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The Current Greatest Technical Challenges to GNSS / PNT Simulation

September 28, 2021

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Spirent Federal answers questions on simulation challenges in 2021

Phillip Bonilla, senior systems engineer at Spirent Federal Systems, answers three questions about the current state of PNT testing and simulation.

Phillip Bonilla, Senior Systems Engineer, Spirent Federal


How has your approach to simulation changed over the years and in response to what changes in GNSS/PNT?

Spirent has provided highly accurate simulation solutions since the early phases of GPS availability, starting with defined hardware for each signal type. As the GNSS landscape has grown, Spirent has worked closely with leading developers, adding key flexibility and functionality to adapt and provide a growing product portfolio. By adopting a robustly defined system architecture, and employing signal-agnostic hardware, Spirent simulators can generate any of the available constellations and frequencies, with no more than a few clicks of a mouse.

While broadening the support for the increasing number of constellations has been a focus, so too has the necessity to provide users with high numbers of available channels and auxiliary simulation needs. To complement GNSS simulation, significant effort is being devoted to resilient application testing, providing users with flexible solutions for introducing jamming and spoofing to the test environment. Our agnostic hardware supports signal generation using software defined radio (SDR), including interference sources and user-defined IQ signal data. As customer demands have grown, alternative RF and PNT sensors have been—and continue to be—incorporated, allowing users an expanded and comprehensive test environment.

The new Spirent simulator generates alternative RF navigation signals concurrently with GNSS signals.


What are currently the greatest technical challenges to GNSS/PNT simulation?

Today, nearly all industries rely on GNSS or other PNT sources to some extent. With such varied and widespread use, laboratory testing is critical, and maintaining the highest levels of accuracy, reliability and robustness remains one of the greatest challenges. For modern hardware-in-the-loop configurations, simulation systems must be able to keep latency consistent to enable powerful post-processing of results. With this challenge in mind, we at Spirent design and manufacture our own hardware, ensuring precision and ultra-low latency.

Another significant test challenge posed by modern applications is the growth in vehicle speed and maneuverability. Creating a truly realistic test environment for supersonic and even hypersonic vehicles with high rates of spin and jerk places huge demands on a simulator. Spirent recently has introduced the industry’s first 2 kHz update rate, enabling the most accurate trajectories for the most mobile technologies.

Lastly, positioning engines are becoming more complex. In addition to GNSS and inertial, vision systems and a range of other sensors and signals-of-opportunity are providing developers greater opportunity for precision and robustness. Therefore, a core part of Spirent’s mission statement is delivering test equipment that is designed to be integrated into wider test benches and ensuring that equipment is always orders of magnitude more accurate than any device under test.

In what markets and applications are your simulators used? Are they used only in labs or also in the field?

Spirent simulators are used in all phases of the product life cycle across nearly all applications. Receiver manufacturers use our solutions beginning with initial research and development, throughout product development, and well into production and field testing. Along with the ability to use Spirent’s simulators for live range testing, Spirent’s GSS6450 record and playback system enables users to record the real world in high dynamic detail for repeatable lab testing.

This article first appeared on in the Simulator Innovator Q&A.

About Spirent Federal Systems

Spirent Federal Systems was formed in July 2001 by Spirent Communications as a wholly owned subsidiary and U.S. proxy company. Spirent Federal markets and sells Spirent Communications' products in North America. The company also provides value-added features and ongoing customer support. Spirent Federal Systems is headquartered in Pleasant Grove, UT, with support and sales offices throughout the US. Follow us on LinkedIn and Twitter.

About Spirent

Spirent Communications plc. (LSE: SPT) is the leading global provider of automated test and assurance solutions for networks, cybersecurity, and positioning. The company provides innovative products, services and managed solutions that address the test, assurance and automation challenges of a new generation of technologies, including 5G, SD-WAN, cloud, autonomous vehicles and beyond. From the lab to the real world, Spirent helps companies deliver on their promise to their customers of a new generation of connected devices and technologies. For more information, please visit and follow us on LinkedIn, Twitter and Facebook.

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