CN111245508B - X-ray communication link capturing method - Google Patents

Abstract

The invention provides an X-ray communication link capturing method based on two-degree-of-freedom pulsar radiation direction vector search, which comprises the steps of firstly, establishing a pulsar radiation vector observation coordinate system comprising a body coordinate system of a body and a collimator coordinate system, establishing a collimator mathematical model based on the observation coordinate system, and establishing a pulsar signal radiation direction vector observation model based on the collimator mathematical model; on the basis of an observation model, a two-degree-of-freedom radiation direction vector search algorithm is provided, so that the rapid search and acquisition of radiation vectors are realized, and the unassisted rapid acquisition of an X-ray communication link is realized on the basis of the prior agreement between an X-ray communication transceiver and the direction of the radiation direction vector. The capture method provided by the invention does not depend on a special radio frequency or optical link, has strong anti-interference capability and autonomy and is suitable for application of deep space X-ray communication.

Description

X-ray communication link capturing method

Technical Field

The invention relates to a communication method in the field of aerospace application, in particular to an unassisted rapid acquisition method for an X-ray communication link based on pulsar radiation direction vector search.

Background

X-ray Communications (XCOM) is an emerging deep space communication technology, which utilizes the good characteristics of high energy, high frequency, low attenuation and low dispersion of X-rays to realize high-reliability and high-speed communication, and is a deep space communication mode with great potential. Before the X-ray communication is established, the link capture of a transmitting end and a receiving end needs to be realized, and the communication can be carried out after the link capture is finished. The link acquisition methods used in existing optical communications are typically implemented using additional radio frequency or optical acquisition links. The additional rf or optical trapping both increases the weight of the device, while the rf or optical link is highly susceptible to environmental interference, resulting in instability of the trapping link.

The X-ray pulsar is a naturally-existing celestial body, and can radiate X-ray signals in two axial directions while rotating stably around a rotation axis. Because the star surface of the pulsar is very stable and is far away from the solar system, when X-ray pulsar signals are observed from the solar system, small changes of the star surface in a short period can be ignored, and the radiation direction of the X-ray pulsar signals reaching the solar system can be considered to be parallel and stable. The stability of the direction of the pulsar radiation provides directional information for other systems in deep space. The capture of XCOM link using X-ray pulsar signal radiation direction vector is a feasible method.

Disclosure of Invention

Aiming at the problems of the existing link capturing method used in optical communication, the invention provides an X-ray communication link capturing method based on two-degree-of-freedom pulsar radiation direction vector search, which is realized by utilizing X-ray pulsar signal vector observation without an additional capturing link, saves the weight of equipment, is not influenced by environment interference, and has high reliability and strong autonomy.

The invention adopts the following technical scheme:

an X-ray communication link capturing method based on two-degree-of-freedom pulsar radiation direction vector search comprises a two-degree-of-freedom rotary table, wherein an X-ray detector and a collimator are arranged on the two-degree-of-freedom rotary table, and the collimator is positioned in front of the X-ray detector;

the capturing method comprises the following steps:

step 1: establishing a pulsar radiation vector observation coordinate system which comprises a referenceBody coordinate system (x) of spacecraft body_b,y_b,z_b) And collimator coordinate system (x)_c,y_c,z_c)，

Body coordinate system (x)_b,y_b,z_b) The center of mass of (1) is the center of mass of the spacecraft, x of the body coordinate system_bThe axis pointing in the direction of the long axis of the spacecraft, z_bThe axis being perpendicular to the longitudinal section of the spacecraft, x_b,y_b,z_bForming a right-handed spiral coordinate system;

collimator coordinate system (x)_c,y_c,z_c) Z of (a)_cAxial direction of the shaft as collimator, x_c、y_cThe axes being at the bottom of the collimator and perpendicular to each other, z_cAxis perpendicular to x_cy_cPlane of lying, x_c、y_c、z_cForm a right-handed helical coordinate system, x_cy_cThe plane rotates along with the rotation of the two-degree-of-freedom turntable;

body coordinate system (x)_b,y_b,z_b) And collimator coordinate system (x)_c,y_c,z_c) The origin of coordinates of (a) is set to the same point, and [ alpha ] is set to x_cAt x_boy_bProjection x in plane_c' and x_bBeta is z_cAnd z_cAt x_boy_bIn-plane projection z_cThe included angle of `;

step 2: based on the body coordinate system (x)_b,y_b,z_b) And collimator coordinate system (x)_c,y_c,z_c) Establishing a collimator observation model, and obtaining an effective area S when the included angle between the axis of the collimator and the vector of the radiation direction of the pulsar is delta according to the collimator observation model_e(δ), then the effectively detected photon flux intensity of the X-ray detector is:

