The Design And Simulation Of The Communication Modem Of The Well Data Acquisition System

Low voltage power line carrier technology is a communication method developed in recent years using low power lines as a medium of communication way.Having been generally applied in public life,if can use power lines as existing resources in fields such as the implement of communication,it will be more convenient in many areas including bank,enterprise,the public life.At the same time,power lines carrier technology,in addition to its common recognized stability,has compliance for multiple carrier forms.Besides,it can be flexible to deal with complex noise advantages with power lines.In abroad,power line communication monitoring system has been used in the mid-range large-scale communication systems.In home,after a period of development the field of power line carrier study,it has approached mature in application products for large-scale power line communication,for example,electric meter reading system has been applied in some cities.The application of power line can be practical in oil well exploration systems.If there is possibility to utilize power line to implement the with the control and communication between up and down oil well systems,it will bring great convenience and benefit to the existing monitoring and control oil well system.Now,a lot of the exploring factories have carried on the experimental work of power line monitoring oil well system.In this article,using this technology,a system of communication is designed to assume the task of monitoring and controlling of the signal transmission.It is also responsible for the signal’s spread spectrum processing to increase the reliability of communication and reducing the bit error rate.Meanwhile,in the process of coupling and power lines,a pointed design of filter circuit is combined with IC,further reducing the noise interference.These works not only ensure the monitoring on the height of the inside tubing liquid surface in real-time,but greatly increase the perception in the mine environment as well.Therefore,a solid foundation is established for the stable and steady production.The main difficulty in the project of is the data transmission error caused by decrease of signal-to-noise ratio.When the power lines are used as a communication medium,signal attenuation will occur because of the effect of the AC noise on the data communication.However,choosing spread spectrum tech as the communication method is able to exclude the random disturbance on power lines in respect of other approaches,because its spread spectrum carrier signal bandwidth are usually broader(decades to a few hundred kHz).Therefore,the proportion of interfere-affected frequency range is the relatively smaller.In addition,the system employs the working method of SSCP485 chips through the micro compute unit.This reduces the size of the integrate circuit and promote the overall high temperature resistant performance.In the actual experiments on 1200m long power lines carrier communication,it is correct for data signal to transmit and receive below the ESR 10 exp-5.This proves the spread spectrum communication can solve the noise interference problems perfectly in power lines carrier communication.Meanwhile,it is proved that the system has stable and reliable performance in signal transmission and receiving,AD transform,serial communication between MCU and PC.This paper firstly introduces the background of the low voltage electricity lines carrier and domestic and international research achievements,then the low power lines carrier technology is introduced in detail.After that,the spread spectrum carrier technology is introduced and illustrated.Next will be the hardware circuit design and software structure.Finally we analyze the result of the experiment and simulation.