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Multi Channel Digitzation Design And Realization Of If Module Inmaglev Communication Systems

Posted on:2016-06-23Degree:MasterType:Thesis
Country:ChinaCandidate:P XieFull Text:PDF
GTID:2272330473955070Subject:Circuits and Systems
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Unlike traditional train, maglev train doesn’t need to touch the ground, which means it has a lot of advantages that traditional train does not have. In this case, maglev train has broad prospects for development. But traditional wheel-rail train communication system cannot be applied in maglev train, only wireless communication can be used to accomplish the data transmission between the train and ground station. Millimeter wave communication is the preferred method for maglev train-ground communication system due to high transmission rate and strong anti-interference and other merits.Based on FPGA technology, IF module of train-ground communication system is completed in this thesis with digital implement, which avoids complex circuit, poor anti-interference performance, high costs, equipment upgrades and maintenance and other inconvenient shortcomings that traditional simulative method surfering.By comparing the properties of the continuous and uncontinuous phase 2FSK signals and combining the characteristics of maglev train-ground communication systems, DDS technology is selected to complete modulation section of IF module. To address slow out-of-band attenuation of the modulated signal spectrum and other issues, raised cosine FIR filter is designed. DAC3152 is used to convert the digital modulated signal to an analog modulated signal. To achieve the required output power, HMC474SC70 amplifier is employed to complete the amplification of the modulated signal power.Digital quadrature demodulation method is used to complete demodulation of output signal of millimeter-wave receiver chain circuit. ADC087B200 is used to convert analog signal into digital signal. To assure that the ADC works in optimum operating level range, amplifier and T-type attenuator are designed to adjust the level range of the signal to be demodulated. This thesis shows the detailed design steps of modulation and demodulation modules, and simulations of each module are completed by Modelsim. In order to reduce physical debugging workload and cost savings, ChipScope Pro software program is used to complete FPGA board-level debugging.Due to space diversity combining technology of train-ground communication system, demodulation part of IF module is designed in eight–channel. To solve the mutual interference between the various channels, design for PCB board is analyzed in detail in this paper. Using the method of block design, increasing the isolation between each channel and optimizing the PCB EMC issues to make the system achieve optimal performance.Finally, the physical circuit is processed and tested, the test results show that performance of the IF module is good enough to achieve the desired targets and meet the system requirements.
Keywords/Search Tags:field programmable gate array, binary frequency shift keying, quadrature demodulation, electro magnetic compatibility
PDF Full Text Request
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