We put forth a project, that is: using the backscatter technique to realize adaptive long-distance HF broadcasting system in order to improve the quality of HF broadcasting. Then, we analyze errors of the system due t...We put forth a project, that is: using the backscatter technique to realize adaptive long-distance HF broadcasting system in order to improve the quality of HF broadcasting. Then, we analyze errors of the system due to the deviation of the ionospheric parameters' prediction. From the analysis, we draw the conclusion that our project is feasible. In addition, we point out that we can use frequency-spreading and information-coding technique to acquire more clear ionograms. We also offer a judgment on how to choose the control propagation mode on condition of multihop and the existence of more than one propagation mode on the signals' path.展开更多
A hierarchical cluster analysis has been made on the geomagnetic and geoelectric data of Nagoya ( Φ =21.1°), Japan (1978 1981, 1985, 1987) and geomagnetic data of Wuchang ( Φ =19.1°), China (1985 199...A hierarchical cluster analysis has been made on the geomagnetic and geoelectric data of Nagoya ( Φ =21.1°), Japan (1978 1981, 1985, 1987) and geomagnetic data of Wuchang ( Φ =19.1°), China (1985 1995). From the cluster diagram it is seen that the monthly mean occurrence of Pc3 4 observed at these two sites can be best grouped into 3 clusters.展开更多
To fit the autocorrelation functions (ACFs) of HF radar ionospheric backscattered signal to an analytical function, which is obtained theoretically by introducing a Lagrangian description of turbulent motion, can esti...To fit the autocorrelation functions (ACFs) of HF radar ionospheric backscattered signal to an analytical function, which is obtained theoretically by introducing a Lagrangian description of turbulent motion, can estimate directly the turbulent parameters of the scatters. We use this method to analyze the HF radar ACFs. A statistical study has been performed with the multi-frequency data, and shown that the statistical results are not the same in different frequency bands. We found that the influences of the limit radar time resolution and the received noise played the important roles in causing this inconsistency, both of them result in an additional expansion to the spectral width, and cause more Lorentzian behavior to ACFs; these two limitations affect the form of ACFs more seriously in the higher frequency band. We verified this by a simple simulation.展开更多
文摘We put forth a project, that is: using the backscatter technique to realize adaptive long-distance HF broadcasting system in order to improve the quality of HF broadcasting. Then, we analyze errors of the system due to the deviation of the ionospheric parameters' prediction. From the analysis, we draw the conclusion that our project is feasible. In addition, we point out that we can use frequency-spreading and information-coding technique to acquire more clear ionograms. We also offer a judgment on how to choose the control propagation mode on condition of multihop and the existence of more than one propagation mode on the signals' path.
文摘A hierarchical cluster analysis has been made on the geomagnetic and geoelectric data of Nagoya ( Φ =21.1°), Japan (1978 1981, 1985, 1987) and geomagnetic data of Wuchang ( Φ =19.1°), China (1985 1995). From the cluster diagram it is seen that the monthly mean occurrence of Pc3 4 observed at these two sites can be best grouped into 3 clusters.
文摘To fit the autocorrelation functions (ACFs) of HF radar ionospheric backscattered signal to an analytical function, which is obtained theoretically by introducing a Lagrangian description of turbulent motion, can estimate directly the turbulent parameters of the scatters. We use this method to analyze the HF radar ACFs. A statistical study has been performed with the multi-frequency data, and shown that the statistical results are not the same in different frequency bands. We found that the influences of the limit radar time resolution and the received noise played the important roles in causing this inconsistency, both of them result in an additional expansion to the spectral width, and cause more Lorentzian behavior to ACFs; these two limitations affect the form of ACFs more seriously in the higher frequency band. We verified this by a simple simulation.
