Research And Development Of Digital Up/down Converter Based On Software Defined Radio

In the Software Defined Radio, digital up/down converter is a key module whichis located between high-speed A/D, D/A and baseband signal processing modules.Limited by the current device development level, the digital IF is a common technicalsolutions. Therefore,it is of great significance to develop an e?cient digital up/downconverter for software radio system based on multirate signal processing theory.In the paper, a digital up/down converter for high-speed digital radio transceiveris completed by Using software-defined radio ideas, advanced model-based developmenttools, as well as the FPGA chips. And an e?cient decimation filter is researched anddeveloped, enhancing the technical performance of digital up/down converter.First, performance and computational e?ciency of the interpolation filter and dec-imation filter will have a direct impact on the realization of digital up/down converter,for the interpolation filter and decimation filter calculations there is a large amount ofresource consumption. A high-speed decimation filter, ie compensation cascade cosinefilter, which has a lagre stop-band attenuation, small pass-band ?uctuation, and e?-ciency structure, is designed through the analysis of CIC filters, cascaded cosine filterand ISOP filter. Simulation shows that the proposed compensation cascaded cosinefilter can complete high-speed anti-aliasing filtering and image rejection filter filtering.Then the scheme of digital up/down converter is planned according to DQPSKWireless transceiver requirements. The various functional modules of digital up/downconverter: NCO, CIC filter, compensation cascaded cosine filter, HB filters, FIR filters,and a modified costas loop are designed and simulated with the use of System Generatorsoftware and model-based development methods.The model simulation, the hardwareco-simulation and real-time voice tests with the use of Lyrtech software-defined radiodevelopment platform based on Xilinx-FPGA chip and TI-DSP chip show that digitalup/down converter is correct functionally and meets system design requirements.