The Research And Application Of Single Site Location Techniques In Shortwave Domain

To deprive the ability to obtain information of the electronic equipments of the enemies, the electronic countermeasures jam, deceive or destroy them, which the electromagnetic wave used as the medium. As the basic function of the modern High Frequency (HF) electronic warefare systems, the shortwave positioning is not only an important means of the electronic warefare, but also provides information that support for the relevant departments to exclude illegal radio and shortwave jamming in the civil area. The performance of the single sitle location (SSL) is affected by the ionospehere and realizes locatization of the shortwave radiation signals by using of the characteristics of the ionospheric refraction and scattering. The SSL techiniques can avoid the disadvantages of the multi-station intersection positioning systems which put forward a very high request to those problems such ast the suitable station layout, good communication, time synchronization,and equipment support and so on. The traditional SSL system locates the distant radiation sources mainly depends on the measurement of the ionosphere vertical sounding and the ionospheric model. The positioning accuracy is low because it is hard to access the real-time changes of the ionosphere in which the HF signals propagate. Since the backscatter sounding can monitor the large area of the ionosphere, it can obtain the ionospheric parameters (height, electron density profiles and the semi-thickness) accurately. With the DOA of incident signals (the elevation and azimuth), the position of the HF incident signals can be achieved in single station. Based on these, we implemented a new SSL system named the backscatter sounding SSL system (BS-SSL) and studied the related techniques of system. At the same time, we also proposed a cooperation source SSL system using the pulse-to-pulse modulation signals as for the multi-mode propagation of the HF signals in the ionosphere?By the simple transformation of the shortwave radio, the system locates it and provides support information for tactical decisions and rescues. The main works and innovations of this paper include the following aspects:1. We proposed the concept of the HF positioning by the backscatter sounding of the ionosphere firstly. As an important means of the ionosphere sounding, backscatter-sounding can monitors a large-scale ionospheric state in a single station. It has incomparable advantages with the vertical and oblique sounding in large-scale ionospheric observations and achieves a real sense of single site location. This paper introduces the structure of the new system and the related technology in the process of complementation of the system. we also valided the system with experiments, and the results shows a good performance in the quiet ionosphere.2. The new SSL system is premised on the basis of obtaining the backscatter sounding ionogram (BSI) recorded by the Wuhan Ionospere Synthesis Sounding (WISS) system which is developed by the ionosphere laboratory of Wuhan University, and fit the need of quick positioning by scaling and inversion automatically. By taking advantages of the morphological image processing and multi-resolution wavelet analysis, the vertical echoes and F layer leading edges are extracted by the subregion of a BSI. We improved the inversion algorithm based on single layer quasi-parabolic model by using the extraction results. the time costed shortened greatly by cutting down the search interval with the vertical information. We also discussed the inversion approach based on the International Reference Ionosphere (IRI), the experiments shows that this method has a good performance to study the electron density profile and the space weather of the East Asian region.3. Another key technique of the BS-SSL system is estimation the directions of arrival (DOA) accurately.Thus the two-dimensional (2D) DOA estimation based on the plane arrays are studied. The discussions focused on the princples of the 2D interference direction finder and the 2D Multiple Signal Classification (MUSIC) algorithms. The errors of the interference direction finder with diffirent arrays are discussed in the paper. As it takes so much time to search for the DO As of the 2D MUSIC spectrum, we proposed the grid partical swarm optimization (GPSO) algorithm that ensures high estimation accuracy and shortens the search time greatly, which is valuable for the enginnerring applications.4. Since the motility of our own HF radio, the real-time location information should be known by the control center. Based on the research of the former new SSL system, a cooperation source localization SSL system which could provide the real-time position of our field radio is proposed. Considering inter-pulse phased signals can obtain the different propagation mode (time-delay). We preliminary discussed the principle DOA estimation of those signals, and simulated and analyzed the estimation of data constructed by the results of correlation of the pseudorandom-phased signals. We also discussed the principle of the passive single site location with the different arrival elevation of the same signal. The uniqueness of the solution is discussed with the consideration of the curvature of the Earth, and compared the positioning errors with that assumption the ground is plane. The results shows the estimation errors of the latter become larger with the gound range increasing, but the error of the former are within 10%.