Low-orbit enhanced signal anti-cheating method

Abstract

The invention provides a low-orbit enhanced signal anti-cheating method and electronic equipment. The method comprises the following steps: receiving an L-band navigation signal and an X-band signal representing a low-orbit enhanced signal; acquiring a Doppler measurement value of the signal tracking loop of the X frequency band, determining a Doppler auxiliary value of the L frequency band signal, and realizing L frequency band signal tracking; acquiring pseudo-range values and pseudo-range added values of the X frequency band and the L frequency band, and a difference between pseudo-range variations of the two frequency bands, if the difference is greater than a preset value, judging that the difference is influenced by a deception signal, and resetting the loop tracking quantity of the L frequency band; and completing the positioning of the X frequency band and the L frequency band and the difference of the positioning results, judging the working state of the L frequency band signal and whether the L frequency band signal is deceived or not based on the difference value, if so, carrying out loop soft start on the L frequency band signal, and resetting the initial position of the code loop according to the information. According to the invention, aiming at the current situation of L-band signals, the characteristic that other working bands are different from conventional navigation signals is utilized to realize cheating prevention.

Description

Technical Field

[0001] The present invention relates to the field of spacecraft technology, and in particular to a low-orbit enhanced signal anti-spoofing method. Background Art

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

[0003] The space segment of the satellite navigation system consists of multiple satellites distributed around the world. It transmits L-band navigation signals to the earth's surface and its adjacent space through transmitting antennas. The power level reaching the surface is around -130dbm, which is equivalent to exciting a raw voltage signal of tens of nanovolts inside the antenna. The RF signal energy received by the antenna is very low, 20dB lower than the thermal noise. Immediately after the antenna, the navigation signal enters the RF channel, where the RF signal completes the signal filtering, amplification and down-conversion. After sampling by the ADC, the digital signal processing begins. Due to the low power of the navigation signal, it is easy to be interfered with and deceived and cannot work properly, and may even be misled to output time, space and space information that is not conducive to the user. Therefore, it is particularly important to improve the robustness of the navigation signal through various means. Summary of the invention

[0004] The technical problem to be solved by the present invention is how to improve the robustness of navigation signals and enhance the anti-spoofing effect; in view of this, the present invention provides a low-orbit enhanced signal anti-spoofing method and electronic equipment.

[0005] The technical solution adopted by the present invention is a low-orbit enhanced signal anti-spoofing method, comprising:

[0006] Step S1, completing the assembly process, receiving the satellite navigation signal from the zenith, including the L-band navigation signal and the X-band signal representing the low-orbit enhancement signal;

[0007] Step S2, obtaining 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, using the X-band signal to determine the Doppler auxiliary value of the L-band signal

[0009] 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;

[0010] Step S5, obtain the time of the first L-band pseudorange value and record it as T0, and the corresponding X-band pseudorange value is ρ X，0 , the L-band pseudorange value corresponding to time T0 is ρ L，0 ;

[0011] 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 ;

[0012] Step S7: determining the difference Δρ between the pseudorange changes of the two frequency bands based on the pseudorange increase value. L-X ;

[0013] Step S8, if Δρ L-X If it is greater than the preset value, it is judged to be affected by a spoofing signal, and the L-band loop tracking amount is reset to eliminate the influence of the spoofing signal;

[0014] Step S9: Least square method is applied to complete positioning in 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 ;

[0015] Step S10, determining the difference ΔP between the L-band positioning result and the X-band positioning result;

[0016] Step S11, judging the working state of the L-band signal and whether it has been spoofed based on ΔP;

[0017] Step S12: If the L-band signal is already 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 spoofed signal.

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

[0019]

[0020] Among them, f L is the L-band carrier frequency, f X is the carrier frequency of the X-band.

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

[0022] In one embodiment, in step S6, the pseudorange increase value of each frequency band 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] Among them, Δρ X is the pseudorange increase value of the X-band, Δρ L Adds value to pseudorange for L-band.

