A novel algorithm for rapidly positioning using Doppler-aided RangeFit

The global navigation satellite system(GNSS) can position rapidly within one second if the sum of the initial position error,initial time error,and other factors is less than 150 km;that is,the initial time error can not be larger than 210 s even when the initial position error is zero.So the time to first fix(TTFF) of the GNSS could be within one second only in the instance of a hot start or Aided GNSS.To resolve the problem,a novel algorithm for rapid positioning using a Doppler-aided range fit was proposed.The algorithm can function in conditions other than a hot start and Aided GNSS.Analysis and tests in real data show that the proposed algorithm works correctly and achieves the TTFF within one second when the initial time error exceeds one thousand or even ten thousand seconds,as well as in the condition of an unknown initial position error.