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Session A4: High Accuracy Positioning and Correction for Mass Market Devices

Precise+®: Supercorrelation® for Precise GNSS Positioning in Deep-Urban Environments
Javier Gonzalo Garcia, Hery Mwenegoha, Ongun Kurt, Henry Eriksson-Martin, Chris Higgins, Jack Latham, Dana Jamal, Simon Gibbs, Mark Crockett, Steve Mole, Jez Ellis-Gray, Manuel del Castillo, Focal Point Positioning
Location: Windsong 1-2
Date/Time: Thursday, Sep. 17, 4:46 p.m.

Achieving reliable, centimetre-level high-precision GNSS positioning in deep-urban canyons and under dense foliage remains one of the most significant challenges in navigation. In these environments, severe multi-path, diffracted signals, and strong Non-Line-of-Sight (NLOS) components critically degrade the performance of state-of-the-art (SOTA) GNSS receivers, often making high-precision carrier phase tracking impossible. In this paper, we introduce Precise+®, a novel technology developed by Focal Point Positioning (FPP) designed to fundamentally enhance positioning accuracy, availability, and reliability under these extreme conditions.
Built upon FPP’s patented Supercorrelation® technology [1] [2], Precise+ breaks traditional tracking paradigms by dynamically compensating for user, clock, and satellite dynamics. This allows for vastly extended coherent accumulation times, which inherently boosts receiver sensitivity while providing exceptional directional selectivity. Consequently, Precise+ successfully mitigates the degradation caused by NLOS components. The core innovation of this technology is its unique ability to generate and utilise robust carrier phase measurements for high-precision positioning in scenarios previously considered impossible for current SOTA receivers, which typically rely on open-sky conditions to effectively leverage reference base stations or high-precision corrections.
Crucially, Precise+ is designed as an inherently hardware-agnostic solution. Rather than requiring specialised silicon, the technology can be integrated into almost any modern GNSS receiver architecture as a software or firmware upgrade at the Digital Signal Processing (DSP) level. This seamless deployment model unlocks unprecedented high-precision capabilities across a vast array of mass-market and industrial applications. From autonomous automotive platforms and Advanced Driver Assistance Systems (ADAS) to size-and-power-constrained consumer devices such as smartphones and wearables, Precise+ provides a highly scalable path to overcome long-standing navigation bottlenecks without the cost or delay of hardware redesigns.
To validate the Precise+ technology, we developed a highly capable, comprehensive Software Defined Receiver (SDR). Evolved from an ESA-funded project [3] [4], this SDR processes raw GNSS Intermediate Frequency (IF) samples and supports multi-constellation, dual-frequency operations, including GPS (L1C/A, L5Q), Galileo (E1C, E5aQ), Beidou (B1C, B2a), and QZSS (L1C/A, L5Q). Furthermore, the architecture can seamlessly integrate accelerometer and gyroscope measurements from an Inertial Measurement Unit (IMU) to support deep-coupled GNSS+INS configurations. Implemented in C++ to maximise the processing performance and to simplify the integration of the Precise+ technology into different platforms, the receiver is built around the tight integration of a Measurement Engine (ME) and a Positioning Engine (PE). The ME leverages supercorrelated coherent integration to generate robust pseudo-ranges (PRs), pseudo-range rates (PRRs), and carrier phase measurements (Accumulated Delta Ranges, or ADRs). Operating in a continuous feedback loop, the PE not only calculates the Position, Velocity, and Time (PVT) solution but also acts as a dynamic guiding reference for the ME. The PE features flexible operational modes, including Standard Precision (SP) and High-Precision (HP+), both of which can be augmented with inertial data (SP_INS, HP+_INS). Critically, the advanced HP+ modes rely heavily on the PE’s ability to consume the highly robust ADRs generated by the Precise+ enabled ME.
We present a rigorous evaluation of the Precise+ technology across both the measurement and positioning domains, utilising extensive synthetic and real-world datasets:
Synthetic Evaluation: Using an RF GNSS signal simulator, a comprehensive suite of synthetic signals was generated to isolate and assess specific variables, including user dynamics, cyclic power variations for sensitivity assessment, and echo modelling to simulate multi-path reflections.
Empirical Evaluation: Real-world data collection was conducted in highly challenging environments, notably the City of London (characterised by severe urban canyon multi-path) and Thetford Forest, UK (characterised by dense canopy and signal diffraction).
We benchmarked multiple Precise+ configurations (varying coherent accumulation intervals, GNSS-only vs. GNSS+INS) against industry-leading SOTA receivers, both with and without inertial assistance, and with and without live external corrections.
The results demonstrate a paradigm shift in performance under strong multi-path conditions. In the measurement domain, Precise+ exhibits a drastic reduction in cycle slips, significantly enhanced tracking sensitivity, and vastly improved measurement reliability through the active rejection of NLOS signals. In the positioning domain, the system delivered accuracy improvements across all statistical percentiles in both deep-urban and under-foliage scenarios when compared directly to similarly configured third-party SOTA receivers.
The presentation will offer a thorough analysis of the synthetic and field test results for the Precise+ technology, along with a detailed look at the receiver architecture used for its implementation. This evidence demonstrates a clear route toward achieving widespread high-precision navigation, across all major device categories, even in challenging environments.
References:
[1] R. Faragher, N. Couronneau, and R. M. Crockett, “A method, apparatus, computer program, chip set, or data structure for correlating a digital signal and a correlation code,” US Patent US9 780 829B1, Oct 3, 2017.
[2] R. Faragher, N. Couronneau, M. Powe, P. Esteves, M. Crockett, H. Martin, E. Ziglioli, C. Higgins, and D. Buckle, “Supercorrelation: Enhancing the accuracy and sensitivity of consumer GNSS receivers with a DSP upgrade,” in Proceedings of the 31st International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2018), 9 2018, pp. 357–375.
[3] Garcia, J.G.; van der Merwe, J.R.; Esteves, P.; Jamal, D.; Benmendil, S.; Higgins, C.; Grey, R.; Coetzee, E.; Faragher, R. Development of a Custom GNSS Software Receiver Supporting Supercorrelation. Eng. Proc. 2023, 54, 9. https://doi.org/10.3390/ENC2023-15423
[4] Garcia, J.G.; van der Merwe, J.R.; Mwenegoha, H.; Esteves, P.; Benmendil, S.; Coetzee, E.; Ellis, J.; Eriksson-Martin, H.; Grey, R.; Higgins, C.; et al. Enhancing GNSS Robustness in Automotive Applications with Supercorrelation: Experimental Results in Urban Scenarios. Eng. Proc. 2025, 88, 75. https://doi.org/10.3390/engproc2025088075

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