If Digital Receiver Design

The digital intermediate frequency (IF) technique is developing at the top speed at present. IF digital receiver has become one of the most important parts of radar system, communication, measurement and control system. Therefore, the IF digital receiver has been paid the focus attention among the researchers.From the practical use of the engineering, and based on specific technical index requirements, IF digital receiver based on SDR has been researched in this thesis, including intermediate frequency amplitude modulation signal sampling, down conversion and demodulation.Conventional receiver depends on hardware much more. The emergence of software radio results in receiver's renovation. SDR is based on a versatile programmable platform to realize all kinds of criterions and communication mode, to meet requirements of many increasing new models and functions. The agility of systems is highly improved. But the ideal SDR can hardly be realized now because of the deficiency of the electronic devices and technology in present day. As a compromising method, a SDR receive platform based on direct mid-frequency band-pass sampling is researched in this thesis, which is one of the feasible software radio systems nowadays.In hardware design, the ad6645 and ep2c5tl44c8 were taken as the core devices and at the same time, the data acquisition circuit, the digital down-conversion circuit and some associated peripheral circuit have been realized in this thesis.In software design, the digital down converter module were established based on ep2c5tl44c8 including numerical control oscillator modules, mixing modules and extraction filtering module.The hardware circuit and software design are the core of the whole system. After debugging, the system can finish these tasks of the sampling AM signal, down-conversion, demodulation. The experiment results show that the performance of the system is excellent and has a strong versatility and flexibility.