The Design And Implementation Of Responding Ionospheric Oblique Detection System

The reflection effect of the ionosphere provides a natural propagation medium for shortwave communication,it has the advantages of all-weather,difficulty in being destroyed,and easy communication link establishment,making shortwave communication widely used in rescue and disaster relief,radio stations,military communications and skywave over-the-horizon radar and other fields.The ionosphere is a random parametric channel due to the influence of solar radiation.The frequency band interference is serious and the communication environment is complex and changeable.A dedicated response detection system is required for real-time ionospheric detection and shortwave communication frequency selection to guide the establishment of shortwave communication links.Based on the existing detection technology in the laboratory and combining the respective advantages of the ionospheric oblique detection and the third-generation automatic link establishment technology,this paper designs and implements a response-type ionospheric oblique detection system based on an embedded platform.The thesis designs and implements an embedded ionospheric oblique response detection system based on Field Programmable Gate Array(FPGA)and Advanced Reduced Instruction Set Processor(ARM).The system can be applied to frequency selection of shortwave communication,network detection of ionospheric oblique,and the reflection beacon source of skywave over-the-horizon radar detection.The system has the characteristics of simple structure,flexible deployment,wide application range and strong ability to signal detection.The introduced complete complementary code can effectively suppress coherent interference in the synchronous oblique network detection of the ionosphere.By introducing different types of "frequency groups",the data processing process is simplified.The system can set up a combination of multiple response "frequency groups" according to different application scenarios to improve the accuracy of frequency selection.The system has designed two working modes:synchronous response detection mode and asynchronous response detection mode.Multiple working modes expand the application scenarios of the system.The hardware system adopts the idea of software radio to simplify the system structure,and adopts the digital intermediate frequency receiving structure to make the system have the characteristics of standardization,modularization and scalability.A set of data processing and frequency optimization algorithms are designed to enable the system to detect target signals in a complex environment,and to meet the requirements of real-time data processing and system control under the condition of limited available resources.The system index test was completed,the experiment of synchronous mode response detection and the experiment of asynchronous mode response detection were carried out,and the detection performance of complete complementary code and complementary code was compared and analyzed in synchronous network detection.The test and experimental data analysis results verify the feasibility and correctness of the system design.