A computer implemented method of providing RSTD data comprising receiving an uncertainty window centered around an expected RSTD value, determining the PDP of each reference OFDM symbol within the uncertainty window, obtaining a main PDP by calculating a parameter indicative of signal quality for each determined PDP, the main PDP having the highest signal quality, obtaining a preceding PDP of the Main PDP, obtaining a succeeding PDP of the Main PDP, determining PDP metrics comprising, determining a channel metric for each of the main, preceding and succeeding PDPs, determining a channel main tap for each of the main, preceding and succeeding PDPs, determining a delay estimate for each of the main, preceding and succeeding PDPs, wherein if the main PDP is a combined PDP, performing coherence testing on the PDP metrics to detect any ambiguity in the delay estimate of the main PDP, and correcting any ambiguity.

A computer implemented method of providing RSTD data comprising receiving an uncertainty window centered around an expected RSTD value, determining the PDP of each reference OFDM symbol within the uncertainty window, obtaining a main PDP by calculating a parameter indicative of signal quality for each determined PDP, the main PDP having the highest signal quality, obtaining a preceding PDP of the Main PDP, obtaining a succeeding PDP of the Main PDP, determining PDP metrics comprising, determining a channel metric for each of the main, preceding and succeeding PDPs, determining a channel main tap for each of the main, preceding and succeeding PDPs, determining a delay estimate for each of the main, preceding and succeeding PDPs, wherein if the main PDP is a combined PDP, performing coherence testing on the PDP metrics to detect any ambiguity in the delay estimate of the main PDP, and correcting any ambiguity.

Provided herein is a method for separating Loran sky and ground waves based on a Levenberg-Marquart algorithm, including: (1) collecting a plurality of Loran sky-ground wave signals followed by normalization to obtain a normalized signal; (2) preprocessing the normalized signal by inverse Fourier transform method to obtain an initialization parameter; (3) establishing a mathematical model for the Loran sky-ground wave signals in time domain; and (4) solving parameters of the mathematical model using the Levenberg-Marquart algorithm to separate the Loran sky and ground waves.

Provided herein is a method for separating Loran sky and ground waves based on a Levenberg-Marquart algorithm, including: (1) collecting a plurality of Loran sky-ground wave signals followed by normalization to obtain a normalized signal; (2) preprocessing the normalized signal by inverse Fourier transform method to obtain an initialization parameter; (3) establishing a mathematical model for the Loran sky-ground wave signals in time domain; and (4) solving parameters of the mathematical model using the Levenberg-Marquart algorithm to separate the Loran sky and ground waves.