CN114200485A - Deception jamming identification method and system based on auxiliary of aircraft - Google Patents

Deception jamming identification method and system based on auxiliary of aircraft Download PDF

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Publication number
CN114200485A
CN114200485A CN202111467802.XA CN202111467802A CN114200485A CN 114200485 A CN114200485 A CN 114200485A CN 202111467802 A CN202111467802 A CN 202111467802A CN 114200485 A CN114200485 A CN 114200485A
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navigation
signal
aircraft
interference
identified
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张伟
张爽娜
董启甲
刘也
于春锐
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Space Star Technology Co Ltd
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Space Star Technology Co Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/13—Receivers
    • G01S19/21—Interference related issues ; Issues related to cross-correlation, spoofing or other methods of denial of service
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/13—Receivers
    • G01S19/21—Interference related issues ; Issues related to cross-correlation, spoofing or other methods of denial of service
    • G01S19/215—Interference related issues ; Issues related to cross-correlation, spoofing or other methods of denial of service issues related to spoofing
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/13—Receivers
    • G01S19/33—Multimode operation in different systems which transmit time stamped messages, e.g. GPS/GLONASS

Abstract

A deception jamming identification method and system based on the assistance of an air-facing vehicle are disclosed, wherein the method comprises the following steps: directly acquiring a signal to be identified, and analyzing the signal to be identified to obtain a first pseudo range of the ground anti-interference navigation receiver and the GNSS satellite; directly acquiring a navigation enhancement signal broadcast by an aircraft, and analyzing the navigation enhancement signal to obtain a second pseudo-range of the ground anti-interference navigation receiver (3) and the GNSS satellite (1); calculating a difference between the first pseudorange and the second pseudorange; when the difference is smaller than a preset difference threshold value, determining that the signal to be identified is a navigation signal of the GNSS satellite (1), and when the difference is larger than or equal to the difference threshold value, determining that the signal to be identified is a deception jamming signal of the jamming source.

Description

Deception jamming identification method and system based on auxiliary of aircraft
Technical Field
The invention relates to the field of navigation anti-interference, in particular to a deception jamming identification method and system based on the assistance of an aircraft.
Background
With the gradual establishment of a global satellite navigation system and the rapid development of a navigation positioning technology, the precision of satellite navigation positioning is more and more accurate, and a satellite navigation service plays a more important role in the aspects of society and life, but inevitably, in the process of satellite navigation signal propagation, a navigation signal received by a ground navigation receiver is always interfered intentionally or unintentionally, so that the positioning result of the receiver is wrong, and therefore, the safety application of the satellite navigation system is gradually paid attention by a wide range of users.
The jamming of satellite navigation signals is classified into two types, namely, compressive jamming and deceptive jamming. The suppressed interference is mainly caused by transmitting a high-power noise interference signal to submerge a real target signal into interference, so that normal reception of the real signal by a receiving device is affected, for example, by transmitting electromagnetic noise with stronger signal power than a navigation signal. At present, remarkable achievements are obtained aiming at the compression type interference, and the technologies such as adaptive space-time filtering, array antenna and the like can be adopted for inhibiting. Spoofing interference is more complex and more difficult to eliminate than suppressing interference. Spoofing interference achieves spoofing by intentionally creating a false signal that is similar in structure to the true navigation signal, causing the receiver to capture the spoofed signal in an unintended state. According to the generation mode of the deception jamming signal, the generation mode can be divided into a forwarding deception jamming mode and a generating deception jamming mode, and a hybrid deception jamming mode which simultaneously utilizes the two modes is adopted, and the form of the jamming signal is the same as or similar to that of the GNSS signal.
