Architectures for Joint GPS/LEO Satellite Carrier Phase Receivers Designed for Rapid Robust Resolution of Carrier Cycle Ambiguities on Mobile Platforms

摘要

The emerging satellite telecommunication industry has seen substantial progress in the design and manufacture of low-cost, low-power transceivers which interface directly with Low Earth Orbit (LEO) Telecom Satellites. Herein, we describe the architecture of a joint GPS-LEO navigation receiver which tracks LEOS in conjunction with GPS in order to rapidly resolve cycle ambiguities on both the GPS and LEO signals. The objective is to achieve centimeter-level navigation performance using pre-existent LEO transceiver hardware, designed for low-cost data communication. The obstacles to be overcome include: synchronization of the LEO and GPS receivers, precise time-tagging of carrier-phase measurements without the use of hardware accumulators and latches, accommodating different frequency-dependent phase lags for each of the receiver paths, and the ability to scale the number of trackable LEO satellites and/or antennas in firmware. Different techniques for performing the integrated phase measurement, consistent with these objectives, are discussed. We describe the radio-frequency hardware, together with an efficient information smoother which we apply to the estimation of cycle ambiguities.