Clock detection-based deception jamming detection method

Abstract

The invention provides a deception jamming detection method based on clock detection, which comprises the following steps of: calculating the clock error and clock drift information of a satellite navigation positioning device by using the position and speed of the satellite navigation positioning device, continuously calculating the clock error, and when the calculated clock error information is inconsistent with the calculated clock error information, judging the deception jamming of the satellite navigation positioning device. If yes, it is considered that the satellite navigation positioning device is subjected to deception interference, early warning is sent to a user, and the positioning reliability is improved. According to the method, the deception signal can be rapidly detected under the condition that deception jamming exists, a certain deception signal removing capacity exists, the algorithm application is simple, no complex equation or equation with huge operand exists, the algorithm programming implementation on a DSP or FPGA hardware platform can be ensured in the aspects of real-time performance and operand, and engineering implementation is easy.

Description

Technical Field

[0001] The present invention relates to the field of satellite navigation technology, and in particular to a deception interference detection method based on clock detection. Background Art

[0002] In the use environment of military satellite navigation and positioning devices, there are often situations where artificial deception interference is imposed. Deception interference is achieved by broadcasting signals that are identical or similar to real satellite navigation signals, causing satellite navigation and positioning devices to receive and use deception signals, resulting in positioning errors, thereby achieving the purpose of deception interference.

[0003] Currently, satellite navigation positioning devices cannot correctly locate themselves when encountering deception interference. Summary of the invention

[0004] The present invention provides a deception interference detection method based on clock detection, which can solve the technical problem that a satellite navigation positioning device cannot correctly locate when encountering deception interference.

[0005] The present invention provides a deception interference detection method based on clock detection, the method comprising:

[0006] S10, the satellite navigation positioning device captures the satellite navigation signal, and performs bit synchronization and frame synchronization on the tracking satellite based on the satellite navigation signal;

[0007] S20, acquiring pseudorange and ephemeris parameters of each satellite on the basis of completing frame synchronization between the satellite navigation positioning device and the tracking satellite;

[0008] S30, acquiring the launch time of each satellite based on the pseudorange of each satellite, and obtaining the position information of each satellite based on the launch time and ephemeris parameters of each satellite;

[0009] S40, establishing a position-velocity solution equation for the satellite navigation and positioning device based on the position information and pseudorange of each satellite, the position information and clock difference of the satellite navigation and positioning device; linearizing the position-velocity solution equation for the satellite navigation and positioning device to obtain a first observation equation for the position and a second observation equation for the velocity;

[0010] S50, performing least square iteration on the first observation equation to obtain position information and clock error of the satellite navigation positioning device; performing least square iteration on the second observation equation to obtain velocity information and clock drift of the satellite navigation positioning device;

[0011] S60, determining whether the continuous positioning time of the satellite navigation positioning device including the current time is greater than a first preset time, if so, go to S70, otherwise, go to S10;

[0012] S70, determine whether the clock difference and clock drift both meet the detection conditions. If so, there is no deception interference, and the position information and speed information of the satellite navigation positioning device are used as the positioning result. Otherwise, there is deception interference, and go to S10.

[0013] Preferably, the method further comprises: when the continuous loss of lock time of the satellite navigation positioning device is greater than a second preset time, no longer performing clock difference and clock drift detection, and switching to S10.

[0014] Preferably, determining whether the clock difference satisfies the detection condition includes:

[0015] Determine whether the absolute value of the difference between the clock error calculated by the least squares solution at the current moment and the recursive clock error at the current moment is less than the preset clock error threshold. If so, it is determined that the clock error meets the detection condition; otherwise, it is determined that the clock error does not meet the detection condition.

[0016] Preferably, the recursive clock difference at the current time is obtained by the following formula:

[0017] dtSm=dt+ddtSm*T

[0018] The preset clock error threshold is obtained by the following formula:

[0019] DTthresh=PPB*T*n*(n+1) / 2+n / 2*PPB*T*T

[0020] Wherein, dtSm is the recursive clock error at the current moment, dt is the clock error calculated by the least square method at the current moment, ddtSm is the average clock drift during the continuous positioning time, T is the positioning solution period, DTthresh is the preset clock error threshold, PPB is the crystal oscillator frequency deviation, and n is the number of recursive clock error times.