After receiving the deception jamming signal, the GNSS receiver obtains wrong satellite position information and wrong pseudo-range information, and thus, a positioning result with a large error is solved. The key to suppressing the jamming is to identify whether the received signal is a jamming signal. If a certain signal in the receiver is identified to be a deception jamming signal, the receiver can directly reject the signal.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the method overcomes the defects of the prior art, aims at the requirements for the deception jamming identification technology in the navigation electronic countermeasure based battle, combines the advantages of the aircraft, and utilizes the aircraft to broadcast the navigation enhancement signal to assist in realizing GNSS deception jamming identification. On one hand, the ground anti-interference navigation receiver directly receives the GNSS signal, and obtains a first pseudo-range through capturing, tracking, synchronizing, decoding and the like. On the other hand, the ground anti-interference navigation receiver can preliminarily judge the summary position of the ground anti-interference navigation receiver by receiving the navigation enhancement signal from the aircraft and simultaneously measuring the direction of arrival information of the navigation enhancement signal, can estimate the summary position of the visible GNSS satellite according to the GNSS message forwarded by the aircraft, and calculates the second pseudo-range according to the ground terminal position and the position of the GNSS. And comparing the first pseudo-range with the second pseudo-range, if the difference value of the first pseudo-range and the second pseudo-range exceeds a preset threshold value, considering the directly received GNSS satellite signal as an interference signal, and directly rejecting the interference signal, otherwise, considering the interference signal as a real GNSS signal.
The purpose of the invention is realized by the following technical scheme:
the invention provides a deception jamming identification method based on aircraft approaching assistance, which comprises the following steps:
acquiring a signal to be identified; the signal to be identified comprises a navigation signal of a GNSS satellite directly acquired by a ground anti-interference navigation receiver or an interference signal of an interference source directly acquired by the ground anti-interference navigation receiver;
acquiring a navigation enhancement signal of the aircraft, wherein the aircraft is not interfered by an interference source or the interference of the interference source can be eliminated;
analyzing a signal to be identified to obtain a first pseudo range of a ground anti-interference navigation receiver and a GNSS satellite;
analyzing the navigation enhancement signal to obtain a second pseudo range of the ground anti-interference navigation receiver and the GNSS satellite;
calculating a difference between the first pseudorange and the second pseudorange; and
and when the difference value is smaller than a preset difference value threshold value, determining that the signal to be identified is a navigation signal of the GNSS satellite.
In one embodiment, the GNSS satellite includes any one of the four satellite navigation constellations GPS, BDS, GLONASS, and GALILEO.
In one embodiment, the navigation enhancement signal is modulated by quadrature phase shift keying, and the signal format of the navigation enhancement signal is expressed as:
Figure BDA0003392261030000031
wherein P is the transmitting signal power of the aircraft, CI(t) and CQ(t) spreading codes for ranging modulated on branch I, Q, DI(t) and DQ(t) navigation messages modulated on branch I, Q, DI(t) includes the position of the aircraft, clock difference, DQ(t) navigation messages including the retransmission of said GNSS satellites, f0The carrier frequency of the navigation enhancement signal of the aircraft facing the sky is represented, and t represents a time variable.
In an embodiment, the resolving the signal to be identified to obtain a first pseudorange includes:
acquiring the receiving time of the signal to be identified;
acquiring the code phase of the signal to be identified through acquisition and tracking;
acquiring navigation messages of the signals to be identified through synchronization and decoding; the navigation message of the signal to be identified comprises information used for positioning, such as time information, GNSS satellite orbit parameters, ionospheric delay and the like, and the position and clock error of the GNSS satellite can be obtained through the navigation message of the signal to be identified.
Obtaining the transmitting time of the signal to be identified according to the code phase of the signal to be identified; and
and obtaining the first pseudorange according to the receiving time of the signal to be identified, the clock error of the ground anti-interference navigation receiver, the transmitting time of the signal to be identified and the clock error of the GNSS satellite.
