GNSS-SDR v0.0.20 released

This release provides bug fixes and new features. Most relevant changes with respect to the former release are listed below:

Improvements in Interoperability:

• Improved error handling in UDP connections.
• Make it possible to receive multiple constellations using a single channel wideband device (HackRF/LimeSDR/USRP). Demonstration: here and here.

• Add the following signal sources for use when GNSS-SDR is operating on SoC FPGA boards (-DENABLE_FPGA=ON):

  • ADRV9361_Z7035_Signal_Source_FPGA: Analog Devices ADRV9361-Z7035 board.
  • FMCOMMS5_Signal_Source_FPGA: FMCOMMS5 analog front-end.
  • MAX2771_EVKIT_Signal_Source_FPGA: MAX2771 evaluation kit analog front-end.
  • DMA_Signal_Source_FPGA: FPGA DMA working in post-processing mode.

  When building GNSS-SDR for the SoC FPGA, the following options can be passed to CMake with possible values of ON or OFF, and their default value is OFF:

  • -DENABLE_AD9361: Checks if the IIO driver is installed and builds the ADRV9361_Z7035_Signal_Source_FPGA and the FMCOMMS5_Signal_Source_FPGA sources.
  • -DENABLE_MAX2771: Checks if the SPIdev driver is installed and builds the MAX2771_EVKIT_Signal_Source_FPGA source.
  • -DENABLE_DMA_PROXY: Checks if the DMA proxy driver is installed for controlling the DMA in the FPGA and enables its usage.
• Add the ION_GSMS_Signal_Source, which is able to process raw data files described with the ION GNSS Software Defined Receiver Metadata Standard. It requires the -DENABLE_ION=ON building configuration option.
• The Monitor and PVT blocks are now able to send data to multiple UDP ports.
• Add experimental decoding of Galileo’s I/NAV ARAIM Integrity Support Message (ISM) as defined in the OS SIS ICD v2.1. Values, if received, are only logged but not used.
• Added new Cshort_To_Gr_Complex Data Type Adapter implementation.
• The Osmosdr_Signal_Source has gained two new optional configuration parameters: iq_balance_mode and dc_offset_mode, both of which are set to Automatic by default.
• Implemented missing GPS almanac decoding.

Improvements in Maintainability:

• Updated GSL implementation to v0.42.0. See the gsl-lite release.
• Code formatting now based on clang-format 19.

Improvements in Portability:

• Fix building against google-glog 0.7.x.
• Find dependencies in the loongarch64 architecture.
• Soft transition from GFlags and Google Logging (glog) to Abseil Logging and Flags libraries. While gflags and glog have dutifully served GNSS-SDR for over a decade, they are now showing signs of aging. The latest version of gflags dates back six years now, although the master branch seems to be maintained. Glog remains well maintained, with its latest version v0.7.1 released in June 2024, but with no active development of new features and stuck at C++14. Abseil, on the other hand, represents a contemporary evolution in software development, supports C++17 and C++20, and has absorbed the functionalities of flags and logging from its predecessors. Furthermore, as Abseil has become a prerequisite for the latest versions of Protocol Buffers, its eventual inclusion in GNSS-SDR’s indirect dependencies is inevitable. Leveraging Abseil allows for eliminating the need for gflags and glog, thereby reducing the number of mandatory dependencies for GNSS-SDR in forthcoming GNU/Linux distributions. For seamless integration, GNSS-SDR requires a quite recent minimum version of Abseil, v20240116. If an older version is detected, the library will not be utilized, and GNSS-SDR will fall back to using gflags and glog, which still can be used and are fully supported. A new CMake configuration option -DENABLE_GLOG_AND_GFLAGS=ON is available to force the usage of glog and gflags instead of Abseil, even if a valid version of that library is present. If the Abseil version installed in your system is too old but you still want to try it, you can also force the downloading and building of a recent version with the new CMake configuration flag -DENABLE_OWN_ABSEIL=ON (requires CMake >= 3.24, otherwise it has no effect). This change has a downside in maintainability, since the source code becomes plagued with preprocessor directives required to maintain compatibility both with gflags and glog, and with Abseil.
• Historically, GNSS-SDR linked against the GnuTLS library for cryptographic functions. If GnuTLS was not found, then the building system looked for and linked against OpenSSL as a fallback. This was due to the OpenSSL 1.x dual license scheme, which was incompatible with GPL v3.0 license, preventing it from being a mandatory dependency for GNSS-SDR in most GNU/Linux distributions. This issue was solved with the release of OpenSSL 3.0.0, which transitioned to the Apache License 2.0, fully compatible with GPL v3.0. Accordingly, the GNSS-SDR building system now looks for OpenSSL in the first place and, if not found, then it looks for GnuTLS as a fallback. The new CMake configuration option -DENABLE_GNUTLS=ON allows linking against GnuTLS instead of OpenSSL.
• Allow linking against Boost 1.87.0.
• Replace the System V queues by boost::interprocess, improving portability.
• Improve detection of Homebrew or Macports in macOS.

Improvements in Reliability:

• Implementation of the Galileo Open Service Navigation Message Authentication (OSNMA), a data authentication function for the Galileo Open Service worldwide users, freely accessible to all. OSNMA provides receivers with the assurance that the received Galileo navigation message is coming from the system itself and has not been modified. OSNMA is enabled by default if the receiver configuration defines Galileo E1 OS channels. More details can be found in Introducing GNSS Navigation Message Authentication.

Improvements in Usability:

• Tidy up the conf/ folder.
• Add install and uninstall targets to the nav_msg_listener utility.

• Potential Breaking Change: The source tree has been refactored to follow a more conventional folder structure. This may disrupt user pipelines that relied on the previous structure and could break development branches that were branched off from next before this change. The key changes are:

  • The tests and utils directories have been moved from the src folder to the root of the source tree.
  • The empty build and data folders have been removed. Users can create a building folder using mkdir build or by having CMake handle it: cmake -S . -B build.
  • All default names for dump or input files starting with ../data/<filename> have been changed to ./<filename>.

As usual, compressed tarballs are available from GitHub and Sourceforge.