Maglev Communication Systems IF Module Digital Realization

Maglev train has broad prospects for development as its high speed, comfort andso on. To ensure the safe operation of the maglev train, the Maglev communicationsystem must be real-time, reliable completion of the transmission of the data signal.The maglev communication system adopts millimeter wave communication, whichis comprised of millimeter wave transceiver antennas, millimeter wave transceiverfront-end module, the IF modem module, codec module and data monitoring module.When using an analog method, the implementation of the IF modem module iscomplex, and it’s anti-jamming performance is bad. Other drawbacks include the bighardware size, high cost, length debug cycle, and it’s inconvenient for the maintenanceand updating of equipment.To solve the above-mentioned problems, nothing that the frequency shift keyinghas a strong anti-jamming performance and hardware has programmable features whendigital implement, this thesis selects frequency shift keying mode, applies a fieldprogrammable gate array (FPGA) technology, to achieve IF Module digitized. Mainlyas follows:1. By analyzing the characteristics of binary frequency shift keying, combiningsubjects background, select the IF module using direct digital frequency synthesis (DDS)technology to achieve continuous phase frequency shift keying, and select digitalquadrature demodulation recovery baseband signal.2. To achieve undistorted transmission of the baseband signal, complete the designof the raised cosine filter. The filter can compress baseband signal bandwidth, at thesame time, make "tailing" effect minimum, which can interference to the neighboringbase band signal, to ensure the transmission of signals without distortion.3. Design a high-performance DDS unit. The unit can be completephase-continuous frequency shift keying under the control of the filtered output of thebaseband signal. Meanwhile, the unit can output the mutually orthogonal fixed carrierfrequency, and complete digital quadrature demodulation.4. Design a cascaded integrator comb (CIC) filter unit. After digital down-conversion, the output difference frequency component has moved to thebaseband, the over-sampling rate at this time is larger. To facilitate the processing of thesubsequent unit, cascaded integrator comb filters can implement the down-sampling rate,while achieving low-pass filtering.Finally, cascade each unit to complete the IF module design and test theperformance. The results show that the IF module can achieve real-time, reliable highspeed data transmission.