In an embodiment, the resolving the navigation enhancement signal to obtain a second pseudorange includes:
analyzing the navigation enhancement signal to obtain the position of the aircraft and a third pseudo range of the ground anti-interference navigation receiver and the aircraft;
acquiring the direction of arrival of the navigation enhancement signal by adopting a DOA estimation algorithm;
obtaining the position of the ground anti-interference navigation receiver according to the direction of arrival of the navigation enhancement signal, the position of the aircraft and a third pseudo range of the ground anti-interference navigation receiver and the aircraft;
estimating the position of the GNSS satellite according to the navigation message for forwarding the GNSS satellite; and
and calculating to obtain the second pseudorange according to the position of the ground anti-interference navigation receiver and the position of the GNSS satellite.
In an embodiment, the obtaining the direction of arrival of the navigation enhancement signal by using the DOA estimation algorithm includes: acquiring the direction of arrival of the navigation enhancement signal by adopting a multiple signal classification algorithm (MUSIC algorithm), wherein the direction of arrival of the navigation enhancement signal comprises a pitch angle theta and an azimuth angle theta of the navigation enhancement signal
Figure BDA0003392261030000041
In one embodiment, the calculation of the position of the aircraft and the third pseudorange between the ground antijam navigation receiver and the aircraft includes:
acquiring the receiving time of the navigation enhancement signal;
acquiring a code phase of the navigation enhancement signal through acquisition and tracking;
acquiring navigation messages of the navigation enhancement signals through synchronization and decoding; wherein the message of the navigation enhancement signal comprises the position and clock error of the aircraft and the forwarded navigation message of the GNSS satellite;
obtaining the transmitting time of the navigation enhancing signal according to the code phase of the navigation enhancing signal; and
and obtaining the third pseudorange according to the receiving time of the navigation enhancement signal, the clock error of the ground anti-interference navigation receiver, the transmitting time of the navigation enhancement signal and the clock error of the aircraft flying to the sky.
In one embodiment, the interference source is arranged within a set range of the ground anti-interference navigation receiver, and the interference source is used for generating deception jamming signals.
An embodiment of the invention provides a deception jamming identification system based on the assistance of an aircraft, which comprises: the system comprises a GNSS satellite, an air-facing aircraft and a ground anti-interference navigation receiver which are in communication connection with each other; the ground anti-interference navigation receiver is used for executing the following steps:
acquiring a signal to be identified; the signal to be identified comprises a navigation signal of the GNSS satellite directly acquired by the ground anti-interference navigation receiver or an interference signal of an interference source directly acquired by the ground anti-interference navigation receiver;
acquiring a navigation enhancement signal of the aircraft, wherein the aircraft is not interfered by the interference source or can eliminate the interference of the interference source;
analyzing the signal to be identified to obtain a first pseudo range of the ground anti-interference navigation receiver and the GNSS satellite;
analyzing the navigation enhancement signal to obtain a second pseudo range of the ground anti-interference navigation receiver and the GNSS satellite;
calculating a difference between the first pseudorange and the second pseudorange; and
and when the difference value is smaller than a preset difference value threshold value, determining that the signal to be identified is a navigation signal of the GNSS satellite.
Drawings
Fig. 1 is a flowchart illustrating a spoofed interference identification method based on aircraft approaching assistance according to an embodiment of the present invention.
Fig. 2 is a flowchart illustrating a method for directly receiving GNSS satellite signals to obtain a first pseudorange according to an embodiment of the invention.
Fig. 3 is a flowchart illustrating a method for obtaining a second pseudorange based on an auxiliary of a temporary flight vehicle according to an embodiment of the present invention.
Fig. 4 is a schematic diagram for acquiring the position of the ground anti-jamming navigation receiver (3) according to an embodiment of the present invention.
Fig. 5 is a flowchart illustrating a method for directly receiving a navigation enhancement signal to obtain a third pseudorange according to an embodiment of the present invention.
Fig. 6 is a flowchart illustrating a DOA estimation method based on a two-dimensional MUSIC algorithm according to an embodiment of the present invention.
