Study Of Transmission System Of The Sensor Signals Based On The Power Line Carrier Communication

In the detection and control of the modern production process, sensor signal acquisition is one of the most common and important projects. Some measurement and control systems which measure devices and sensors are far away from computer control system. At present, the methods widely used includes the radio transmission, cable systems and the infrared transmission. But the radio transmision occupies the wireless frequency resource, cable system costs too much and the infrared transmission can't pass through the walls to realize the centralized control of all the equipments. And the infrark is fairly abundant and dependent. If power line communication (PLC) is used, then energy flow and information flow can be used simultaneously. That is to say, the problems caused by other methods can be solved.This paper mainly discusses a new application in sensor signal transmission system based on the technology of power line carrier communication. The entire system consists of three parts, including sensor data acquisition unit, single chip main control module and the transmitting and receiving unit by power line carrier. Fisrtly, sensor signals are converted from analog signals to digital signals through A/D converter;secondly, the digital signals we just obtained will be modulated by BPSK modulation technology. Thirdly, modulating signals will be coupled to the low-voltage power line network through carrier transmitting circuit;then modulating signals will be transmitted to the designated receiver through the low-voltage network;finally, modulating signals will be separated by demodulation, signal coupling circuit and carrier receiving circuit. 16-bit A/D converter chip AD7715, applied in the sensor data acquisition unit,has programmable gain amplifier on chip to amplfy the small signals in the sensor for transmiting A/D. Single chip main control unit has the capacity of achieving the control of AD7715 with ST89C516RD+, while coordinating the transmitting and receiving of power line carrier. The peripheral circuit is designed based on the chip RISE3401. And the chip, employs Binary Phase Shift Keying BPSK with high speed data transmission. According to the designed hardware circuit, relative software is compiled and the tests about the hardware and software are carried out.Power line carrier signal transmission test is carried out within distribution transformers' region. The test results show that the system can send and receive the data without error in a certain distance , which can transmitte the sensor acquisition signals effctively. Based on the summary of the full paper, this topic not only analyzes the current problem in carrier transmission systems, but directs the further research.