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Maximum likelihood phase estimation method based on X-ray pulsar

A technique of maximum likelihood estimation and phase estimation, which is applied in the field of navigation and can solve the problems such as the decrease of signal phase measurement accuracy, the reduction of signal information utilization rate, and the loss of useful information.

Inactive Publication Date: 2014-05-07
XIDIAN UNIV
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Problems solved by technology

[0004] The premise of the above method is that the signal profile is required to be accumulated. The process of profile accumulation is actually a process of signal averaging. In this process, some useful information will be lost, resulting in a decrease in the accuracy of the phase measurement of the signal, and the accumulation process shields the orbital movement. The resulting Doppler frequency change reduces the utilization of signal information

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  • Maximum likelihood phase estimation method based on X-ray pulsar
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[0061] The present invention will be described in further detail below in conjunction with the accompanying drawings:

[0062] Reference figure 1 In this invention, the Poisson distribution-based time series model in the X-ray pulsar signal Poisson model construction unit is constructed as follows: Due to the high stability of the radiation period, X-ray pulsar radiation can be regarded as a kind of periodic stationary process. The stability of the pulsar allows us to accurately predict the phase of the pulsar signal in the solar system center (SSB) reference coordinates at any moment. In this coordinate system, the phase of the pulsar signal can be expressed by the following expression:

[0063] Φ n SSB ( t ) = Φ n SSB ( t 0 ) + f n · ( t - t 0 ) + O ( m ) - - - ( 1 )

[0064] among them Is the phase of the nth star at universal time t, f n Is the pulse frequency of the nth pulsar, O(m) ...

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Abstract

The invention discloses a maximum likelihood phase estimation method based on an X-ray pulsar. The maximum likelihood phase estimation method based on the X-ray pulsar comprises the following steps: constructing an X-ray pulsar signal Poisson model structual unit according to the process for measuring the arrival time of a photon which is striken to a detection material of an X-ray detector; fitting the X-ray pulsar profile by utilizing a plurality of Gaussian distribution probability functions and constructing an X-ray pulsar signal simulation structural unit; constructing a maximum likelihood estimation unit for estimating the initial phase and cycle; and constructing a phase parallel computing unit for improving the peak value searching performance of a cost function in a new model. Not only is the calculation quantity reduced, the calculation time is shortened, but also the high operation precision is ensured, and the maximum likelihood phase estimation method based on the X-ray pulsar has significant meaning in studying the X-ray pulsar signal navigation.

Description

Technical field: [0001] The invention belongs to the field of navigation technology, and particularly relates to the phase estimation of signals generated by X-ray pulsars, which are used for determining the position and speed of low-earth orbit and deep-air vehicles. Background technique: [0002] As early as 1974, people considered pulsars for positioning because they could generate pulse signals with stable frequencies. In recent years, many studies have proved that navigation based on the arrival time of pulsars is feasible. X-rays radiated by X-ray pulsars contain most of the energy radiated by them, so only small-sized and light-weight X-ray detectors are needed. Existing global navigation satellite systems can also perform autonomous navigation for low-Earth orbiting vehicles, but because their navigation signals cannot be obtained in deep space, these systems are restricted to work in deep space. In addition to being distributed throughout the Milky Way galaxy, X-ray pu...

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Application Information

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IPC IPC(8): G01C21/24
CPCG01C21/02
Inventor 张华许录平焦荣宋诗斌申洋赫马炎李冀俊孙景荣刘清华何小川冯冬竹
Owner XIDIAN UNIV
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