Surveyors know better than most that accuracy is everything. A few centimeters can mean the difference between a boundary correctly staked and a costly legal dispute, or between an inspection that passes or fails. For decades, GNSS has been the trusted backbone of positioning and surveying, empowering surveyors, engineers, and contractors to deliver results with confidence.
But today, that backbone faces a growing threat. GNSS jamming, spoofing and signal manipulation are no longer theoretical concerns. They are occurring with increasing frequency worldwide, made easier than ever aided by inexpensive equipment and open-source software that is increasingly accessible. Legacy GNSS signals that underpin many professional-grade solutions, such as GPS, are especially vulnerable as they are unencrypted and their structure is widely published, making them easy targets for malicious actors. For professions that rely on precise and reliable positioning, the consequences can be severe.
Though there are several solutions on the market for jamming, spoofing has remained largely an unresolved issue – until now. Trimble has now introduced a first-of-its-kind solution: Trimble RTX-NMA (Navigation Message Authentication). By leveraging the Trimble RTX global correction service, RTX-NMA delivers real-time authentication of GNSS navigation messages, defending against spoofed signals and corrupted ephemeris. Combined with Galileo OSNMA, Trimble customers now have three constellations – GPS, BeiDou, and Galileo – protected from spoofing attacks, representing a milestone in GNSS security.
The Growing Challenge of GNSS Security
Navigation messages transmitted by GNSS satellites are essential. They contain satellite orbital parameters, clock corrections, ionospheric models, almanacs, and even leap-second updates. These parameters are what allow a receiver to compute position, velocity, and timing. But they are also a weak point.
Threats to GNSS navigation messages include:
◾ Jamming: Occurs when a signal is disrupted or denied, making it difficult or impossible for the receiver to interpret the information correctly. It bombards devices with excessive noise or corrupted data, causing them to operate incorrectly.
◾ Spoofing: Attackers broadcast fake signals that mimic real ones designed to mislead receivers, tricking a receiver into delivering inaccurate location data. This can result in incorrect measurements, improper actions, or even complete system breakdowns.
◾ Signal-in-Space Errors: Even authentic satellites occasionally transmit bad data due to malfunctions or ground-segment issues.
◾ Transmission Errors: Interference or poor conditions can corrupt navigation messages, resulting in unreliable positioning.
Introducing Trimble RTX-NMA
Trimble RTX-NMA is designed to counter vulnerabilities within signals head-on. It is the first commercially available solution to authenticate navigation messages on GPS and BeiDou signals, complementing Galileo’s OSNMA. Together, they provide the most comprehensive multi-constellation spoofing defense on the market today.
Trimble RTX-NMA
Trimble RTX-NMA works to detect both fake GNSS signals and faulty ephemeris data through a combination processes, including:
◾ Real-Time Authentication: Provides real-time authentication of broadcast ephemeris data using RTX Reference Stations around the world, ensuring that the navigation messages received by multiple GNSS reference station receivers are genuine and trustworthy.
◾ Faulty Ephemeris Detection: Validates broadcast ephemeris data, identifying and flagging faulty or inaccurate information, thus preventing unreliable data from being included in the correction stream and used at the rover receiver.
◾ Enhanced Security: Using advanced cryptographic techniques like AES encryption and stream authentication, it adds additional layers of security.
◾ Broad Compatibility: Focuses on the legacy GNSS signals across the GPS and BeiDou constellations and is compatible with other navigation message authentication systems, such as Galileo OSNMA, providing a comprehensive approach to GNSS security across multiple constellations.
The result is a multi-layered defense against both spoofing and genuine satellite anomalies, adding resilience to every position computed by Trimble receivers.
Creating a Spoof-Resistant Environment
For surveyors in the field, RTX-NMA provides transparency. Receiver interfaces now display which satellites are authenticated and verified, not authenticated (insufficient data was received or the satellite does not broadcast authentication), and those that failed authentication (the encryption process proved the data false). Signals that are “not authenticated” often result from blockages in urban canyons or under tree cover, while “failed” signals are those truly identified as fake signals meant to provide false information. This distinction reduces false alarms while ensuring genuine spoofed or corrupted signals are excluded. While more testing in spoofing environments is needed, the framework suggests a new level of resilience for critical applications, creating a near “spoof-resistant” environment for signals.
Applications Across Industries
While surveyors stand at the center of GNSS integrity, RTX-NMA has implications far beyond surveying, including precision farming to ensure planting and harvesting stay on track, machine control and grade management in construction environments, prevention of lane-level errors in the automotive space, and critical navigation and timing functionality for aviation and maritime. For each of these industries, RTX-NMA offers peace of mind that GNSS data is not just accurate, but trustworthy.
Benefits of Trimble RTX-NMA
The system delivers three clear benefits for users. First and foremost is increased dependability . By authenticating navigation messages and detecting faulty data, RTX-NMA ensures more dependable positioning solutions. Along with reliability is enhanced security: RTX-NMA protects against malicious spoofing attacks that could compromise safety or operations across the globe. Lastly, RTX-NMA offers improved integrity. Faulty ephemeris detection safeguards the quality of the navigation data used in rover solutions. RTX-NMA is compatible with various Trimble GNSS receivers and modules, making it a versatile solution for a wide range of applications with broader compatibility.
Looking Ahead: The Future of GNSS Security
For centuries, surveyors have been guardians of accuracy, tasked with measuring and defining the world with precision. Today, with GNSS as the backbone of positioning, surveyors must also be guardians of trust. GNSS spoofing and jamming are not going away. If anything, they are becoming more prevalent as global reliance on GNSS increases. The surveying profession, along with industries such as agriculture, construction, and autonomous vehicles, will increasingly depend on authenticated signals – and some in extremely critical manners.
Trimble RTX-NMA makes the life of geospatial professionals easier, giving them trust in their work and the signals they’re utilizing. By detecting spoofed signals, excluding faulty ephemeris, and authenticating navigation data in real time, RTX-NMA provides professionals with a robust shield against faulty actors. Whether guiding tractors in the field, machines on a job site, or survey crews on a boundary line, RTX-NMA ensures that GNSS signals remain not just precise, but reliable and secure.
This is not just a technical feature — it is a revolution in GNSS dependability. For surveyors, it is an assurance that the invisible framework of satellites above can continue to support the visible framework of the built environment below.
Trimble RTX-NMA represents a significant step forward for many industries. By bringing authentication to legacy signals and integrating it with a global correction service, Trimble has raised the bar for GNSS security.
Jason W. Evans, PS, is the portfolio manager, positioning services at Trimble.