[0021] Preferably, determining whether the clock drift satisfies the detection condition includes:

[0022] When the number of satellites of the single positioning system is equal to four or the number of satellites of the dual positioning system is equal to five, determine whether the absolute value of the difference between the clock drift calculated by the least squares solution at the current moment and the clock drift calculated by the least squares solution at the previous moment is less than a first preset clock drift threshold; if so, determine that the clock drift satisfies the detection condition; otherwise, determine that the clock drift does not satisfy the detection condition;

[0023] When the number of satellites in a single positioning system is greater than four or the number of satellites in a dual positioning system is greater than five, determine whether the absolute value of the difference between the clock drift calculated by the least squares solution at the current moment and the clock drift calculated by the least squares solution at the previous moment is less than a second preset clock drift threshold; if so, determine that the clock drift satisfies the detection condition; otherwise, determine that the clock drift does not satisfy the detection condition;

[0024] Among them, the first preset clock drift threshold is smaller than the second preset clock drift threshold, the single positioning system adopts Beidou or GPS for separate positioning, and the dual positioning system adopts Beidou and GPS combined positioning.

[0025] Preferably, the satellite navigation positioning device position speed solution equation is established by the following formula:

[0026]

[0027] In the formula, ρ J is the pseudorange of the Jth satellite, J = 1, 2, ..., n, n is the total number of satellites after elimination, X J , Y J , Z J are the X, Y, and Z coordinates of the Jth satellite, respectively. U , Y U , Z U are the X, Y, and Z coordinates of the satellite navigation positioning device, C is the speed of light, and t u For the clock difference.

[0028] Preferably, the first observation equation about the position is obtained by the following formula:

[0029] z1=Hx1+ε

[0030] in,

[0031] x1=(X U ,Y U ,Z U ,t u )

[0032]

[0033] In the formula, z1 is the first observation, H is the coefficient matrix, x1 is the first state quantity, ε is the measurement error, are respectively the X, Y and Z unit vectors of the satellite navigation and positioning device pointing to the Jth satellite.

[0034] Preferably, the second observation equation about speed is obtained by the following formula:

[0035] z2=Hx2+ε

[0036] Where z2 = B

[0037]

[0038] In the formula, z2 is the second observation, x2 is the second state quantity, B is the Doppler observation, are the X, Y, and Z speeds of the satellite navigation positioning device, respectively, u ′ is the clock drift.

[0039] By applying the technical solution of the present invention, the clock error and clock drift information of the satellite navigation positioning device obtained by solving the position and speed of the satellite navigation positioning device are used to continuously calculate the clock error. When the solved clock error information is inconsistent with the calculated clock error information, it is considered that the satellite navigation positioning device is subject to deception interference, and an early warning is issued to the user, thereby improving the reliability of positioning. The method can quickly detect deception signals in the presence of deception interference, and has a certain ability to eliminate deception signals. The algorithm is simple to apply, without complex or huge calculation formulas. The real-time performance and the amount of calculation can ensure the algorithm programming implementation on the DSP or FPGA hardware platform, that is, it is easy to implement in engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The included drawings are used to provide a further understanding of the embodiments of the present invention, which constitute a part of the specification, are used to illustrate the embodiments of the present invention, and together with the text description, explain the principles of the present invention. Obviously, the drawings in the following description are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0041] Figure 1 A flow chart of a deceptive interference detection method based on clock detection provided according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0042] It should be noted that, in the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0044] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, numerical expressions and numerical values ​​do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be regarded as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0045] like Figure 1 As shown, the present invention provides a deception interference detection method based on clock detection, the method comprising:

[0046] S10, the satellite navigation positioning device captures the satellite navigation signal, and performs bit synchronization and frame synchronization on the tracking satellite based on the satellite navigation signal;

[0047] S20, acquiring pseudorange and ephemeris parameters of each satellite on the basis of completing frame synchronization between the satellite navigation positioning device and the tracking satellite;

[0048] S30, acquiring the launch time of each satellite based on the pseudorange of each satellite, and obtaining the position information of each satellite based on the launch time and ephemeris parameters of each satellite;

[0049] S40, establishing a position-velocity solution equation for the satellite navigation and positioning device based on the position information and pseudorange of each satellite, the position information and clock difference of the satellite navigation and positioning device; linearizing the position-velocity solution equation for the satellite navigation and positioning device to obtain a first observation equation for the position and a second observation equation for the velocity;

[0050] S50, performing least square iteration on the first observation equation to obtain position information and clock error of the satellite navigation positioning device; performing least square iteration on the second observation equation to obtain velocity information and clock drift of the satellite navigation positioning device;

[0051] S60, determining whether the continuous positioning time of the satellite navigation positioning device including the current time is greater than a first preset time, if so, go to S70, otherwise, go to S10;

[0052] S70, determine whether the clock difference and clock drift both meet the detection conditions. If so, there is no deception interference, and the position information and speed information of the satellite navigation positioning device are used as the positioning result. Otherwise, there is deception interference, and go to S10.

