Orbit Ephemeris Failure Detection in a GNSS Regional Application

IRNSS Orbit Determination and Broadcast Ephemeris Assessment

The Indian Regional Navigation Satellite System (IRNSS) is an emerging satellite based navigation system offering an independent positioning and timing service over India and neighboring regions. Based on satellite laser ranging data collected by selected stations of the International Laser Ranging Service (ILRS) precise orbits have been determined for the first pair of inclined geosynchronous ...

TriG - A GNSS Precise Orbit and Radio Occultation Space Receiver

The GPS radio occultation (RO) technique [1] produces measurements in the ionosphere and neutral atmosphere [2] that contribute to monitoring space weather and climate change; and improving operational weather prediction. The high accuracy of RO soundings, traceable to SI standards, makes them ideal climate benchmark observations. For weather applications, RO observations improve the accuracy o...

GNSS in Practical Determination of Regional Heights

Autonomous broadcast ephemeris improvement for GNSS using inter-satellite ranging measurements

This paper discusses the concept of using inter-satellite ranging (ISR) measurements of the satellites of a Global Navigation Satellite System (GNSS) for autonomous broadcast ephemeris improvement. Firstly the inter-satellite ranging is modeled to obtain the clock and orbit error observables. The orbit error observable is analyzed and its observation equation is provided. Both least-squares est...

The gravity field, orientation, and ephemeris of Mercury from MESSENGER observations after three years in orbit

We have analyzed 3 years of radio tracking data from the MESSENGER spacecraft in orbit around Mercury and determined the gravity field, planetary orientation, and ephemeris of the innermost planet. With improvements in spatial coverage, force modeling, and data weighting, we refined an earlier global gravity field both in quality and resolution, and we present here a spherical harmonic solution...