Patent ID: 8525727

Claim:
A navigation system, comprising: an antenna; and Global Navigation Satellite System (GNSS) receiver circuitry coupled to the antenna for receiving GNSS signals from a plurality of satellites, and comprising: a measurement engine for determining, from each of the received GNSS signals, a pseudorange value and a pseudorange variance, the measurement engine comprising: a digital measurement engine channel for determining the pseudorange value and pseudorange variance for an associated one of the GNSS signals, comprising: code generator circuitry, for generating a replica code at a plurality of delay times; a delay-locked loop for measuring correlation between the associated GNSS signal and the replica code at a selected code-phase relationship, comprising a plurality of correlators, each for correlating the associated GNSS signal with the replica code at an associated delay time, the plurality of correlators including at least an early correlator and a late correlator; and a delay-locked loop discriminator having inputs coupled to the plurality of correlators, for generating an error signal responsive to a difference in the correlations by the early and late correlators; a filter for generating a discriminator output signal responsive to the error signal and circuitry for calculating the pseudorange value from the measured correlations for each GNSS signal, and for calculating the pseudorange variance for each GNSS signal from a variance of the discriminator signal output signal the measured correlations over time.