A fast pulse phase estimation method for X-ray pulsar signals based on epoch folding

An X-ray pulsar/starlight Doppler deeply-integrated navigation method is proposed in this paper. A starlight Doppler measurement-aided phase propagation model, which can remove the orbital effect within the recorded photon Time Of Arrivals (TOAs), is derived, and guarantees that the pulse phase can be extracted from the converted photon TOAs using computationally efficient methods. Some simulations are performed by a hardware-in-loop system to verify the performance of the integrated pulse phase estimation method as well as of the integrated navigation method. The integrated pulse phase estimation method could achieve an estimation performance similar to the existing method for orbiting vehicles at the cost of much less computational complexity, is capable of handling the signals of millisecond pulsars, and is applicable to various vehicles. In addition, the proposed integrated navigation method could provide reliable positioning results for various vehicles.

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Stellar Angle-Aided Pulse Phase Estimation and Its Navigation Application

Aerospace ◽

10.3390/aerospace8090240 ◽

2021 ◽

Vol 8 (9) ◽

pp. 240

Author(s):

Yusong Wang ◽

Yidi Wang ◽

Wei Zheng ◽

Minzhang Song ◽

Guanghua Li

Keyword(s):

Autonomous Navigation ◽

Computational Cost ◽

Estimation Method ◽

Angle Measurement ◽

Phase Estimation ◽

Integrated Navigation ◽

X Ray ◽

Pulse Phase ◽

Basic Measurement ◽

Navigation Method

X-ray pulsar-based navigation (XNAV) is a promising autonomous navigation method, and the pulse phase is the basic measurement of XNAV. However, the current methods for estimating the pulse phase for orbiting spacecraft have a high computational cost. This paper proposes a stellar angle measurement-aided pulse phase estimation method for high Earth orbit (HEO) spacecraft, with the aim of reducing the computational cost of pulse phase estimation in XNAV. In this pulse phase estimation method, the effect caused by the orbital motion of the spacecraft is roughly removed by stellar angle measurement. Furthermore, a deeply integrated navigation method using the X-ray pulsar and the stellar angle is proposed. The performances of the stellar angle measurement-aided pulse phase estimation method and the integrated navigation method were verified by simulation. The simulation results show that the proposed pulse phase estimation method can handle the signals of millisecond pulsars and achieve pulse phase estimation with lower computational cost than the current methods. In addition, for HEO spacecraft, the position error of the proposed integrated navigation method is lower than that of the stellar angle navigation method.

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Pulse Phase Estimation of X-ray Pulsar with the Aid of Vehicle Orbital Dynamics

Journal of Navigation ◽

10.1017/s0373463315000727 ◽

2015 ◽

Vol 69 (2) ◽

pp. 414-432 ◽

Cited By ~ 9

Author(s):

Yidi Wang ◽

Wei Zheng

Keyword(s):

Orbital Dynamics ◽

Phase Estimation ◽

Time Of Arrival ◽

Likelihood Estimator ◽

Initial State ◽

Signal Model ◽

X Ray ◽

Pulse Phase ◽

Vehicle Position ◽

Definition Of

A pulse phase estimation of an X-ray pulsar with the aid of vehicle orbital dynamics is proposed. The original continue-time X-ray pulsar signal model is modified to be a term of vehicle position and velocity varying with time, and a modified definition of pulse time of arrival is given. The modified signal model is further linearized around the predicted position and velocity of the vehicle to the second order. The initial phase and the coefficients of the extended signal model can be estimated by maximum likelihood estimator. Some simulations are performed to verify the method and show the method has robustness to the initial error within initial state of the vehicle and is capable of handling the phase-estimation problem for pulsars with low fluxes.

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On-Orbit Pulse Phase Estimation Based on CE-Adam Algorithm

Aerospace ◽

10.3390/aerospace8040095 ◽

2021 ◽

Vol 8 (4) ◽

pp. 95

Author(s):

Yusong Wang ◽

Yidi Wang ◽

Wei Zheng

Keyword(s):

Estimation Method ◽

Real Data ◽

Estimation Accuracy ◽

Accurate Estimation ◽

Phase Estimation ◽

Processing Unit ◽

Time Cost ◽

Central Processing ◽

Cpu Time ◽

Pulse Phase

Pulse phase is the basic measurements of X-ray pulsar-based navigation, and thus how to estimate a pulse phase for an orbiting spacecraft is important. The current methods for on-orbit pulse phase estimation could provide an accurate estimation performance enhancing with the photon amount, but its central processing unit (CPU) time cost also increases sharply with the increase of photon amount. In this paper, an on-orbit pulse phase estimation method based on the cross-entropy adaptive moment estimation (CE-Adam) algorithm is proposed to reduce the CPU time cost while retaining decent estimation accuracy. This method combines the CE and Adam algorithms, and is able to obtain a global optimum with low CPU time cost. The performance of the proposed algorithm is verified by simulation data and real data from the Neutron Star Internal Composition Detector (NICER). The results show that the proposed algorithm could greatly reduce the CPU time cost, which is about 1.5% of the CE algorithm, and retain similar estimation accuracy of pulse phase with CE algorithm.

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