Multi-rate Multimodal Key Techniques Of Digital Intermediate Frequency Receiver

With the rapid development of modern communication technology, communication systems from analog to digital become a trend. Traditional digital receiver systems with single mode and fixed structure could not effectively interconnect with each other. The digital receiver architecture based on software defined radio, which provided a satisfactory solution to this problem, has been paid more and more attention. The structure is characterized by fixed hardware platform with software programming only way to achieve various functions, in line with the strong universality requirements of modern communication. Therefore, many domestic and foreign researches have focused on multi-mode, multi-channel, multi-rate IF digital receiver based on software defined radio. The techniques of signal processing to receive have emerged as the times require and have important application prospect.In this dissertation, relying on a scientific research project, the techniques around IF digital receivers of multi-mode signal channelized separation and multi-rate signal processing are researched and designed. The thesis paid more attention on the efficient optimization of filter design and realization. The work is shown as follows.First of all, on the basis of the described the basic principles of multi-rate and multi-mode, focused on efficient filter structure which is suitable for multi-rate signal processing in order to saving resources.Secondly, in accordance with the requirements of project, selecting an architecture framework based on software defined radio technology of IF digital receiver. On the basis of this framework, analysis the various modules of the system and the parameters were further refined and qualified.Thirdly, depending on system design, the multi-channel signal separation module and the multi-rate signal processing module are researched, designed and simulated. For the separation of different pass-band signals into multi-channel, the digital down conversion channel separation structure is carried out to design and simulation by using MATLAB. For multi-rate signal processing part, proposeing a modified method which parameters are set and controlled by software programming. The study of continually sample rate conversion structure is focused on, which simulated and tested by using MATLAB.Finally, selecting the key devices of the FPGA development board to keep up with the needs of IF digital receiver requirements. With a fixed hardware platform, the channel separation structure, CIC filter module, HB filter module, FIR filter module and interpolation filter module were designed on the FPGA respectively with software programming. The results prove that the chosen structure with practical value has good performance.