Research On Ionospheric Perturbation Correction Algorithm For Sky-wave Othr

OTH Radar has many good qualities such as over-the-horizon detection,long-distance communication and anti-stealth. That’s the reason why it’s widelyused nowadays and every country has put great human and financial resources.Signal from OTHR is refracted by the ionosphere, which is a dispersed, non-even,time-varying medium and has a serious influence on the radio waves travellingthrough it. Because of its complexity, it’s called a double-edged sword. To make thebest use of the ionosphere, it’s necessary and crucial to study the theoreticalcharacteristics of ionosphere fundamentally and develop effective ionosphericdecontamination algorithm.The thesis consists of these following parts:Firstly, an overview of the ionosphere is given. There are several layers in theionosphere, which are D, E, and F generally. Its impact including refraction,reflection and absorption cannot be neglected. Three commonly-used sounders areintroduced at the end of this part.Then we focus on the ionospheric model. Three simple models and onecomplicated model, namely IRI are orderly presented. Then combining thetechnique of3-D Ray Tracing, we obtain the phase path of ionosphere, which is inrelation to phase. All these provide a guidance and reference for further research.Lastly5typical ionospheric phase contamination correction algorithms arediscussed and analyzed, which are PGA, TCA, short-time segmenting algorithm,maximum entropy spectrum algorithm and P&B algorithm respectively. Theirperformances are compared by simulation, which demonstrates that P&B has abroader use than others.