Design And Research Of Millimeter Wave Field Strength Measurement System

As modern lifestyles change,transport has become the lifeblood of economic development.At present,the cruising speed of civil passenger transport is generally900km/h and the operating speed of high-speed railway is 300km/h.The emergence of600 km high-speed magnetic levitation fills the speed gap between civil passenger transport and high-speed railway and meets the modern transport needs of intercity traffic integration.In the future,high-speed magnetic levitation will certainly become a new driving force for China’s economic development.As one of the core components of the high-speed maglev system,the millimetre wave vehicle-to-ground communication system achieves safe and reliable two-way data exchange between the maglev train and the ground control centre,and its signal quality directly affects the safe operation of the train.This thesis designs a multi-channel,multi-frequency automated field strength measurement device based on the field strength detection requirements of the high-speed maglev millimetre wave vehicle-to-ground communication system,and designs and builds a test platform to test its performance.The main elements are as follows.1)Through reviewing the relevant literature at home and abroad,conducting an in-depth research on the current development status of field strength detection technology at home and abroad,analysing the characteristics and limitations of existing field strength measurement solutions,and based on the existing field strength detection solutions,conducting an in-depth study on the millimetre wave signal reception structure,detection method,distance measurement technology,etc.Based on the architecture of the millimetre wave vehicle-to-ground communication system,an automated,multi-channel,multi-frequency field strength measurement scheme.2)According to the system scheme and actual engineering requirements,an integrated hardware platform consisting of RF receiver,IF detector unit,AD sampling unit,signal processing unit,distance measurement unit and wireless data transmission unit is designed and implemented.3)Based on the digital signal processing platform composed of ZYNQ and MCU,combined with the functions of each unit of the hardware platform,the workflow of the field strength detection system was sorted out,and the program development was completed to realise the automatic measurement of field strength.4)Experiments were designed to test the performance of the field strength measurement system.The dynamic range of the detected waves was tested from-77 d Bm to-27 d Bm,and the reasons for the deviations were analysed.The whole system realized the reception and processing of 38 GHz millimeter wave signals,and completed the correlation between field strength magnitude and position.Finally,a test platform was built and the field strength was detected using the measurement device in different environments,and the correspondence between field strength magnitude and position was obtained.The characteristics and causes of field strength variation in different environments were analysed,and the influence of multipath effect on signal quality was found,and the improvement of signal quality by multi-channel reception was assessed,contributing new development ideas to future research on field strength detection in the millimetre wave band.