Research Of Frequency Hopping Signal Detecting And Parameter Estimation Technology

The frequency hopping communication system has strong anti-interference,antiinterception and anti-fading capabilities.Because of these advantages,it has brought great difficulties to the detection of frequency hopping communication systems.In addition,the popular UAV aircraft currently on the market used the frequency hopping communication system,and the difficulty of investigation makes the "flying illegally" event happen frequently.The purpose of this paper is research of frequency hopping signal detecting.The main work and innovations of this paper are as follows:1.Research on frequency hopping communication systems and non-stationary signal analysis methods.The composition and characteristics of the frequency hopping communication system are studied briefly,and the UAV signal is taken as an example to introduce the UAV frequency hopping communication system.The frequency hopping signal is a non-stationary signal,and the frequency of the signal will change with time.The traditional signal analysis method cannot describe the non-stationary signal.Therefore,it is necessary to jointly describe the characteristics of the non-stationary signal from the time domain and the frequency domain.The theoretical study of analytical methods laid a foundation for the full text.2.Using power spectrum data as a source of data for detecting frequency hopping signals.Firstly,studing the modified periodogram method for estimating the power spectral density of random processes with a finite number of data.After that,the power spectrum smoothing is used to better suppress the fluctuation characteristics of the power spectrum data.Then,analyzing two signal detection methods,double threshold threshold method and template matching method,and simulation experiments show that the template matching method has better detection performance.Finally,parameter estimation is performed on the detection result to determine the frequency hopping signal.3.Using the time-frequency diagram as a source of data for detecting frequency hopping signals.Firstly,the time-frequency map is obtained by the spectral method.Then the energy threshold denoising method and the histogram denoising method are used respectively for the time-frequency image denoising.The simulation results show that the energy threshold denoising method has a good performance under low SNR.Then morphological processing of the time-frequency diagram to eliminate noise,and binarized time-frequency diagram connected domain markers to obtain information of each timefrequency component,and finally cluster each time-frequency component information to determine the frequency hopping signal.4.Most of the research is at the simulation level.This paper will implement the power spectrum data to detect the frequency hopping signal on the FPGA hardware platform.First defines the system design function and module division,and then design the key modules detaily,then testing the entire system.