->npfb)/(gain);
// copy to type-specific array
for (i=0; i<n; i++)
h[i] = hf[i]*gain;
q->f = FIRPFB(_create)(q->npfb,h,n-1);
//for (i=0; i<n; i++)
// PRINTVAL_TC(h[i],%12.8f);
//exit(0);
return q;
}