Ph_f＝ηS_e(δ)A (1)

wherein, eta represents the detection efficiency, and A is the radiation flux intensity of the X-ray pulsar signal;

and step 3: n in the initial pointing direction_zc0Photon flux intensity observed by the detector is Ph₀Under the condition of (1), setting the search step lengths in the alpha direction and the beta direction as s respectively₁And s₂；

And 4, step 4: step search s along alpha direction and beta direction respectively₁And s₂Obtaining the intensity of the detected photon flux as Ph₂Z is novel_cPointing at n_zc2；

And 5: judging whether the condition 1 is met: ph₂＞Ph₀If condition 1 is satisfied, s is₁＝2s₁，s₂＝2s₂And continuously judging whether the condition 2 is met: | s₁< ε and | s₂If | < epsilon, if the condition 2 is satisfied, the search process is terminated, the step 9 is executed, if the condition 2 is not satisfied, the Ph is enabled₀＝Ph₂，n_zc0＝n_zc2Returning to the step 4; epsilon represents the search precision requirement for ending the search process;

if Ph is₂≤Ph₀If yes, executing step 6;

step 6: step search s along alpha direction and beta direction respectively₁And-s₂And/4, calculating the radiation flux intensity Ph at the moment₃Z is novel_cPointing at n_zc3And judging whether the condition 3 is met: ph₃＞Ph₀If condition 3 is satisfied, order s₁＝s₁，s₂＝-s₂And/2, continuously judging whether the condition 4 is met: | s₁< ε and | s₂If the | < epsilon, if the condition 4 is met, the searching process is terminated, and the step 9 is executed; if the condition 4 is not satisfied, let Ph₀＝Ph₃，n_zc0＝n_zc3Returning to the step 4;

if Ph is₃≤Ph₀If yes, executing step 7;

and 7: stepping search-s along alpha and beta directions respectively₁(ii) 4 and s₂Calculating the radiation flux intensity Ph₄Z is novel_cPointing at n_zc4And judging whether the condition 5 is met: ph₄＞Ph₀If the condition 5 is satisfied, s is₁＝-s₁/2，s₂＝s₂And continuously judging whether the condition 6 is met: | s₁< ε and | s₂If | < epsilon, satisfy condition 6Stopping the searching process and executing the step 9; if the condition 6 is not satisfied, let Ph₀＝Ph₄，n_zc0＝n_zc4Returning to the step 4;

if Ph is₄≤Ph₀If yes, executing step 8;

and 8: stepping search-s along alpha and beta directions respectively₁(iii) 4 and-s₂And/4, calculating radiation flux intensity Ph₅Z is novel_cPointing at n_zc5And judging whether the condition 7 is met: ph₅＞Ph₀Then let s₁＝-s₁/2，s₂＝-s₂And/2, continuously judging whether the condition 8 is met: | s₁< ε and | s₂If the | < epsilon, if the condition 8 is met, the searching process is terminated, and step 9 is executed; if the condition 8 is not satisfied, let Ph₀＝Ph₅，n_zc0＝n_zc5Returning to the step 4;

and step 9: after the search process is ended, the obtained radiation direction vector of the pulsar signal uses n_zcDenotes that p is_eAnd p_rIndicating the antenna pointing direction at both ends of the X-ray communication transceiver, assuming that p has been agreed in advance_eAnd p_rAnd n_zcAre respectively theta₁And theta₂Then n is obtained_zcAnd then determining the orientation of an X-ray communication emission source and the orientation of a receiving detector to realize the acquisition of the X-ray communication link.

Preferably, s is searched stepwise in the alpha direction₁Means that rotating the collimator increases the angle alpha by s₁Calculating the photon flow intensity at the moment according to the formula (1);

stepwise search s in the beta direction₂Means that rotating the collimator increases the angle beta by s₂And calculating the photon flux intensity at the moment according to the formula (1).

The invention has the beneficial effects that:

the X-ray communication link capturing method for the two-degree-of-freedom pulsar radiation direction vector search is realized by observing an X-ray pulsar signal, does not need an additional radio frequency or optical link, is not influenced by a space complex environment, has strong autonomy, and provides an easy-to-realize and strong-autonomy link capturing method for X-ray communication.

Drawings

Fig. 1 shows the relationship between the body coordinate system and the collimator coordinate system.

Fig. 2 is a collimator observation model.

Fig. 3 shows the effective area of the bottom surface of the collimator (the effective area does not include the center of the bottom surface).

