Development Of Line Acquisition Unit In Telemetric Digital Seismic Data Acquisition System

Seismic prospecting instruments are continuously updated as technology advances. Construction methods of seismic exploration in field determine the significant difference between seismographs and other geophysical instruments. Telemetry digital seismograph is a revolution within the geophysical instruments industry and is the preferred instrument of the deep Earth exploration and oil and gas exploration. Development of domestic equipment of independent intellectual property has great realistic significance. This paper examines the design principles of foreign types of instruments, and advances in electronic technology in recent years and put forward a telemetry circuit structure of line Acquisition Unit(LAU) in the digital seismograph solutions by comparison LVDS, RS485and PHY devices, the physical layer schemes.The paper includes four parts:(a) design of LAU and development of the circuit;(b) program writing;(c) repeat station the design;(d) data transfer testing to determine the stability of the instrument.The LAU circuit consists of three circuit boards:the interface circuit board, interface control circuit board and the main control circuit board. The interface control circuit board integrated LVDS, RS485and ksz8041interface. Interface control circuit board is made up with a Altera’s Cyclone III chip, integrated FIFO module and interface control board power supply module. The main control circuit board is made up with the PPC405core, PC104, Ethernet port and UART interface.The LAU’s program is writing in VHDL language and debugging in the QuartusⅡ8.0Integrated development environment (IDE). QuartusII8.0IDE provides a full set of FPGA development tools and complete help documentation. The program in LAU is composed of the MⅡ and MⅡM interface program, the physical layer data encoding and decoding procedures, the physical layer interface program.In the arrangement of data acquisition, repeater is similar to collection stations. Repeater is designed to achieve a low-power way. This article describes the advantages and disadvantages of the comparative Altera’s EP3C5E144and Actel’s AGL250in repeater design process.The most time is spent in stability testing of the instrument. I am limited to the design of the LAU because it’s a explore issues. There are some defects in the hardware and software in the instrument. Constantly reproducibility is help to identify problems and solve problems is good for improving the reliability and stability of the instrument.