Research On 1.6?m Pulse Coherent Lidar Time-frequency Fusion Ranging Technology

Compared with microwave,laser has a good bandwidth and better directionality,so it is a more ideal tool for ranging and speed measurement.Existing laser ranging radars have two working modes: continuous and pulse.Among them,the radar using pulsed laser as the light source has high energy and high peak power,so it has a long transmission distance and can be used as a long-range detection radar.The commonly used laser detection methods include direct detection and coherent detection.Traditional laser ranging is mainly carried out by the direct detection method of ranging radar,which has low sensitivity and weak anti-interference ability,and its practical application is greatly limited.Coherent detection has the advantages of stronger detection capability,good stability and higher reliability,but its existing technology is mainly used for speed measurement,and it is difficult to directly and efficiently apply to distance measurement.In view of the advantages of pulsed laser and coherent detection and the current research status,this paper studies the laser ranging radar of 1.6?m human eye safety band pulsed coherent working mode,deduces the ranging theory and performs algorithm simulation to build a radar system Conduct field experiments.Mainly done the following work:First,it introduces the research background and purpose of the subject,and introduces and analyzes the research status of laser ranging radars at home and abroad.At the same time,it investigates the data processing methods of radar ranging echo signals at home and abroad,leading to the main research content of this article.Secondly,the working method and working principle of coherent detection lidar are introduced,and the common laser ranging methods are introduced and compared.At the same time,different types of radar signal processing algorithms are introduced and the corresponding theoretical derivation is given.The threshold filtering algorithm based on wavelet transform and the time-frequency energy algorithm are deduced and analyzed to provide a theoretical basis for the subsequent simulation.Then,based on the above theoretical foundation,and according to the radar technical indicators designed in this subject,taking into account the external environment and the impact of the radar's own noise,the software is used to simulate the ranging of the echo signal,and the simulation results are analyzed.Provide reference for field test.Finally,a 1.6?m single-frequency pulse laser was used as the radar light source to build a lidar ranging system.At the same time,an optical coaxial transceiverantenna was designed and built for field test.According to theoretical derivation and algorithm simulation,the wavelet time-frequency method and time energy method are used to analyze the real echo signal to verify the actual accuracy and timeliness of the above algorithm,and finally the effective range of the system is 200m-2.8km.Results with accuracy less than 0.5m.