Queuing System Based On Power Line Communication

Grounded on the modern micro-controller, electronics and multi-machine network communications technologies, this thesis proposes a Power Line Carrier Communication (PLCC) based electronic Queuing System. It explores and applies the program of a PLCC with spread spectrum communication as the method of modulation and demodulation, and accomplishes a substantially applicable electronic Queuing System. The advantages of such system are as follows.First, the system realizes the lower layer communications by PLCC. It has been proved in reality that a PLCC based on spreading spectrum modulation and demodulation can achieve a higher communicating rate and a lower bit error rate. When applied in the Queuing products, it will erase the encumbrance of second routing in the installation of the products with RS485, and will free the problem of the operating failure, which is due to the liability to interference in Queuing System based on open frequency wireless communications.Second, the system employs, in the program of PLCC's design, a spectrum modulation and demodulation chip, which, independently researched and developed by China, is particularly designated for China's Power Grid structure. It on one hand cuts down the cost of the system by its competitive price and, on the other hand, is able to achieve a favorable performance in communication.Third, a micro-controller of lower price, out of other options, is chosen in the system, in which, meanwhile, a single MCU is designated to perform as many tasks as possible. Functions, such as the call terminal's control over the IC card, the control over the decoding of PS/2 keyboard protocol and the communication protocol in lower layer, are all accomplished by a single AT89S52. hi all a more stable and effective system will be established on a lower cost.Last, the system can work independently from computer. The dispatch software merely operates in a single MCU, a way that can cope with the situation inappropriate to lay a computer.By and large, the thesis researches an electronic Queuing System that is able to root out the problems which are afflicting the current products of Queuing System. Being a competent substitute of the serving products, it shows a promising future in its application.