Opportunistic Navigation with Doppler Measurements from Iridium Next and Orbcomm LEO Satellites

A framework for opportunistic navigation with multi-constellation low Earth orbit (LEO) satellite signals is proposed. A receiver architecture suitable for processing both time division (TDMA) and frequency division multiple access (FMDA) signals from Orbcomm and Iridium NEXT satellites is presented to produce Doppler frequency measurements from multi-constellation LEO satellites. An extended Kalman filter (EKF)-based estimator is formulated to solve for a stationary receiver's position using the resulting Doppler measurements. Experimental results are presented showing receiver positioning with one Orbcomm satellite and four Iridium NEXT satellite with an unprecedented final position error 22.7 m.