Design And Realization Of Digital Module In Short-wave Software Receiver

Short-wave communication is closely related to people's lives, which is largely used in the transmission of voice, telegraph and data, and has an important role in the long-distance military communications. Software radio is an advanced idea and method, and has been widely used in the next-generation wireless communication system. The purpose of this thesis is the design of IF software receiver, which is composed by the circuit of RF front-end and the digital module. The design of hardware and software in the digital module has been implemented in this thesis.The hardware of the system uses the FPGA chip of XC4VLX40 as the signal processor, while using three major peripheral chips to ensure the normal operation of the system. The software of the system implements the following functions:achieving the function of digital down conversion, the total factor of decimation is 2560. The design of NCO in the unit of quadrature mixing uses the algorithm of mirroring, which saves the storage space and increases flexibility; the correction circuit for the bit timing was designed in the unit of digital demodulation, which reduces the impact on the bit timing because of the fading of short-wave signal. The demodulation of 2DPSK was implemented successfully; FPGA can configure the peripheral chips by the interface of SPI; achieving the communication of FPGA and ARM by the interface of UART, so that the demodulated data can be stored in the U disk in real-time through ARM. The thesis gives the simulation results of each module of the system, and finally puts the bit-stream file downloading to the FPGA chip, while observing the waveforms through the online analysis tool of ChipScope. After completing the board-level debugging, we give the waveforms and the bit error rate through a practical test. The result shows that the short-wave digital receiver we designed achieves the desired targets.