Implementation Of Separation Algorithm For Tactical Frequency-Hopping Signals

Frequency-hopping(FH)signals have been broadly employed in both military and civilian applications owing to their superior anti-interference performance and low probability of interception.As a result,research on FH signal detection,blind estimation of FH parameters,and separation technology has become increasingly important.Taking the FH signals in the complex electromagnetic environment as the research object,the key issues in the process of FH signals processing,including blind detection of FH signals,multiple FH signals parameters estimation and multiple FH signals separation are investigated in the thesis.At the same time,a solution for an FH signals separation system implemented on FPGA is proposed,which can satisfy the practical engineering requirements for the process of FH signals processing.The main contents and innovations are summarized as follows:1.The principles and mathematical models underlying frequency-hopping(FH)communication are examined in this thesis,and detailed descriptions of the important parameters and specific indicators of FH signals are provided.The principles and properties of time-frequency analysis methods are also focused on in this thesis.Several generally used time-frequency analysis methods are contrasted in terms of their performance indicators and computational complexity,and the impact of window selection on time-frequency analysis is analyzed.Spectrogram transformation is ultimately selected as the primary method for time-frequency analysis in the thesis.2.The detection algorithm for frequency-hopping(FH)signals is examined in this thesis.A brief introduction and comparative analysis of threshold design schemes for classical FH signal detection are also provided,and a threshold design scheme based on the OTSU method is proposed.3.Implementation algorithms for blind estimation of frequency-hopping(FH)signal parameters and separation are investigated in this thesis.Firstly,the potential problems that may be encountered in practical situations are analyzed,and improvement methods are proposed,including the "code break" elimination based on morphological filtering and the fixed-frequency interference elimination based on power spectrum subtraction.Then,a detailed introduction to the parameter estimation algorithm and separation algorithm for asynchronous FH signals is provided in the thesis,giving a step-by-step description of the algorithms and conducting simulation performance analysis to validate their feasibility and reliability.4.A solution for an FH signals separation system implemented on FPGA is proposed.The system requirements and architecture are clearly defined,and the key modules are designed and implemented.Finally,the system is tested using measured signals.