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Replaced fix point NCO by VOLK phase rotator in CPU multicorrelator

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(around 5% faster).
This optimization is enabled at this time only in
Tracking_DLL_PLL_C_Aid. Sample config can be found in
gnss-sdr_Hybrid_byte_sim.conf
This commit is contained in:
Javier Arribas
2015-12-21 11:59:15 +01:00
parent 847716428e
commit 9acc7e7a20
2 changed files with 6 additions and 5 deletions
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4
conf/gnss-sdr_Hybrid_byte_sim.conf
View File

@@ -198,7 +198,7 @@ Acquisition_1C.sampled_ms=1
;#implementation: Acquisition algorithm selection for this channel: [GPS_L1_CA_PCPS_Acquisition] or [Galileo_E1_PCPS_Ambiguous_Acquisition]
Acquisition_1C.implementation=GPS_L1_CA_PCPS_Acquisition
;#threshold: Acquisition threshold
Acquisition_1C.threshold=0.035
Acquisition_1C.threshold=0.045
;#pfa: Acquisition false alarm probability. This option overrides the threshold option. Only use with implementations: [GPS_L1_CA_PCPS_Acquisition] or [Galileo_E1_PCPS_Ambiguous_Acquisition]
;Acquisition_1C.pfa=0.01
;#doppler_max: Maximum expected Doppler shift [Hz]
@@ -233,7 +233,7 @@ Acquisition_1B.doppler_step=125
;######### TRACKING GPS CONFIG ############
;#implementation: Selected tracking algorithm: [GPS_L1_CA_DLL_PLL_Tracking] or [GPS_L1_CA_DLL_FLL_PLL_Tracking] or [GPS_L1_CA_TCP_CONNECTOR_Tracking] or [Galileo_E1_DLL_PLL_VEML_Tracking]
Tracking_1C.implementation=GPS_L1_CA_DLL_PLL_Tracking
Tracking_1C.implementation=GPS_L1_CA_DLL_PLL_C_Aid_Tracking
;#item_type: Type and resolution for each of the signal samples. Use only [gr_complex] in this version.
Tracking_1C.item_type=gr_complex

7
src/algorithms/tracking/libs/cpu_multicorrelator.cc
View File

@@ -125,11 +125,12 @@ bool cpu_multicorrelator::Carrier_wipeoff_multicorrelator_resampler(
float code_phase_step_chips,
int signal_length_samples)
{
//update_local_carrier(signal_length_samples, rem_carrier_phase_in_rad, phase_step_rad); //replaced by VOLK phase rotator
//volk_32fc_x2_multiply_32fc(d_sig_doppler_wiped, d_sig_in, d_nco_in, signal_length_samples); //replaced by VOLK phase rotator
update_local_carrier(signal_length_samples, rem_carrier_phase_in_rad, phase_step_rad);
lv_32fc_t phase_offset_as_complex[1]= lv_cmake(std::cos(rem_carrier_phase_in_rad),-std::sin(rem_carrier_phase_in_rad));
volk_32fc_s32fc_x2_rotator_32fc(d_sig_doppler_wiped, d_sig_in, std::exp(lv_32fc_t(0, -phase_step_rad)),phase_offset_as_complex, signal_length_samples);
update_local_code(signal_length_samples,rem_code_phase_chips, code_phase_step_chips);
volk_32fc_x2_multiply_32fc(d_sig_doppler_wiped, d_sig_in, d_nco_in, signal_length_samples);
for (int current_correlator_tap = 0; current_correlator_tap < d_n_correlators; current_correlator_tap++)
{
volk_32fc_x2_dot_prod_32fc(&d_corr_out[current_correlator_tap], d_sig_doppler_wiped, d_local_codes_resampled[current_correlator_tap], signal_length_samples);