This release has several improvements in different dimensions, addition of new features and bug fixes:
Improvements in Accuracy:
- Part of the RTKLIB core library has been integrated into GNSS-SDR. There is now a single PVT block implementation which makes use of RTKLIB to deliver PVT solutions, including Single and PPP navigation modes.
- Fixed CN0 estimation for other correlation times than 1 ms.
- Improved computation of tracking parameters and GNSS observables.
- Other minor bug fixes.
Improvements in Availability:
- Internal Finite State Machines rewritten for improved continuity in delivering position fixes. This fixes a bug that was stalling the receiver after about six hours of continuous operation.
- Redesign of the time counter for enhanced continuity.
- Improved flow graph in multi-system configurations: the receiver does not get stalled anymore if no signal is found from the first system.
- Improved acquisition and tracking sensitivity.
- Added mechanisms for Assisted GNSS, thus shortening the Time-To-First-Fix. Provision of data via XML files or via SUPL v1.0. Documented at https://gnss-sdr.org/docs/sp-blocks/global-parameters/
- Other minor bug fixes.
Improvements in Efficiency:
- Added the possibility of non-blocking acquisition, which works well when using real-time data from an RF front-end.
- Improved flow graph in multi-band configurations: satellites acquired in one band are immediately searched in others.
- Complex local codes have been replaced by real codes, alleviating the computational burden.
- New volk_gnsssdr kernels: volk_gnsssdr_16i_xn_resampler_16i_xn.h, volk_gnsssdr_16ic_16i_rotator_dot_prod_16ic_xn.h, volk_gnsssdr_32f_xn_resampler_32f_xn.h, volk_gnsssdr_32fc_32f_rotator_dot_prod_32fc_xn.h
- Some AVX2 implementations added to the volk_gnsssdr library.
- Improvement in C++ usage: Use of const container calls when result is immediately converted to a const iterator. Using these members removes an implicit conversion from iterator to const_iterator.
- Output printers can be shut down, with some savings in memory and storage requirements.
- A number of code optimizations here and there.
Improvements in Flexibility:
- A number of new parameters have been exposed to the configuration system.
- Possibility to choose Pilot or Data component for tracking of GPS L5 and Galileo E5a signals.
- Enabled extended coherent integration times for signal tracking.
- Configurable coherent and/or non-coherent signal acquisition.
- Some configuration parameters can now be overridden by commandline flags for easier use in scripts.
Improvements in Interoperability:
- Added the GPS L5 receiver chain.
- Added the GLONASS L1 SP receiver chain.
- Added the GLONASS L2 SP receiver chain.
- Improvements in the Galileo E5a and GPS L2C receiver chains.
- Updated list of available GNSS satellites.
- Added five more signal sources: "Fmcomms2_Signal_Source" (requires gr-iio), "Plutosdr_Signal Source" (requires gr-iio), "Spir_GSS6450_File_Signal_Source", "Labsat_Signal_Source" and "Custom_UDP_Signal_Source" (requires libpcap). Documented in https://gnss-sdr.org/docs/sp-blocks/signal-source/
- Improved support for BladeRF, HackRF and RTL-SDR front-ends.
- Added tools for the interaction with front-ends based on the AD9361 chipset.
- Intermediate results are now saved in MAT-file format (.mat), readable from Matlab/Octave and from Python via h5py.
- Added the GPX output format.
- Improvements in the generation of KML files.
- Improvements in the NMEA output. The receiver can produce GPGGA, GPRMC, GPGSA, GPGSV, GAGSA and GAGSV sentences.
- Improvements in the RTCM server stability.
- Improvements in the correctness of generated RINEX files.
- The receiver can read and make use of Galileo almanac XML files published by the European GNSS Service Centre at https://www.gsc-europa.eu/system-status/almanac-data
- Own-defined XML schemas for navigation data published at https://github.com/gnss-sdr/gnss-sdr/tree/next/docs/xml-schemas
- Added program rinex2assist to convert RINEX navigation files into XML files usable for Assisted GNSS. Only available building from source. See https://github.com/gnss-sdr/gnss-sdr/tree/next/src/utils/rinex2assist
Improvements in Maintainability:
- Setup of a Continuous Integration system that checks building and runs QA code in a wide range of GNU/Linux distributions (Arch Linux, CentOS, Debian, Fedora, OpenSUSE, Ubuntu) and releases. See https://gitlab.com/gnss-sdr/gnss-sdr
- Creation of multi-system processing blocks, drastically reducing code duplication and maintainability time.
- Automated code formatting with clang-format. This tool is widely available and easy to integrate into many code editors, and it also can be used from the command line. It cuts time spent on adhering to the project's code formatting style.
- Improvement in C++ usage: C-style casts have been replaced by C++ casts. C-style casts are difficult to search for. C++ casts provide compile time checking ability and express programmers' intent better, so they are safer and clearer.
- Improvement in C++ usage: The override special identifier is now used when overriding a virtual function. This helps the compiler to check for type changes in the base class, making the detection of errors easier.
- Improvement in C++ usage: A number of unused includes have been removed. Order of includes set to: local (in-source) headers, then library headers, then system headers. This helps to detect missing includes.
