Iridium Next LEO Satellites as an Alternative PNT in GNSS Denied Environments-Part 1

摘要

Doppler shift based positioning has been experimented and developed during the last 50 years until GNSS constellations became fully operational including GPS, GLONASS, Galileo and more recently BeiDou. Different satellite systems such as ARGOS and COSPAS-SARSAT use Doppler shift position determination algorithms for Search and Rescue applications and offer acceptable positioning accuracy compared to more accurate GNSS solutions (see Ashton et alia in Additional Resources). The main advantages to use these constellations for positioning is that they can work in Denied GNSS environments and can provide Positioning and Timing information to the users. According to that, and with the development necessity of new technologies that are able to deliver navigation solutions whatever the environment and RF conditions, systems called PNT: Positioning Navigation and Timing were developed based on GPS and other GNSS signals as well as based on totally independent positioning systems such as communication satellites like: Orbcomm, Globalstar and recently with Iridium Next satellites constellation. To better ensure accuracy, adaptive and robust Kalman filtering approaches were developed and proposed such as in many related problems published in the literature (Benzerrouk et alia, also Winger, Additional Resources).