Design Of High Speed Logging Cable Communication System Based On Power Line Carrier

Well logging is an important method and technology for exploration and development of mineral resources,and plays an important role in safeguarding national mineral resources reserves.In logging work,high-speed and accurate communication is needed,and power supply is needed for downhole instruments and equipment in the meantime.The current logging communication system generally relies on the use of multi-core cables to achieve data communication and equipment power supply respectively..The length of logging cable is generally between several hundred meters and several thousand meters.Using this method not only increases the cost of cable,but also greatly increases the weight and volume of cable,and also brings difficulties to the loading,unloading and transportation of logging instruments..In the limited wellbore space,it will bring a lot of inconvenience to logging work.At present,some logging probes(such as natural gamma total logging tool)have begun to use single core logging cable to complete power supply and data transmission in order to pursue simplicity and ease of use.With the development of science and technology,the integration degree of chip and system becomes higher and higher,and the volume and weight of corresponding instruments(such as probe)become smaller and smaller.Some other types of logging probe(such as natural gamma ray spectrometry logging tool)also need to use single core logging cable.The introduction of power line carrier communication technology into logging communication system only requires the use of single core cable to complete the communication of long-distance and large data.With its unique advantages,power line carrier communication technology has gradually become the main communication mode in the power system of various countries.After years of development,this technology has greatly improved in communication speed,communication distance and other aspects.At present,the high-speed broadband low-voltage power line carrier chips on the market have advantages in communication speed,but the development of this kind of product is difficult and the development cost is very high.in addition,Its working stability also needs to be improved..In logging communication system,it is not the pursuit of high-speed rate rarely.The reliability and cost of communication are important factors to be considered.Narrow band power line carrier communication technology has the advantages of simple circuit structure,stable operation and low development cost,so it is more suitable for well logging communication system.But at present,the narrow-band power line carrier communication products of domestic enterprises needs to be strengthened in communication rate,distance and bit error rate.These aspects are also the main reasons restricting the development of the technology.If a large amount of data such as energy spectrum is to be transmitted in a long distance and high speed,the existing products are difficult to meet the demand.Based on the theory of power line carrier communication,the logging communication system designed in this paper uses TMS320F28335 DSP Microprocessor as the main controller,square wave as the carrier,and 2ASK modulation to modulate the carrier wave.At the receiving end,The pulse acquisition function of DSP is used to detect and count the pulse generated after the carrier passes to determine whether the carrier exists or not,,and then to determine "0" or "1" corresponding to the original binary data to decode the baseband signal.The system has a simple circuit structure,strong fault tolerance,accurate and reliable data transmission,and stable performance.The test in the laboratory shows that the baud rate of the system is up to 57600 bps,the communication distance is long,.The system can meet the application requirements of various logging operations for communication rate and working stability.