A Novel Time Delay Estimation Bias Reduction Scheme using Maximum Slope Change in GNSS

The early minus late discriminator based delay locked loop (EL-DLL), which is a general code tracking scheme of the global navigation satellite system (GNSS), has enormous time delay estimation bias (beta). The narrow correlated DLL (NC-DLL) and the double delta DLL (Delta⁽²⁾-DLL) were proposed as a beta reduction scheme, where Delta means the spacing between early and late correlation sample. However, the two schemes cannot remove the beta completely and make the dynamic range narrower than the EL-DLL, which lead to very accurate acquisition. This paper proposes a novel tracking scheme that can reduce the beta using maximum slope change without narrow dynamic range.