[0053] The present invention uses the clock error and clock drift information of the satellite navigation positioning device obtained by solving the position and speed of the satellite navigation positioning device to continuously calculate the clock error. When the solved clock error information is inconsistent with the calculated clock error information, it is considered that the satellite navigation positioning device is subject to deception interference, and an early warning is issued to the user, thereby improving the reliability of positioning. The method can quickly detect deception signals in the presence of deception interference, and has a certain ability to eliminate deception signals. The algorithm application is simple, without complex or huge calculation formulas, and the real-time performance and calculation amount can ensure the algorithm programming implementation on the DSP or FPGA hardware platform, that is, it is easy to implement in engineering.

[0054] In order to further understand the present invention, the following Figure 1 The clock detection-based deception interference detection method of the present invention is described in detail, and specifically comprises the following steps:

[0055] Step 1: Satellite acquisition, tracking and synchronization

[0056] The satellite navigation positioning device captures the satellite navigation signal and performs bit synchronization and frame synchronization on the tracking satellite based on the satellite navigation signal; wherein, the frame synchronization is performed after the bit synchronization is completed;

[0057] Step 2: Observation Extraction

[0058] On the basis of completing the frame synchronization between the satellite navigation positioning device and the tracking satellite, the pseudorange, Doppler observation and ephemeris parameters of each satellite after the frame synchronization is completed;

[0059] Step 3: Determine satellite position and velocity calculation

[0060] The launch time of each satellite is obtained based on the pseudorange of each satellite, and the position information and speed information of each satellite are obtained based on the launch time and ephemeris parameters of each satellite according to the satellite position calculation method provided by the satellite navigation interface control file (ICD);

[0061] Step 4: Calculate the position and speed of the satellite navigation positioning device

[0062] According to the available satellites eliminated in step 5, the position and velocity solution equation of the satellite navigation positioning device is established:

[0063]

[0064] In the formula, ρ J is the pseudorange of the Jth satellite, J = 1, 2, ..., n, n is the total number of satellites after elimination, X J , Y J , Z J are the X, Y, and Z coordinates of the Jth satellite, respectively.U , Y U , Z U are the X, Y, and Z coordinates of the satellite navigation positioning device, C is the speed of light, and t u For the clock difference;

[0065] The position and velocity solution equation of the satellite navigation positioning device is linearized to obtain the first observation equation about the position:

[0066] z1=Hx1+ε

[0067] in, is an n×1 vector,

[0068] x1=(X U ,Y U ,Z U ,t u ), is a 4×1 vector,

[0069]

[0070] In the formula, z1 is the first observation, H is the coefficient matrix, x1 is the first state quantity, ε is the measurement error, are the X, Y and Z unit vectors of the satellite navigation positioning device pointing to the Jth satellite;

[0071] in, The same calculation ε is the n×1 measurement error vector, which can contain both random (ranging random jitter) and deterministic (bias) terms;

[0072] The position and velocity solution equation of the satellite navigation positioning device is linearized to obtain the second observation equation for velocity:

[0073] z2=Hx2+ε

[0074] Among them, z2=B, which is an n×1 vector,

[0075] is a 4×1 vector,

[0076] In the formula, z2 is the second observation, x2 is the second state quantity, B is the Doppler observation, are the X, Y, and Z speeds of the satellite navigation positioning device, respectively, u ' is the bell drift;

[0077] Performing least square iteration on the first observation equation to obtain the position information of the satellite navigation positioning device; performing least square iteration on the second observation equation to obtain the speed information of the satellite navigation positioning device;

[0078] Step 5: Determine whether the continuous positioning time of the satellite navigation positioning device including the current time is greater than 5 seconds (i.e., whether it is continuously positioned within 5 seconds). If so, go to step 6; otherwise, go to step 1;

