MRTKLIB is a completely modernized, thread-safe, and modularized C11 library for standard and precise GNSS positioning.

It is designed to overcome the architectural limitations of the original legacy RTKLIB, providing a robust foundation for next-generation GNSS applications, including high-scale server processing, containerized environments, and seamless integration of Japanese QZSS augmentation services.

The structural foundation is based on MALIB (MADOCA-PPP Library) feature/1.2.0 developed by JAXA and TOSHIBA. The PPP/PPP-AR positioning engine comes from MADOCALIB, while the centimetre-level PPP-RTK engine is built on CLASLIB — making MRTKLIB the first open-source implementation to support real-time CLAS PPP-RTK positioning via rtkrcv. Kinematic positioning accuracy is further enhanced by selected algorithm improvements from demo5 RTKLIB. Both post-processing (rnx2rtkp) and real-time processing (rtkrcv) are supported, including L6E (SSR orbit/clock/bias) and L6D (CLAS CSSR) correction streams. Beyond the QZSS services, MRTKLIB also supports IGS-products PPP via the correction axis: float PPP from precise IGS/MGEX files (igs) or a real-time IGS-RTS RTCM-SSR stream (igs-rts), and integer PPP-AR from Bias-SINEX OSB phase biases. It additionally decodes Galileo HAS (High Accuracy Service) corrections from the free, global E6-B C/NAV signal for float PPP (gal-has) in both post-processing and real-time.

MRTKLIB is not just another fork; it is a ground-up architectural redesign aimed at modern software engineering standards:

• Thread-Safe Design: Introduced the mrtk_ctx_t context structure to encapsulate states, error handling, and logging on a per-instance basis, replacing legacy global variables in the major processing pipelines and enabling parallel processing (e.g., handling multiple streams in a single server).
• POSIX & C11 Pure: Purged all Win32 API and legacy #ifdef macros. The core library is purely POSIX/C11 compliant, ensuring perfect portability across Linux, macOS (Apple Silicon), and embedded ARM/RISC-V devices.
• Modern Build System (CMake): Replaced scattered Makefiles with a unified, clean CMake build system. It natively supports standard find_package(LAPACK) for hardware-accelerated matrix operations (replacing bundled proprietary Intel MKL binaries).
• Domain-Driven Directory Structure: Flat source files have been beautifully categorized into specific domains (src/core/, src/pos/, src/rtcm/, src/models/, etc.) for high maintainability.

The ultimate goal is to unify the fragmented QZSS augmentation ecosystem into a single, conflict-free library. Current integration status:

With the MADOCALIB integration complete, users can process L6E (orbit/clock/bias corrections) and L6D (ionospheric STEC corrections) streams seamlessly in both post-processing and real-time modes.

MRTKLIB's positioning engines have been progressively modernized across releases (community-fork back-ports, new correction sources, tooling). Per-version detail is in the CHANGELOG and release notes:

Latest — v0.7.0: Galileo HAS (High Accuracy Service) float PPP — the first feature of the v0.7.x "global SSR correction services" series. MRTKLIB now decodes Galileo HAS corrections (satellite orbit, clock, and code bias for GPS + Galileo) broadcast on the free, global E6-B C/NAV signal in the GTRF/ITRF2020 frame, and applies them in float PPP in both post-processing (mrtk post) and real-time (mrtk run) via correction = "gal-has". A new src/has/ decoder collects HAS pages, recovers each message with an RS(255,32,224) erasure decoder, and decodes the MT1 orbit/clock/code-bias blocks into the existing SSR application path; mrtk l6extract gains .has extraction from SBF GALRawCNAV (block 4024) and mosaic-G5 L6E from block 4271. The decoder is cross-validated bit-exact against cssrlib over 428 MT1 messages (the RS stage against ICD Annex C), and a bundled 2.1 MB 15-minute regression dataset gates the has_* ctest pipeline with a byte-identical trim-equivalence proof. Live float-PPP repeatability is RMS E 7.5 / N 7.3 / U 38 cm; the HAS Initial Service carries no phase biases (float only — PPP-AR awaits HAS FOC) and no iono/tropo corrections, and absolute accuracy currently sits ~0.5–0.6 m horizontal vs a cm-grade ITRF reference (investigation open: #215) (PR #214).