- Improvement in C++ usage: Enhanced const correctness. Misuses of those variables are detected by the compiler.
- Improved code with clang-tidy and generation of a compile_commands.json file containing the exact compiler calls for all translation units of the project in machine-readable form if clang-tidy is detected.
- Applied some style rules to CMake scripts.
- Minimal versions of dependencies identified and detected.
Improvements in Portability:
- Several CMake scripts improvements, more verbose outputs in case of errors. Building configuration has been documented in https://gnss-sdr.org/docs/tutorials/configuration-options-building-time/
- Improved SDK for cross-compilation in embedded devices. Documented in https://gnss-sdr.org/docs/tutorials/cross-compiling/
- Improved control over minimum required versions for core dependencies.
- The software builds with C++11, C++14 and C++17 standards.
- The software can now be built using GCC >= 4.7.2 or LLVM/Clang >= 3.4.0 compilers on GNU/Linux, and with Clang/AppleClang on MacOS.
- The Ninja build system can be used in replacement of make.
- The volk_gnsssdr library can be built using Python 2.7+ or Python 3.6+.
- The volk_gnsssdr library is now ready for AArch64 NEON instructions.
- Improved detection of required and optional dependencies in many GNU/Linux distributions and processor architectures.
- Improvement in C++ usage: The library has been replaced by the more modern and portable (except for the interaction with RTKLIB).
- Improvement in C++ usage: The <stdio.h> library has been replaced by the more modern and portable for file handling.
- Improvement in C++ usage: C++ libraries preferred over C libraries (e.g., instead of <ctype.h>, instead of <math.h>).
- Fix compatibility with Boost 1.67 (closes Debian bug #911882 https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=911882)
- Fixes required by Debian packaging.
- Fixes required by Macports packaging.
- A downside in portability: BLAS and LAPACK libraries are now required even in ARM devices.
- A downside in portability: the matio library >= 1.5.3 is a new required dependency. If not found, it is downloaded and built automatically at building time, but this requires libtool, automake and hdf5 already installed in the system.
- A downside in portability: the PugiXML library is a new required dependency. If not found, it is downloaded and built automatically at building time.
Improvements in Reliability:
- Introduced 3 new Input Filter implementations for pulsed and narrowband interference mitigation:
Notch_Filter_Lite. Documented in https://gnss-sdr.org/docs/sp-blocks/input-filter/
- Improved flow graph stability.
- Introduction of high-integrity C++ practices into the source code and included in the coding style guide. See https://gnss-sdr.org/coding-style/
- Fixed a number of defects detected by Coverity Scan.
- Improvement of QA code and addition of a number of new tests. Documented at https://gnss-sdr.org/docs/tutorials/testing-software-receiver-2/
- Improvement in C++ usage: rand() function replaced by library.
- Improvement in C++ usage: strlen and strncpy have been replaced by safer C++ counterparts.
- Improvement in C++ usage: Some destructors have been fixed, avoiding segmentation faults when exiting the program.
- Website switched from http to https. Links in the source tree switched when available.
Improvements in Reproducibility:
- Setup of a Continuous Reproducibility system at GitLab for the automatic reproduction of experiments. The concept was introduced in https://ieeexplore.ieee.org/document/8331069/ Example added in the src/utils/reproducibility/ieee-access18/ folder.
- Fixes of Lintian warnings related to build reproducibility.
Improvements in Scalability:
- Improvements in multi-system, multi-band receiver configurations. The receiver now accepts any number of channels and systems in the three available bands.
- All possible combinations of signals and integration times are now accepted by the Observables block.
Improvements in Testability:
- Several Unit Tests added. Documentation of testing concepts and available tests at https://gnss-sdr.org/docs/tutorials/testing-software-receiver/
- New extra unit test AcquisitionPerformanceTest checks the performance of Acquisition blocks.
- New extra unit test TrackingPullInTest checks acquisition to tracking transition.
- New extra unit test HybridObservablesTest checks the generation of observables.
- Improved system testing: position_test accepts a wide list of parameters and can be used with external files.
- Receiver channels can now be fixed to a given satellite.
- Testing integrated in a Continuous Reproducibility system (see above).
- Improved CTest support in volk_gnsssdr.
Improvements in Usability:
- All Observables block implementations have been merged into a single implementation for all kinds of GNSS signals, making it easier to configure.
- All PVT block implementations have been merged into a single implementation for all kinds of GNSS signals, making it easier to configure.
- Misleading parameter name GNSS-SDR.internal_fs_hz has been replaced by GNSS-SDR.internal_fs_sps. The old parameter name is still read. If found, a warning is provided to the user. The old name will be removed in future releases.
- Updated and improved online documentation of processing blocks at https://gnss-sdr.org/docs/sp-blocks/
- Improved documentation of required dependency packages in several GNU/Linux distributions.
- Dump and output files can now be stored anywhere.
- Parameter names with the same role have been harmonized within different block implementations.
- Added a changelog, a code of conduct, a contributing guide and a pull-request template in the source tree.
- Added colors to the commandline user interface.
- Updated manfiles.
- Updated examples of configuration files under the conf/ folder.
See the definitions of concepts and metrics at https://gnss-sdr.org/design-forces/