In this article, a design method of asynchronous FIFO memory based on FPGA is put forward. With FPGA as the core controller, We adopt Verilog HDL and top-down design method to build a top-level module design and also analyze the mark logic of asynchronous FIFO and the elimination of semi-stable state under Quartus II development platform. Besides, with the application of Gray code conversion technology, not only the reliable transmission of data is guaranteed but also design efficiency is improved. Through contrast experiment analysis and simulation test, the validity and reliability of asynchronous FIFO memory are verified, meeting the basic requirement that FIFO can hold more enough data without spillovers despite the fullness of data.

Climate changes seriously affect people's daily life, extreme climate events continue to occur throughout the world during 1961-2008. This research 1961-2008 by 51 meteorological stations in Xinjiang, the precipitation and temperature data, show that rising temperatures continue to increase 0.08 degrees Celsius per year and precipitation continues to increase for the 0.71 mm per year in Xinjiang. Climate models were used PRECIS to simulate how the regional climate might change during the present century. The climate of Xinjiang was found to be likely to be even more problematic in the years 2080s than it is at present.

In this article, a design of multi-channel data acquisition system is presented. With FPGA as the core controller, the system can implement logic control over the high-speed ADC and acquire high-speed and high-resolution sample data. Using asynchronous FIFO as a cache, it can transfer data between two different clock domains: ADC data acquisition module and RS485 data module, which helps to improve the work efficiency and data throughput of the system. In the Quartus II development platform, Verilog hardware description language is adopted and finite state machine so that parallel acquisition operation to multi-channel ADC controlled by FPGA can be achieved and the system can become equipped with high-resolution, strong real-timeliness, low noise interference and other advantages. When it comes to the final step, simulation of AD sampling, asynchronous FIFO and RS485 transmission are conducted under the Modelsim environment and on-line testing by Signaltap to the system is synchronously implemented. The validity and reliability of the system are verified.

This work presented the design and implementation of a wireless acquisition system for seismic signal. 4 distributed signal acquisition stations were integrated to the low-power prototype which composed of 48 acquisition channels, and a star-shaped wireless network was built which is suitable for seismic data transmission using the networking mode of multi-pipe and multi-address switching. A distributed seismic data acquisition system was accomplished which has the function of synchronous control and asynchronous transmission. The key technical problems and solutions of time balance distribution between multi-channel time-sharing switching acquisition and temporary storage, and wireless seismic data transmission is analyzed in detail in this paper. Thus the additional accessories of traditional wired seismograph were greatly reduced, to improve its cable layout trouble and low efficiency of construction in an adverse environment. This system increased efficiency more than 50% and took same exploration effect compared with wired mode in the field application.

In view of the digital geophone self-test system application demand for a variety of high quality waveform signal. This paper introduces a kind of design method of direct digital synthesis waveform signal generator based on FPGA. It mainly discusses the principle of the method of frequency synthesis technology, design thinking and implementation method. And using the design method of pipeline structure to improve circuit structure of 48 bits phase accumulator, so as to improve the running speed, and further increase the resolution of frequency synthesis. The test shows that the signal generator can produce sine wave, square wave, sawtooth wave, triangle wave. The frequency resolution can reach 0.18μHz. The highest output frequency is up to 20MHz, and frequency switch time is 20ns.