阅读说明：本技术 基于北斗星间单向链路的航天器测定轨方法 (Spacecraft orbit determination method based on Beidou inter-satellite unidirectional link ) 是由 薛永宏 姜坤 丁翔 乔凯 张磊 于 2020-11-16 设计创作，主要内容包括：本发明涉及一种基于北斗星间单向链路的航天器测定轨方法,包括：S1、北斗卫星通过星间链路天线向航天器发送星间链路信号；S2、航天器仅工作在接收模式,接收北斗卫星发送的信号,并根据接收的信号计算伪距值；S3、累计一定时间的伪距值后,解算航天器轨道参数。本发明的基于北斗星间单向链路的航天器测定轨方法,航天器仅与北斗卫星之间建立单向链路,只接收卫星信号,降低了测定轨实现的技术复杂性和工程实现难度。另一方面,通过单向建链的测定轨精度,高轨卫星可实现百米量级的定轨精度,与双向建链的定轨精度性能相当。(The invention relates to a spacecraft orbit determination method based on a Beidou inter-satellite unidirectional link, which comprises the following steps: s1, the Beidou satellite sends an inter-satellite link signal to the spacecraft through the inter-satellite link antenna; s2, the spacecraft works only in a receiving mode, receives signals sent by the Beidou satellite, and calculates pseudo-range values according to the received signals; and S3, resolving the orbit parameters of the spacecraft after accumulating the pseudo range value for a certain time. According to the spacecraft orbit determination method based on the Beidou inter-satellite unidirectional link, the unidirectional link is only established between the spacecraft and the Beidou satellite, only satellite signals are received, and the technical complexity and the engineering realization difficulty of orbit determination are reduced. On the other hand, the high-orbit satellite can realize orbit determination accuracy of hundred meters by the orbit determination accuracy of the unidirectional link building, and the orbit determination accuracy is equivalent to the orbit determination accuracy of the bidirectional link building.)

1. A spacecraft orbit determination method based on Beidou inter-satellite unidirectional links comprises the following steps:

s1, the Beidou satellite sends an inter-satellite link signal to the spacecraft through the inter-satellite link antenna;

s2, the spacecraft works only in a receiving mode, receives signals sent by the Beidou satellite, and calculates pseudo-range values according to the received signals;

and S3, resolving the orbit parameters of the spacecraft after accumulating the pseudo range value for a certain time.

2. The method of claim 1, wherein in step S1, according to the planned link setup time slot, the beidou satellite sends a signal S to the spacecraft via the intersatellite link antenna^j(t)：

Wherein j represents the satellite number, A represents the signal amplitude, P_IRepresenting the spreading code, P, of the I branch_QRepresenting Q branch spreading code, D_IData code representing modulation on the I-branch, f represents carrier frequency,Indicating the initial phase of the carrier.

3. The spacecraft orbit determination method based on the Beidou inter-satellite unidirectional link according to claim 2, wherein in the step S2, the spacecraft receives and captures Beidou inter-satellite link signals according to the planned link establishment time slot, and obtains the receiving time corresponding to the code phase:

wherein CP is the sampling time t of the receiver in the inter-satellite ranging code_reThe corresponding code phase value.

4. The method for determining the orbit of the spacecraft based on the Beidou inter-satellite one-way link according to claim 3, wherein in the step S2, the uncertainty of the time of capturing the signals by the spacecraft is +/-5 ms, and the orbit determination can be carried out by receiving and capturing 4 or more Beidou satellite inter-satellite link signals.

5. The Beidou inter-satellite unidirectional link-based spacecraft orbit determination method of claim 4, wherein in step S3, pseudo range values are calculated according to received signals, after 1 hour of data accumulation, orbit solution is performed in orbit by combining the accumulated data of the previous day, and spacecraft orbit parameters are obtained.

Calculating the transmission time t of the link signal between the satellites of the navigation satellite according to the spread spectrum code table_tr,iThe pseudorange measurement may be calculated by:

obtaining a simultaneous equation set according to a three-sphere geometric intersection principle:

wherein (x)_i,y_i,z_i,δt_BD,i) I is the position and clock error of 4 Beidou satellites, and is a known parameter; rho_i1,2,3 and 4 are pseudo-range measurement values obtained by signal processing of the inter-satellite link receiver of the spacecraft; (x)_u,y_u,z_u,δt_u) Is the position and clock error of the spacecraft, and the position of the spacecraft accumulated for a period of timeAnd the clock error data are converted into orbit parameters of the spacecraft through fitting.

