void ofdmoqamframe64sync_reset(ofdmoqamframe64sync _q)
{
// reset pilot sequence generator
msequence_reset(_q->ms_pilot);
// reset auto-correlators
autocorr_cccf_clear(_q->autocorr);
_q->rxx_mag_max = 0.0f;
// reset frequency offset estimation, correction
_q->nu_hat = 0.0f;
nco_crcf_reset(_q->nco_rx);
nco_crcf_reset(_q->nco_pilot);
pll_reset(_q->pll_pilot);
// clear input buffer
windowcf_clear(_q->input_buffer);
// clear analysis filter bank objects
firpfbch_clear(_q->ca0);
firpfbch_clear(_q->ca1);
// reset gain parameters
_q->g = 1.0f; // coarse gain estimate
unsigned int i;
for (i=0; i<_q->num_subcarriers; i++)
_q->G[i] = 1.0f;
for (i=0; i<4; i++)
_q->y_phase[i] = 0.0f;
// reset state
_q->state = OFDMOQAMFRAME64SYNC_STATE_PLCPSHORT;
//_q->state = OFDMOQAMFRAME64SYNC_STATE_PLCPLONG0;
_q->timer = 0;
_q->num_symbols = 0;
_q->num_data_symbols = 0;
_q->num_samples = 0;
_q->sample_phase = 0;
}
firpfbch firpfbch_create(unsigned int _num_channels,
unsigned int _m,
float _beta,
float _dt,
int _nyquist,
int _gradient)
{
firpfbch c = (firpfbch) malloc(sizeof(struct firpfbch_s));
c->num_channels = _num_channels;
c->m = _m;
c->beta = _beta;
c->dt = _dt;
c->nyquist = _nyquist;
// validate inputs
if (_m < 1) {
printf("error: firpfbch_create(), invalid filter delay (must be greater than 0)\n");
exit(1);
}
// create bank of filters
c->dp = (DOTPROD()*) malloc((c->num_channels)*sizeof(DOTPROD()));
c->w = (WINDOW()*) malloc((c->num_channels)*sizeof(WINDOW()));
// design filter
// TODO: use filter prototype object
c->h_len = 2*(c->m)*(c->num_channels);
c->h = (float*) malloc((c->h_len+1)*sizeof(float));
if (c->nyquist == FIRPFBCH_NYQUIST) {
float fc = 0.5f/(float)(c->num_channels); // cutoff frequency
liquid_firdes_kaiser(c->h_len+1, fc, c->beta, 0.0f, c->h);
} else if (c->nyquist == FIRPFBCH_ROOTNYQUIST) {
design_rkaiser_filter(c->num_channels, c->m, c->beta, c->dt, c->h);
} else {
printf("error: firpfbch_create(), unsupported nyquist flag: %d\n", _nyquist);
exit(1);
}
unsigned int i;
if (_gradient) {
float dh[c->h_len];
for (i=0; i<c->h_len; i++) {
if (i==0) {
dh[i] = c->h[i+1] - c->h[c->h_len-1];
} else if (i==c->h_len-1) {
dh[i] = c->h[0] - c->h[i-1];
} else {
dh[i] = c->h[i+1] - c->h[i-1];
}
}
memmove(c->h, dh, (c->h_len)*sizeof(float));
}
// generate bank of sub-samped filters
unsigned int n;
unsigned int h_sub_len = 2*(c->m); // length of each sub-sampled filter
float h_sub[h_sub_len];
for (i=0; i<c->num_channels; i++) {
// sub-sample prototype filter, loading coefficients in reverse order
for (n=0; n<h_sub_len; n++) {
h_sub[h_sub_len-n-1] = c->h[i + n*(c->num_channels)];
}
// create window buffer and dotprod object (coefficients
// loaded in reverse order)
c->dp[i] = DOTPROD(_create)(h_sub,h_sub_len);
c->w[i] = WINDOW(_create)(h_sub_len);
#if DEBUG_FIRPFBCH_PRINT
printf("h_sub[%u] :\n", i);
for (n=0; n<h_sub_len; n++)
printf(" h[%3u] = %8.4f\n", n, h_sub[n]);
#endif
}
#if DEBUG_FIRPFBCH_PRINT
for (i=0; i<c->h_len+1; i++)
printf("h(%4u) = %12.4e;\n", i+1, c->h[i]);
#endif
// allocate memory for buffers
// TODO : use fftw_malloc if HAVE_FFTW3_H
c->x = (float complex*) malloc((c->num_channels)*sizeof(float complex));
c->X = (float complex*) malloc((c->num_channels)*sizeof(float complex));
c->X_prime = (float complex*) malloc((c->num_channels)*sizeof(float complex));
firpfbch_clear(c);
// create fft plan
c->fft = FFT_CREATE_PLAN(c->num_channels, c->X, c->x, FFT_DIR_BACKWARD, FFT_METHOD);
return c;
}
