| Shortwave communication is a historical wireless communication. Because of the small volume, both mobile and fixed communication ability, low construction and maintenance costs, shortwave communication has a significant strategic status in the remote military communications. The transmitting antenna need to build in the open space, and at most a few hundred meters away from the traditional shortwave transmitting station, it is easy to expose shortwave transmitting station position thereby pose a threat to its security. Therefore, a remote shortwave emission system is studied and devised in this thesis. The system can transmit data remotely, realize long-distance realtime monitoring for the status of the transmitter, and can complete the remote setting of the emission parameters under the situation of far away from the transmitting antenna. This study has important meaning and the pragmatic value to the application of shortwave communication.This paper firstly reviews the development of related technologies, and processes the requirements analysis of the remote shortwave emission system. Then the overall design of system is given, and the rationale for the key technologies are analyzed. The system is consisted of emission unit and control unit, and the emission unit is located near the transmitting antenna. The remote monitoring is achieved ground on Modbus/TCP protocol via Ethernet. To complete transmit data remotely, the control unit has to finish the data collecting, and send to the emission unit by UDP protocol after encoding by FFmpeg. Then the emission unit has to complete data decoding, signal conversion and modulation output. According to the system scheme, the system hardware platform is builded, and the functions and working principles of each module are progressively elaborated. After the system SDE is given, we present the software overall design, focused on the developing of communication module and audio information handling module, and the realization of other functional modules have also been described in detail. Finally, the test contents and platform are given to perform the system function testing, and the test outcome are analyzed.The functional test results of remote shortwave emission system validate the correctness and feasibility of the system design. This design provides a new method for transmitter station working far away from the transmitting antenna. The emission unit is designed according to standard protocol of Modbus, providing a technical foundation for shortwave cooperative communication based on Ethernet. |
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