Fig. 4 shows the effective detection area (the effective area includes the center of the bottom) of the X-ray detector.

Fig. 5 illustrates the X-ray communication link acquisition principle.

Detailed Description

The following description of the embodiments of the present invention will be made with reference to the accompanying drawings:

with reference to fig. 1 to 5, an X-ray communication link capturing method based on two-degree-of-freedom pulsar radiation direction vector search comprises a two-degree-of-freedom turntable, wherein an X-ray detector and a collimator are arranged on the two-degree-of-freedom turntable, and the directions of the X-ray detector and the collimator can be adjusted through the adjustment of the turntable.

The collimator is an elongated tubular device for filtering out part of the background noise in space when observing the X-ray source, and is located in front of the X-ray detector.

The capturing method comprises the following steps:

step 1: establishing a pulsar radiation vector observation coordinate system which comprises a body coordinate system (x) of a reference spacecraft body_b,y_b,z_b) And collimator coordinate system (x)_c,y_c,z_c)。

Body coordinate system (x)_b,y_b,z_b) The center of mass of (1) is the center of mass of the spacecraft, x of the body coordinate system_bThe axis pointing in the direction of the long axis of the spacecraft, z_bThe axis being perpendicular to the longitudinal section of the spacecraft, x_b,y_b,z_bForming a right-handed spiral coordinate system.

Collimator coordinate system (x)_c,y_c,z_c) Z of (a)_cWith axis being collimatorAxially directed direction, x_c、y_cThe axes being at the bottom of the collimator and perpendicular to each other, z_cAxis perpendicular to x_cy_cPlane of lying, x_c、y_c、z_cForm a right-handed helical coordinate system, x_cy_cThe plane rotates along with the rotation of the two-degree-of-freedom turntable.

Body coordinate system (x)_b,y_b,z_b) And collimator coordinate system (x)_c,y_c,z_c) The origin of coordinates of (a) is set to the same point, and the relationship between the two coordinate systems can be represented by α and β. As shown in FIG. 1, where α is x_cAt x_boy_bProjection x in plane_c' and x_bBeta is z_cAnd z_cAt x_boy_bIn-plane projection z_cThe angle of the angle.

Step 2: based on the body coordinate system (x)_b,y_b,z_b) And collimator coordinate system (x)_c,y_c,z_c) An observation model of the collimator is established, as shown in fig. 2, and fig. 2 shows a geometric model of the collimator and a projection condition of the bottom surface. As can be seen from the observation model of the collimator in fig. 2, when the angle between the axial direction of the collimator and the radiation direction vector of the pulsar signal changes, the effective area of the bottom surface of the collimator changes because the collimator is a long cylindrical device. When the pulsar signal is directly irradiated on the collimator, namely the radiation direction vector of the pulsar signal is parallel to the axis of the collimator, the effective area of the bottom surface of the collimator is the ground radius of the collimator, and when the included angle between the radiation direction vector of the pulsar signal and the axis of the collimator is delta, the effective area is reduced. Calculating the effective area S of the bottom surface by using the geometric area observed by the collimator_e(δ) (i.e. the shaded area in fig. 3 and 4) versus the angle δ:

delta represents the included angle between the direction of the collimator and the radiation direction vector n of the pulsar signal, r is the radius of the collimator, and h is the length of the collimator. Let η denote the detection efficiency and a be the radiation flux intensity of the X-ray pulsar signal, the photon flux intensity received by the X-ray detector can be expressed as:

Ph_f＝ηS_e(δ)A (1)

as can be seen from the formulas (1) and (2), the intensity of photon flux received by the X-ray detector is directly related to the included angle between the collimator and the radiation direction vector of the pulsar signal. Can prove that S_e(δ) is a monotonically decreasing function with respect to δ. Therefore, the radiation direction vector search is converted into the photon flux intensity search through the collimator observation model modeling.

And step 3: n in the initial pointing direction_zc0Photon flux intensity observed by the detector is Ph₀Under the condition of (1), setting the search step lengths in the alpha direction and the beta direction as s respectively₁And s₂；

Step search s along alpha direction₁Means that rotating the collimator increases the angle alpha by s₁Calculating the photon flow intensity at the moment according to the formula (1);

stepwise search s in the beta direction₂Means that rotating the collimator increases the angle beta by s₂And calculating the photon flux intensity at the moment according to the formula (1).

