X射線脈沖星信號檢測及位相測量技術(shù)研究
發(fā)布時間：2018-07-15 13:27
【摘要】：脈沖星導航概念自提出以來,已經(jīng)經(jīng)過了近半個世紀,但直到十多年前利用X射線脈沖星導航定位可行性得到論證后,才逐漸受到重視。得益于其獨特的信號輻射方式以及脈沖周期的穩(wěn)定性,X射線脈沖星已成為目前人們所認識的十分理想的天文導航信源,并在空間航天器自主導航領域表現(xiàn)出了良好的應用前景。目前,國際上已經(jīng)開展了利用X射線脈沖星的自主導航技術(shù)的空間試驗研究,但這項新型技術(shù)仍處在基礎理論研究和可行性驗證階段。特別是在國內(nèi),有關(guān)脈沖星導航的實質(zhì)性的研究才剛剛起步,諸如極弱X射線脈沖星信號高精度計時觀測、高效高性能位相測量、時間傳遞誤差修正等制約X射線脈沖星導航(XPNAV)精度提高的關(guān)鍵問題仍沒有得到很好的解決。本文主要圍繞XPNAV中的信號檢測、累積輪廓建立和位相測量等問題展開研究,主要工作內(nèi)容包括： (1)分析了可用于脈沖星信號檢測的多個特征參量,如周期、輪廓和流量強度等。單獨利用周期或輪廓頻域特征檢測和辨識脈沖星信號的方法可行,但對于強度極弱、探測技術(shù)較為復雜的X射線脈沖星信號,這些方法并不令人滿意。已有研究表明,由于頻域方法存在諧波和色噪聲等因素的影響,在對X射線脈沖星信號的檢測中存在失效的情況,而時域方法有時表現(xiàn)的更好。將累積輪廓、流量和周期三個重要特征應用于X射線脈沖星信號檢測中,提出基于Bayesian估計的時域檢測方法。利用仿真數(shù)據(jù)和(?)XTE衛(wèi)星的實測數(shù)據(jù)進行實驗驗證顯示,該法性能優(yōu)于同類的基于高斯分布模型的檢測方法,在檢測信號的同時能在一定精度下給出信號位相偏移值。 (2)利用累積輪廓進行位相測量是XPNAV導航信息獲取的基本途徑,輪廓累積的重要性不言而喻。對轉(zhuǎn)化到SSB原點處的X射線脈沖星光子序列,傳統(tǒng)的輪廓累積方法是先識別信號周期,然后再按周期折疊累加得到脈沖輪廓。這種方法依賴于周期識別的準確性,對累積輪廓質(zhì)量也無評價標準。本文分析了脈沖星累積輪廓和周期的強相關(guān)性,提出了周期未知時直接進行輪廓累積的最小熵方法,并對其進行證明,在此基礎上,討論了該方法在周期識別中的作用。利用仿真數(shù)據(jù)和RXTE衛(wèi)星的實測數(shù)據(jù)實驗驗證了該方法的有效性。脈沖星累積輪廓通常被認為是脈沖星輻射區(qū)結(jié)構(gòu)一維分布的反映,人們在對大量累積輪廓統(tǒng)計分析中發(fā)現(xiàn)這些輪廓均具有核成分,進而提出利用累積輪廓的高斯成分分離方法分析脈沖星輻射區(qū)結(jié)構(gòu)。我們將高斯成分分離方法用于脈沖星累積輪廓建模,發(fā)現(xiàn)該模型可以很好地逼近標準輪廓,并將該模型用于累積輪廓位相測量的CRLB分析中,以評價累積輪廓成分對位相測量的影響。結(jié)果顯示輪廓成分間的相關(guān)性和輪廓成分寬度是影響測相精度的兩個重要因素。 (3)考慮到Taylor FFT等頻域位相測量的實質(zhì)是在投影定理下用各次諧波的線性疊加對原函數(shù)擬合,提出了基于最小熵準則的位相測量高斯擬合方法。實驗說明,所提方法在相對較低信噪比條件下,性能優(yōu)于Taylor FFT方法。鑒于該方法對輪廓質(zhì)量要求較高,在實際應用中可能造成困難,本文建立了一種新的脈沖星信號概率模型,用于描述在觀測時間內(nèi)光子到達頻度隨采樣時間的分布。分析表明該模型可以很好的刻畫輪廓形變與周期誤差間的關(guān)系。進而本文提出基于該模型的位相和位相速率聯(lián)合測量方法,將多普勒效應視為參量,利用所提概率模型描述信號的直接累積輪廓,然后利用優(yōu)化方法求解。仿真實驗說明該方法對累積輪廓質(zhì)量要求較低,能進行位相和位相速率聯(lián)合測量,且位相測量精度優(yōu)于Taylor FFT方法。 (4)從XPNAV的性能來看,其定位誤差不到最小模糊距離的十分之一,因此連續(xù)正常工作時,可以不考慮整周期模糊問題。而對于初始位置未知或者因系統(tǒng)故障導致位置記憶喪失的情況,模糊問題是不可避免的。窮舉搜索法是XPNAV常用且有效的解模糊方法,其不足之處在于復雜度高。本文提出一種快速空間搜索方法。該方法依據(jù)脈沖星的特征周期將搜索空間劃分為多個子空間,利用相位投影增量建立基于滿二叉樹的快速搜索算法遍歷子空間解模糊。仿真實驗說明,得益于搜索空間約束和快速二叉樹搜索,該方法能有效提高模糊空間搜索速率。 (5)盡管XPNAV相對于其它天文導航方法優(yōu)勢明顯,但目前為止,它并不算一個成熟的導航方法。傳統(tǒng)的天文自主導航方法利用地球等對星光掩蔽作用進行軌道航天器定軌,利用星敏感器觀測恒星和地球問的角距等作為信息輸入,與XPNAV機理完全不同。為提高導航精度,增強自主性,提出一種將脈沖星位相測量和星敏感器星光角距測量結(jié)合的信息融合天文自主導航方法,并基于UKF (Unscented Kalman Filter)使用真軌道參數(shù)做了仿真實驗,結(jié)果表明組合兩種導航方法能有效提高位置和速度估計精度。進而我們也對XPNAV與其它導航系統(tǒng)組合的可能性和有效性做了分析討論。 (6)地面仿真系統(tǒng)研制在導航系統(tǒng)研究中具有重要意義,由于在地面上無法接收脈沖星的空間輻射X射線信號,對XPNAV而言地面仿真尤其重要。本文設計了一種X射線脈沖星導航信號仿真方案,重點討論了虛擬參考系建立、信號建模以及硬件系統(tǒng)構(gòu)成。
