It′s generally believed that the appropriate stimuli for sound field tests are warble tones and narrow band noise, while pure tone can only be a signal used in the free field and earphone listening conditions. In thi...It′s generally believed that the appropriate stimuli for sound field tests are warble tones and narrow band noise, while pure tone can only be a signal used in the free field and earphone listening conditions. In this study, we take a measurement of sound pressure distribution, sound field variability, and effects of frequency shifting on sound pressure levels (SPLs) at reference points of pure tone in an audiometric test room. It was found that the pure tone SPLs were also distributed uniformly at some sound field areas although it was not so well as warble tones. This indicated that the test results were relatively stable to head movement and/or frequency shifting in those regions, which was confirmed by the clinical measurements on 20 subjects with severe sensorineural hearing loss. Our study concluded that pure tones could also be suitable for sound field audiometry if subjects were seated at a proper location on the basis of the sound field calibrations.展开更多
GF-14 satellite is a new generation of sub-meter stereo surveying and mapping satellite in China,carrying dual-line array stereo mapping cameras to achieve 1∶10000 scale topographic mapping without Ground Control Poi...GF-14 satellite is a new generation of sub-meter stereo surveying and mapping satellite in China,carrying dual-line array stereo mapping cameras to achieve 1∶10000 scale topographic mapping without Ground Control Points(GCPs).In fact,space-based high-precision mapping without GCPs is a challenging task that depends on the close cooperation of several payloads and links,of which on-orbit geometric calibration is one of the most critical links.In this paper,the on-orbit geometric calibration of the dual-line array cameras of GF-14 satellite was performed using the control points collected in the high-precision digital calibration field,and the calibration parameters of the dual-line array cameras were solved as a whole by alternate iterations of forward and backward intersection.On this basis,the location accuracy of the stereo images using the calibration parameters was preliminarily evaluated by using several test fields around the world.The evaluation result shows that the direct forward intersection accuracy of GF-14 satellite images without GCPs after on-orbit geometric calibration reaches 2.34 meters(RMS)in plane and 1.97 meters(RMS)in elevation.展开更多
Based on the laboratory calibration before launch of CBERS-02 IRMSS thermal infrared channel,the onboard blackbody calibration,the radiometric cross-calibration against TERRA MODIS corresponding channel and the in-fli...Based on the laboratory calibration before launch of CBERS-02 IRMSS thermal infrared channel,the onboard blackbody calibration,the radiometric cross-calibration against TERRA MODIS corresponding channel and the in-flight field calibration at Lake Qinghai:water surface radiometric calibration test site of China on Aug.17,2004 are carried out in this research.When making onboard blackbody calibration of CBERS-02 IRMSS,it is necessary to understand inside structures and light path in IRMSS camera and receive and process calibration blackbody signals at normal and high temperatures.Onboard blackbody calibration results of each detector are very important to relative radiometric calibration of images processing and absolute radiometric calibration of each detector.In-flight field calibration mainly contains field experiments,obtaining synchronous images,spectrum marching and MODTRAN radiative transmi-ssion computation.Radiometric cross-calibration of CBERS-02 IRMSS thermal band against TERRA MODIS selected 6 times synchronous images of two sensors passing through Lake Qinghai and Lake Taihu from August to December,2004 to compute the cross calibration data.Combining the in-flight field calibration and radiometric cross calibration data,the absolute radiometric calibration coefficients are calculated by the linear regression method.This new calibration model can obviously control the radiometric calibration uncertainties aroused by the single point method used in the in-flight calibration of CBERS-02 IRMSS,this kind of sensors cannot receive the cosmic background radiation.In this research,the radiometric calibration coefficients obtained through the linear regression model are 8.53(gain,unit:DN/W m?2sr?1μm?1)and 44.92(offset,unit:DN).展开更多
文摘It′s generally believed that the appropriate stimuli for sound field tests are warble tones and narrow band noise, while pure tone can only be a signal used in the free field and earphone listening conditions. In this study, we take a measurement of sound pressure distribution, sound field variability, and effects of frequency shifting on sound pressure levels (SPLs) at reference points of pure tone in an audiometric test room. It was found that the pure tone SPLs were also distributed uniformly at some sound field areas although it was not so well as warble tones. This indicated that the test results were relatively stable to head movement and/or frequency shifting in those regions, which was confirmed by the clinical measurements on 20 subjects with severe sensorineural hearing loss. Our study concluded that pure tones could also be suitable for sound field audiometry if subjects were seated at a proper location on the basis of the sound field calibrations.
基金Independent Project of State Key Laboratory of Geo-information Engineering(SKLGIE2022-ZZ-01)The Youth Science Innovation Fund(No.2023-01)。
文摘GF-14 satellite is a new generation of sub-meter stereo surveying and mapping satellite in China,carrying dual-line array stereo mapping cameras to achieve 1∶10000 scale topographic mapping without Ground Control Points(GCPs).In fact,space-based high-precision mapping without GCPs is a challenging task that depends on the close cooperation of several payloads and links,of which on-orbit geometric calibration is one of the most critical links.In this paper,the on-orbit geometric calibration of the dual-line array cameras of GF-14 satellite was performed using the control points collected in the high-precision digital calibration field,and the calibration parameters of the dual-line array cameras were solved as a whole by alternate iterations of forward and backward intersection.On this basis,the location accuracy of the stereo images using the calibration parameters was preliminarily evaluated by using several test fields around the world.The evaluation result shows that the direct forward intersection accuracy of GF-14 satellite images without GCPs after on-orbit geometric calibration reaches 2.34 meters(RMS)in plane and 1.97 meters(RMS)in elevation.
基金suppor ted by the Hundred Talents Program of CAS(Grant No.KZCX0415)the Scientific Research Foundation for the Returned Overseas Chinese Scholars of the State Education Ministry(Grant No.HX040013)Commission of Science Technology and Industry for National Defense(Grant No.KHSX0401).
文摘Based on the laboratory calibration before launch of CBERS-02 IRMSS thermal infrared channel,the onboard blackbody calibration,the radiometric cross-calibration against TERRA MODIS corresponding channel and the in-flight field calibration at Lake Qinghai:water surface radiometric calibration test site of China on Aug.17,2004 are carried out in this research.When making onboard blackbody calibration of CBERS-02 IRMSS,it is necessary to understand inside structures and light path in IRMSS camera and receive and process calibration blackbody signals at normal and high temperatures.Onboard blackbody calibration results of each detector are very important to relative radiometric calibration of images processing and absolute radiometric calibration of each detector.In-flight field calibration mainly contains field experiments,obtaining synchronous images,spectrum marching and MODTRAN radiative transmi-ssion computation.Radiometric cross-calibration of CBERS-02 IRMSS thermal band against TERRA MODIS selected 6 times synchronous images of two sensors passing through Lake Qinghai and Lake Taihu from August to December,2004 to compute the cross calibration data.Combining the in-flight field calibration and radiometric cross calibration data,the absolute radiometric calibration coefficients are calculated by the linear regression method.This new calibration model can obviously control the radiometric calibration uncertainties aroused by the single point method used in the in-flight calibration of CBERS-02 IRMSS,this kind of sensors cannot receive the cosmic background radiation.In this research,the radiometric calibration coefficients obtained through the linear regression model are 8.53(gain,unit:DN/W m?2sr?1μm?1)and 44.92(offset,unit:DN).
