Hardware Design And Implementation Of Multi-target Ranging System Based On LFMCW

In the passive distributed antenna system(DAS),it is difficult to detect the fault of the network of coaxial cable.It is time-consuming,laborious,and hard to operate,if we depend on manual detection alone.Generally,the coaxial cable has constant characteristic impedance,which will be discontinuous only if there's something wrong with it or at the joint.On this basis,the author introduces the linear frequency modulation continuous wave(LFMCW)radar technology,carries on the linear frequency modulation between 1.7GHz and 2.9GHz,and achieves multi-target ranging in DAS,to help solve the problem.In order to meet the special requirements of the system,such as the closed space,the relative large bandwidth,multiple reflection and high resolution requirement,some special designs are needed.The author first introduces the existing technology on cable detection,and LFMCW radar development status.Next,the principle of LFMCW radar,the method to analysis DAS with S parameter,and both modeling and simulation based on MATLAB and ADS are introduced.Then,it lists the relevant indicators and design of the system.Principle and performance of some key components are analyzed,such as direct digital synthesizer(DDS),and the phase-locked loop(PLL).The hardware system includes the RF part,control and data processing part,as well as the part of analog to digital conversion(ADC).The RF part is the core,and its performance directly restricts the ability to achieve the target.The author presents the detailed hardware design,including essential schematic,PCB layout and pictures of the actual objects.In order to ensure the reliability of the system and provide guidance for further improvement of performance,some simulations and tests are carried out.According to actual environment test,most performance meets the design requirements,while small part is slightly lower.Finally,the deficiencies of the system are summarized,and some improved methods are given.