And 4, step 4: step search s along alpha direction and beta direction respectively₁And s₂Obtaining the intensity of the detected photon flux as Ph₂Z is novel_cPointing at n_zc2。

And 5: judging whether the condition 1 is met: ph₂＞Ph₀If condition 1 is satisfied, s is₁＝2s₁，s₂＝2s₂And continuously judging whether the condition 2 is met: | s₁< ε and | s₂If | < epsilon, if the condition 2 is satisfied, the search process is terminated, the step 9 is executed, if the condition 2 is not satisfied, the Ph is enabled₀＝Ph₂，n_zc0＝n_zc2Returning to the step 4; epsilon represents the search precision requirement for ending the search process;

if Ph is₂≤Ph₀Then step 6 is performed.

Step 6:step search s along alpha direction and beta direction respectively₁And-s₂And/4, calculating the radiation flux intensity Ph at the moment₃Z is novel_cPointing at n_zc3And judging whether the condition 3 is met: ph₃＞Ph₀If condition 3 is satisfied, order s₁＝s₁，s₂＝-s₂And/2, continuously judging whether the condition 4 is met: | s₁< ε and | s₂If the | < epsilon, if the condition 4 is met, the searching process is terminated, and the step 9 is executed; if the condition 4 is not satisfied, let Ph₀＝Ph₃，n_zc0＝n_zc3Returning to the step 4;

if Ph is₃≤Ph₀Then step 7 is performed.

And 7: stepping search-s along alpha and beta directions respectively₁(ii) 4 and s₂Calculating the radiation flux intensity Ph₄Z is novel_cPointing at n_zc4And judging whether the condition 5 is met: ph₄＞Ph₀If the condition 5 is satisfied, s is₁＝-s₁/2，s₂＝s₂And continuously judging whether the condition 6 is met: | s₁< ε and | s₂If the | < epsilon, if the condition 6 is met, the searching process is terminated, and the step 9 is executed; if the condition 6 is not satisfied, let Ph₀＝Ph₄，n_zc0＝n_zc4Returning to the step 4;

if Ph is₄≤Ph₀Then step 8 is performed.

And 8: stepping search-s along alpha and beta directions respectively₁(iii) 4 and-s₂And/4, calculating radiation flux intensity Ph₅Z is novel_cPointing at n_zc5And judging whether the condition 7 is met: ph₅＞Ph₀Then let s₁＝-s₁/2，s₂＝-s₂And/2, continuously judging whether the condition 8 is met: | s₁< ε and | s₂If the | < epsilon, if the condition 8 is met, the searching process is terminated, and step 9 is executed; if the condition 8 is not satisfied, let Ph₀＝Ph₅，n_zc0＝n_zc5And returning to the step 4.

And step 9: after the search process is ended, the radiation direction vector of the pulsar signal is obtainedQuantity n_zcDenotes that p is_eAnd p_rIndicating the antenna pointing direction at both ends of the X-ray communication transceiver, assuming that p has been agreed in advance_eAnd p_rAnd n_zcAre respectively theta₁And theta₂Then n is obtained_zcAnd then determining the orientation of an X-ray communication emission source and the orientation of a receiving detector to realize the acquisition of the X-ray communication link.

It is to be understood that the above description is not intended to limit the present invention, and the present invention is not limited to the above examples, and those skilled in the art may make modifications, alterations, additions or substitutions within the spirit and scope of the present invention.

Claims (2)

1. An X-ray communication link capturing method based on two-degree-of-freedom pulsar radiation direction vector search is characterized by comprising a two-degree-of-freedom rotary table, wherein an X-ray detector and a collimator are arranged on the two-degree-of-freedom rotary table, and the collimator is positioned in front of the X-ray detector;

the capturing method comprises the following steps:

step 1: establishing a pulsar radiation vector observation coordinate system which comprises a body coordinate system (x) of a reference spacecraft body_b,y_b,z_b) And collimator coordinate system (x)_c,y_c,z_c)，

Body coordinate system (x)_b,y_b,z_b) The center of mass of (1) is the center of mass of the spacecraft, x of the body coordinate system_bThe axis pointing in the direction of the long axis of the spacecraft, z_bThe axis being perpendicular to the longitudinal section of the spacecraft, x_b,y_b,z_bForming a right-handed spiral coordinate system;

collimator coordinate system (x)_c,y_c,z_c) Z of (a)_cAxial direction of the shaft as collimator, x_c、y_cThe axes being at the bottom of the collimator and perpendicular to each other, z_cAxis perpendicular to x_cy_cPlane of lying, x_c、y_c、z_cForm a right-handed helical coordinate system, x_cy_cThe plane rotates along with the rotation of the two-degree-of-freedom turntable;

body coordinate system (x)_b,y_b,z_b) And collimator coordinate system (x)_c,y_c,z_c) The origin of coordinates of (a) is set to the same point, and [ alpha ] is set to x_cAt x_boy_bProjection x in plane_c' and x_bBeta is z_cAnd z_cAt x_boy_bIn-plane projection z_cThe included angle of `;

step 2: based on the body coordinate system (x)_b,y_b,z_b) And collimator coordinate system (x)_c,y_c,z_c) Establishing a collimator observation model, and obtaining an effective area S when the included angle between the axis of the collimator and the vector of the radiation direction of the pulsar is delta according to the collimator observation model_e(δ), then the effectively detected photon flux intensity of the X-ray detector is:

