Sea-echo Doppler Spectrum Of Over-the-horizon Radar And The Moving Ship Detection On Ocean Surface

Sky-wave over-the-horizon radar(OTHR) is a long-distance surveillance radar which can see beyond the horizon by backward refraction of the ionosphere, It has the feature of long early warning time, large areas scout, anti-stealth, and so on. Within HF band, Bragg scattering occurs when Hertzian waves refract ocean surface-waves, thus over-the-horizon radar is widely used to remotely sensing ocean surface-waves, and ship detection can be done by increasing the ratio of signal to sea-echo Doppler spectrum.Chapter 1 provides the background of this work and characteristic of OTHR. A brief introduction of this dissertation is concerned.Chapter 2 , according to Barrick's forst-order and second-order sea-echo section equations of HF radar, simulates the second-order sea-echo doppler spectrum, by using the equal-frequence contour line and basing on the second-order section equation, in the polar coordinate, a careful analysis for the simulated result is also given.Chapter 3 obtains the retrieval of parameters of wind above sea surface and ocean wave spectra from simulated narrow beam HF radar backscatter, gives the simulate results.Chapter 4 firstly presents the general principle for signal detection, and then analyses several ways which are used in moving ship detection on ocean surface, gains some valuable results.Chapter 5 bring forward several improved methods which are used in correction techniques of ionospheric distortion. Those methods include: MESE(Maximum Entropy Spectral Estimation) , EV(engen vector) algorithms to estimate the slowly-changing phase pass perturbation, the estimation algorithm which bases on time-frequency analysis. The results of real data has proved the effects of ionospheric distortion(phase pass perturbation, multi pass effects).