Method and system for estimating position using dual real time kinematic engines

A system for estimating the position of an object by a location-determining receiver associated with the object, the system comprising:

• a phase measurement device for measuring a first carrier phase of a first carrier signal and a second carrier phase of a second carrier signal received by the location-determining receiver, the phase measurement device comprising a signal generator for generating a reference signal having a reference phase, a first correlator for receiving the reference signal and the received first carrier signal to generate a first output signal indicative of the measured first carrier phase and a second correlator for receiving the reference signal and the received second carrier signal to generate a second output signal indicative of the measured second carrier phase, the phase measurement device comprising a signal generator for generating a reference signal having a reference phase, a first correlator for receiving the reference signal and the received first carrier signal to generate a first output signal indicative of the measured first carrier phase and a second correlator for receiving the reference signal and the received second carrier signal to generate a second output signal indicative of the measured second carrier phase;
• a primary real time kinematic (RTK) engine for receiving the measured first carrier phase and the measured second carrier phase and estimating a primary integer ambiguity associated with at least one of the measured first carrier phase and the measured second carrier phase by a primary RTK engine;
• a signal quality evaluator for determining if the first carrier signal or the second carrier signal has a signal quality below a threshold signal quality level during an earlier evaluation period or epoch;
• and
• a secondary real time kinematic (RTK) engine for estimating a secondary integer ambiguity associated with at least one of the measured first carrier phase and the measured second carrier phase during a later period following the earlier evaluation period.

A method for estimating the position of an object by a location-determining receiver associated with the object, the method comprising:

• measuring a first carrier phase of a first carrier signal and a second carrier phase of a second carrier signal received by the location-determining receiver;
• estimating a primary integer ambiguity set associated with at least one of the measured first carrier phase and the measured second carrier phase by a primary real time kinematic (RTK) engine;
• determining if the primary integer ambiguity set is resolved correctly to the predefined reliability rate during an earlier evaluation period;
• and
• estimating a secondary integer ambiguity set associated with at least one of the measured first carrier phase and the measured second carrier phase by a secondary real time kinematic (RTK) engine during a later period following the earlier evaluation period;
• resetting the secondary RTK engine and reinitialize the secondary RTK engine if primary integer ambiguity and the secondary integer ambiguity are identical for less than four double difference integer ambiguity states;
• and
• using output from the primary RTK engine to estimate a solution for integer ambiguity after the secondary RTK engine reinitialization.