[0079] Step 6: Determine whether the clock error and clock drift both meet the detection conditions. If so, there is no deception interference, and the position information and speed information of the satellite navigation positioning device are used as the positioning result. Otherwise, there is deception interference, and step 1 is performed;

[0080] In this step, determining whether the clock drift meets the detection conditions includes:

[0081] When the number of satellites in a single positioning system is equal to four or the number of satellites in a dual positioning system is equal to five, determine whether the absolute value of the difference between the clock drift calculated by the least squares solution at the current moment and the clock drift calculated by the least squares solution at the previous moment is less than 0.5 m / s. If so, the clock drift is determined to meet the detection conditions. Otherwise, the clock drift is determined to not meet the detection conditions and it is considered that the clock drift is abnormal, which may be caused by deception interference.

[0082] When the number of satellites in a single positioning system is greater than four or the number of satellites in a dual positioning system is greater than five, determine whether the absolute value of the difference between the clock drift calculated by the least squares solution at the current moment and the clock drift calculated by the least squares solution at the previous moment is less than 20m / s. If so, the clock drift is determined to meet the detection conditions. Otherwise, the clock drift is determined to not meet the detection conditions and is considered abnormal, which may be caused by deception interference.

[0083] In this step, determining whether the clock error satisfies the detection condition includes:

[0084] Set up a sliding window with a window size equal to the clock errors of the current time and the 10 consecutive least square solutions before the current time, and perform real-time clock error recursion using the following formula:

[0085] dtSm=dt+ddtSm*T

[0086] The preset clock error threshold is obtained by the following formula:

[0087] DTthresh=PPB*T*n*(n+1) / 2+n / 2*PPB*T*T

[0088] Where, dtSm is the recursive clock error at the current moment, dt is the clock error calculated by the least square method at the current moment, ddtSm is the average clock drift during the continuous positioning time, T is the positioning solution period, which is 0.5s, DTthresh is the preset clock error threshold, PPB is the crystal oscillator frequency deviation, which is 48m / s, and n is the number of recursive clock error times, which is equal to the calculation time divided by T.

[0089] Determine whether the absolute value of the difference between the clock error solved by the least squares method at the current moment and the recursive clock error at the current moment is less than the preset clock error threshold. If so, it is determined that the clock error meets the detection conditions. Otherwise, it is determined that the clock error does not meet the detection conditions and the clock error is considered abnormal, which may be caused by deception interference.

[0090] When the clock error meets the detection conditions, continue to update the clock error solved by the least square method at the current moment and the recursive clock error at the current moment.

[0091] When the satellite navigation positioning device is continuously out of lock for more than 10 minutes, the clock error and clock drift detection is no longer performed and the process goes to S10.

[0092] When deception interference exists, an early warning will be issued to the satellite navigation positioning device; otherwise, no early warning will be issued and the positioning result will be output normally.

[0093] This embodiment only uses its own clock information, and can perform deception interference detection when the satellite navigation positioning device is in a positioning or non-positioning state; and as long as the satellite navigation positioning device is positioned for 5 consecutive seconds after being turned on, the method can be used to detect deception signals.

[0094] In summary, the present invention provides a deception interference detection method based on clock detection, which uses the clock error and clock drift information of the satellite navigation positioning device obtained by solving the position and speed of the satellite navigation positioning device to continuously calculate the clock error. When the solved clock error information is inconsistent with the calculated clock error information, it is considered that the satellite navigation positioning device is subject to deception interference, and an early warning is issued to the user, thereby improving the reliability of positioning. The method can quickly detect deception signals in the presence of deception interference, and has a certain ability to eliminate deception signals. The algorithm is simple to apply, without complex or huge calculation formulas, and the real-time performance and calculation amount can ensure the algorithm programming implementation on the DSP or FPGA hardware platform, that is, it is easy to implement in engineering.

