Design And Implementation Of The Multimedia Transmission System Based On PLC

Power line carrier communication is becoming more and more popular and an ideal choice for information transmission network due to its features, such as low cost, high coverage without re-wiring and so on. Power line carrier technology has been expanded in a wide range, but most confined to switching value control, automatic data logging, smart home and so on, with short rate and small information bearing capacity. With the rapid development of digital technology, the increase of the rate in transmission network and the expansion of information content can be realized by means of digital processing. With previous experience, this paper designs the power line carrier transmission system based on P300/JPEG300 by using power line carrier chip P300 as well as digital image compression technology.Firstly, this thesis gives an analysis and a contrast of the advantages and disadvantages of the currently various common transmission medium in the introduction, in order to give reasons for adopting low-voltage power line as transmission medium and exemplify the significance of this task.Secondly, in Chapter Two, this thesis makes a generalization and summarization about the two key technologies this task involves:power-line carrier communication technology and JPEG image compression technology. Among them, a qualitative analysis is made about the difficult problems of technology of interference and attenuating property in power line transmission, which then pertinently introduces spread spectrum communication technology to solve obstacles encountered in power-line carrier. It studies and researches about the working principle of image compression, summarizes the technical characteristics of image compression chips, introduces the performance parameter of chips and explains the functions and tasks of chips in the system module.Afterwards, this thesis proposes the analysis and design of system module in Chapter Three and provides the network layout diagram of the whole system. It divides the transmission system of power-line carrier image into two modules, i.e. transmitter and receiver, and divides each module into several small functional modules. With the basis of information flow trend, it gives an introduction of every functional unit in every module, which could serve as the foundation for the following realization process.Then, in Chapter Four and Chapter Five, this thesis accomplishes the hardware and software design of the whole system. In the hardware design, it has adopted SCCP300 as the dedicated chips to realize this equipment, and it also gives a detailed analysis about the selected power-line carrier chip and image compression chip. What follows next is that the selected chips are recruited to accomplish the two types of experimental facilities, i.e. acquisition end and transmission end. Based on the characteristics of power-line carrier communication, signal amplifying circuit, filter circuit and power interface are specifically designed. For all the above hardware design, the designer has demonstrated the structure diagram and hardware illustrative diagram. In the software design, an overall planning is carried out for the functions that the software is to realize. The whole task is divided into several task modules, including read-write procedure of power-line carrier chip, SCM control procedure (receiving and transmitting), as well as image acquisition and display procedure. Software function is also tested, and the quality of the received image is visually measured.Lastly, in Chapter Six and Chapter Seven, this thesis conducts testing and summarization about the system. In the testing part, the system is placed in the environments of different power network loads and different transmission distances. Through the comparison of images gained from power-line transmission, the reliability condition of this system is achieved. Finally, it makes a conclusion about this system's deficiency and looks into its development trend.