mirror of https://github.com/gnss-sdr/gnss-sdr
262 lines
9.4 KiB
C++
262 lines
9.4 KiB
C++
/*!
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* \file gps_l2_m_pcps_acquisition_fpga.cc
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* \brief Adapts an FPGA-offloaded PCPS acquisition block
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* to an AcquisitionInterface for GPS L2 M signals
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* \authors <ul>
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* <li> Javier Arribas, 2019. jarribas(at)cttc.es
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* </ul>
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*
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* -----------------------------------------------------------------------------
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*
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* GNSS-SDR is a Global Navigation Satellite System software-defined receiver.
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* This file is part of GNSS-SDR.
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*
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* Copyright (C) 2010-2020 (see AUTHORS file for a list of contributors)
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* SPDX-License-Identifier: GPL-3.0-or-later
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*
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* -----------------------------------------------------------------------------
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*/
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#include "gps_l2_m_pcps_acquisition_fpga.h"
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#include "GPS_L2C.h"
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#include "configuration_interface.h"
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#include "gnss_sdr_fft.h"
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#include "gnss_sdr_flags.h"
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#include "gnss_synchro.h"
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#include "gps_l2c_signal_replica.h"
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#include "uio_fpga.h"
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#include <glog/logging.h>
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#include <gnuradio/gr_complex.h> // for gr_complex
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#include <volk/volk.h> // for volk_32fc_conjugate_32fc
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#include <volk_gnsssdr/volk_gnsssdr_alloc.h>
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#include <algorithm> // for copy_n
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#include <cmath> // for abs, pow, floor
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#include <complex> // for complex
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GpsL2MPcpsAcquisitionFpga::GpsL2MPcpsAcquisitionFpga(
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const ConfigurationInterface* configuration,
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const std::string& role,
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unsigned int in_streams,
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unsigned int out_streams) : gnss_synchro_(nullptr),
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role_(role),
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threshold_(0),
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channel_(0),
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doppler_step_(0),
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in_streams_(in_streams),
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out_streams_(out_streams)
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{
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pcpsconf_fpga_t acq_parameters;
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std::string default_dump_filename = "./acquisition.mat";
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LOG(INFO) << "role " << role;
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int64_t fs_in_deprecated = configuration->property("GNSS-SDR.internal_fs_hz", 2048000);
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fs_in_ = configuration->property("GNSS-SDR.internal_fs_sps", fs_in_deprecated);
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acq_parameters.fs_in = fs_in_;
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acq_parameters.repeat_satellite = configuration->property(role + ".repeat_satellite", false);
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DLOG(INFO) << role << " satellite repeat = " << acq_parameters.repeat_satellite;
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doppler_max_ = configuration->property(role + ".doppler_max", 5000);
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if (FLAGS_doppler_max != 0)
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{
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doppler_max_ = FLAGS_doppler_max;
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}
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acq_parameters.doppler_max = doppler_max_;
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auto code_length = static_cast<unsigned int>(std::round(static_cast<double>(fs_in_) / (GPS_L2_M_CODE_RATE_CPS / static_cast<double>(GPS_L2_M_CODE_LENGTH_CHIPS))));
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acq_parameters.code_length = code_length;
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// The FPGA can only use FFT lengths that are a power of two.
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float nbits = ceilf(log2f(static_cast<float>(code_length)));
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unsigned int nsamples_total = pow(2, nbits);
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unsigned int select_queue_Fpga = configuration->property(role + ".select_queue_Fpga", 0);
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acq_parameters.select_queue_Fpga = select_queue_Fpga;
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// UIO device file
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std::string device_io_name;
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// find the uio device file corresponding to the acquisition
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if (find_uio_dev_file_name(device_io_name, acquisition_device_name, 0) < 0)
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{
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std::cout << "Cannot find the FPGA uio device file corresponding to device name " << acquisition_device_name << std::endl;
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throw std::exception();
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}
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acq_parameters.device_name = device_io_name;
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acq_parameters.samples_per_code = nsamples_total;
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acq_parameters.downsampling_factor = configuration->property(role + ".downsampling_factor", 1.0);
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acq_parameters.total_block_exp = configuration->property(role + ".total_block_exp", 14);
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acq_parameters.excludelimit = static_cast<uint32_t>(std::round(static_cast<double>(fs_in_) / GPS_L2_M_CODE_RATE_CPS));
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// compute all the GPS L2C PRN Codes (this is done only once upon the class constructor in order to avoid re-computing the PRN codes every time
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// a channel is assigned)
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auto fft_if = gnss_fft_fwd_make_unique(nsamples_total); // Direct FFT
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// allocate memory to compute all the PRNs and compute all the possible codes
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volk_gnsssdr::vector<std::complex<float>> code(nsamples_total);
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volk_gnsssdr::vector<std::complex<float>> fft_codes_padded(nsamples_total);
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d_all_fft_codes_ = volk_gnsssdr::vector<uint32_t>(nsamples_total * NUM_PRNs); // memory containing all the possible fft codes for PRN 0 to 32
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float max; // temporary maxima search
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int32_t tmp;
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int32_t tmp2;
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int32_t local_code;
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int32_t fft_data;
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for (unsigned int PRN = 1; PRN <= NUM_PRNs; PRN++)
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{
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gps_l2c_m_code_gen_complex_sampled(code, PRN, fs_in_);
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// fill in zero padding
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for (unsigned int s = code_length; s < nsamples_total; s++)
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{
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code[s] = std::complex<float>(0.0, 0.0);
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}
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std::copy_n(code.data(), nsamples_total, fft_if->get_inbuf()); // copy to FFT buffer
