Research On Key Technologies For Passive Reception Of Nonuniform-Uniform Secondary Sampling Signal Processing

The performance of the passive reconnaissance and reception system is severely constrained by the level of analog-digital converter(ADC)hardware that cannot meet the requirements of electromagnetic spectrum monitoring due to the rapid advancement of science and technology and the growing complexity of the electromagnetic environment.There are many difficulties in wide spectrum real-time signal interception,detection,parameter estimation,modulation recognition,etc.In order to overcome the problem between hardware and sampling theorem,research on passive ultra-wide band signal reception using the existing low-speed ADC is required.In this thesis,the Nyquist Folding Receiver(NYFR),a passive receiving nonuniform uniform quadratic sampling receiver,is examined in detail,including its design,mechanism,revised architecture,and signal processing method.1.The typical design of non-uniform uniform secondary sampling is investigated based on Nyquist folding receiver and the periodic non-uniform sampling theory.The Bessel function property of the sampling spectrum amplitude of a widely used clock modulation based on sinusoidal frequency modulation(SFM)is examined.The nonuniform sampling theorem is then used to get the generic expression of the NYFR sampling spectrum,and extend the conclusion to non-periodic clock modulation.Based on this,two aspects of the architecture’s parameter settings—parameter selection and clock modulation selection—were examined.2.Systematically studied the problem of signal detection and parameter estimation for signals with arbitrary modulation received through the NYFR architecture,breaking through the limitations of previous studies only focusing on several limited modulation types.From the energy domain,it pointed out the problems of power spectrum reduction and noise increase of the NYFR received signal,and discussed the performance differences between the NYFR architecture and the conventional architecture when applying traditional signal detection methods;The characteristic variation formulas of the signal were obtained sequentially from the time domain,frequency domain,and modulation domain.The differences and similarities between the NYFR-based secondary sampling architecture and the conventional architecture in parameter estimation were analyzed,and several difficult problems in the field of parameter estimation were pointed out.The innovation of this thesis is reflected in the in-depth analysis of the non-uniform uniform secondary sampling prototype architecture,and two improved non-uniform uniform secondary sampling architectures are proposed: the quadratic sampling architecture based on dual antennas and dual channels solves problems such as NZ estimation and modulation type estimation,and proposes a spatial parameter estimation method based on element spacing coding,which has strong robustness;A new secondary sampling architecture based on common divisor sampling and the corresponding NZ and frequency estimation algorithms are proposed to solve the shortcomings of NYFR and common divisor samplings,such as NZ estimation and false spectral peaks.The possible nonideal input signal conditions are analyzed respectively.The two architectures and algorithms improved and proposed in this thesis have the advantages of strong applicability,fast,accuracy,and unambiguous.The work in this thesis,which can use an existing low-speed ADC for instantaneous passive reconnaissance in ultra-wideband,has been put through simulation studies to confirm its viability and performance,serving as a reference for related research.