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

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

[0028] If the AP is less than the first judgment threshold, it is determined that the working state of the L-band signal is normal;

[0029] If the AP is greater than the first judgment threshold and less than the second judgment threshold, then enter the alarm state; the AP changes continuously monitored in the alarm state;

[0030] When AP is greater than the second judgment threshold, it is determined that the L-band signal has been spoofed and enters a spoofed state.

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

[0032] Another aspect of the present invention provides an electronic device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the computer program, when executed by the processor, implements the steps of the low-orbit enhanced signal anti-spoofing method as described in any one of the above items.

[0033] Another aspect of the present invention further provides a computer storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the low-orbit enhanced signal anti-spoofing method as described in any one of the above items are implemented.

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

[0035] The low-orbit enhanced signal anti-spoofing method provided by the present invention fully utilizes the current status of existing low-orbit deception equipment, mainly targeting the L-band signal, and uses the characteristics of other working frequency bands that are different from conventional navigation signals to achieve anti-spoofing. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A schematic flow chart of a method for preventing spoofing of low-orbit enhanced signals according to an embodiment of the present invention;

[0037] Figure 2 Schematic diagram of a method for anti-spoofing of low-orbit enhanced signals according to an embodiment of the present invention;

[0038] Figure 3 Schematic diagram of anti-spoofing of low-orbit enhanced signal pseudorange raw observation according to an embodiment of the present invention;

[0039] Figure 4 A schematic diagram of anti-spoofing of low-orbit enhanced signal positioning results according to an embodiment of the present invention;

[0040] Figure 5 Schematic diagram of an electronic device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0041] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined purpose, the present invention is described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0042] Unless otherwise defined, all terms (including technical terms and scientific terms) used in this article have the same meaning as commonly understood by ordinary technicians in the field to which this application belongs. It should also be understood that terms (such as terms defined in commonly used dictionaries) should be interpreted as having the same meaning as their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined in this article.

[0043] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0044] The first embodiment of the present invention is a method for preventing deception of low-orbit enhanced signals, such as Figure 1 As shown, including:

[0045] Step S1, completing the assembly process, receiving the satellite navigation signal from the zenith, including the L-band navigation signal and the X-band signal representing the low-orbit enhancement signal;

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

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

[0048] 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;

[0049] Step S5, obtain the time of the first L-band pseudorange value and record it as T0, and the corresponding X-band pseudorange value is ρ X，0 , the L-band pseudorange value corresponding to time T0 is ρ L，0 ;

[0050] 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 ;

[0051] Step S7: determining the difference Δρ between the pseudorange changes of the two frequency bands based on the pseudorange increase value. L-X ;

[0052] Step S8, if Δρ L-X If it is greater than the preset value, it is judged to be affected by a spoofing signal, and the L-band loop tracking amount is reset to eliminate the influence of the spoofing signal;

[0053] Step S9: Based on steps S2 to S8, positioning is performed 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 ;

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

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

[0056] Step S12: If the L-band signal is already 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 spoofed signal.

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

[0058] Step S1, such 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 equipped to receive satellite navigation signals from the zenith, specifically including L-band navigation signals and X-band signals of the low-orbit augmentation system.

[0059] Step S2, obtaining the Doppler measurement value of the signal tracking loop in the X-band through the signal tracking loop, denoted as d X .

[0060] Step S3, based on 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, the Doppler dynamic stress caused by the relative motion between the terminal and the satellite is eliminated, and a first-order tracking loop with a bandwidth of 0.05 Hz is set to achieve L-band signal tracking.

[0064] Step S5, such as Figure 3 As shown, based on step S2 to step 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 it is greater than 5m, it is judged to be affected by a spoofing signal, and the L-band loop tracking quantity 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 the 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, according to the position obtained by the two-band navigation signals of the aircraft obtained in step S9, the difference between the L-band positioning result and the X-band positioning result is calculated, which is specifically expressed by the following formula:

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

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

[0075] There are three specific states: normal state, alarm state, and spoofed state. The default is normal state. If AP∈(20m, 50m), it will enter the alarm state, indicating that the navigation device may have been spoofed and interfered. In the alarm state, the changes of AP are continuously monitored. If AP>20m in subsequent epochs and ΔP shows a trend of increasing, when AP>50m, it is judged that the L-band signal has been spoofed. If AP∈(20m, 50m) is always true, it will be in the alarm state.