[Abstract]:Since the concept of pulsar navigation has been proposed for nearly half a century, it has been gradually paid more attention to the feasibility of using X ray pulsar navigation and positioning until more than 10 years ago. Thanks to its unique mode of signal radiation and the stability of the pulse cycle, the X ray pulsar has become a great reason that people have known at present. In the field of autonomous navigation of space spacecraft, space experiments have been carried out by X ray pulsar autonomous navigation technology, but the new technology is still in the stage of basic theoretical research and feasibility verification. The substantial research of star navigation has just started, such as the high precision time observation of the extremely weak X ray pulsar signal, high performance and high performance phase measurement, time transfer error correction and other key problems that restrict the improvement of the precision of the X ray pulsar navigation (XPNAV). This paper mainly focuses on the signal detection in the XPNAV. Research on contour establishment and phase measurement has been carried out.
(1) several characteristic parameters, such as cycle, contour and flow intensity, which can be used for pulsar signal detection, are analyzed. The method of detecting and identifying pulsar signals using the characteristics of periodic or contour frequency domain alone is feasible. However, these methods are not satisfactory for X ray pulse star signals with very weak intensity and more complex detection technology. It is shown that, due to the influence of harmonic and color noise in the frequency domain, the detection of the X ray pulsar signal is invalid, and the time domain method sometimes performs better. The three important features of the cumulative contour, flow and period are applied to the X ray pulsar signal detection, and the time domain detection based on the Bayesian estimation is proposed. Method. The simulation data and the measured data of (?) XTE satellite show that the performance of the method is better than that of the same kind of detection method based on Gauss distribution model, and the phase shift of signal can be given at a certain precision while the signal is detected.
