Study On High-Speed Reliable Data Transmission For Oil Seismic Exploration

Oil is the most important strategic resources, with the development of science technology and the improvement of living standard. With the high-speed development of economy, the demand for oil is on the increase. Oil is a restrict factor which has effect on the national economic plan, development and the society stable. Seismic exploration has been taken as an important measure to oil exploration. More than half of the oil exploration is seismic exploration. Based on the characters of complex geological environment, High Accuracy and High Density Seismic Exploration are the direction and inevitable choice for future seismic instrumentation.Fast Ethernet and RS485 is widely used is seismic instrumentation design, but they cannot gratify demand of development of the seismic instrumentation. Gigabit Ethernet will play an important part in the data transmission of seismic instrumentation. OSI/RM protocol and TCP/IP protocol which realizes Reliable data transmission has been used in the data transmission of seismic instrumentation. According to Pitcairn: processing 1bit TCP data use about 1 Hz CPU under 100Mbps. With the higher transmission speeds processing 1bit TCP data consume more than 1 Hz CPU. If the old agreement is still in used, higher performance is required for the data-processing ability of CPU. According to the test, the throughput of TCP/IP is 220Mbps by using PowerPC which is working in 400Mhz. Using more powerful CPU will bring the increasing power, volume, cost and other issues. Based on the characters of seismic data transmission, the methods that software protocol optimization and hardware accelerators are used to reduce the burden of CPU and increase the throughput of data. The main specific works are:According to the character of data transmission of seismic, a Proprietary protocol is designed and achieved. By using the protocol the data processing ability of CPU is maximized. Analyzed traditional data transmission protocol, and according to the character of seismic data transmission, an optimization module is designed. Based on this model devised a highly efficient data transfer protocol, during the implementation, the mac driver is optimized by interrupt merging, and Combined with a simple routing. The reliability of data transmission is achieved by using group waiting and resending choosing. A method which is similar Token Ring is combined whit group waiting and choosing resending and this method Provide a traffic control. The new protocol that named RHDE (reliable high speed data transmission protocol) can increase the data transmission speed and achieve Reliable transmission. Test shows the speed by using RHDT protocol is up to 920Mbps.Parts of the protocol stack use the hardware features to reduce CPU burden. Reliability checking and data resend module is completed in FPGA. By this way the CPU burdens is offload. For reliable transmission CPU is assisted with the FPGA. By this way, the ability that FPGA handle events in parallel is fully used. Not only the transmission efficiency which compared to pure software has been improved, but also reduced the consumption of CPU in data transmission.The result is expect to reach the limit speed of Gigabit Ethernet.This paper is divided into the following chapters.Chapter I is introduction, introducing the development and current status of seismic instruments and research purpose and meaning.Chapter II is introduces the direction of seismic instruments -- large number and small group interval. Then we introduced the data transmission mode which used in seismic instruments. And combined the data transmission characteristics of seismic, the using prospect of the Gigabit Ethernet is also been discussed.Chapter III describes the efficiency of several reliable transmission strategy .And the reliable transmission strategies which is used in TCP/IP and reliable UDP is analyzed. We proposed that the original agreement is no longer appropriate to the new seismic instruments. A new protocol which is combined data transmission characteristics of seismic instruments is required.Chapter IV designed a new protocol model with Cross-layer design. The new protocol is carry out. The new protocol has the reliable transmission, flow control function and include a simple routing capability. A method which is similar Token Ring is combined with group waiting and choosing resending and this method provide a traffic control. A high efficiency can archive by using the method above. Chapter V proposed using FPGA hardware-assisted transfer to achieve reliability data transmission to solve the high usage of CPU and the defects that cannot do parallel data processing. The designed the reliability of the transmission model. Finally, the feasibility of the model is tested through the emulative result.Chapter VI is a summary of this paper, and concluded that further research directions.