ECD Estimation in Loran C Signal using Gradient Steepest Descent Method based on Least Square Error

Loran-C is a positioning system based on TDOA. The third standard zero crossing point is used to detect Loran-C pulses in receiver. In practice, due to noise and interference, the location calculation of this point is in error. One of the most important and effective parameter to identify the third standard zero crossing point in Loran-C pulse is ECD estimated value. One of the methods for estimating the ECD is USCG transmitted pulse method which is based on the least squares error between the received and ideal signal. The disadvantage of this algorithm is that the estimation of ECD must be obtained through a numerical procedure which is not time-efficient. In this paper, two techniques have been proposed to optimize the USCG transmitted pulse method. In the first method, ECD measurement is obtained experimentally. The second method is the gradient steepest descent method which calculates step size intelligently. The results show that although the empirical method has enough accuracy, but it needs much time to do calculations, while the gradient steepest descent method, in additional small computation complexity, has high accuracy in ECD estimation.