Precision in the Airwaves
We are living in a digital age. People have come to rely on their digital devices and would be lost without them. Once navigating with paper maps, people are now self-reliant on their different GPS applications to get them from point A to Z. Often we take for granted the time and energy that went into producing that product, but we fully put our trust that it will take us where we need to go.
GPS is also an important tool not just for civilians but for warfighters and astronauts who are often going into unfamiliar and dangerous territory with a team. They need to trust their systems to guide them, prepare them and get them home safely. And they need to know that their system can overcome challenges from potential adversaries.
Establishing Trust in Testing
Draper has testing capabilities that help to give end-users that sense of trust. Our tools give us the capability to predict, model and analyze GPS receiver and antenna performance from concept through testing.
Controlled Reception Pattern Antennas (CRPA) are active antennas that are designed to provide increased robustness to positioning systems and to protect against jamming and spoofing. Properly integrated CRPAs and other adaptive antenna systems provide increased robustness to positioning systems and are becoming more widely used across industries.
Designing and testing CPRAs can present many challenges. Designing a test regimen requires a system-of-systems approach to ensure that every element is tested both in isolation and as a whole functioning system. Evaluating the performance of the physical antenna is particularly challenging, because it requires signals from the Global Navigation Satellite System (GNSS), interference and (if required) spoofing signals all to be transmitted over the air.
Draper uses Ansys high frequency structure simulator (HFSS) software to design and simulate high-speed, high-frequency electronic products such as GPS antennas. The HFSS software enables engineers and circuit designers to simulate electromagnetic issues such as losses due to attenuation, coupling, radiation, and reflection. Draper also uses Adaptive Nulling Effects for Scenarios (ANEFS) to model CRPA behavior and predict their performance in varying threat environments. We have a license through the Aerospace corporation to utilize on ANEFS on gov projects.
Simulations are run using the Global Positioning System (GPS) Interference and Navigation Tool (GIANT) tool. The simulations are used to evaluate and understand the GPS system performance and the operational effectiveness of those systems in both benign and combat-challenged environments. A typical GIANT simulation run consists of one or more GPS/INS-equipped platforms moving along a route in an electronic environment that includes zero to many GPS interference sources or jammers.
Draper’s Radio Frequency Chambers and Wavefront Simulator
Over the air testing is then conducted in one of Draper’s radio frequency test chambers. These chambers are used to measure antenna performance, examining the received power at the antenna along different approach vectors. This is used to create an assessment of how well it can receive signals, and in combination with our models or wavefront simulator we can use it to assess how it would perform in different environments.
The wavefront simulator (Spirent TS2508R) is new to our testing capabilities. It can simulate GPS and interference signals across multiple antenna elements enabling null-steering and beam-forming testing. Additionally, it can be used to test integrity monitoring, and navigation warfare capabilities.
L: RF Chamber and R: Wavefront Simulator
Draper staff are working to ensure reliability and awareness when systems with GPS are operating out in the field, so when it gets into the hand of the user, they can trust they will be prepared for what comes their way.