Application Of Laser Data’s Mdodulation Transmission Technology On CTP System

With the rapid development of economy and technology, the society’s requirement is getting higher and higher, such as quality of printing, efficiency on producing, resource’s utilization and environmental protection. The CTP technology has got developed rapidly with its unique advantages; and it is focused by business on printing plate. According to the actual needs of the CTP system, this paper proposes to use the technology, modulating laser to transfer data, to achieve the functionality of high-speed as well as real-time transmission data during plate-making, combined with the optical wireless communication technology. This article describes the method of modulation on laser in detail, and analyzes the principle of modulation and symbolic structure, which we use variously. Also, it studies on power’s utilization, the ratio between transmission rate and bandwidth, errors’ characteristic with simulation. So these basic theories pave the way for the selection of appropriate modulation. This article also expounds the encoding and decoding method on RS code, and analysis the process of decoding in the point on mathematic in detail. It also simulates the ability on error correction for RS code. And, this paper designed the hardware circuit for transmitter and receiver. The hardware uses FPGA as the core controller, combined with laser driver module, amplifier module and signal recovery module, to achieve the function of laser emitted, receiving and recovering signals. This author uses hardware description language to program the FPGA, completing the control of data cache, PPM modulation and demodulation, RS encoding and decoding, and control on overall timing. And then the author simulates the key modules.