Research And FPGA Implementation Of Digital Spread Spectrum Receiver

With rapid development of modern communication technology, the confidentiality of communications performance, anti-interference ability of the increasingly high demand, resulted in a spread-spectrum communication technology. At present, the spread spectrum communication technology in military communications and civilian communication has been widely used, are currently the core technology of the third-generation mobile communications standard. Because of the rich logic cells, high integration and flexibility in configuration and many other advantages of FPGA, It has been widely used algorithm implementation and verification of prototype products. Spread spectrum communication system needs high-speed and complex signal processing, high-speed processing capability of the FPGA makes spread spectrum communication system of the chip possible.The despreading and demodulation of the digital spread-spectrum receiver was discussed, the ability of spread-spectrum technology to improve system performance was analyzed, the principles and methods of realizing the DSSS based on FPGA was deeply studied in the paper at first; To compare with a variety of program implementation, a despreading program was determined; Finally an digital spread-spectrum receiver was designed and realized. With Protel99SE instrument, the functional structure of the system hardware design, power integrity design was completed; with QuartusII 6.0 software platform, a quick capture system, PN code tracking system, despreading demodulation modules, FPGA embedded block RAM storage and PC interface module design was completed, which capture system used a fast parallel digital matched filter and PN code tracking system used early late tracking loop delay door.The implementation methods and processes of direct sequence spread spectrum receiver based on FPGA were detailed in the paper. In accordance with FPGA high-speed parallel processing capabilities and characteristics of the entire hardware implementation, Both the schematic diagram and the VHDL language were used to design, as well as Megafunction. Finally a digital spread spectrum receiver was designed and implemented based on the Cyclone chip of ALTERA Company. Experimental results show that the receiver system is running stable and reliable and meet the requirements of the pre-performance index.