An intensity dependent x-ray photon detection method and apparatus

Abstract

The present application relates to the technical field of astronomical navigation, and particularly relates to an X-ray photon detection method and device based on intensity correlation, which comprises the following steps: step one, simultaneously observing a same pulsar by using two detection units, recording X-ray photon arrival time, and completing initial collection of X-ray pulsar signals; step two, converting the X-ray photon arrival time; step three, calculating and removing X-ray noise photons; step four, processing the X-ray signal photons after noise removal, and obtaining high signal-to-noise ratio X-ray photon arrival time sequences; and step five, folding the high signal-to-noise ratio X-ray photon arrival time sequences to obtain a test profile, comparing the test profile with a standard profile, and obtaining high-precision TOA information. The present application uses the difference between X-ray signal photons and noise photons for analysis, effectively removes noise photons from the same line-of-sight direction and the same energy spectrum range of the pulsar, and effectively improves the signal-to-noise ratio of the detection signal.

Description

Technical Field

[0001] This invention relates to the field of astronomical navigation technology, specifically to an intensity-dependent X-ray photon detection method and apparatus. Background Technology

[0002] X-ray pulsar navigation (XPNAV), a revolutionary astronomical navigation method, relies on the core principle of using highly stable X-ray pulse signals emitted by distant pulsars as natural spatiotemporal beacons. Spacecraft-borne detectors receive these signals from deep space, precisely measuring the time of arrival (TOA) and comparing it to the predicted TOA at the Solar System Barycenter (SSB). This allows for the calculation of the spacecraft's highly accurate position, velocity, and even attitude information relative to the SSB, enabling fully autonomous navigation in deep space. Theoretically, its accuracy potential can reach the hundreds or even tens of meters, making it crucial for deep space exploration missions.

[0003] According to the principle of pulsar navigation, the accuracy of the time difference of arrival (TOA) measurement is the cornerstone of the accuracy of the entire navigation system. The higher the accuracy of the TOA obtained by the system, the higher the navigation accuracy. Obtaining the TOA usually involves the following processes: X-ray pulsar navigation detector acquires X-ray signals radiated by pulsars → signal denoising → pulse profile folding → profile comparison → TOA acquisition.

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

[0005] In traditional X-ray pulsar navigation systems, filtering and noise reduction methods are typically used, or a high signal-to-noise ratio is achieved by increasing the detection area and detection time. However, these detection methods cannot eliminate noise photons from the same line-of-sight and energy spectrum range as the pulsar. At the same time, increasing the detection time will lead to slow TOA data updates, which cannot meet the needs of dynamic spacecraft (such as during orbital maneuvers) for rapid and continuous positioning. Summary of the Invention

[0006] To address the application requirements of high signal-to-noise ratio (SNR) X-ray photon detection and the technical problem of being unable to eliminate noise photons from the same line-of-sight and energy spectrum range as pulsars, this invention proposes an intensity-correlated X-ray photon detection method and device. By utilizing the difference analysis between X-ray signal photons and noise photons, an intensity-correlated X-ray detection system is constructed to effectively eliminate noise photons from the same line-of-sight and energy spectrum range as pulsars, effectively improving the SNR of the detection signal, thus laying a technical foundation for high-precision TOA acquisition.

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

[0008] Step 1: Simultaneous observation of the same pulsar using two detection units, recording the arrival time of X-ray photons, and completing the initial acquisition of X-ray pulsar signals;

[0009] Step 2: Conversion of X-ray photon arrival time;

[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 the test profile, compare it with the standard profile, and obtain high-precision TOA information.

[0013] Furthermore, the two detection units mentioned 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 arcminute.

[0015] Furthermore, step two specifically involves: calling the pulsar database and the solar planetary ephemeris database to eliminate the error term of X-ray photons and converting the photon arrival time to the location at the center of the solar system.

[0016] Furthermore, step three specifically involves: using the statistical differences between pulsar signal photons and noise photons on the intensity coherence function to eliminate noise photons.

[0017] Furthermore, for X-ray signal photons, their intensity coherence function is given by equation (1).

[0018]

[0019] For X-ray noise photons, their intensity coherence function is given by equation (2).

[0020]

[0021] By utilizing the difference in intensity coherence function between noise photons and signal photons, noise photons can be effectively eliminated.

[0022] An intensity-dependent X-ray photon detection device, comprising

[0023] The dual-detector module is used to simultaneously acquire signals from the same pulsar and perform time conversion.

[0024] The photon arrival time conversion module is used to convert the arrival time of X-ray photons;

[0025] The intensity coherence calculation module is used to eliminate noise signals and achieve effective extraction of X-ray photon signals;

[0026] Pulsar photon arrival time inversion module for high signal-to-noise ratio X-ray photon arrival time series extraction;

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

[0028] The beneficial effects achieved by this invention are as follows:

[0029] 1. This invention constructs an intensity-correlated X-ray detection system. By analyzing the differences between X-ray signal photons and noise photons, it effectively eliminates noise photons from the same line of sight and energy spectrum range as the pulsar, thereby effectively improving the signal-to-noise ratio of the detection signal.

[0030] 2. Traditional pulsar navigation detection methods often improve the signal-to-noise ratio by increasing the detection area and extending the detection time, which leads to a deterioration in the real-time performance of the system. However, this invention improves the signal-to-noise ratio by using an innovative detection mechanism, 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 even when the detection area and time are limited.

[0031] 3. This invention encompasses 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 in concert. Starting from photon acquisition, it goes through time conversion, noise removal, signal inversion, and finally TOA extraction, forming a complete and efficient process, providing strong technical support for high-precision TOA acquisition and X-ray pulsar navigation applications. Attached Figure Description

[0032] Figure 1 This is a technical diagram of an intensity-dependent X-ray photon detection method and device.

