Multi-channel Digital Downconverter Research And Design

Software Radio Technology is considered to be the third revolution in communications field, which is to be appeared after the analog to digital communications and behind the fixed communications to mobile communications. Software Radio Technology is also another new revolution from hardware to software. It is high time that people placed great emphasis on this technology in the military field and the civic area. As one of the core technology, Digital down converter is the point of the subject study in this thesis.Research is unfolded by focusing on digital down converter as one of the core technology. First of all, the reseach is based on mathematical theory and model. Following being tested adequately by using mathematical model, the circuits can be constructed by Verilog HDL(Verilog hardware description language) and be constituted into different module libraries. After being simulated by software, the simulating result of the circuit may be identical with the test result by using mathematical model. By contrast, the hare ware circuits of each module must be making optimization design and be reseaching deeply. In specific applications every module made by optimization design must be satisfied with the needs of the property in wireless communication system. And the research will become more common and applicative in the engineering field, and establish the platform of software and hardware for designing wireless software.The module of digital down converter is composed by NCO(Numerically controlled oscillators),CIC(Cascaded integrator comb) filter, HB(Half-Band) filter and FIR(Finite Impulse Response)filter. This thesis is based on researching every module. Several filters are designed by the structure, which is high effective extraction yield, for decreasing resource of the filters and operating the DSP at the same time. The method of LUT(Look Up Table) must be set for appropriate use of resource in FPGA. For the use of application, parallel transmission in multiple signal channels may be adopted.The method of reseach: Use the system design tool--DSPbuilder. It doesn't need to change the platform in the top of system construct design to complete the design, simulation, synthesis and download of the the NCO, HB filter, CIC filter and FIR filter. Verification of the whole function module can be used by mathematical model and electric design automation language.At last, every module can be constructed to achieve the digital up converter system. Download the data by Digital up converter to simulate the system and the function of RTL level for testing and verifying the correctness and the feasibility of this method are presented.