mirrors/gnss-sdr
1
0
Fork 0
mirror of https://github.com/gnss-sdr/gnss-sdr synced 2025-11-18 08:05:17 +00:00
Code Issues Releases Wiki Activity

GNSS-SDR Major changes:

Browse Source 
New tracking libraries:
        -  tracking_discriminators: Library with a set of code tracking and carrier tracking discriminators that is used by the tracking algorithms. (fully documented, including math algorithms using doxygen!)
        -  tracking_2rd_DLL_filter: Class that implements 2 order DLL filter for code tracking loop.
        -  tracking_2rd_PLL_filter: Class that implements 2 order PLL filter for carrier tracking loop.
        -  tracking_FLL_PLL_filter:  Class that implements hybrid FLL and PLL filter for tracking carrier loop.
        -  CN_estimators: Library with a set of Carrier to Noise estimators and lock detectors. (fully documented, including math algorithms using doxygen!)

    Tracking:
        - gps_l1_ca_dll_pll_tracking: The existing DLL + PLL tracking module, which is the K.Borre and D.Akos one, is now completely re-factored. Now uses the above described libraries.
        - gps_l1_ca_dll_fll_pll_tracking: This is a brand new tracking module, which implements the FLL assisted PLL described in Kaplan (2nd edition). (also documentedwith references)

    Configuration options:
        - The following tracking parameters are added:
            ;######### TRACKING CONFIG ############
            ; Tracking.implementation=GPS_L1_CA_DLL_PLL_Tracking or GPS_L1_CA_DLL_FLL_PLL_Tracking 
            Tracking.implementation=GPS_L1_CA_DLL_FLL_PLL_Tracking
            ;PLL filter bandwidth in Hz.
            Tracking.pll_bw_hz=50.0;
            ;DLL filter bandwidth in Hz.
            Tracking.dll_bw_hz=2.0;
            ;FLL filter bandwidth in Hz.
            Tracking.fll_bw_hz=50;
            ;filter order: choice between 2 or 3 at this moment, only for FLL assisted PLL
            Tracking.order=2;
            ;Correlator space in chips units
            Tracking.early_late_space_chips=0.5;

Other files have also been modified with minor changes to adapt to new modules or minor bug fixes.


git-svn-id: https://svn.code.sf.net/p/gnss-sdr/code/trunk@80 64b25241-fba3-4117-9849-534c7e92360d
This commit is contained in:
Javier Arribas
2011-11-22 17:21:54 +00:00
parent 004cd776d9
commit 34d1c5110b
31 changed files with 2192 additions and 474 deletions
Download Patch File Download Diff File Expand all files Collapse all files

97
src/algorithms/tracking/libs/tracking_discriminators.cc Normal file
View File

@@ -0,0 +1,97 @@
/*!
* \file tracking_discriminators.cc
* \brief Library with a set of code tracking and carrier tracking discriminators that is used by the tracking algorithms
* \author Javier Arribas, 2011. jarribas(at)cttc.es
*
*
* -------------------------------------------------------------------------
*
* Copyright (C) 2010-2011 (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 <http://www.gnu.org/licenses/>.
*
* -------------------------------------------------------------------------
*/
#include "tracking_discriminators.h"
#include <math.h>
// All the outputs are in RADIANS
/*!
* FLL four quadrant arctan discriminator:
* \f{equation}
* \frac{\phi_2-\phi_1}{t_2-t1}=\frac{ATAN2(cross,dot)}{t_1-t_2},
* \f}
* where \f$cross=I_{PS1}Q_{PS2}-I_{PS2}Q_{PS1}\f$ and \f$dot=I_{PS1}I_{PS2}+Q_{PS1}Q_{PS2}\f$,
* \f$I_{PS1},Q_{PS1}\f$ are the inphase and quadrature prompt correlator outputs respectively at sample time \f$t_1\f$, and
* \f$I_{PS2},Q_{PS2}\f$ are the inphase and quadrature prompt correlator outputs respectively at sample time \f$t_2\f$. The output is in [radians/second].
*/
float fll_four_quadrant_atan(gr_complex prompt_s1, gr_complex prompt_s2,float t1, float t2)
{
float cross,dot;
dot=prompt_s1.imag()*prompt_s2.imag()+prompt_s1.real()*prompt_s2.real();
cross=prompt_s1.imag()*prompt_s2.real()-prompt_s2.imag()*prompt_s1.real();
return atan2(cross,dot)/(t2-t1);
}
/*!
* PLL four quadrant arctan discriminator:
* \f{equation}
* \phi=ATAN2(Q_{PS},I_{PS}),
* \f}
* where \f$I_{PS1},Q_{PS1}\f$ are the inphase and quadrature prompt correlator outputs respectively. The output is in [radians].
*/
float pll_four_quadrant_atan(gr_complex prompt_s1)
{
return atan2(prompt_s1.real(),prompt_s1.imag());
}
/*!
* PLL Costas loop two quadrant arctan discriminator:
* \f{equation}
* \phi=ATAN\left(\frac{Q_{PS}}{I_{PS}}\right),
* \f}
* where \f$I_{PS1},Q_{PS1}\f$ are the inphase and quadrature prompt correlator outputs respectively. The output is in [radians].
*/
float pll_cloop_two_quadrant_atan(gr_complex prompt_s1)
{
if (prompt_s1.imag()!=0.0)
{
return atan(prompt_s1.real()/prompt_s1.imag());
}else{
return 0;
}
}
/*!
* DLL Noncoherent Early minus Late envelope normalized discriminator:
* \f{equation}
* error=\frac{E-L}{E+L},
* \f}
* where \f$E=\sqrt{I_{ES}^2,Q_{ES}^2}\f$ is the Early correlator output absolute value and
* \f$L=\sqrt{I_{LS}^2,Q_{LS}^2}\f$ is the Late correlator output absolute value. The output is in [chips].
*/
float dll_nc_e_minus_l_normalized(gr_complex early_s1, gr_complex late_s1)
{
float P_early, P_late;
P_early=std::abs(early_s1);
P_late=std::abs(late_s1);
return (P_early-P_late)/((P_early+P_late));
}