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

[0034] Figure 3 This is an example diagram of the test profile of the dual-detector unit after noise reduction;

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

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

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

[0038] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, if the word "and / or" appears throughout the text, it means including three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution that simultaneously satisfies A and B. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

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

[0040] Step 1: Simultaneous observation of the same pulsar using two detection units, recording the arrival time of X-ray photons, and completing the initial acquisition of X-ray pulsar signals;

[0041] Step 2: Conversion of X-ray photon arrival time;

[0042] Step 3: Calculate and remove noisy 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 the 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 spatially and temporally. Spatially, the two detection units can be two different detection areas of the same detector or two independent detectors. Temporally, the two detection units can correspond to the same detector that collects photon data in two different time periods.

[0046] If the two detection units use two independent detectors, certain installation conditions must be met between them, and the two detectors must maintain simultaneous pointing of their optical axes. The optical axes of the two detectors are not aligned, which mainly affects two aspects: first, they cannot be simultaneously aligned with the pulsar, leading to pulsar signal loss; second, it affects the loss of effective area during simultaneous observation, thus affecting the accuracy of TOA measurements. If the effective area of ​​both detectors is S, and taking one detector as the standard, the angle of deviation of the optical axis of the other detector is θ, then the effective area loss caused by that detector during simultaneous observation is S(1-cosθ). Of the two factors mentioned above, the inability to simultaneously align with the pulsar is the main influencing factor. Considering that the angular diameter of pulsars is on the order of angular components, when two independent detectors are installed simultaneously, their optical axis pointing must be kept within 1 arcminute. Therefore, to avoid errors caused by the installation of two independent detectors, using a single detector for spatial or temporal partitioned detection is the optimal embodiment of the detection unit of this invention.

[0047] Step two specifically involves: by calling the pulsar database and the solar planetary ephemeris database, eliminating the Roemer delay and Shapiro delay corrections for X-ray photons during the actual detection process, and converting the photon arrival time to the location at the center of the solar system's mass.

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

[0049] Based on the strong periodicity of X-ray signal photons, its essence is a periodic pulsed thermal light field distribution, and its intensity coherence function is shown in equation (1).

[0050]

[0051] For X-ray noise photons, their essence is the distribution of a multimode thermal optical field, and the intensity coherence function of the multimode thermal optical field is shown in equation (2).

[0052]

[0053] By utilizing the difference in intensity coherence function between X-ray noise photons and signal photons, noise photons can be effectively eliminated.

[0054] An intensity-dependent X-ray photon detection device, comprising

[0055] The dual-detector module is used to simultaneously acquire signals from the same pulsar and perform time conversion.

[0056] The photon arrival time conversion module is used to convert the arrival time of X-ray photons;

[0057] The intensity coherence calculation module is used to eliminate X-ray noise signals and achieve effective extraction of X-ray photon signals;

[0058] Pulsar photon arrival time inversion module for high signal-to-noise ratio X-ray photon arrival time series extraction;

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

[0060] To verify the extraction effect of the extraction method based on the optimal estimation of periodic TOA proposed in this invention, the following simulation example was used to analyze the algorithm. The simulation conditions are shown below.

[0061] Table 1 Parameter settings in the simulation example

[0062] 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 ]]> Points Time 100s

[0063] Figures 2 to 4 The following is a simulation example of the denoising effect of the intensity-dependent X-ray photon detection method. Figure 2 The original test profile obtained by the dual detector unit; Figure 3 The test profile of the dual detectors after noise reduction; Figure 4This represents the information of the noise photons that have been removed. Simulation examples demonstrate that the intensity-correlated X-ray photon detection system proposed in this invention can effectively extract signal photons, suppress and remove background noise. Furthermore, contour folding analysis of the removed noise signal shows that it cannot fold out the effective contour of the Crab, thus effectively removing noise photons.

[0064] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the 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 within the protection scope of the present invention.

Claims

1. A method for detecting X-ray photons based on intensity correlation, characterized in that, Includes the following steps: Step 1: Simultaneous observation of the same pulsar using two detection units, recording the arrival time of X-ray photons, and completing the initial acquisition of X-ray pulsar signals; Step 2: Conversion of X-ray photon arrival time; 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 the test profile, compare it with the standard profile, and obtain high-precision TOA information; Step three specifically involves: using the statistical differences between pulsar signal photons and noise photons in the intensity coherence function to eliminate noise photons; For X-ray signal photons, their intensity coherence function is given by equation (1). （1） For X-ray noise photons, their intensity coherence function is given by equation (2). (2) By utilizing the difference in intensity coherence function between noise photons and signal photons, noise photons can be effectively eliminated.

2. The intensity-correlated X-ray photon detection method according to claim 1, characterized in that, The two detection units mentioned 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 intensity-correlated X-ray photon detection method 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 within 1 arcminute.

4. The intensity-correlated X-ray photon detection method according to claim 1, characterized in that, Step two specifically involves: calling the pulsar database and the solar planetary ephemeris database to eliminate the error term of X-ray photons and converting the photon arrival time to the location at the center of the solar system.

5. An intensity-dependent X-ray photon detection device, characterized in that, The apparatus is configured according to any one of the intensity-related X-ray photon detection methods described in claims 1-4, including: The dual-detector module is used to simultaneously acquire signals from the same pulsar and perform time conversion. The photon arrival time conversion module is used to convert the arrival time of X-ray photons; The intensity coherence calculation module is used to eliminate noise signals and achieve effective extraction of X-ray photon signals; Pulsar photon arrival time inversion module for high signal-to-noise ratio X-ray photon arrival time series extraction; The TOA extraction module is used to obtain high-precision TOA information.

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