X-ray photon detection method and device based on intensity correlation

Abstract

The invention relates to the technical field of celestial navigation, in particular to an X-ray photon detection method and device based on intensity correlation, and the method comprises the following steps: 1, employing two detection units to observe the same pulsar at the same time, recording the arrival time of X-ray photons, and completing the initial collection of X-ray pulsar signals; 2, converting the arrival time of the X-ray photons; 3, X-ray noise eliminating photons are calculated; 4, processing the de-noised X-ray signal photons to obtain an arrival time sequence of the X-ray photons with a high signal-to-noise ratio; and 5, folding the arrival time sequence of the X-ray photons with the high signal-to-noise ratio to obtain a test contour, and comparing the test contour with a standard contour to obtain high-precision TOA information. According to the method, the difference analysis of X-ray signal photons and noise photons is utilized, so that the noise photons from the same sight direction and the same energy spectrum range of the pulsar are effectively eliminated, and the signal-to-noise ratio of a detection signal is effectively improved.

Description

Technical Field

[0001] The present invention relates to the field of celestial navigation technology, and in particular to an intensity-correlation-based X-ray photon detection method and device. Background Art

[0002] X-ray pulsar navigation (XPNAV) is a revolutionary astronomical navigation method. Its core principle is to use the extremely stable X-ray pulse signals emitted by distant pulsars as natural space-time beacons. Detectors onboard spacecraft receive these signals from deep space and precisely measure the pulse's time of arrival (TOA). By comparing this time with the predicted arrival time at the Solar System Barycenter (SSB), the spacecraft's highly accurate position, velocity, and even attitude relative to the SSB can be calculated, enabling fully autonomous navigation in deep space. Its potential accuracy, theoretically reaching hundreds or even tens of meters, is crucial for deep space exploration missions.

[0003] According to the principles of pulsar navigation, the accuracy of the pulse time difference of arrival (TOA) is the cornerstone of the entire navigation system's precision. The higher the TOA accuracy, the higher the navigation precision. Acquiring TOA typically involves the following steps: X-ray pulsar navigation detectors collect X-ray signals emitted by pulsars → signal denoising → pulse profile folding → profile comparison → TOA acquisition.

[0004] According to the TOA acquisition process, X-ray photon detection with a high signal-to-noise ratio is the primary factor for high-precision TOA acquisition. Improving the signal-to-noise ratio of the X-ray signal that can be obtained by the X-ray pulsar navigation detector can effectively improve the TOA measurement accuracy.

[0005] Traditional X-ray pulsar navigation systems typically use filtering to remove noise or increase the detection area and detection time in exchange for a high signal-to-noise ratio. However, these detection methods cannot eliminate noise photons originating from the same line of sight and energy spectrum as the pulsar. Furthermore, the increased detection time slows down TOA data updates, making it unable to meet the requirements for fast, continuous positioning required by dynamic spacecraft, such as during orbital maneuvers. Summary of the Invention

[0006] In response to the application requirements of high signal-to-noise ratio X-ray photon detection and the technical problem of being unable to eliminate noise photons from the same line of sight direction and the same energy spectrum range as the pulsar, the present invention proposes an X-ray photon detection method and device based on intensity correlation. By utilizing the difference analysis between X-ray signal photons and noise photons, an X-ray detection system based on intensity correlation is constructed to effectively eliminate noise photons from the same line of sight direction and the same energy spectrum range as the pulsar, effectively improving the signal-to-noise ratio of the detection signal, thereby laying a technical foundation for high-precision TOA acquisition.

[0007] To achieve the above object, the technical solution of the present invention is: an X-ray photon detection method based on intensity correlation, comprising the following steps:

[0008] Step 1: Use two detection units to simultaneously observe the same pulsar, record the arrival time of X-ray photons, and complete the initial acquisition of X-ray pulsar signals;

[0009] Step 2: Convert the arrival time of X-ray photons;

[0010] Step 3: Calculate and remove X-ray noise photons;

[0011] Step 4: Process the denoised X-ray signal photons to obtain a high signal-to-noise ratio X-ray photon arrival time series;

[0012] Step 5: Fold the high signal-to-noise ratio X-ray photon arrival time series to obtain a test profile, compare it with the standard profile, and obtain high-precision TOA information.

[0013] Furthermore, the two detection units described in step one include one of the following three situations: spatially, the two detection units are two different detection areas of the same detector or two independent detectors; temporally, the two detection units are the same detector that collects photon data in two consecutive time periods.

[0014] Furthermore, when the two detection units are two independent detectors, the optical axes of the two independent detectors are pointed within 1 arc minute.

[0015] Furthermore, the step 2 is specifically as follows: calling the pulsar database and the solar and planetary ephemeris database, eliminating the error term of the X-ray photons, and converting the photon arrival time to the center of mass of the solar system.