Fig. 7 is a schematic diagram illustrating a system for identifying a deceptive jamming based on aircraft-approaching assistance according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
A deception jamming identification method based on the assistance of an air-facing vehicle comprises the following steps: directly acquiring a signal to be identified, and analyzing the signal to be identified to obtain a first pseudo range of the ground anti-interference navigation receiver and the GNSS satellite; directly acquiring a navigation enhancement signal broadcast by an aircraft, and analyzing the navigation enhancement signal to obtain a second pseudo-range of the ground anti-interference navigation receiver 3 and the GNSS satellite 1; calculating a difference between the first pseudorange and the second pseudorange; when the difference is smaller than a preset difference threshold, determining that the signal to be identified is a navigation signal of the GNSS satellite 1, and when the difference is larger than or equal to the difference threshold, determining that the signal to be identified is a deception jamming signal of the jamming source.
Fig. 1 is a flowchart illustrating a spoofed jamming identification method based on aircraft-approaching assistance according to an embodiment of the present application. As shown in fig. 1, the method comprises the steps of:
step 100: and acquiring a signal to be identified.
The signal to be identified comprises a navigation signal of the GNSS satellite 1 directly acquired by the ground anti-interference navigation receiver 3 or an interference signal of an interference source 4 directly acquired by the ground anti-interference navigation receiver 3;
the GNSS satellite 1 includes any one of four satellite navigation constellations of GPS, BDS, GLONASS, and GALILEO. The navigation signal transmitted by the GNSS satellite 1 is structurally divided into three layers of a carrier, a pseudo code and a data code (i.e., navigation text), the pseudo code is periodic and has good autocorrelation and cross-correlation properties, and the pseudo code is also called a ranging code because the pseudo code is used as the ranging code in the GNSS, and the code phase information refers to phase information of the pseudo code modulated on the navigation signal. The data code is a binary code of a navigation message carried in a GNSS navigation signal, the navigation receiver performs carrier demodulation and pseudo code de-spread on the received navigation signal to obtain the data code, and the data code can be finally compiled into the navigation message according to the format of the navigation message. The GNSS navigation message contains important information for positioning, such as time information, GNSS satellite operation orbit parameters, ionospheric delay and the like.
Because the signals sent by the GNSS satellite are high-frequency signals, and currently general signal processing equipment cannot directly process the high-frequency signals, the embodiment of the application converts the high-frequency signals into baseband signals after receiving the high-frequency signals of the GNSS navigation satellite, so as to meet the requirements of signal processing. It should be understood that different methods may be selected according to the requirements of the actual application scenario to acquire the navigation signal, for example, the high-frequency navigation signal may be acquired by a third-party device or the high-frequency navigation signal may be acquired by the third-party device and converted into a baseband signal that can be directly processed, and then the navigation signal is directly sent to the signal processing device (for example, the above-mentioned ground anti-interference navigation receiver, etc.), as long as the signal processing device can acquire an available navigation signal, the specific method for acquiring the navigation signal in the embodiment of the present application is not limited.
Step 110: and acquiring a navigation enhancement signal of the aircraft.
The aircraft 2 broadcasts the navigation enhancement signal, the navigation enhancement signal is not interfered by an interference source 4, the navigation enhancement signal is modulated by quadrature phase shift keying, and the signal format of the navigation enhancement signal is represented as follows:
Figure BDA0003392261030000071
wherein P is the transmitting signal power of the aircraft 2, CI(t) and CQ(t) spreading codes for ranging modulated on branch I, Q, DI(t) and DQ(t) navigation messages modulated on branch I, Q, DI(t) includes the position of the aircraft 2, the clock difference, DQ(t) comprises forwarding the navigation messages of said GNSS satellite 1, f0The carrier frequency of the navigation enhancement signal of the aircraft facing the sky is represented, and t represents a time variable.
