Acoustic vector sensor consists of pressure and particle velocity sensors,which measure the three-dimensional acoustic particle velocity,as well as the pressure at one location at the same time.By preserving the ampli...Acoustic vector sensor consists of pressure and particle velocity sensors,which measure the three-dimensional acoustic particle velocity,as well as the pressure at one location at the same time.By preserving the amplitude and phase information of the pressure and particle velocity,they possess a number of advantages over traditional scalar sensors.Signal-to-noise ratio (SNR) gain (which is often called array gain) is one of such advantages and is always interested by all of us.But it is not unchangeable if the spatial correlation of the noise field varies.Much more important,it is difficult to be given if the noise becomes complex.In this paper,spatial correlation of the vector field of isotropic volume-noise and surface-generated noise has been introduced briefly.Based on the results,the combined SNR output of a vector linear array is investigated and the maximum gain is given in the specified noise.Computer simulation shows that the output of one array in the same noise is not the same in different gestures.And then we find the best gesture through SNR calculation and obtain the biggest gain,which has important meaning to guide how to deploy an array in practice.We also should use the array with respect to the characteristics of the real ambient noise,especially in anisotropic noise field.展开更多
The Anhui Experiment, a pilot experiment of "Yangtze River Geoscience Project "conducted in October,2015,is a large active-source experiment using airgun sources. It was the first 3-dimensional seismic surve...The Anhui Experiment, a pilot experiment of "Yangtze River Geoscience Project "conducted in October,2015,is a large active-source experiment using airgun sources. It was the first 3-dimensional seismic survey with active sources in the Yangtze River. The sources are airguns in 20 fixed shot points,and the observation system consists mainly of109 permanent stations and 11 wide-angle profiles. Using the data from permanent stations,we investigated the seismic signals generated by airgun sources in the Yangtze River. The results show that the airgun signals are observable in the records from permanent stations to a maximum distance of 300 km. Further analysis on absolute amplitude of airgun signals shows that:( 1) the strength of airgun signals is of the order of10 nm at 50 km away from the source,and then,decreases significantly to less than 1nm at 200 km;( 2) an azimuthal anisotropy is observed in spatial distribution of the strength of airgun signals,which may be related to the geometry of Yangtze River; and( 3) a low ambient noise level is essential for retrieving weak airgun signals from the records,and the high-quality China National Seismic Network and regional networks offer a great opportunity to retrieving airgun signals with amplitude as small as nanometers.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No.50909028
文摘Acoustic vector sensor consists of pressure and particle velocity sensors,which measure the three-dimensional acoustic particle velocity,as well as the pressure at one location at the same time.By preserving the amplitude and phase information of the pressure and particle velocity,they possess a number of advantages over traditional scalar sensors.Signal-to-noise ratio (SNR) gain (which is often called array gain) is one of such advantages and is always interested by all of us.But it is not unchangeable if the spatial correlation of the noise field varies.Much more important,it is difficult to be given if the noise becomes complex.In this paper,spatial correlation of the vector field of isotropic volume-noise and surface-generated noise has been introduced briefly.Based on the results,the combined SNR output of a vector linear array is investigated and the maximum gain is given in the specified noise.Computer simulation shows that the output of one array in the same noise is not the same in different gestures.And then we find the best gesture through SNR calculation and obtain the biggest gain,which has important meaning to guide how to deploy an array in practice.We also should use the array with respect to the characteristics of the real ambient noise,especially in anisotropic noise field.
基金jointly supported by the Fundamental Research Funds for Central Public Welfare Research Institutes(DQJB15B09)National Natural Science Foundation of China(41574052,41374070)Academician of Chen Yong Workstation Project of Yunnan Province(2014IC007)
文摘The Anhui Experiment, a pilot experiment of "Yangtze River Geoscience Project "conducted in October,2015,is a large active-source experiment using airgun sources. It was the first 3-dimensional seismic survey with active sources in the Yangtze River. The sources are airguns in 20 fixed shot points,and the observation system consists mainly of109 permanent stations and 11 wide-angle profiles. Using the data from permanent stations,we investigated the seismic signals generated by airgun sources in the Yangtze River. The results show that the airgun signals are observable in the records from permanent stations to a maximum distance of 300 km. Further analysis on absolute amplitude of airgun signals shows that:( 1) the strength of airgun signals is of the order of10 nm at 50 km away from the source,and then,decreases significantly to less than 1nm at 200 km;( 2) an azimuthal anisotropy is observed in spatial distribution of the strength of airgun signals,which may be related to the geometry of Yangtze River; and( 3) a low ambient noise level is essential for retrieving weak airgun signals from the records,and the high-quality China National Seismic Network and regional networks offer a great opportunity to retrieving airgun signals with amplitude as small as nanometers.