[0095] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0096] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0097] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A deception interference detection method based on clock detection, characterized in that: The method comprises: S10, the satellite navigation positioning device captures the satellite navigation signal, and performs bit synchronization and frame synchronization on the tracking satellite based on the satellite navigation signal; S20, acquiring pseudorange and ephemeris parameters of each satellite on the basis of completing frame synchronization between the satellite navigation positioning device and the tracking satellite; S30, acquiring the launch time of each satellite based on the pseudorange of each satellite, and obtaining the position information of each satellite based on the launch time and ephemeris parameters of each satellite; S40, establishing a position-velocity solution equation for the satellite navigation and positioning device based on the position information and pseudorange of each satellite, the position information and clock difference of the satellite navigation and positioning device; linearizing the position-velocity solution equation for the satellite navigation and positioning device to obtain a first observation equation for the position and a second observation equation for the velocity; S50, performing least square iteration on the first observation equation to obtain position information and clock error of the satellite navigation positioning device; performing least square iteration on the second observation equation to obtain velocity information and clock drift of the satellite navigation positioning device; S60, determining whether the continuous positioning time of the satellite navigation positioning device including the current time is greater than a first preset time, if so, go to S70, otherwise, go to S10; S70, determine whether the clock difference and clock drift both meet the detection conditions. If so, there is no deception interference, and the position information and speed information of the satellite navigation positioning device are used as the positioning result. Otherwise, there is deception interference, and go to S10.

2. The method according to claim 1, characterized in that The method further includes: when the continuous loss of lock time of the satellite navigation positioning device is greater than a second preset time, no longer performing clock difference and clock drift detection, and turning to S10.

3. The method according to claim 1, characterized in that Determining whether the clock error meets the detection conditions includes: Determine whether the absolute value of the difference between the clock error calculated by the least squares solution at the current moment and the recursive clock error at the current moment is less than the preset clock error threshold. If so, it is determined that the clock error meets the detection condition; otherwise, it is determined that the clock error does not meet the detection condition.

4. The method according to claim 1, characterized in that: The recursive clock error of the current time is obtained by the following formula: dtSm = dt + ddtSm * T The preset clock error threshold is obtained by the following formula: DTthresh=PPB*T*n*(n+1) / 2+n / 2*PPB*T*T Wherein, dtSm is the recursive clock error at the current moment, dt is the clock error calculated by the least square method at the current moment, ddtSm is the average clock drift during the continuous positioning time, T is the positioning solution period, DTthresh is the preset clock error threshold, PPB is the crystal oscillator frequency deviation, and n is the number of recursive clock error times.

5. The method according to claim 1, characterized in that Determining whether the clock drift meets the detection conditions includes: When the number of satellites of the single positioning system is equal to four or the number of satellites of the dual positioning system is equal to five, determine whether the absolute value of the difference between the clock drift calculated by the least squares solution at the current moment and the clock drift calculated by the least squares solution at the previous moment is less than a first preset clock drift threshold; if so, determine that the clock drift satisfies the detection condition; otherwise, determine that the clock drift does not satisfy the detection condition; When the number of satellites in a single positioning system is greater than four or the number of satellites in a dual positioning system is greater than five, determine whether the absolute value of the difference between the clock drift calculated by the least squares solution at the current moment and the clock drift calculated by the least squares solution at the previous moment is less than a second preset clock drift threshold; if so, determine that the clock drift satisfies the detection condition; otherwise, determine that the clock drift does not satisfy the detection condition; Among them, the first preset clock drift threshold is smaller than the second preset clock drift threshold, the single positioning system adopts Beidou or GPS for separate positioning, and the dual positioning system adopts Beidou and GPS combined positioning.

6. The method according to claim 1, characterized in that The position and velocity solution equation of the satellite navigation positioning device is established by the following formula: In the formula, ρ J is the pseudorange of the Jth satellite, J = 1, 2, ..., n, n is the total number of satellites after elimination, X J , Y J , Z J are the X, Y, and Z coordinates of the Jth satellite, respectively. U , Y U , Z U are the X, Y, and Z coordinates of the satellite navigation positioning device, C is the speed of light, and t u For the clock difference.

7. The method according to claim 1, characterized in that The first observation equation about the position is obtained by the following formula: z1=Hx1+ε in, x1=(X U ,Y U ,Z U ,t u ) In the formula, z1 is the first observation, H is the coefficient matrix, x1 is the first state quantity, ε is the measurement error, are respectively the X, Y and Z unit vectors of the satellite navigation and positioning device pointing to the Jth satellite.

8. The method according to claim 1, characterized in that The second observation equation about velocity is obtained by the following formula: z2=Hx2+ε Where z2 = B In the formula, z2 is the second observation, x2 is the second state quantity, B is the Doppler observation, are the X, Y, and Z speeds of the satellite navigation positioning device, respectively, u ′ is the clock drift.

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