AUTOMOTIVES
Driving precision: Why GNSS testing is now critical for automotive innovation
By Mia Swain, lead product line manager, Spirent M
odern vehicles are no longer just machines for mobility - they’re complex, connected platforms that rely heavily on precise positioning and timing. At the centre of this evolution is Global Navigation Satellite System (GNSS) technology, once used purely as a navigation aid for drivers but now a foundational input for critical vehicle functions. As reliance on GNSS grows, so does the need to rigorously test how these systems behave in the full range of conditions they will encounter in the real world. For automotive developers, the margin for error is shrinking. If vehicle positioning, navigation and timing (PNT) output is degraded or disrupted, the consequences can cascade through advanced driver assistance systems (ADAS), autonomy stacks and safety-critical applications. Robust, comprehensive and repeatable testing is not a nice-to-have - it’s an engineering imperative.
From navigation to critical infrastructure
GNSS underpins many of the most advanced functions in today’s vehicles. It provides the lane-level positioning that ADAS and automated driving systems use for localisation and decision-making. GNSS is a core input to sensor fusion engines, where it combines with inertial measurement units (IMUs), wheel speed sensors, vision and radar to deliver a resilient understanding of the vehicle’s environment and movement.
Its role extends to functional safety systems like eCall, where accurate location data is vital in the event of a crash. It also provides the timing required for synchronisation across in-vehicle networks and for vehicle-to-everything (V2X) communication - making GNSS both a spatial and temporal reference point. In every case, GNSS data is consumed by multiple electronic control units (ECUs) across the vehicle. A position error or loss of signal may not manifest as a GNSS failure - it could present as a system-level fault.
Testing for the real world The challenges GNSS faces on the road are signifi cant. Urban canyons, tunnels, multi-level highways and underground car parks can refl ect or obscure signals. Beyond natural obstructions, vehicles must also contend with interference, jamming and the growing risk of spoofi ng attacks - intentional or otherwise.
Critically, many of these aren’t rare edge cases. For many vehicles - especially in dense urban environments - they’re daily operating conditions. Validating GNSS performance under such conditions requires more than checking whether a receiver outputs a position. It demands full-system testing that refl ects how integrated vehicle systems behave when PNT services degrade or become unusable.
This is where hardware-in-the-loop (HIL) testing becomes invaluable. In a HIL environment, ECUs can be tested in a real- time, closed-loop system where GNSS conditions are simulated and controlled. Engineers can inject specifi c threat scenarios, like multipath, obscuration, or jamming signatures, and observe how the vehicle responds. This allows for safe, repeatable testing of situations that are dangerous or impossible to recreate on the road. It also enables earlier validation in the development cycle, reducing the cost and complexity of additional hardware spins. Even after development, testing doesn’t stop. On the production line, vehicles need
to verify GNSS functionality quickly and deterministically, without relying on live- sky signals. All vehicles must be tested and evaluated against the same conditions with coordinated pass/fail criteria. This means using test systems that can simulate known- good signals in a controlled environment. Typical checks include: • Receiver cold-start and power-up validation
• Position and time accuracy • Constellation tracking status These functional tests must be fast, scalable and repeatable across production stations to keep pace with modern manufacturing demands.
The evolving landscape of GNSS Testing
GNSS is now a critical input across the vehicle lifecycle, from design and integration to fi nal assembly. As systems become more autonomous, connected and safety-critical, the pressure to get GNSS performance right only intensifi es. Spirent has been developing PNT simulation systems for over 40 years, supporting customers across the automotive ecosystem—from chipset developers and Tier 1 suppliers to OEMs and service providers. Its test platforms help engineers simulate real-world GNSS conditions in a controlled, repeatable environment, supporting activities from early-stage development and integration through to production line verifi cation.
FEBRUARY 2026 | ELECTRONICS FOR ENGINEERS 31
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