According to the Doppler sensitive of the phase coded pulse compression signal, a Doppler estimating and compensating method based on phase is put forward to restrain the Doppler sidelobes, raise the signal-to-noise r...According to the Doppler sensitive of the phase coded pulse compression signal, a Doppler estimating and compensating method based on phase is put forward to restrain the Doppler sidelobes, raise the signal-to-noise ratio and improve measuring resolution. The compensation method is used to decompose the echo to amplitude and phase, and then compose the new compensated echo by the amplitude and the nonlinear component of the phase. Furthermore the linear component of the phase can be used to estimate the Doppler frequency shift. The computer simulation and the real data processing show that the method has accurately estimated the Doppler frequency shift, successfully restrained the energy leakage on spectrum, greatly increased the echo signal-to-noise ratio and improved the detection performance of the radio system in both time domain and frequency domain.展开更多
Using Computerized Ionospheric Tomography （CIT） in combination with GPS observations from the Crustal Movement Observation Network of China （CMONOC）, this study reconstructed the electron density distributions ove...Using Computerized Ionospheric Tomography （CIT） in combination with GPS observations from the Crustal Movement Observation Network of China （CMONOC）, this study reconstructed the electron density distributions over China before the 2011 Tohoku Mw 9.0 earthquake and discovered a prominent ionospheric anomaly on March 8, 2011. Analysis of the solar-terrestrial space environment around the time of the Tohoku earthquake indicated that the March 8 ionospheric anomaly was likely related to the earthquake. Finally, the paper discusses the drift of the ionospheric anomaly, which was inferred from the anomaly being observed by GPS reference sites in China.展开更多
The real-time information of the distant ionosphere can be acquired by using the Wuhan ionospheric oblique backscattering sounding system(WIOBSS),which adopts a discontinuous wave mechanism.After the characteristics o...The real-time information of the distant ionosphere can be acquired by using the Wuhan ionospheric oblique backscattering sounding system(WIOBSS),which adopts a discontinuous wave mechanism.After the characteristics of the ionospheric echo Doppler spectra were analyzed,the signal preprocessing was developed in this paper,which aimed at improving the Doppler spectra.The results indicate that the preprocessing not only makes the system acquire a higher ability of target detection but also suppresses the radio frequency interference by 6-7 dB.展开更多
基金supported partly by the National Natural Science Foundation of China(40804042)the Post DoctorFoundation of China(20070420919).
文摘According to the Doppler sensitive of the phase coded pulse compression signal, a Doppler estimating and compensating method based on phase is put forward to restrain the Doppler sidelobes, raise the signal-to-noise ratio and improve measuring resolution. The compensation method is used to decompose the echo to amplitude and phase, and then compose the new compensated echo by the amplitude and the nonlinear component of the phase. Furthermore the linear component of the phase can be used to estimate the Doppler frequency shift. The computer simulation and the real data processing show that the method has accurately estimated the Doppler frequency shift, successfully restrained the energy leakage on spectrum, greatly increased the echo signal-to-noise ratio and improved the detection performance of the radio system in both time domain and frequency domain.
基金supported by the National Natural Science Foundation of China (41174030)the Director Foundation of Institute of Seismology,China Earthquake Administration (IS200916012)
文摘Using Computerized Ionospheric Tomography （CIT） in combination with GPS observations from the Crustal Movement Observation Network of China （CMONOC）, this study reconstructed the electron density distributions over China before the 2011 Tohoku Mw 9.0 earthquake and discovered a prominent ionospheric anomaly on March 8, 2011. Analysis of the solar-terrestrial space environment around the time of the Tohoku earthquake indicated that the March 8 ionospheric anomaly was likely related to the earthquake. Finally, the paper discusses the drift of the ionospheric anomaly, which was inferred from the anomaly being observed by GPS reference sites in China.
基金supported by the National Natural Science Foundation of China(Grant No.40474066).
文摘The real-time information of the distant ionosphere can be acquired by using the Wuhan ionospheric oblique backscattering sounding system(WIOBSS),which adopts a discontinuous wave mechanism.After the characteristics of the ionospheric echo Doppler spectra were analyzed,the signal preprocessing was developed in this paper,which aimed at improving the Doppler spectra.The results indicate that the preprocessing not only makes the system acquire a higher ability of target detection but also suppresses the radio frequency interference by 6-7 dB.
