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Global navigation tester simulates multiple satellite constellations using FPGA-based NI Vector Signal Transceiver

Xilinx Employee
Xilinx Employee
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By Dave Wilson, Academic Marketing Director, National Instruments

 

When National Instruments (NI) announced its first FPGA-based VST (Vector Signal Transceiver) in at NI Week in August, 2012, M3 Systems realized that it could meld its expertise in developing high-performance positioning and navigation equipment with NI hardware to create interesting tools for the GNSS (Global Navigation Satellite System) markets. The first such tool is M3’s StellaNGC multi-constellation GNSS simulator, which is used for testing positioning and navigation equipment by simulating the signals transmitted by the multiple positioning satellite constellations currently in medium earth orbit. Those constellations include multiple satellites in the USA’s GPS (Global Positioning System), Europe’s Galileo, Russia’s GLONASS, and China’s BeiDou/COMPASS global navigation systems. Each constellation uses different communications frequencies, which complicates the design of a multi-constellation GNSS simulation system like the StellaNGC.

 

M3 Systems StellaNGC.jpg

 

 

M3’s StellaNGC makes a GNSS receiver believe that it is traveling along a user-defined trajectory by simulating the RF transmissions that would be received from each satellite in a relevant constellation along this trajectory. The heart of the StellaNGC GNSS simulator is the Constellator, which M3 developed in cooperation with CNES, the French space agency. The constellator simulates the position of each satellite for each selected constellation. M3 used NI’s LabVIEW for easy integration of the Constellator along with other must-have features such as trajectory definition, atmospheric models, and antenna patterns.

 

Two atmospheric layers have a real impact on the quality of GNSS positioning accuracy. The ionosphere, an upper atmospheric region that is ionized by solar radiation, can significantly affect the quality of RF signals received from the satellites, particularly during solar eruptions. The troposphere, the region of the atmosphere where we all live, experienced weather conditions that also significantly affect the accuracy of the received RF signals. M3 implemented realistic atmospheric models to challenge the accuracy of the position calculated by the DUT (device under test). Simulation of the atmospheric models provides realistic use-case conditions and improves the quality of the automated test.

 

Calculating the simulated satellite signals is one thing. Generating them in real time is another. This task could not be done with software alone because software isn’t fast enough. It requires the real-time capabilities of the Xilinx Virtex-6 FPGA embedded in the NI PXIe-5644R 6GHz VST. M3 built a complete test system using off-the-shelf NI hardware including an NI PXIe-8135 2.3 GHz Quad-Core PXI Express Controller and the NI PXIe-5644R VST plugged into an NI PXIe-1082 chassis. Programming was done in NI’s LabVIEW and LabVIEW FPGA.

 

 

Here’s an 11-minute video that more fully describes the M3 StellaNGC GNSS simulator:

 

 

 

 

 

For more information on the 6GHz VST, see “National Instruments’ 6GHz Vector Signal Transceiver gets bandwidth, FPGA upgrades.

 

 

Note: David Bourdier, Yohann Gouttefroy, Mark Dury, Marc Pollina from M3 Systems in France submitted this project to the NI Engineering Impact Awards 2014 competition. It was a finalist in the RF and Communications category.