Next: investigate the HAS absolute-accuracy offset (#215); BeiDou PPP-B2b as the next v0.7.x global SSR service; tuned SPP P5/P6 (clock-jump + position EKF) on the GSDC smartphone benchmark (#165)

• Real-time CLAS L6D: Dual-channel support uses stream 3 for L6 ch1 and stream 2 (base slot, unused in PPP-RTK) for L6 ch2.
• Real-time L6E: The rtksvr provides a single correction input (inpstr3). Multiple QZSS L6E channels (e.g., QZS-3 and QZS-4) are supported when the receiver multiplexes them into one SBF stream.
• Real-time PPP-AR+iono: Ionospheric STEC correction via L6D is available in CLAS PPP-RTK mode but not in the MADOCA PPP-AR+iono path (post-processing only).

Real-time CLAS PPP-RTK positioning performance can be monitored on a public Grafana dashboard:

CLAS Summary Dashboard

The dashboard shows fix rate, ENU accuracy, satellite visibility, and correction age streamed from an active mrtk run session.

• CMake (>= 3.15)
• C11 compatible compiler (GCC, Clang)
• LAPACK/BLAS (Optional but recommended for fast matrix operations. e.g., liblapack-dev on Ubuntu, Accelerate framework on macOS) — requires the LP64 (32-bit integer) interface; ILP64 providers are not supported (for example, avoid OpenBLAS built with INTERFACE64=1). On CMake ≥ 3.22, MRTKLIB requests a 32-bit integer BLAS/LAPACK interface by setting BLA_SIZEOF_INTEGER=4. This is a CMake selection hint, not a complete ABI verifier for all BLAS/LAPACK package layouts: if FindBLAS/FindLAPACK still resolves an ILP64 provider (e.g. an ILP64 OpenBLAS published as plain libopenblas.so with no 64-suffixed name), make an LP64 BLAS/LAPACK provider visible to CMake explicitly. On older CMake, install an LP64 build of your BLAS/LAPACK provider (the default for most distributions).

MRTKLIB uses standard CMake workflow. Out-of-source builds are strictly recommended.

# Clone the repository
git clone https://github.com/h-shiono/MRTKLIB.git
cd MRTKLIB

# Configure the project
cmake -B build -DCMAKE_BUILD_TYPE=Release

# Build the library and apps
cmake --build build -j

The unified mrtk binary will be located in the build/ directory.

Configuration files (TOML) are stored in the conf/ directory. Test data and regression datasets are available in tests/data/.

# Example: Running post-processing analysis
./build/mrtk post -k conf/malib/rnx2rtkp.toml tests/data/rtklib/rinex/xxxx.obs ...

# Example: Real-time positioning
./build/mrtk run -s -o conf/claslib/rtkrcv.toml

MRTKLIB is developed using an AI-assisted workflow. Algorithm porting, test authoring, and code migration are performed with Claude Code (Anthropic). Architecture, implementation strategy, and final review are directed by the project author; porting strategy design is also supported by Gemini Pro (Google).

All commits, test results, and architectural decisions remain under human authorship and review.

MRTKLIB includes both robust unit tests (utest) and regression tests to ensure core stability when merging complex GNSS algorithms.

cd build
ctest --output-on-failure

The codebase is fully documented using Doxygen. To generate the API reference and call graphs:

cmake --build build --target doc

Documentation will be generated in build/doc/html/index.html.

If you use MRTKLIB in your research or product, please cite it via its archived release on Zenodo. You can cite all versions by using the concept DOI 10.5281/zenodo.20373746; Zenodo also mints a version-specific DOI for each individual release.

@software{mrtklib,
  author    = {Shiono, Hayato},
  title     = {{MRTKLIB: Modernized RTKLIB for Next-Generation GNSS}},
  publisher = {Zenodo},
  doi       = {10.5281/zenodo.20373746},
  url       = {https://doi.org/10.5281/zenodo.20373746}
}

MRTKLIB is distributed under the BSD 2-Clause License.

This project stands on the shoulders of giants:

For detailed licensing information, please refer to LICENSE.

Kinematic (geodetic). The PPC-Dataset (Precise Positioning Challenge 2024), kindly released as open data by:

Taro Suzuki, Chiba Institute of Technology https://github.com/taroz/PPC-Dataset

Smartphone (SPP). The Google Smartphone Decimeter Challenge 2023 (GSDC-2023), released on Kaggle by Google for the ION GNSS+ conference and used here under the Kaggle competition rules:

https://www.kaggle.com/competitions/smartphone-decimeter-2023

See docs/reference/benchmark.md (kinematic) and docs/reference/benchmark-gsdc.md (smartphone) for usage instructions.