6. The spacecraft orbit determination method based on the Beidou intersatellite unidirectional link according to claim 5, further comprising the step that the spacecraft downloads an on-board orbit determination solution result, an original ranging value and ranging time to a ground system, the ground system carries out unidirectional orbit determination solution filtering, the ground solution result and the on-board solution result are compared, and spacecraft orbit determination performance verification analysis is completed.

Technical Field

The invention belongs to the technical field of spacecraft measurement and control, and particularly relates to a spacecraft orbit determination method based on a Beidou inter-satellite unidirectional link.

Background

Determining orbit is an important task for spacecraft to be in orbit. The method for measuring the orbit of the spacecraft by utilizing the Beidou inter-satellite link is a new scheme for measuring the orbit of the spacecraft, and has the main advantages that the orbit measuring function of the spacecraft can be realized; and a bidirectional link can be established to realize the backup communication function. The method has important significance for improving the on-orbit autonomous operation capability of the spacecraft. At present, orbit determination of the spacecraft by adopting the Beidou inter-satellite link is carried out by establishing a bidirectional time division link with the Beidou satellite. The process of establishing a link for determining the orbit in two directions with the Beidou satellite can be divided into two stages of time-frequency coarse synchronization and two-way link establishment. In the coarse synchronization stage, the spacecraft receives the Beidou signals to complete the coarse synchronization of the self time frequency and the Beidou satellite. And after time-frequency coarse synchronization is completed, entering a bidirectional link establishment stage, mutually sending signals by the Beidou satellite and the spacecraft in a time slot, respectively calculating to obtain pseudo range values, accumulating the bidirectional pseudo range values for a certain time, performing orbit calculation to obtain spacecraft orbit parameters, and completing an orbit determination task. Therefore, the orbit of the spacecraft is determined through the two-way link, the two-way time division link needs to be established with the Beidou satellite, and in the process of establishing the link, the spacecraft is required to have higher time-frequency precision and stability in order to achieve time-frequency alignment, and the engineering implementation cost is relatively high.

Disclosure of Invention

The invention aims to solve the technical problems and provides the spacecraft orbit determination method based on the one-way link between the Beidou satellites, which is low in implementation difficulty.

In order to achieve the above purpose, the invention provides a spacecraft orbit determination method based on a Beidou inter-satellite unidirectional link, which comprises the following steps:

s1, the Beidou satellite sends an inter-satellite link signal to the spacecraft through the inter-satellite link antenna;

s2, the spacecraft works only in a receiving mode, receives signals sent by the Beidou satellite, and calculates pseudo-range values according to the received signals;

and S3, resolving the orbit parameters of the spacecraft after accumulating the pseudo range value for a certain time.

According to one aspect of the invention, in step S1, according to the planned link establishment time slot, the Beidou satellite transmits a signal S to the spacecraft through the inter-satellite link antenna^j(t)：

Wherein j represents the satellite number, A represents the signal amplitude, P_IRepresenting the spreading code, P, of the I branch_QRepresenting Q branch spreading code, D_IData code representing modulation on the I-branch, f represents carrier frequency,Indicating the initial phase of the carrier.

According to an aspect of the present invention, in step S2, the spacecraft receives and captures the beidou interstellar link signal according to the planned link establishment time slot, and obtains a receiving time corresponding to the code phase:

wherein CP is the sampling time t of the receiver in the inter-satellite ranging code_reThe corresponding code phase value.

According to an aspect of the present invention, in step S2, the uncertainty of the time of the spacecraft acquisition signal is ± 5ms, and at least 4 or more Beidou satellite inter-satellite link signals are received and acquired.

According to one aspect of the present invention, in step S3, a pseudo range value is calculated from the received signal, and after 1 hour of data is accumulated, in-orbit solution is performed in combination with the accumulated data of the previous day:

calculating the transmission time t of the link signal between the satellites of the navigation satellite according to the spread spectrum code table_tr,iThe pseudorange measurement may be calculated by:

obtaining a simultaneous equation set according to a three-sphere geometric intersection principle:

wherein (x)_i,y_i,z_i,δt_BD,i) The i is the position and clock error of 4 Beidou satellites and is known data; rho_i1,2,3 and 4 are pseudo-range measurement values obtained by signal processing of the inter-satellite link receiver of the spacecraft; (x)_u,y_u,z_u,δt_u) The method is characterized in that the position and clock error of the spacecraft are accumulated, and the data of the position and clock error of the spacecraft are converted into orbit parameters of the spacecraft through fitting.

