Cdma Experimental Teaching System Design And Implementation Of Technology Research

Spread spectrum is a technology in which applied of spread spectrum technology to realize location and encrypted communication. It was first used in military and mainly to improve the system ability of anti-interference and confidentiality. With the rapid development of communication technologies, the ITU has putted the theory which based on spread spectrum code division multiple access (CDMA) technology as one of the third generation mobile communication system standardized protocol, therefore it's solid position in the mobile communications has been established. This marked the spread spectrum communication technology has entered a new stage.It is not only played an irreplaceable role in military communications, but also extensively infiltrated into all areas of civilian communications, such as:mobile communication, radio positioning systems, satellite communications, microwave communications, global personal communications, wireless LAN and so on.The goal of this paper is to achieve an experiment communication system which based on CDMA spread spectrum and can provide users with a good experimental platform to learn spread-spectrum communication technology. In this paper we achieve the software and hardware design of experiment system primarily through the following aspects,First, we gave an overview of the basic principles of spread spectrum communication and the development of CDMA technology, also we introduced programmable logic devices and Verilog HDL hardware description language. Then we proposed experimental system design, including the source module, convolution encoding and decoding modules, interleave and deinterleave modules, spread-spectrum code module, code synchronization module and modem modules, and focused on describing a modified Costas Loop to extract the carrier technology and the use of digital phase-locked loop to extracted bit synchronous clock technology.At last,we realized the above modules in hardware description language and downloaded it to the hardware test platform to achieve its function. This paper also gave waveforms of key points from simulation and the actual circuit.