The Experiments About High Resolution And Low Drift Of Seismic Data Acquisition

Nowadays, large dynamic and broadband are the most important technical features of the observation and detection of earthquake, of which the critical device is a feedback seismometers and data acquisition unit. Digital seismic data acquisition is an important part of digital earthquake observation, its core function is to convert analog signals form seismic sensors into digital signals, the level of analog-digital converter technology determine the quality of the data observed to a large extent. In such a technical level, inherent low-frequency noise in semiconductor chips influenced the observation of long period, and it has became a further important factor for improving the level of observation, in the meanwhile, it also affect various factors for improving the level of observation of earthquake precursors. All the said noises, of which the internal noise of electronic devices (especially 1 / f noise is represented by low-frequency noise) is the key indicators which restrict device sensitivity and detection accuracy.In this paper, based on the technical analysis of analog-digital converter, several popular analog-digital converter in recent years were described here, the requiredΣ-ΔA / D converter was selected correspond to experimental performance characteristics, and analyzed the "AutoZero" feature of the high-resolution digital multimeter, and the noise tests were done in both open and close cases to find impacts on the noise respectively. noise test of laboratory data acquisition EDAS-24IP device were compared, based on single-input, differential inputs, etc. our experimental program were obtained after comparing, i.e. take advantage of the use of pre-switch method to eliminate and reduce the noise, and simulation tests were studied.After the analysis of the 1/f noise in theory, in three aspects of switch program, sampling rate conversion and over-sampling, a comprehensive possibilities of the feasibility of program. Several chips were chosen after a careful comparative study of mainstream chips, including the AD chips audio PCM4222, which was applied to seismic data acquisition, is also a major innovation of this article. And the design and implementation of the circuit were finished, after system test of program, the powerful evidence of decrease or elimination of 1/f noise were obtained, the results were corresponding with the previous theoretical analysis.The purpose of this paper is applying audio 24-bit ADC chip to design a technology solutions with a high resolution and low drift seismic data acquisition. And the application of the modulation-demodulation technology convert slow voltage quantity into audio signal, and take advantages of the amplifier chip and ADC chip by their excellent features on audio band, from the square wave and pseudo-random methods, both of them proved the said results, moreover, circuit wafer was finished. The test and comparison from final circuit, got the desired results were obtained.