A low earth orbit enhanced signal anti-spoofing method

Abstract

The present invention proposes a method and electronic device for preventing spoofing of low-orbit augmented signals. The method comprises: receiving an L-band navigation signal and an X-band signal representing the L-orbit augmented signal; obtaining Doppler measurement values ​​of the X-band signal tracking loop, determining a Doppler auxiliary value for the L-band signal, and implementing L-band signal tracking; obtaining pseudorange values, pseudorange increments, and the difference between the pseudorange changes of the X-band and L-band frequencies; if the difference is greater than a preset value, determining that the signal is affected by a spoofing signal and resetting the L-band loop tracking value; completing X-band and L-band positioning and the difference between the positioning results; and determining the operating status of the L-band signal and whether it has been spoofed based on the difference. If it is spoofed, soft-starting the L-band signal loop and resetting the initial position of the code loop based on the information provided. This invention addresses the current status of L-band signals and utilizes the characteristics of other operating frequency bands that differ from conventional navigation signals to achieve anti-spoofing.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of space vehicles, in particular to a low-orbit enhanced signal anti-deception method. BACKGROUND

[0002] With the rapid development of modern science and technology, high-precision navigation equipment is one of the important basic guarantee platforms in the fields of communication, power, industry, business and national defense construction, and the demand for accurate space-time service is becoming more and more extensive. People have put forward higher and higher requirements for the precision, robustness and integrity of space-time service. How to obtain high-precision space-time service in various complex environments is the key to guarantee the normal and reliable operation of various systems.

[0003] The space segment of the satellite navigation system is composed of multiple satellites distributed around the world. The L-band navigation signal is transmitted to the earth surface and its adjacent space through the transmitting antenna. The power level reaching the ground is about-130dbm, which is equivalent to the original voltage signal of tens of nanovolts excited inside the antenna. The received radio frequency signal energy of the antenna is very low, which is 20dB lower than the thermal noise. Immediately after the antenna, the navigation signal enters the radio frequency channel, and the signal filtering and amplification and down-conversion are completed by the radio frequency signal. After being sampled by the ADC, the digital signal processing link begins. Due to the low power of the navigation signal, it is easy to be interfered and deceived and cannot work normally, and even the space-time information output is not conducive to the user. Therefore, it is particularly important to improve the robustness of the navigation signal through various means. SUMMARY

[0004] The technical problem to be solved by the present application is how to improve the robustness of the navigation signal and improve the anti-deception effect. In view of this, the present application provides a low-orbit enhanced signal anti-deception method and an electronic device.

[0005] The technical scheme adopted by the present application is a low-orbit enhanced signal anti-deception method, comprising:

[0006] Step S1, complete assembly processing, receive satellite navigation signals from the zenith, including L-band navigation signals and X-band signals representing low-orbit enhanced signals;

[0007] Step S2, acquire the Doppler measurement value of the signal tracking loop of the X-band through the signal tracking loop, denoted as d X ;

[0008] Step S3, according to the Doppler measurement value, determine the Doppler auxiliary value of the L-band signal using the X-band signal

[0009] Step S4, combine As an auxiliary value of signal tracking, the Doppler dynamic stress caused by relative motion between the terminal and the satellite is eliminated, a first-order tracking loop with a preset bandwidth is set, and L-band signal tracking is realized.

[0010] In step S5, the time of obtaining the first L-band pseudorange value is acquired and recorded as T0, and the corresponding X-band pseudorange value is ρ X，0 . The L-band pseudorange value corresponding to T0 is ρ L，0 .

[0011] In step S6, the X-band pseudorange value obtained at the subsequent epoch T k is recorded as ρ X，k , the L-band pseudorange value obtained is recorded as ρ L，k , and the pseudorange increment values Δρ X and Δρ L of each frequency band are determined.

[0012] In step S7, based on the pseudorange increment values, the difference Δρ L-X between the two-frequency pseudorange change amounts is determined.

[0013] In step S8, if Δρ L-X is greater than a preset value, it is judged that the signal is affected by spoofing, the L-band loop tracking amount is reset, and the influence of the spoofing signal is eliminated.

