Multi-duct trans-hemispheric propagation of VLF signals in the presence of ionospheric heating.

摘要

Matched filter technique applied to guided trans-hemispheric propagation of the VLF signals at low geomagnetic latitudes has yielded limited results in the past. The main drawback was the inability of the technique to eliminate the unguided modes of transmission. In this dissertation, the extension of the matched filter technique to account for multiducted transmissions is developed. The technique is tested on ducted trans-hemispheric propagation of 28.5 kHz signals from the Navy VLF transmitter located in Puerto Rico and it is shown that it can be used to identify and eliminate unguided modes. Data collected at magnetically conjugate points in Puerto Rico and Argentina is analyzed and transmission times and amplitudes of the ducted VLF signal are measured. In addition, the double-ended multi-ducted correlation receiver technique is used in the presence of ionospheric heating. The effects of multiple modes of ionospheric heating on single and multihop conjugate transitions are characterized and evidence of duct drift is observed.