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LEO opportunities and challenges

Low Earth Orbit (LEO) satellite constellations already provide a variety of benefits, from communications to imaging to disaster detection and mitigation. The next generations of LEO constellations will provide users around the world with specialized positioning, navigation, and timing services, as well as high-speed wireless data links, and open up new opportunities for areas with limited communications technologies.

With these great opportunities come a number of challenges, including:

• Satellite precision orbit determination (POD).
• Satellite attitude and maneuvering at ultra-high dynamics
• Environmental challenges (and differences from any test facility on Earth)
• Development and testing of new signals
• Development and testing of ground control elements

Spirent developed SimORBIT to support LEO satellite testing with a GNSS simulator.

SimORBIT is an advanced orbit propagation tool that allows the computation and modeling of LEO satellite orbits with a very high accuracy (in either ECEF or ECI coordinates). This tool implements a dynamic model specifically designed to meet the stringent requirements of precise orbit determination for LEO satellites. The high accuracy of the software tool is made possible by state-of-the-art models that take into account the main disturbances affecting satellites.

With SimORBIT, the user can:

• create new constellations, either from scratch or by importing a RINEX file
• start a simulation to calculate satellite orbits with high accuracy
• display results that have been previously calculated

Specifications / Features

• Accurate orbital model that can be used as a reference trajectory propagator
• Generation of orbits for individual satellites or constellations (up to 85 satellites)
• Fully consistent with IERS 2010 conventions
• Implemented in ITRF, conversion to GCRF is possible
• Customizable input parameters for satellites (e.g. drag coefficient, mass, cross-sectional area)
• Several numerical integrators available
• Output in standard formats
• Extensible for higher precision