Step 120: and analyzing the signal to be identified to obtain a first pseudo range of the ground anti-interference navigation receiver and the GNSS satellite.
The ground anti-interference navigation receiver directly receives the signal to be identified, and the first pseudo range of the ground anti-interference navigation receiver 3 and the GNSS satellite is obtained by processing the signal to be identified.
Step 130: and analyzing the navigation enhancement signal to obtain a second pseudo-range of the ground anti-interference navigation receiver (3) and the GNSS satellite.
And the ground anti-interference navigation receiver directly receives the navigation enhancement signal, obtains a forwarded GNSS navigation message by performing signal processing on the navigation enhancement signal, and obtains a second pseudo range of the ground anti-interference navigation receiver 3 and the GNSS satellite under the assistance of the forwarded GNSS navigation message.
Step 140: a difference between the first pseudorange and the second pseudorange is computed.
Calculating a difference between the first pseudorange and the second pseudorange; the second pseudorange is obtained with the aid of the aircraft 2, and the aircraft 2 is not interfered by the interference source 4 or the interference of the interference source 4 is eliminated, so that the second pseudorange has high reliability, and the second pseudorange can be used as a reference standard of the first pseudorange, and the first pseudorange and the second pseudorange are compared differentially.
Step 150: and when the difference value is smaller than a preset difference value threshold value, determining that the signal to be identified is a navigation signal of the GNSS satellite.
Presetting a difference threshold, comparing the difference between the first pseudo-range and the second pseudo-range with a preset difference threshold, and when the difference is smaller than the preset difference threshold, determining that the signal to be identified is the navigation signal of the GNSS satellite 1
In some embodiments, as shown in fig. 2, step 120 may include the following sub-steps:
step 121: acquiring the receiving time of the signal to be identified;
the ground anti-interference navigation receiver 3 acquires the signal to be identified, and reads out the receiving time of the signal to be identified according to the clock of the ground anti-interference navigation receiver 3, namely the receiving time of the signal to be identified; a clock difference exists between the clock of the ground anti-interference navigation receiver 3 and the standard time, namely the clock difference of the ground anti-interference navigation receiver 3;
in some embodiments, the standard time is GPS time, BDS time, UTC time, or the like.
Step 122: acquiring a code phase of the signal to be identified;
the ground anti-interference navigation receiver 3 acquires the code phase of the signal to be identified after capturing and tracking the signal to be identified;
the code phase of the signal to be identified refers to the position of the newly received one-moment pseudo code in a whole-period pseudo code, the value of the newly received one-moment pseudo code is between 0 and L1, and the newly received one-moment pseudo code is not an integer generally, wherein L1 is the number of chips contained in the whole-period pseudo code.
Step 123: acquiring navigation messages of the signals to be identified
Acquiring navigation messages of the signals to be identified through synchronization and decoding; the navigation message of the signal to be identified comprises information used for positioning, such as time information, GNSS satellite orbit parameters, ionospheric delay and the like, and the position and clock error of the GNSS satellite can be obtained through the navigation message of the signal to be identified.
The navigation messages of the signals to be identified are arranged into a data stream in the form of a frame and subframe structure, each satellite transmits the navigation messages frame by frame, and when each frame of message is transmitted, the satellite transmits the navigation messages frame by subframe.
In some embodiments, the navigation message of the signal to be identified is composed of frames, each frame is composed of subframes, each subframe is composed of words, each word is composed of bits, and each bit corresponds to a pseudo code period.