[0014] In step S9, the least square method is applied in the X-band and the L-band respectively to complete positioning, the L-band positioning position information is recorded as P L , and the X-band positioning position information is recorded as P X .

[0015] In step S10, the difference ΔP between the L-band positioning result and the X-band positioning result is determined.

[0016] In step S11, based on ΔP, the working state of the L-band signal and whether it has been spoofed are judged.

[0017] In step S12, if the L-band signal has been in a spoofed state, the L-band signal loop is soft-started, and the code ring initial position is reset according to the pseudorange time information, so as to eliminate the influence of the spoofing signal.

[0018] In one embodiment, in step S3, the Doppler auxiliary value is obtained by the following formula:

[0019]

[0020] Wherein, f L is the L-band carrier frequency, and f X is the X-band carrier frequency.

[0021] In one embodiment, the preset value of the bandwidth in step S4 is 0.05 Hz.

[0022] In one embodiment, the pseudo-range increase value of each frequency band in step S6 is obtained by the following formula:

[0023] Δρ X = ρ X,k - ρ X,0

[0024] Δρ L = ρ L,k - ρ L,0

[0025] wherein Δρ X is the pseudo-range increase value of the X frequency band, and Δρ L is the pseudo-range increase value of the L frequency band.

[0026] In one embodiment, the preset value in step S8 is 5 m.

[0027] In one embodiment, the working state of the L frequency band signal includes a normal state, an alarm state, and a spoofed state, and step S11 specifically includes:

[0028] If the AP is less than a first judgment threshold, the working state of the L frequency band signal is determined as the normal state;

[0029] If the AP is greater than the first judgment threshold and less than a second judgment threshold, the alarm state is entered, and the AP change is continuously monitored in the alarm state;

[0030] When the AP is greater than the second judgment threshold, the L frequency band signal is determined as being spoofed, and the spoofed state is entered.

[0031] In one embodiment, the first judgment threshold is configured as 20 m, and the second judgment threshold is configured as 50 m.

[0032] Another aspect of the present application also provides an electronic device, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor, and the computer program, when executed by the processor, implements the steps of the low-orbit enhanced signal anti-spoofing method according to any one of the above.

[0033] Another aspect of the present application also provides a computer storage medium, which stores a computer program, and the computer program, when executed by a processor, implements the steps of the low-orbit enhanced signal anti-spoofing method according to any one of the above.

[0034] Compared with the prior art, the present application has at least the following advantages:

[0035] The low-orbit enhanced signal anti-spoofing method provided by the application fully applies the current situation that the existing low-orbit spoofing equipment mainly targets L-band signals, and realizes anti-spoofing by using the characteristics that other working frequency bands are different from conventional navigation signals. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 The low-orbit enhanced signal anti-spoofing method flowchart according to the embodiment of the application;

[0037] Figure 2 The low-orbit enhanced signal anti-spoofing method flowchart according to the embodiment of the application;

[0038] Figure 3 The low-orbit enhanced signal anti-spoofing method flowchart according to the embodiment of the application;

[0039] Figure 4 The low-orbit enhanced signal anti-spoofing method flowchart according to the embodiment of the application;

[0040] Figure 5 The electronic device according to the embodiment of the application. DETAILED DESCRIPTION

[0041] In order to further clarify the technical means and effects of the present application for achieving the predetermined purpose, the present application will be described in detail as follows in combination with the drawings and preferred embodiments.

[0042] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0043] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0044] The first embodiment of the present application is a low-orbit enhanced signal anti-spoofing method, as shown in Figure 1 The method comprises the following steps:

[0045] Step S1, complete assembly processing, receive satellite navigation signals from the zenith, including L-band navigation signals and X-band signals representing low-orbit enhanced signals;

[0046] Step S2, through the signal tracking loop, obtain the Doppler measurement value of the signal tracking loop of the X-band, denoted as d X ;

[0047] Step S3, determining Doppler auxiliary value of the L-band signal by using the X-band signal according to the Doppler measurement value

[0048] Step S4, setting a first-order tracking loop with a preset bandwidth as an auxiliary value of signal tracking to eliminate Doppler dynamic stress caused by relative motion between the terminal and the satellite, and realizing L-band signal tracking

