Software Radio Receivers Based On RF Passband Sampling

The traditional radio receivers rely on the hardware strongly, there are many disadvantages such as the cycle of the function expand and the perfection of their hardware platform is long, the cost is high and the generalization to different communication systems and the adaptability to different communication signals are too bad. The appearance of the SDR (Software Radio/Software-Defined Radio) has offered a new idea and method to design and implement the multi-function wireless communication systems, which can overcome and solve these defects and problems of the traditional hardware radio receivers. The SDR will have wide development prospects.The digitized technology of the signal is one of the key technologies of the software radio, there are three kinds of digitized schemes currently which are the RF whole breadth lowpass sampling, the broadband medium frequency passband sampling and the RF passband sampling directly. Under the current hardware engineering level, the broadband medium frequency passband sampling is widely used, but the RF passband sampling directly is most close to ideal software radio. Based on the foundation of software radio, how to design the RF passband sampling receivers is expounded, the hardware structure and key technology of receiver are researched, a single channel software radio receiver structure is designed and simulated. The simulation results proved the feasibility of SDR technology.The process of implementation is: Sample the modulated signals with the frequency of 0.5MHz~1000MHz according to the principles of the radio frequency passband sampling directly, and demodulate them with the coherent detector and programmable logic device FPGA. The total design is based on the ISE developing platform of XILINX Company, and the realization is in Virtex-II series FPGA. In this way, the size of the modulator and demodulator is small, the power dissipation is low, the integrated level is high, the system can be software-upgrading and has strong anti-interference ability. Therefore the scheme in this paper accords with the developing direction of the future communication technologies.