[0016] Furthermore, the step three is specifically as follows: using the statistical difference in intensity coherence function between pulsar signal photons and noise photons to eliminate noise photons.

[0017] Furthermore, for X-ray signal photons, the intensity coherence function is expressed by formula (1):

[0018]

[0019] For X-ray noise photons, the intensity coherence function is expressed by formula (2):

[0020]

[0021] The noise photons are effectively eliminated by utilizing the difference in intensity coherence function between noise photons and signal photons.

[0022] An X-ray photon detection device based on intensity correlation, comprising

[0023] Dual detector module, used to simultaneously collect and time-shift signals from the same pulsar;

[0024] Photon arrival time conversion module, used for converting the arrival time of X-ray photons;

[0025] Intensity coherence calculation module, used to remove noise signals and achieve effective extraction of X-ray photon signals;

[0026] Pulsar photon arrival time reversal module, used for extracting high signal-to-noise ratio X-ray photon arrival time series;

[0027] The TOA extraction module is used to obtain high-precision TOA information.

[0028] The beneficial effects achieved by the present invention are:

[0029] 1. The present invention constructs an intensity-correlated X-ray detection system, which uses differential analysis between X-ray signal photons and noise photons to effectively eliminate noise photons coming from the same line of sight and energy spectrum as the pulsar, thereby effectively improving the signal-to-noise ratio of the detection signal.

[0030] 2. Traditional pulsar navigation detection methods often increase the signal-to-noise ratio by increasing the detection area and extending the detection time, resulting in poor real-time performance of the system. The present invention uses an innovative detection system to improve the signal-to-noise ratio without relying on increasing the detection area and detection time. It can ensure the navigation accuracy and real-time performance of the pulsar navigation system when the detection area and time are limited.

[0031] 3. The present invention covers an X-ray pulsar navigation dual-detector module, a photon arrival time conversion module, an intensity coherence calculation module, a pulsar photon arrival time inversion module, and a TOA extraction module. Each module has a clear division of labor and works together, starting from photon acquisition, going through time conversion, noise removal, signal inversion, and finally to TOA extraction, forming a complete and efficient process, providing strong technical support for high-precision TOA acquisition and X-ray pulsar navigation applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a technical diagram of an X-ray photon detection method and device based on intensity correlation;

[0033] Figure 2 is an example of the original test profile obtained by the dual detector unit;

[0034] Figure 3 This is an example of the test profile of the dual detection unit after denoising;

[0035] Figure 4 This is an example diagram of the removed noise photon information. DETAILED DESCRIPTION

[0036] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0037] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0038] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, if the meaning of "and / or" appearing in the full text is to include three parallel schemes, taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme in which A and B are satisfied at the same time. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0039] like Figures 1 to 4 As shown, an X-ray photon detection method based on intensity correlation includes the following steps:

[0040] Step 1: Use two detection units to simultaneously observe the same pulsar, record the arrival time of X-ray photons, and complete the initial acquisition of X-ray pulsar signals;

[0041] Step 2: Convert the arrival time of X-ray photons;

[0042] Step 3: Calculate and remove noise photons;

[0043] Step 4: Process the denoised X-ray signal photons to obtain a high signal-to-noise ratio X-ray photon arrival time series;

[0044] Step 5: Fold the high signal-to-noise ratio X-ray photon arrival time series to obtain a test profile, compare it with the standard profile, and obtain high-precision TOA information.

[0045] The two detection units in step one can be distinguished in space and time. In terms of space, the two detection units can be two different detection areas of the same detector, or two independent detectors; in terms of time, the two detection units can correspond to the same detector that collects photon data in two consecutive time periods.

[0046] If the two detection units use two independent detectors, then the two detectors need to meet certain installation conditions, and the two detectors need to keep their optical axes pointing at the same time. The different directions of the optical axes of the two detectors have two main effects. First, they cannot be aimed at the pulsar at the same time, which will lead to the loss of pulsar signals. Second, it affects the loss of effective area during simultaneous observation, which in turn affects the TOA measurement accuracy. The effective areas of the two detectors are both S. Taking one of the detectors as the standard, the angle of deviation of the optical axis of the other detector is θ, and the effective area loss caused by the detector during simultaneous observation is S(1-cosθ). Among the two factors mentioned above, the inability to aim at the pulsar at the same time is the main influencing factor. Considering that the angular diameter of the pulsar is at the angular component level, when the two independent detectors are installed at the same time, the optical axis pointing of the two detectors needs to be kept within 1 arc minute. Therefore, in order to avoid the errors caused by the two independent detectors during the installation process, using the same detector for spatial or temporal partitioned detection is the optimal embodiment of the detection unit of the present invention.

[0047] The specific steps of step 2 are: by calling the pulsar database and the solar and planetary ephemeris database, the Roemer delay and Shapiro delay corrections of X-ray photons in the actual detection process are eliminated, and the photon arrival time is converted to the center of mass of the solar system.

