Research On Target Signal Processing Method Based On 3mm Active And Passive Detection System

Based on the technology of millimeter-wave active and passive composite detection and the related engineering project,this paper mainly studied and designed the 3mm active and passive composite detection system.It is divided into analysis and design,research of active and passive signal processing,realization of software and hardware and experimental verification.The main research work includes:(1)According to the characteristics of active radars and passive radiometers,an active and passive composite detection system as combination of both is proposed.Classifications of millimeter-wave active and passive composite detection systems are introduced and the specific classification block diagram is provided.Each category's system is simply introduced.3mm active and passive composite detection system's principle block diagram is given.Its structure,components and working principles are expounded.(2)Two kinds of transmitted signal wave LFMCW and FSK-CW's principles of ranging and speed measuring are analyzed.Accuracy and resolution of ranging and speed measuring are also analyzed in quantitative or qualitative way.Owing to fence effect and spectrum leakage of discrete spectrum analysis,a ratio correction algorithm based on amplitude(Rife algorithm)and a ratio correction algorithm based on complex spectrum(Quinn algorithm)are proposed.Because of noise interference,improved ratio correction algorithms based on frequency shifting technology(I-Rife algorithm and I-Quinn algorithm)are proposed.Actual frequency is shifted to the middle of two sampling frequencies to raise accuracy of spectrum correction.Four kinds of spectrum correction algorithm's accuracy and resolution are analyzed.Two kinds of multi-targets recognition algorithm are proposed to solve the problem that traditional triangular wave fails to recognize multi-targets.One is a multi-targets recognition algorithm based on triangular wave with variable periods and the other is a multi-targets recognition algorithm based on improved LFMCW.For triangular wave with variable periods,targets' tolerance functions of ranging and speed which can be regarded as the same one are given.For improved LFMCW,it is verified that it can recognize actual targets correctly under all circumstances.Two kinds of multi-targets recognition algorithm's effectiveness and accuracy are verified by simulation.(3)Basis of millimeter-wave radiation theory and classifications of millimeter-wave radiometers are introduced.Two kinds of radiometer's system block diagrams and working principles are expounded.The model of radiometer scanning targets is built.Metal targets' expressions of antenna temperature and antenna temperature contrast ratio are inferred and characteristics of radiometers' output waveforms with different heights are analyzed by simulation.Based on characteristics of radiometers' output waveform and the scanning process,targets' two-dimension center recognition algorithm based on the radiometer with binary channels is proposed.The tangential center of one target can be determined when single channel's output signal reaches the maximum value.The radial center of one target can be determined when the product of binary channels' output signals reaches the maximum value.The concrete flow chart of signal processing is given.(4)The software and hardware realization of 3mm active and passive composite detection system's signal processing.Active detection module designs and generates a triangular wave modulation signal with period of 20.04 us.Active detection module also realizes a digital narrowband bandpass filter with fixed center frequency and related auxiliary circuits.Passive detection module completes the software realization of targets' two-dimension center recognition algorithm and related auxiliary circuits designs.Finally,we implemented active and passive detection experiments on the developed 3mm active and passive composite detection proto in the field.The experiments show that the proto can work properly under active and passive condition and has fine detection accuracy.