Improving Detection Performance of Ionospheric Disturbances due to Earthquake by Optimization of Sequential Measurement Combination
Résumé
Energy generated from earthquake (EQ) is transferred to the ionosphere and results in co - sei s mic ionospheric disturbances ( CI D). C ID can be observed in the ionospheric combination using L1, L2 frequency carrier phase. As ionospheric trend due to normal conditions such as elevatio n angle of satellites is generally larger than disturbances, a proper measure is required to extract disturba n ce s ignals . Derivative , or sequential combination, is a simple and effective way to remove the normal trend in the ionospheric delay. W hen using derivative, however, disturbance s ignals can often be obscured by no ise due to its small amplitude. In order to reduce the noise while preserving the time rate of data, and thus to improve signal - to - noise ratio (SNR) , we designed a new derivative method using optimization under a couple of assumptions . W ith simulation data , it is found that N, the number of epochs used for sequential combination , turne d out to be the best when N=16 0 with maximum SNR. Finally, t he proposed algorithm’s SNR was compared to that of the previous study which also used derivative method. 1 20 ~260 % improvement s w ere observed for the proposed method compared to the conventional method
Origine : Fichiers éditeurs autorisés sur une archive ouverte