[0049] Step S5, obtaining a time of a first L-band pseudo-range value and recording as T0, and an X-band pseudo-range value corresponding to T0 as p X，0 L，0 ;

[0050] Step S6, obtaining an X-band pseudo-range value at a subsequent epoch T k , recording as p X，k , obtaining an L-band pseudo-range value as p L，k , and determining pseudo-range increment values of each band, Δp X , Δp L ;

[0051] Step S7, determining a difference Δp L-X between the two-band pseudo-range variation based on the pseudo-range increment values

[0052] Step S8, if Δp L-X is greater than a preset value, judging that the L-band signal is affected by a spoofing signal, resetting an L-band loop tracking amount, and eliminating the influence of the spoofing signal

[0053] Step S9, based on steps S2 to S8, completing positioning in the X-band and the L-band respectively by using a least square method, recording L-band positioning position information as P L , and recording X-band positioning position information as P X ;

[0054] Step S10, determining a difference ΔP between the L-band positioning result and the X-band positioning result

[0055] Step S11, judging a working state of the L-band signal and whether the L-band signal has been spoofed based on ΔP

[0056] Step S12, if the L-band signal has been in a spoofed state, soft-starting an L-band signal loop, and resetting a code ring initial position according to pseudo-range time information to eliminate the influence of the spoofing signal

[0057] The above implementation method will be described in detail below according to an application example.

[0058] Step S1, as​​Figure 2 As shown, a navigation antenna is installed on the upper surface of the aircraft, and an anti-spoofing satellite navigation receiver is assembled to receive satellite navigation signals from the zenith, including L-band navigation signals and X-band signals of the low-orbit augmentation system.

[0059] Step S2: Obtain the Doppler measurement value of the X-band signal tracking loop through the signal tracking loop, which is recorded as d X .

[0060] Step S3, according to the d obtained in step S2 X , calculate the Doppler auxiliary value of the L-band signal using the X-band signal, specifically by the following formula:

[0061]

[0062] Among them, f L is the L-band carrier frequency, f X is the carrier frequency of the X band.

[0063] Step S4, based on the result obtained in step S3 Carry out L-band signal tracking and As an auxiliary value for signal tracking, it eliminates the Doppler dynamic stress caused by the relative motion between the terminal and the satellite, sets a first-order tracking loop with a bandwidth of 0.05 Hz, and realizes L-band signal tracking.

[0064] Step S5, as Figure 3 As shown, based on steps S2 to S4, the pseudorange value of the L-band is completed, and the time of obtaining the first pseudorange value of the L-band is recorded as T0, and the corresponding pseudorange value of the X-band is ρ X，0 , the L-band pseudorange value corresponding to time T0 is ρ L，0 .

[0065] Step S6, in the subsequent epoch T k The X-band pseudorange value obtained at the moment is recorded as ρ X，k , the obtained L-band pseudorange value is recorded as ρ L，k Based on step S5, calculate the pseudorange increase value Δρ of each frequency band X , Δρ L , the specific formula is as follows:

[0066] Δρ X =ρ X，k -ρ X，0

[0067] Δρ L =ρ L，k -ρ L，0

[0068] Step S7: Based on step S6, calculate the difference Δρ between the pseudorange changes of the two frequency bands. L-X The specific formula is as follows:

[0069] Δρ L-X =Δρ L -Δρ X

[0070] Step S8, if Δρ L-X If the distance is greater than 5m, it is determined to be affected by a spoofing signal, and the L-band loop tracking value is reset to eliminate the influence of the spoofing signal.

[0071] Step S9, as Figure 4 As shown, based on steps S2 to S8, positioning is completed using the X band and L band respectively. The L band positioning position information is recorded as P L , X-band positioning information is recorded as P X .

[0072] Step S10: Calculate the difference between the L-band positioning result and the X-band positioning result based on the position obtained by the two-band navigation signals of the aircraft obtained in step S9. The specific formula is as follows:

[0073] AP=|P L -P X |

[0074] Step S11: Based on the AP obtained in step S10, determine whether the L-band signal has been spoofed. The details are as follows:

[0075] There are three specific states: normal, alarm, and spoofed. The default state is normal. If AP∈(20m, 50m), the system enters the alarm state, indicating that the navigation device may have been spoofed. In the alarm state, the AP is continuously monitored. If AP>20m in subsequent epochs and ΔP shows a continuously increasing trend, when AP>50m, the L-band signal is determined to have been spoofed. If AP∈(20m, 50m) is always true, the system remains in the alarm state.

