A fuzzy variable coefficient variable structure guidance law is designed for intercepting high-speed maneuvering targets with terminal line-of-sight angle constraints. Firstly， an adaptive variable structure guidance law is proposed to adaptively adjust the velocity approaching the sliding mode surface according to the distance of the missile target. Then， the chattering is eliminated by replacing the switch term in guidance law with the saturation function. Simulation results show that the proposed guidance law can meet the requirements of line-of-sight angle constraint and miss distance for intercepting high-speed non-maneuvering and maneuvering targets， but it requires a large overload. To this end， a fuzzy control method is introduced and a fuzzy controller is designed to optimize the guidance coefficient in the variable structure guidance law. Finally， a fuzzy variable structure guidance law with a variable coefficient is obtained to satisfy the line-of-sight angle constraint and restrain the required system overload.

An estimation and sorting method for frequency-hopping signals based on improved connected region labeling is proposed to tackle the problem that small unmanned aerial vehicles （UAVs） are difficult to identify in a complex electromagnetic environment. Firstly， the energy threshold statistical method based on local windows is used to denoise the signal in the time and frequency domains. Then， the conventional connected region labeling method is improved to design a method to associate segments of the connected region and a method to suppress interference， which solves the problems of connected region breaks and interference mixing. After that， in the case of the mixing of multi-frequency-hopping signals， the connected region is reconstructed by the time–frequency amplitude difference. Finally， parameter extraction and signal sorting and identification are carried out according to the improved label map of the connected region. The simulation shows that under the environment of noise， interference， and multi-frequency-hopping signal aliasing， the estimation accuracy of signal parameters and the correct identification probability of target signals are significantly higher than those of the conventional connected region labeling method.

For the first time， Russia used the "Dagger" hypersonic weapon to destroy a large underground warehouse in Ukraine in combat， causing the world to pay more attention to hypersonic weapons and a growing sense of urgency. Hypersonic weapons have the advantages of fast flight speed， strong maneuver ability and difficult flight trajectory prediction， which makes the traditional missile defense system "paralyzed overnight". As countries around the world accelerate the weaponization of hypersonic technology， the hypersonic weapon defense system is also being built simultaneously. Aiming at the defense problem of foreign hypersonic weapons， the development status of foreign hypersonic weapons and the construction of hypersonic weapons defense system in the United States and Russia are analyzed in depth， and the development direction of foreign hypersonic weapons defense system construction is sorted out. The research results can promote the development of advanced defense technology.