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fft_if->execute(); // Run the FFT of local code
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volk_32fc_conjugate_32fc(fft_codes_padded.data(), fft_if->get_outbuf(), nsamples_total); // conjugate values
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max = 0; // initialize maximum value
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for (unsigned int i = 0; i < nsamples_total; i++) // search for maxima
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{
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if (std::abs(fft_codes_padded[i].real()) > max)
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{
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max = std::abs(fft_codes_padded[i].real());
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}
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if (std::abs(fft_codes_padded[i].imag()) > max)
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{
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max = std::abs(fft_codes_padded[i].imag());
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}
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}
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// map the FFT to the dynamic range of the fixed point values an copy to buffer containing all FFTs
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// and package codes in a format that is ready to be written to the FPGA
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for (uint32_t i = 0; i < nsamples_total; i++)
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{
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tmp = static_cast<int32_t>(floor(fft_codes_padded[i].real() * (pow(2, QUANT_BITS_LOCAL_CODE - 1) - 1) / max));
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tmp2 = static_cast<int32_t>(floor(fft_codes_padded[i].imag() * (pow(2, QUANT_BITS_LOCAL_CODE - 1) - 1) / max));
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local_code = (tmp & SELECT_LSBits) | ((tmp2 * SHL_CODE_BITS) & SELECT_MSBbits); // put together the real part and the imaginary part
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fft_data = local_code & SELECT_ALL_CODE_BITS;
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d_all_fft_codes_[i + (nsamples_total * (PRN - 1))] = fft_data;
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// d_all_fft_codes_[i + nsamples_total * (PRN - 1)] = lv_16sc_t(static_cast<int32_t>(floor(fft_codes_padded[i].real() * (pow(2, QUANT_BITS_LOCAL_CODE - 1) - 1) / max)),
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// static_cast<int32_t>(floor(fft_codes_padded[i].imag() * (pow(2, QUANT_BITS_LOCAL_CODE - 1) - 1) / max)));
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}
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}
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acq_parameters.all_fft_codes = d_all_fft_codes_.data();
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acquisition_fpga_ = pcps_make_acquisition_fpga(acq_parameters);
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channel_ = 0;
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doppler_step_ = 0;
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gnss_synchro_ = nullptr;
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threshold_ = 0.0;
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if (in_streams_ > 1)
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{
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LOG(ERROR) << "This implementation only supports one input stream";
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}
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if (out_streams_ > 0)
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{
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LOG(ERROR) << "This implementation does not provide an output stream";
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}
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}
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void GpsL2MPcpsAcquisitionFpga::stop_acquisition()
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{
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// stop the acquisition and the other FPGA modules.
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acquisition_fpga_->stop_acquisition();
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}
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void GpsL2MPcpsAcquisitionFpga::set_threshold(float threshold)
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{
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threshold_ = threshold;
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DLOG(INFO) << "Channel " << channel_ << " Threshold = " << threshold_;
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acquisition_fpga_->set_threshold(threshold_);
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}
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void GpsL2MPcpsAcquisitionFpga::set_doppler_max(unsigned int doppler_max)
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{
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doppler_max_ = doppler_max;
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acquisition_fpga_->set_doppler_max(doppler_max_);
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}
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// Be aware that Doppler step should be set to 2/(3T) Hz, where T is the coherent integration time (GPS L2 period is 0.02s)
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// Doppler bin minimum size= 33 Hz
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void GpsL2MPcpsAcquisitionFpga::set_doppler_step(unsigned int doppler_step)
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{
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doppler_step_ = doppler_step;
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acquisition_fpga_->set_doppler_step(doppler_step_);
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}
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void GpsL2MPcpsAcquisitionFpga::set_gnss_synchro(Gnss_Synchro* gnss_synchro)
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{
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gnss_synchro_ = gnss_synchro;
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acquisition_fpga_->set_gnss_synchro(gnss_synchro_);
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}
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signed int GpsL2MPcpsAcquisitionFpga::mag()
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{
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return acquisition_fpga_->mag();
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}
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void GpsL2MPcpsAcquisitionFpga::init()
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{
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acquisition_fpga_->init();
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}
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void GpsL2MPcpsAcquisitionFpga::set_local_code()
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{
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acquisition_fpga_->set_local_code();
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}
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void GpsL2MPcpsAcquisitionFpga::reset()
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{
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acquisition_fpga_->set_active(true);
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}
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void GpsL2MPcpsAcquisitionFpga::set_state(int state)
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{
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acquisition_fpga_->set_state(state);
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}
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void GpsL2MPcpsAcquisitionFpga::connect(gr::top_block_sptr top_block)
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{
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if (top_block)
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{ /* top_block is not null */
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};
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// Nothing to connect
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}
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void GpsL2MPcpsAcquisitionFpga::disconnect(gr::top_block_sptr top_block)
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{
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if (top_block)
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{ /* top_block is not null */
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};
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// Nothing to diconnect
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}
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gr::basic_block_sptr GpsL2MPcpsAcquisitionFpga::get_left_block()
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{
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return nullptr;
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}
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gr::basic_block_sptr GpsL2MPcpsAcquisitionFpga::get_right_block()
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{
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return nullptr;
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}
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