Network Geolocation Of HF Skywave Based On Direction-Finding

With the rapid development of communication technology, HF signal as a carrier, plays an indispensable role in military communications and economic development. Due to the limit of HF band resources and advantages of HF geolocation system of low cost, simple, positioning of radiation far away, the development on HF geolocation technology is of great significance. However, the development of HF geolocation technology is relatively slow. And most systems have low positioning accuracy. Therefore, this article focuses on the HF network geolocation algorithm based on the measured direction.Ionospheric channel model and direction-finding method is the foundation of HF network localization algorithm. This paper studies the characteristics of HF ionospheric channel. Watterson channel modeling is selected, and simulation analysis shows that the channel model has good ionospheric channel characteristics. Because the HF band is crowded, the received signal of one observation station may contain multiple HF signals, and there may be some independent signals with the source of radiation, this paper proposes HF signal validity identification algorithm based on the cluster analysis and the signal matching algorithm based on correlation analysis. And the two methods can achieve higher accuracy or success rates. The paper selects array-based direction algorithm to find the direction of the HF signal and analyses the influence of different channel parameters on the precision of direction measurement.Based on the studies before, the paper proposes a sphere network localization algorithm. The algorithm takes into account the impact of the Earth’s curvature. Multiple observation stations are used to get multiple points of intersection. This paper gives the arithmetic average, weighted average, maximum likelihood estimation method to estimate optimal position of the radiation and deduces the positioning accuracy of the CRB. Through simulation results we get conclusion that using maximum likelihood estimation method can make the positioning accuracy approaching CRB.Finally, the paper proposes the method of choosing observation stations. Paper gets several important conclusions that the relationship of the distances between observations when the precision of direction measurement is fixed and the relationship of lines connected stations and radiation when the distance is fixed.