(2) phase measurement using cumulative contour is the basic way for XPNAV navigation information acquisition. The importance of contour accumulation is self-evident. For the X ray pulsar photon sequence converted to the origin of SSB, the traditional method of contour accumulation is to identify the signal cycle first and then fold and accumulate the pulse contour according to the cycle. This method depends on the week. In this paper, we analyze the strong correlation between the accumulative contour and the period of the pulsars, and put forward the minimum entropy method for the direct contour accumulation when the period is unknown. On this basis, the function of the method in the periodic recognition is discussed. The simulation data and the RXTE are used. The experimental data test of the satellite shows the effectiveness of the method. The accumulative contour of pulsar is usually considered as a reflection of the one-dimensional distribution of the structure of the pulsar radiation area. People find that these outlines have nuclear components in the statistical analysis of a large number of cumulative outlines, and then the Gauss component separation method of cumulative contour is proposed to analyze pulsars. The structure of the radiation area. We use the Gauss component separation method to model the cumulative contour of pulsars. It is found that the model can be well approximated to the standard contour, and the model is used in the CRLB analysis of the cumulative profile phase measurement to evaluate the influence of the cumulative contour components on the phase measurement. The results show the correlation and contour between the contour components. The width is the two important factor affecting the accuracy of phase measurement.
(3) considering the essence of the phase measurement of Taylor FFT and other frequency domain phase measurements is to fit the original function with the linear superposition of every harmonic in the projection theorem, a phase measurement Gauss fitting method based on the minimum entropy criterion is proposed. The experiment shows that the proposed method is superior to the Taylor FFT method under the relatively low SNR condition. A new probability model of pulsar signal is established in this paper to describe the distribution of photon arrival frequency within the observation time. The analysis shows that the model can well describe the relationship between the contour deformation and the periodic error. The Doppler effect is considered as a parameter, and the proposed probability model is used to describe the direct cumulative contour of the signal, and then the optimization method is used to solve the problem. The simulation experiment shows that the method is low in the quality of the cumulative contour, and can be combined to measure the phase and phase velocity, and the phase measurement accuracy is better than Taylo. R FFT method.
(4) from the performance of XPNAV, the positioning error is less than 1/10 of the minimum fuzzy distance, so the fuzzy problem is unavoidable when the initial position is unknown or the position memory loss caused by the system failure. The exhaustive search method is commonly used and effective for the XPNAV. In this paper, a fast spatial search method is proposed. This method divides the search space into multiple subspaces based on the characteristic period of the pulsar, and builds a fast search algorithm based on the full two forked tree by the phase projection increment. Search space constraint and fast two binary tree search method can effectively improve the search speed of fuzzy space.
(5) although XPNAV has obvious advantages over other astronomical navigation methods, it is not a mature navigation method so far. The traditional astronomical autonomous navigation method uses the earth and so on to track the orbit of the orbital spacecraft, and uses the star sensor to observe the angle of the star and the earth as the information input, and the XPNAV machine. In order to improve the navigation accuracy and enhance the autonomy, an information fusion method for astronomical autonomous navigation is proposed, which combines the pulse star phase measurement with the star sensor star angle measurement, and based on the real orbit parameters of the UKF (Unscented Kalman Filter), the results show that the combined two navigation methods can be effectively improved. We also analyze and discuss the possibility and effectiveness of combining XPNAV with other navigation systems.
(6) the development of the ground simulation system is of great significance in the study of the navigation system. Because of the inability to receive the space radiated X ray signals of the pulsar on the ground, the ground simulation is especially important for the XPNAV. This paper designs a simulation scheme of the X ray pulsar navigation signal, focusing on the establishment of the virtual reference system, the signal modeling and the hard work. Component system composition.
【學位授予單位】：西安電子科技大學
【學位級別】：博士
【學位授予年份】：2011
【分類號】：P145.6
[Abstract]:Since the concept of pulsar navigation has been proposed for nearly half a century, it has been gradually paid more attention to the feasibility of using X ray pulsar navigation and positioning until more than 10 years ago. Thanks to its unique mode of signal radiation and the stability of the pulse cycle, the X ray pulsar has become a great reason that people have known at present. In the field of autonomous navigation of space spacecraft, space experiments have been carried out by X ray pulsar autonomous navigation technology, but the new technology is still in the stage of basic theoretical research and feasibility verification. The substantial research of star navigation has just started, such as the high precision time observation of the extremely weak X ray pulsar signal, high performance and high performance phase measurement, time transfer error correction and other key problems that restrict the improvement of the precision of the X ray pulsar navigation (XPNAV). This paper mainly focuses on the signal detection in the XPNAV. Research on contour establishment and phase measurement has been carried out.