[0076] Step S12: Get the working status of L-band signal according to step S11. If it is determined that L-band has been deceived, soft start the L-band signal loop. The information resets the code ring to its initial position to eliminate the influence of deceptive signals.

[0077] Compared with the prior art, this embodiment has at least the following effects:

[0078] (1) The present invention assists L-band navigation signal tracking with X-band Doppler tracking frequency, further reducing the L-band signal tracking bandwidth and the impact of deceptive signals on the signal tracking loop.

[0079] (2) The present invention compares the changes in the L-band pseudorange and the X-band pseudorange to monitor whether the L-band pseudorange observation is affected by the spoofing signal, thereby eliminating the influence of the spoofing signal on the pseudorange measurement value.

[0080] (3) The present invention uses the X-band of the low-orbit enhanced navigation signal to achieve positioning. By comparing the X-band positioning results with the L-band navigation positioning results, it is determined whether the positioning is guided by a spoofing signal, and the influence of the spoofing signal on the positioning result is eliminated.

[0081] A second embodiment of the present invention is an electronic device, such as Figure 5 As shown, it can be understood as a physical device, including a processor and a memory storing processor-executable instructions. When the instructions are executed by the processor, the following operations are performed:

[0082] Step S1, completing the assembly process and receiving satellite navigation signals from the zenith, including L-band navigation signals and X-band signals representing low-orbit augmentation signals;

[0083] Step S2: Obtain the Doppler measurement value of the X-band signal tracking loop through the signal tracking loop, which is recorded as d X ;

[0084] Step S3: Determine the Doppler auxiliary value of the L-band signal using the X-band signal according to the Doppler measurement value.

[0085] Step S4: As an auxiliary value for signal tracking, it eliminates the Doppler dynamic stress caused by the relative motion between the terminal and the satellite, sets a first-order tracking loop with a preset bandwidth, and implements L-band signal tracking.

[0086] Step S5: Get the time of the first L-band pseudorange value and record it as T0. The corresponding X-band pseudorange value is ρ X，0 , the L-band pseudorange value corresponding to time T0 is ρ L，0 ;

[0087] Step S6, in the subsequent epoch T k The X-band pseudorange value obtained at the moment is recorded as ρ X，k , the obtained L-band pseudorange value is recorded as ρ L，k , determine the pseudorange increase value Δρ of each frequency band X , Δρ L ;

[0088] Step S7: Determine the difference Δρ between the pseudorange changes of the two frequency bands based on the pseudorange increase value. L-X ;

[0089] Step S8, if Δρ L-X is greater than a preset value, it is judged that the signal is affected by a spoofing signal, the L-band loop tracking amount is reset, and the spoofing signal is eliminated;

[0090] Step S9, based on steps S2 to S8, positioning is completed by using the X-band and the L-band respectively, the L-band positioning position information is recorded as P L , and the X-band positioning position information is recorded as P X .

[0091] Step S10, the difference ΔP between the L-band positioning result and the X-band positioning result is determined.

[0092] Step S11, based on ΔP, the working state of the L-band signal and whether the L-band signal has been spoofed are judged.

[0093] Step S12, if the L-band signal has been spoofed, the L-band signal loop is soft-started, and the code ring initial position is reset according to the information, so as to eliminate the influence of the spoofing signal.

[0094] The third embodiment of the present application, the flow of the low-orbit enhanced signal anti-spoofing method of the present embodiment is the same as that of the first and second embodiments, and the difference lies in that, in engineering implementation, the present embodiment can be realized by means of software and a necessary general hardware platform, and of course, it can also be realized by hardware, but in many cases, the former is a better implementation mode. Based on such understanding, the method of the present application can be embodied in the form of a computer software product, which is stored in a storage medium (such as ROM / RAM, magnetic disc, optical disc), and includes a plurality of instructions for making a device execute the method described in the embodiments of the present application.

