The Design And Implementation Of Wireless DSSS System

In recent years, high-quality and reliable wireless video transmission is becoming the research focus. But the products available in the market are limited and can not meet the requirement for transmitting high quality video with long distance and fast movement. To resolve the big contradiction, a new wireless transmission system is urgently needed to be developed.The project is proposed under this background and the primary task is to implement a wireless transmission system from the hardware perspective. The system adopts superheterodyne architecture. It consists of intermediate frequency (IF) band and radio frequency (RF) band hardware design. The intermediate frequency band design adopts QPSK modulation technology to meet the requirement of fast moving transmission. The radio frequency band design adopts integrated microwave RF chips to the modules' design to achieve high transmission performance. In baseband, convolutional coder and viterbi decoder are used to improve the whole system's SNR.At first, the paper introduces wireless transceivers' different achitectures and their advantages and disadvantages.Then it introduces the basic theories of RF circuits design and the design techniques of each functional modules.Then the paper discusses the wireless transceivers' scheme in detail, including the design of IF band circuit and RF band circuit. The system structure is then confirmed according to the functional requirement. In this paper, the detailed hardware design is the most important content including the circuit design of IF part and RF part. For RF part, the hardware design for 340MHz RF transceiver is implemented. Meanwhile, simulation analysis is completed to some functional modules of the system before debugging the circuits, word. The rest content of this paper is to design a Viterbi decoder with FPGA technology. The emulated and synthesized results of this design are received by all kinds of EDA tools. Through these results the Viterbi decoder's correctness and practicability can be validated.In conclusion, an entire hardware design scheme is brought forward and implemented in this paper which has also passed the system test and transmission trial. This good result makes a solid base for the future system development.