(1) several characteristic parameters, such as cycle, contour and flow intensity, which can be used for pulsar signal detection, are analyzed. The method of detecting and identifying pulsar signals using the characteristics of periodic or contour frequency domain alone is feasible. However, these methods are not satisfactory for X ray pulse star signals with very weak intensity and more complex detection technology. It is shown that, due to the influence of harmonic and color noise in the frequency domain, the detection of the X ray pulsar signal is invalid, and the time domain method sometimes performs better. The three important features of the cumulative contour, flow and period are applied to the X ray pulsar signal detection, and the time domain detection based on the Bayesian estimation is proposed. Method. The simulation data and the measured data of (?) XTE satellite show that the performance of the method is better than that of the same kind of detection method based on Gauss distribution model, and the phase shift of signal can be given at a certain precision while the signal is detected.
(2) phase measurement using cumulative contour is the basic way for XPNAV navigation information acquisition. The importance of contour accumulation is self-evident. For the X ray pulsar photon sequence converted to the origin of SSB, the traditional method of contour accumulation is to identify the signal cycle first and then fold and accumulate the pulse contour according to the cycle. This method depends on the week. In this paper, we analyze the strong correlation between the accumulative contour and the period of the pulsars, and put forward the minimum entropy method for the direct contour accumulation when the period is unknown. On this basis, the function of the method in the periodic recognition is discussed. The simulation data and the RXTE are used. The experimental data test of the satellite shows the effectiveness of the method. The accumulative contour of pulsar is usually considered as a reflection of the one-dimensional distribution of the structure of the pulsar radiation area. People find that these outlines have nuclear components in the statistical analysis of a large number of cumulative outlines, and then the Gauss component separation method of cumulative contour is proposed to analyze pulsars. The structure of the radiation area. We use the Gauss component separation method to model the cumulative contour of pulsars. It is found that the model can be well approximated to the standard contour, and the model is used in the CRLB analysis of the cumulative profile phase measurement to evaluate the influence of the cumulative contour components on the phase measurement. The results show the correlation and contour between the contour components. The width is the two important factor affecting the accuracy of phase measurement.
(3) considering the essence of the phase measurement of Taylor FFT and other frequency domain phase measurements is to fit the original function with the linear superposition of every harmonic in the projection theorem, a phase measurement Gauss fitting method based on the minimum entropy criterion is proposed. The experiment shows that the proposed method is superior to the Taylor FFT method under the relatively low SNR condition. A new probability model of pulsar signal is established in this paper to describe the distribution of photon arrival frequency within the observation time. The analysis shows that the model can well describe the relationship between the contour deformation and the periodic error. The Doppler effect is considered as a parameter, and the proposed probability model is used to describe the direct cumulative contour of the signal, and then the optimization method is used to solve the problem. The simulation experiment shows that the method is low in the quality of the cumulative contour, and can be combined to measure the phase and phase velocity, and the phase measurement accuracy is better than Taylo. R FFT method.
(4) from the performance of XPNAV, the positioning error is less than 1/10 of the minimum fuzzy distance, so the fuzzy problem is unavoidable when the initial position is unknown or the position memory loss caused by the system failure. The exhaustive search method is commonly used and effective for the XPNAV. In this paper, a fast spatial search method is proposed. This method divides the search space into multiple subspaces based on the characteristic period of the pulsar, and builds a fast search algorithm based on the full two forked tree by the phase projection increment. Search space constraint and fast two binary tree search method can effectively improve the search speed of fuzzy space.
(5) although XPNAV has obvious advantages over other astronomical navigation methods, it is not a mature navigation method so far. The traditional astronomical autonomous navigation method uses the earth and so on to track the orbit of the orbital spacecraft, and uses the star sensor to observe the angle of the star and the earth as the information input, and the XPNAV machine. In order to improve the navigation accuracy and enhance the autonomy, an information fusion method for astronomical autonomous navigation is proposed, which combines the pulse star phase measurement with the star sensor star angle measurement, and based on the real orbit parameters of the UKF (Unscented Kalman Filter), the results show that the combined two navigation methods can be effectively improved. We also analyze and discuss the possibility and effectiveness of combining XPNAV with other navigation systems.
(6) the development of the ground simulation system is of great significance in the study of the navigation system. Because of the inability to receive the space radiated X ray signals of the pulsar on the ground, the ground simulation is especially important for the XPNAV. This paper designs a simulation scheme of the X ray pulsar navigation signal, focusing on the establishment of the virtual reference system, the signal modeling and the hard work. Component system composition.
【學位授予單位】：西安電子科技大學
【學位級別】：博士
【學位授予年份】：2011
【分類號】：P145.6
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