[0095] Through the description of the specific embodiments, the technical means and effects taken by the present application to achieve the predetermined purposes can be understood more deeply and specifically, however, the accompanying drawings are only provided for reference and illustration, and are not used to limit the present application.

Claims

1. A method for preventing low-orbit enhanced signal deception, characterized in that: include: Step S1, completing the assembly process and receiving satellite navigation signals from the zenith, including L-band navigation signals and X-band signals representing low-orbit augmentation signals; Step S2: Obtain the Doppler measurement value of the X-band signal tracking loop through the signal tracking loop, which is recorded as d X ; Step S3: Determine the Doppler auxiliary value of the L-band signal using the X-band signal according to the Doppler measurement value. Step S4: As an auxiliary value for signal tracking, it eliminates the Doppler dynamic stress caused by the relative motion between the terminal and the satellite, sets a first-order tracking loop with a preset bandwidth, and implements L-band signal tracking. Step S5: Get the time of the first L-band pseudorange value and record it as T0. The corresponding X-band pseudorange value is ρ X,0 , the L-band pseudorange value corresponding to time T0 is ρ L,0 ; Step S6, in the subsequent epoch T k The X-band pseudorange value obtained at the moment is recorded as ρ X,k , the obtained L-band pseudorange value is recorded as ρ L,k , determine the pseudorange increase value Δρ of each frequency band X , Δρ L ; Step S7: Determine the difference Δρ between the pseudorange changes of the two frequency bands based on the pseudorange increase value. L-X ; Step S8, if Δρ L-X If it is greater than the preset value, it is determined to be affected by a spoofing signal, and the L-band loop tracking value is reset to eliminate the influence of the spoofing signal; Step S9: Positioning is completed using the least square method in the X band and the L band respectively. The L band positioning position information is recorded as P L , X-band positioning information is recorded as P X ; Step S10, determining the difference ΔP between the L-band positioning result and the X-band positioning result; Step S11, judging the working status of the L-band signal and whether it has been spoofed based on ΔP; Step S12: If the L-band signal is in a spoofed state, the L-band signal loop is soft-started, and the initial position of the code loop is reset according to the pseudo-range time information to eliminate the influence of the spoofing signal.

2. The method for preventing LEO enhanced signal deception according to claim 1, characterized in that: In step S3, the Doppler auxiliary value Obtained by the following formula: Among them, f L is the L-band carrier frequency, f X is the carrier frequency of the X band.

3. The method for preventing LEO enhanced signal deception according to claim 1, characterized in that: In step S4, the preset value of the bandwidth is 0.05 Hz.

4. The method for preventing LEO enhanced signal deception according to claim 1, characterized in that: In step S6, the pseudorange increase value of each frequency band is obtained by the following formula: Dr. X =ρ X,k -r X,0 Dr. L =ρ L,k -r L,0 Where Δρ X is the pseudorange increase value of the X band, Δρ L Adds value to pseudorange for L-band.

5. The method for preventing LEO enhanced signal deception according to claim 1, characterized in that: In step S8, the preset value is 5m.

6. The method for preventing LEO enhanced signal deception according to claim 1, characterized in that: The working status of the L-band signal includes: normal state, alarm state, and deception state. Step S11 specifically includes: If ΔP is less than the first judgment threshold, it is determined that the working state of the L-band signal is normal; If ΔP is greater than the first judgment threshold and less than the second judgment threshold, then enter the alarm state; continuously monitor the change of ΔP in the alarm state; When ΔP is greater than the second judgment threshold, it is determined that the L-band signal has been spoofed and the system enters a spoofed state.

7. The method for preventing LEO enhanced signal deception according to claim 6, characterized in that: The first judgment threshold is configured as 20m, and the second judgment threshold is configured as 50m.

8. An electronic device, comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the computer program is executed by the processor, the steps of the low-orbit enhanced signal anti-spoofing method according to any one of claims 1 to 7 are implemented.

9. A computer storage medium having a computer program stored thereon, wherein when the computer program is executed by a processor, the steps of the low-orbit enhanced signal anti-spoofing method according to any one of claims 1 to 7 are implemented.

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