/*! * \file pcps_acquisition_fpga.h * \brief This class implements a Parallel Code Phase Search Acquisition in the FPGA. * * Note: The CFAR algorithm is not implemented in the FPGA. * Note 2: The bit transition flag is not implemented in the FPGA * * Acquisition strategy (Kay Borre book + CFAR threshold). *
    *
  1. Compute the input signal power estimation *
  2. Doppler serial search loop *
  3. Perform the FFT-based circular convolution (parallel time search) *
  4. Record the maximum peak and the associated synchronization parameters *
  5. Compute the test statistics and compare to the threshold *
  6. Declare positive or negative acquisition using a message queue *
* * Kay Borre book: K.Borre, D.M.Akos, N.Bertelsen, P.Rinder, and S.H.Jensen, * "A Software-Defined GPS and Galileo Receiver. A Single-Frequency * Approach", Birkhauser, 2007. pp 81-84 * * \authors * * ------------------------------------------------------------------------- * * Copyright (C) 2010-2017 (see AUTHORS file for a list of contributors) * * GNSS-SDR is a software defined Global Navigation * Satellite Systems receiver * * This file is part of GNSS-SDR. * * GNSS-SDR is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * GNSS-SDR is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with GNSS-SDR. If not, see . * * ------------------------------------------------------------------------- */ #ifndef GNSS_SDR_PCPS_ACQUISITION_FPGA_H_ #define GNSS_SDR_PCPS_ACQUISITION_FPGA_H_ #include #include "fpga_acquisition.h" #include "gnss_synchro.h" typedef struct { /* pcps acquisition configuration */ unsigned int sampled_ms; unsigned int doppler_max; long freq; long fs_in; int samples_per_ms; int samples_per_code; unsigned int select_queue_Fpga; std::string device_name; lv_16sc_t *all_fft_codes; // memory that contains all the code ffts } pcpsconf_fpga_t; class pcps_acquisition_fpga; typedef boost::shared_ptr pcps_acquisition_fpga_sptr; pcps_acquisition_fpga_sptr pcps_make_acquisition(pcpsconf_fpga_t conf_); /*! * \brief This class implements a Parallel Code Phase Search Acquisition that uses the FPGA. * * Check \ref Navitec2012 "An Open Source Galileo E1 Software Receiver", * Algorithm 1, for a pseudocode description of this implementation. */ class pcps_acquisition_fpga : public gr::block { private: friend pcps_acquisition_fpga_sptr pcps_make_acquisition(pcpsconf_fpga_t conf_); pcps_acquisition_fpga(pcpsconf_fpga_t conf_); void send_negative_acquisition(); void send_positive_acquisition(); pcpsconf_fpga_t acq_parameters; bool d_active; float d_threshold; float d_mag; float d_input_power; float d_test_statistics; int d_state; unsigned int d_channel; unsigned int d_doppler_step; unsigned int d_fft_size; unsigned int d_num_doppler_bins; unsigned long int d_sample_counter; Gnss_Synchro* d_gnss_synchro; std::shared_ptr acquisition_fpga; public: ~pcps_acquisition_fpga(); /*! * \brief Set acquisition/tracking common Gnss_Synchro object pointer * to exchange synchronization data between acquisition and tracking blocks. * \param p_gnss_synchro Satellite information shared by the processing blocks. */ inline void set_gnss_synchro(Gnss_Synchro* p_gnss_synchro) { d_gnss_synchro = p_gnss_synchro; } /*! * \brief Returns the maximum peak of grid search. */ inline unsigned int mag() const { return d_mag; } /*! * \brief Initializes acquisition algorithm. */ void init(); /*! * \brief Sets local code for PCPS acquisition algorithm. * \param code - Pointer to the PRN code. */ void set_local_code(); /*! * \brief If set to 1, ensures that acquisition starts at the * first available sample. * \param state - int=1 forces start of acquisition */ void set_state(int state); /*! * \brief Starts acquisition algorithm, turning from standby mode to * active mode * \param active - bool that activates/deactivates the block. */ void set_active(bool active); /*! * \brief Set acquisition channel unique ID * \param channel - receiver channel. */ inline void set_channel(unsigned int channel) { d_channel = channel; } /*! * \brief Set statistics threshold of PCPS algorithm. * \param threshold - Threshold for signal detection (check \ref Navitec2012, * Algorithm 1, for a definition of this threshold). */ inline void set_threshold(float threshold) { d_threshold = threshold; } /*! * \brief Set maximum Doppler grid search * \param doppler_max - Maximum Doppler shift considered in the grid search [Hz]. */ inline void set_doppler_max(unsigned int doppler_max) { acq_parameters.doppler_max = doppler_max; acquisition_fpga->set_doppler_max(doppler_max); } /*! * \brief Set Doppler steps for the grid search * \param doppler_step - Frequency bin of the search grid [Hz]. */ inline void set_doppler_step(unsigned int doppler_step) { d_doppler_step = doppler_step; acquisition_fpga->set_doppler_step(doppler_step); } /*! * \brief Parallel Code Phase Search Acquisition signal processing. */ int general_work(int noutput_items, gr_vector_int& ninput_items, gr_vector_const_void_star& input_items, gr_vector_void_star& output_items); }; #endif /* GNSS_SDR_PCPS_ACQUISITION_FPGA_H_*/