Doppler asymmetric spatial heterodyne spectroscopy(DASH)technique has developed rapidly in passive Doppler-shift measurements of atmospheric emission lines over the last decade.With the advantages of high phase shift ...Doppler asymmetric spatial heterodyne spectroscopy(DASH)technique has developed rapidly in passive Doppler-shift measurements of atmospheric emission lines over the last decade.With the advantages of high phase shift sensitivity,compact,and rugged structure,DASH is proposed to be used for celestial autonomous navigation based on Doppler radial velocity measurement in this work.Unlike atmospheric emission lines,almost all targeted lines in the research field of deep-space exploration are the absorption lines of stars,so a mathematical model for the Doppler-shift measurements of absorption lines with a DASH interferometer is established.According to the analysis of the components of the interferogram received by the detector array,we find that the interferogram generated only by absorption lines in a passband can be extracted and processed by a method similar to the approach to studying the emission lines.In the end,numerical simulation experiments of Doppler-shift measurements of absorption lines are carried out.The simulation results show that the relative errors of the retrieved speeds are less than 0.7%under ideal conditions,proving the feasibility of measuring Doppler shifts of absorption lines by DASH instruments.展开更多
The mobile channel is slow fading and time selective, thus the multiplicative and additive noise of the channel will smear the spectral line, or arouse Doppler spread. This spread will make the parameters estimation a...The mobile channel is slow fading and time selective, thus the multiplicative and additive noise of the channel will smear the spectral line, or arouse Doppler spread. This spread will make the parameters estimation accuracy degrade. The goal of this paper is to analytically assess this degradation when Carrier Frequency Offset (CFO) and Doppler shift exist jointly. Then the finite-sample Cramer-Rao Lower Bound (CRLB) is derived and close-form asymptotical expression is given for large-sample CRLB. These expressions give insights into the performance room for frequency estimation. Also the variance of Doppler shift estimator is simulated to illustrate the theoretical results.展开更多
基金Project supported by the National Basic Research Program of China(Grant No.2014CB744204).
文摘Doppler asymmetric spatial heterodyne spectroscopy(DASH)technique has developed rapidly in passive Doppler-shift measurements of atmospheric emission lines over the last decade.With the advantages of high phase shift sensitivity,compact,and rugged structure,DASH is proposed to be used for celestial autonomous navigation based on Doppler radial velocity measurement in this work.Unlike atmospheric emission lines,almost all targeted lines in the research field of deep-space exploration are the absorption lines of stars,so a mathematical model for the Doppler-shift measurements of absorption lines with a DASH interferometer is established.According to the analysis of the components of the interferogram received by the detector array,we find that the interferogram generated only by absorption lines in a passband can be extracted and processed by a method similar to the approach to studying the emission lines.In the end,numerical simulation experiments of Doppler-shift measurements of absorption lines are carried out.The simulation results show that the relative errors of the retrieved speeds are less than 0.7%under ideal conditions,proving the feasibility of measuring Doppler shifts of absorption lines by DASH instruments.
文摘The mobile channel is slow fading and time selective, thus the multiplicative and additive noise of the channel will smear the spectral line, or arouse Doppler spread. This spread will make the parameters estimation accuracy degrade. The goal of this paper is to analytically assess this degradation when Carrier Frequency Offset (CFO) and Doppler shift exist jointly. Then the finite-sample Cramer-Rao Lower Bound (CRLB) is derived and close-form asymptotical expression is given for large-sample CRLB. These expressions give insights into the performance room for frequency estimation. Also the variance of Doppler shift estimator is simulated to illustrate the theoretical results.