[0048] Step three is specifically: using the statistical difference in the intensity coherence function between pulsar signal photons and noise photons to eliminate noise photons.

[0049] According to the strong periodic characteristics of X-ray signal photons, its essence is the periodic pulse thermal light field distribution, and its intensity coherence function is expressed by formula (1)

[0050]

[0051] For X-ray noise photons, their essence is the distribution of multi-mode thermal light field. The intensity coherence function of the multi-mode thermal light field is expressed by formula (2):

[0052]

[0053] The noise photons are effectively eliminated by utilizing the difference in intensity coherence function between X-ray noise photons and signal photons.

[0054] An X-ray photon detection device based on intensity correlation, comprising

[0055] Dual detector module, used to simultaneously collect and time-shift signals from the same pulsar;

[0056] Photon arrival time conversion module, used for converting the arrival time of X-ray photons;

[0057] Intensity coherence calculation module, used to remove X-ray noise signals and achieve effective extraction of X-ray photon signals;

[0058] Pulsar photon arrival time reversal module, used for extracting high signal-to-noise ratio X-ray photon arrival time series;

[0059] The TOA extraction module is used to obtain high-precision TOA information.

[0060] In order to verify the extraction effect of the extraction method based on periodicity conforming to the TOA optimal estimation proposed in the present invention, the following simulation example is used to simulate and analyze the algorithm, and the simulation conditions are as follows.

[0061] Table 1 Parameter settings in simulation examples

[0062] Target pulsar Crab Period (ms) 33.729 Signal flow <![CDATA[1.54ph / s / cm 2 ]]> Noise flow <![CDATA[15.4ph / s / cm 2 ]]> Detector area <![CDATA[100cm 2 ]]> Integration time 100s

[0063] Figures 2 to 4 This is a simulation example of the denoising effect of the X-ray photon detection method based on intensity correlation, where Figure 2 Original test profile acquired for the dual-detector unit; Figure 3 is the test profile of the dual detector after denoising; Figure 4The simulation shows that the intensity-correlated X-ray photon detection system proposed in this invention can effectively extract signal photons and suppress and eliminate background noise. Furthermore, a contour folding analysis of the eliminated noise signal shows that no effective Crab contour can be folded, effectively eliminating noise photons.

[0064] It will be understood that the present invention is described by way of some embodiments, and it will be appreciated by those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are intended to be protected by the present invention.

Claims

1. An X-ray photon detection method based on intensity correlation, characterized in that: The following steps are involved: Step 1: Use two detection units to simultaneously observe the same pulsar, record the arrival time of X-ray photons, and complete the initial acquisition of X-ray pulsar signals; Step 2: Convert the arrival time of X-ray photons; Step 3: Calculate and remove X-ray noise photons; Step 4: Process the denoised X-ray signal photons to obtain a high signal-to-noise ratio X-ray photon arrival time series; Step 5: Fold the high signal-to-noise ratio X-ray photon arrival time series to obtain a test profile, compare it with the standard profile, and obtain high-precision TOA information.

2. The X-ray photon detection method based on intensity correlation according to claim 1, characterized in that: The two detection units described in step one include one of the following three situations: spatially, the two detection units are two different detection areas of the same detector or two independent detectors; temporally, the two detection units are the same detector that collects photon data in two consecutive time periods.

3. The X-ray photon detection method based on intensity correlation according to claim 2, characterized in that: When the two detection units are two independent detectors, the optical axes of the two independent detectors are pointed within 1 arc minute.

4. The X-ray photon detection method based on intensity correlation according to claim 1, characterized in that: The second step is specifically: calling the pulsar database and the solar and planetary ephemeris database, eliminating the error term of the X-ray photons, and converting the photon arrival time to the center of mass of the solar system.

5. The X-ray photon detection method based on intensity correlation according to claim 1, characterized in that: The step three is specifically as follows: using the statistical difference between the intensity coherence function of pulsar signal photons and noise photons to eliminate the noise photons.

6. The X-ray photon detection method based on intensity correlation according to claim 5, characterized in that: For X-ray signal photons, the intensity coherence function is expressed by formula (1) For X-ray noise photons, the intensity coherence function is expressed by formula (2): The noise photons are effectively eliminated by utilizing the difference in intensity coherence function between noise photons and signal photons.

7. An X-ray photon detection device based on intensity correlation, characterized in that: The device is configured according to the method for detecting X-ray photons based on intensity correlation according to any one of claims 1 to 6, comprising: Dual detector module, used to simultaneously collect and time-shift signals from the same pulsar; Photon arrival time conversion module, used for converting the arrival time of X-ray photons; Intensity coherence calculation module, used to remove noise signals and achieve effective extraction of X-ray photon signals; Pulsar photon arrival time reversal module, used for extracting high signal-to-noise ratio X-ray photon arrival time series; The TOA extraction module is used to obtain high-precision TOA information.

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