According to one aspect of the invention, the spacecraft downloads the on-board orbit determination calculation result, the original ranging value and the ranging time to the ground system, the ground system performs one-way orbit determination calculation filtering, and compares the ground calculation result with the on-board calculation result to complete spacecraft orbit determination performance verification analysis.

According to the spacecraft orbit determination method based on the Beidou inter-satellite unidirectional link, the unidirectional link is only established between the spacecraft and the Beidou satellite, only satellite signals are received, and the technical complexity and the engineering realization difficulty of orbit determination are reduced. On the other hand, the high-orbit satellite can realize orbit determination accuracy of hundred meters by the orbit determination accuracy of the unidirectional link building, and the orbit determination accuracy is equivalent to the orbit determination accuracy of the bidirectional link building.

Drawings

FIG. 1 is a diagram schematically showing the analysis of the orbit determination performance of a high orbit satellite by the spacecraft orbit determination method based on the Beidou inter-satellite unidirectional link according to the invention.

Detailed Description

The present invention is described in detail below with reference to the drawings and the specific embodiments, which are not repeated herein, but the embodiments of the present invention are not limited to the following embodiments.

The invention provides a spacecraft orbit determination method based on a Beidou inter-satellite unidirectional link, which comprises the following steps that S1, a Beidou satellite sends an inter-satellite link signal to a spacecraft through an inter-satellite link antenna; s2, the spacecraft works only in a receiving mode, receives signals sent by the Beidou satellite, and calculates pseudo-range values according to the received signals; and S3, resolving the orbit parameters of the spacecraft after accumulating the pseudo range value for a certain time.

Specifically, in step S1, according to the planned link establishment time slot, the beidou satellite transmits a signal S to the spacecraft through the inter-satellite link antenna^j(t)：

Wherein j represents the satellite number, A represents the signal amplitude, P_IRepresenting the spreading code, P, of the I branch_QRepresenting Q branch spreading code, D_IData code representing modulation on the I-branch, f represents carrier frequency,Indicating the initial phase of the carrier.

In step S2, the spacecraft receives and captures the Beidou interstellar link signals according to the planned link establishment time slot, captures a time uncertainty of ± 5ms, receives and captures more than 4 Beidou interstellar link signals to obtain a receiving time corresponding to the code phase:

wherein CP is the sampling time t of the receiver in the inter-satellite ranging code_reThe corresponding code phase value.

In step S3, a pseudo range value is calculated from the received signal, 1 hour of data is accumulated, and then orbit solution is performed on the orbit in association with the accumulated data of the previous day:

calculating the transmission time t of the link signal between the satellites of the navigation satellite according to the spread spectrum code table_tr,iThe pseudorange measurement may be calculated by:

obtaining a simultaneous equation set according to a three-sphere geometric intersection principle:

wherein (x)_i,y_i,z_i,δt_BD,i) The i is the position and clock error of 4 Beidou satellites and is known data; rho_i1,2,3 and 4 are pseudo-range measurement values obtained by signal processing of the inter-satellite link receiver of the spacecraft; (x)_u,y_u,z_u,δt_u) Is the position and clock error of the spacecraft. And then, accumulating the position and clock error data of the spacecraft for a period of time, and converting the data into orbit parameters of the spacecraft through fitting.

And finally, the spacecraft downloads the on-board orbit determination calculation result, the original ranging value and the ranging time to a ground system, the ground system performs one-way orbit determination calculation filtering, and the ground calculation result and the on-board calculation result are compared to finish the performance verification analysis of the on-board orbit determination of the spacecraft.

According to the spacecraft orbit determination method based on the Beidou inter-satellite unidirectional link, the unidirectional link is only established between the spacecraft and the Beidou satellite, only satellite signals are received, and the technical complexity and the engineering realization difficulty of orbit determination are reduced. On the other hand, the high-orbit satellite can realize orbit determination accuracy of hundred meters by the orbit determination accuracy of the unidirectional link building, and the orbit determination accuracy is equivalent to the orbit determination accuracy of the bidirectional link building.

As shown in fig. 1, according to an embodiment of the invention, simulation analysis is performed on the orbit determination performance of the geostationary orbit satellite by using the spacecraft orbit determination method based on the Beidou inter-satellite unidirectional link. By accumulating the ranging data of 1 hour and accumulating the data of two days, the performance that the error of track measurement and 24-hour forecast is less than 200 meters can be realized.

The above description is only one embodiment of the present invention, and is not intended to limit the present invention, and it is apparent to those skilled in the art that various modifications and variations can be made in the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.