Acurate and Robust Loran-C Cycle Identification

A Loran-C system is a land based navigation system. Location finding in a Loran-C system is based on the time delay estimation so that exact delay estimation plays a crucial role in positioning accuracy. Finding the reference point of each Loran-C system emitted pulse is called cycle identification. Cycle identification accuracy depends on many parameters such as signal to noise ratio (SNR), envelope to cycle difference (ECD) and the signal sampling frequency. In this paper, it is proposed a modification to our previous paper to increase robustness of cycle identification against the white Gaussian noise and also two other methods to find the exact location of the reference point of each pulse between two samples. When it is used the intersample cycle identification, high sampling frequency will not be required which concludes low complexity, therefore low cost analog to digital converter can be used in the Loran-C systems receivers. The proposed methods were compared for different location of the reference point between two samples. The simulations result show that the modified method outperforms the previous method especially in low SNR conditions.