Ph_f＝ηS_e(δ)A (1)

wherein, eta represents the detection efficiency, and A is the radiation flux intensity of the X-ray pulsar signal;

and step 3: n in the initial pointing direction_zc0Photon flux intensity observed by the detector is Ph₀Under the condition of (1), setting the search step lengths in the alpha direction and the beta direction as s respectively₁And s₂；

And 4, step 4: step search s along alpha direction and beta direction respectively₁And s₂Obtaining the intensity of the detected photon flux as Ph₂Z is novel_cPointing at n_zc2；

And 5: judging whether the condition 1 is met: ph₂＞Ph₀If condition 1 is satisfied, s is₁＝2s₁，s₂＝2s₂And continuously judging whether the condition 2 is met: | s₁< ε and | s₂If | < epsilon, if the condition 2 is satisfied, the search process is terminated, the step 9 is executed, if the condition 2 is not satisfied, the Ph is enabled₀＝Ph₂，n_zc0＝n_zc2Returning to the step 4; epsilon represents the search precision requirement for ending the search process;

if Ph is₂≤Ph₀If yes, executing step 6;

step 6: step search s along alpha direction and beta direction respectively₁And-s₂And/4, calculating the radiation flux intensity Ph at the moment₃Z is novel_cPointing at n_zc3And judging whether the condition 3 is met: ph₃＞Ph₀If condition 3 is satisfied, order s₁＝s₁，s₂＝-s₂And/2, continuously judging whether the condition 4 is met: | s₁< ε and | s₂If the | < epsilon, if the condition 4 is met, the searching process is terminated, and the step 9 is executed; if the condition 4 is not satisfied, let Ph₀＝Ph₃，n_zc0＝n_zc3Returning to the step 4;

if Ph is₃≤Ph₀If yes, executing step 7;

and 7: stepping search-s along alpha and beta directions respectively₁(ii) 4 and s₂Calculating the radiation flux intensity Ph₄Z is novel_cPointing at n_zc4And judging whether the condition 5 is met: ph₄＞Ph₀If the condition 5 is satisfied, s is₁＝-s₁/2，s₂＝s₂And continuously judging whether the condition 6 is met: | s₁< ε and | s₂If the | < epsilon, if the condition 6 is met, the searching process is terminated, and the step 9 is executed; if the condition 6 is not satisfied, let Ph₀＝Ph₄，n_zc0＝n_zc4Returning to the step 4;

if Ph is₄≤Ph₀If yes, executing step 8;

and 8: stepping search-s along alpha and beta directions respectively₁(iii) 4 and-s₂And/4, calculating radiation flux intensity Ph₅Z is novel_cPointing at n_zc5And judging whether the condition 7 is met: ph₅＞Ph₀If condition 7 is satisfied, s is₁＝-s₁/2，s₂＝-s₂And/2, continuously judging whether the condition 8 is met: | s₁< ε and | s₂If the | < epsilon, if the condition 8 is met, the searching process is terminated, and step 9 is executed; if the condition 8 is not satisfied, let Ph₀＝Ph₅，n_zc0＝n_zc5Returning to the step 4;

and step 9: after the search process is ended, the obtained radiation direction vector of the pulsar signal uses n_zcDenotes that p is_eAnd p_rIndicating the antenna pointing direction at both ends of the X-ray communication transceiver, assuming that p has been agreed in advance_eAnd p_rAnd n_zcAre respectively theta₁And theta₂Then n is obtained_zcAnd then determining the orientation of an X-ray communication emission source and the orientation of a receiving detector to realize the acquisition of the X-ray communication link.

2. The method as claimed in claim 1, wherein the step search s is performed along the α direction₁Means that rotating the collimator increases the angle alpha by s₁Calculating the photon flow intensity at the moment according to the formula (1);

stepwise search s in the beta direction₂Means that rotating the collimator increases the angle beta by s₂And calculating the photon flux intensity at the moment according to the formula (1).

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