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srsLTE
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CRS SCell searcher: Minimal simplification

This commit is contained in:
Xavier Arteaga 2019-09-12 10:33:38 +02:00 committed by Xavier Arteaga
parent 9ee8cc0ad2
commit f8dcb8bf67
1 changed files with 23 additions and 25 deletions
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48
lib/src/phy/channel/hst.c
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@ -48,36 +48,34 @@ void srslte_channel_hst_update_srate(srslte_channel_hst_t* q, uint32_t srate)
void srslte_channel_hst_execute(
srslte_channel_hst_t* q, cf_t* in, cf_t* out, uint32_t len, const srslte_timestamp_t* ts)
{
if (q) {
if (q->srate_hz) {
// Convert period from seconds to samples
uint64_t period_nsamples = (uint64_t)roundf(q->period_s * q->srate_hz);
if (q && q->srate_hz) {
// Convert period from seconds to samples
uint64_t period_nsamples = (uint64_t)roundf(q->period_s * q->srate_hz);
// Convert timestamp to samples
uint64_t ts_nsamples = srslte_timestamp_uint64(ts, q->srate_hz) + (uint64_t)q->init_time_s * q->srate_hz;
// Convert timestamp to samples
uint64_t ts_nsamples = srslte_timestamp_uint64(ts, q->srate_hz) + (uint64_t)q->init_time_s * q->srate_hz;
// Calculate time modulus in period
uint64_t mod_t_nsamples = ts_nsamples - period_nsamples * (ts_nsamples / period_nsamples);
float t = (float)mod_t_nsamples / (float)q->srate_hz;
// Calculate time modulus in period
uint64_t mod_t_nsamples = ts_nsamples - period_nsamples * (ts_nsamples / period_nsamples);
float t = (float)mod_t_nsamples / (float)q->srate_hz;
float costheta = 0;
float costheta = 0;
if (0 <= t && t <= q->period_s / 2.0f) {
float num = q->period_s / 4.0f - t;
float den = sqrtf(powf(q->dmin_m * q->period_s / (q->ds_m * 2), 2.0f) + powf(num, 2.0f));
costheta = num / den;
} else if (q->period_s / 2.0f < t && t < q->period_s) {
float num = -1.5f / 2.0f * q->period_s + t;
float den = sqrtf(powf(q->dmin_m * q->period_s / (q->ds_m * 2), 2.0f) + powf(num, 2.0f));
costheta = num / den;
}
// Calculate doppler shift
q->fs_hz = q->fd_hz * costheta;
// Apply doppler shift, assume the doppler does not vary in a sub-frame
srslte_vec_apply_cfo(in, -q->fs_hz / q->srate_hz, out, len);
if (0 <= t && t <= q->period_s / 2.0f) {
float num = q->period_s / 4.0f - t;
float den = sqrtf(powf(q->dmin_m * q->period_s / (q->ds_m * 2), 2.0f) + powf(num, 2.0f));
costheta = num / den;
} else if (q->period_s / 2.0f < t && t < q->period_s) {
float num = -1.5f / 2.0f * q->period_s + t;
float den = sqrtf(powf(q->dmin_m * q->period_s / (q->ds_m * 2), 2.0f) + powf(num, 2.0f));
costheta = num / den;
}
// Calculate doppler shift
q->fs_hz = q->fd_hz * costheta;
// Apply doppler shift, assume the doppler does not vary in a sub-frame
srslte_vec_apply_cfo(in, -q->fs_hz / q->srate_hz, out, len);
}
}