Satellite-based positioning system improvement

摘要

A method, device and system for determining a receiver location using weak signal satellite transmissions. The invention involves a sequence of exchanges between an aiding source and a receiver that serve to provide aiding information to the receiver so that the receiver's location may be determined in the presence of weak satellite transmissions. With the aiding information, the novel receiver detects, acquires and tracks weak satellite signals and computes position solutions from calculated pseudo ranges despite the inability to extract time synchronization date from the weak satellite signals. The invention includes as features, methods and apparatus for the calibration of a local oscillator, the cancellation of cross correlations, a Doppler location scheme, an ensemble averaging scheme, the calculation of almanac aiding from a table of orbit coefficients, absolute time determination, and a modified search engine.

主权项

1. A satellite-based positioning system for identifying a location of a receiver in the presence of satellite signal attenuation comprising:
a plurality of orbital satellites sending synchronized encoded signals that have repeated epochs containing synchronization data; and a receiver configured to:
detect, acquire, and track a set of the encoded signals transmitted by a set of the orbital satellites,simultaneously determine code phases of said set of encoded signals with respect to said epochs,receive aiding information broadcast from an aiding source,compute positions of the set of satellites using orbital coefficients hardcoded in the receiver for a number of satellite orbits and the received aiding information, andcompute the position of the receiver based on said computed positions of the set of satellites and on pseudoranges derived from the code phases.