[0076] Step S12, according to step S11, the working state of the L-band signal is obtained. If it is determined that the L-band has been deceived, the L-band signal loop is soft-started. 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 by using the X-band Doppler tracking frequency, thereby further reducing the L-band signal tracking bandwidth and reducing the impact of spoofing 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 result with the L-band navigation positioning result, 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 instructions executable by the processor. When the instructions are executed by the processor, the following operations are performed:

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

[0083] Step S2, obtaining the Doppler measurement value of the signal tracking loop of the X-band through the signal tracking loop, denoted as d X ;

[0084] Step S3, according to the Doppler measurement value, using the X-band signal to determine the Doppler auxiliary value of the L-band signal

[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, obtain the time of the first L-band pseudorange value and record it as T0, and 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: determining 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 If it is greater than the preset value, it is judged to be affected by a spoofing signal, and the L-band loop tracking amount is reset to eliminate the influence of the spoofing signal;

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

[0091] Step S10, determining the difference ΔP between the L-band positioning result and the X-band positioning result;

[0092] Step S11, judging the working state of the L-band signal and whether it has been spoofed based on ΔP;

[0093] Step S12: If the L-band signal is already in a spoofed state, the L-band signal loop is soft-started according to The information resets the initial position of the code ring to eliminate the influence of deceptive signals.

[0094] The third embodiment of the present invention, the process of the low-orbit enhanced signal anti-spoofing method of this embodiment is the same as that of the first and second embodiments, the difference is that in engineering implementation, this embodiment can be implemented by means of software plus a necessary general hardware platform, of course, it can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the method of the present invention can be embodied in the form of a computer software product, which is stored in a storage medium (such as ROM / RAM, disk, CD), including a number of instructions for a device to execute the method described in the embodiment of the present invention.

[0095] Through the description of the specific implementation methods, a deeper and more specific understanding of the technical means and effects adopted by the present invention to achieve the predetermined purpose should be obtained. However, the accompanying drawings are only for reference and illustration purposes and are not intended to limit the present invention.

Claims

1. A method for preventing low-orbit enhanced signal deception, characterized in that: include: Step S1, completing the assembly process, receiving the satellite navigation signal from the zenith, including the L-band navigation signal and the X-band signal representing the low-orbit enhancement signal; Step S2, obtaining the Doppler measurement value of the signal tracking loop of the X-band through the signal tracking loop, denoted as d X ; Step S3, according to the Doppler measurement value, using the X-band signal to determine the Doppler auxiliary value of the L-band signal 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, obtain the time of the first L-band pseudorange value and record it as T0, and 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: determining 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 judged to be affected by a spoofing signal, and the L-band loop tracking amount is reset to eliminate the influence of the spoofing signal; Step S9: Use the least square method to complete positioning 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 state of the L-band signal and whether it has been spoofed based on ΔP; Step S12: If the L-band signal is already 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 spoofed signal.

2. The method for preventing deception of low-orbit enhanced signals 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 deception of low-orbit enhanced signals 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 deception of low-orbit enhanced signals 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 Among them, 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 deception of low-orbit enhanced signals according to claim 1, characterized in that: In step S8, the preset value is 5m.

6. The method for preventing deception of low-orbit enhanced signals according to claim 1, characterized in that: The working states of the L-band signal include: normal state, alarm state, and deceit state. The 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 the alarm state is entered; the change of ΔP is continuously monitored 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 enters a spoofed state.

7. The method for preventing deception of low-orbit enhanced signals 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 as claimed in 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 as claimed in any one of claims 1 to 7 are implemented.

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