Step 124: acquiring the emission time of the signal to be identified
Obtaining the transmitting time of the signal to be identified according to the code phase of the signal to be identified, wherein the calculation formula is as follows:
t(s)＝TOW1+(N1*w1+b1)×Tb1+(code_cycle1+code_ph1/code_chip1)×Tcode_cycle1
wherein t is(s)When the unit of the transmission time of the signal to be identified is seconds, the TOW1 is the period of each subframe taking the second as the unit, the w1 is the number of words in the received complete navigation message data code in the current subframe, the N1 is the number of bits contained in each word, the b1 is the number of bits received in the current word, the code _ cycle1 is the number of the received complete navigation message in the current bit, the code _ ph1 is the current code phase, the code _ chip1 is the number of chips contained in one code period, and the T is the number of chips contained in one code periodb1Is the length of each bit in seconds, Tcode_cycle1Is the length of each code period and has the unit of seconds.
Step 125: obtaining a first pseudorange
And obtaining the first pseudorange according to the receiving time of the signal to be identified, the clock error of the ground anti-interference navigation receiver 3, the transmitting time of the signal to be identified and the clock error of the GNSS satellite 1.
ρ1＝c*[(tu1+δtu)-(t(s)+δts)]
Where c is the speed of light, tu1For receiving the signal to be identifiedM, deltatuFor the clock error, t, of the said ground anti-jamming navigation receiver 3(s)For the time of transmission of the signal to be identified, δtsIs the clock error of the GNSS satellite 1.
In some embodiments, as shown in FIG. 3, step 130 may include the following sub-steps:
step 131: obtaining the position of the aircraft 2 and the third pseudorange
The ground anti-interference navigation receiver 3 acquires the navigation enhancement signal, performs signal processing on the navigation enhancement signal, and acquires the position of the aircraft 2 and a third pseudo range of the ground anti-interference navigation receiver 3 and the aircraft 2;
step 132: obtaining a direction of arrival of the navigation enhancement signal
Acquiring the direction of arrival of the navigation enhancement signal by adopting a DOA estimation algorithm, wherein the direction of arrival of the navigation enhancement signal comprises a pitch angle theta and an azimuth angle of the navigation enhancement signal
Figure BDA0003392261030000091
Because the navigation enhancement signal power is high, the DOA estimation algorithm can be carried out through the array antenna to measure the signal direction-of-arrival information, and the DOA estimation can estimate the signal to the pitch angle theta and the azimuth angle under the condition of the known array flow pattern by utilizing the characteristic that the navigation enhancement signal direction radiation energy is maximum in space
Figure BDA0003392261030000101
Step 133: obtaining the position of the ground anti-interference navigation receiver 3
According to the pitch angle theta and the azimuth angle of the navigation enhancement signal
Figure BDA0003392261030000102
The position of the aircraft 2 and the third pseudo-range of the ground anti-interference navigation receiver 3 and the aircraft 2 are obtained to obtain the position of the ground anti-interference navigation receiver 3;
in one embodiment, as shown in fig. 4, the following relationship is obtained according to the spatial geometry:
Figure BDA0003392261030000103
Figure BDA0003392261030000104
d·cosθ＝z1-z2
in the formula (x)1，y1，z1) The position coordinates of the aircraft 2 in a certain coordinate system, d is a third pseudo range, and the pitch angle theta and the azimuth angle of the navigation enhancement signal
Figure BDA0003392261030000105
Wherein the pitch angle theta is an included angle between the navigation enhancement signal and the Z axis, and the value range is 0-900Azimuth angle
Figure BDA0003392261030000106
The included angle between the projection of the navigation enhancement signal on the XY surface and the X axis is in the range of 0-360 DEG0。
The position (x) of the ground anti-interference navigation receiver (3) can be calculated2，y2，z2)
Figure BDA0003392261030000107
Figure BDA0003392261030000108
z2＝z1-d·cosθ
Step 134: obtaining the position of the GNSS satellite 1
Estimating the GNSS satellite 1 according to the navigation message for forwarding the GNSS satellite 1Position (x)s，ys，zs)；
Step 135: obtaining the second pseudorange
And calculating to obtain the second pseudorange according to the position of the ground anti-interference navigation receiver 3 and the position of the GNSS satellite 1.
Figure BDA0003392261030000109
And the delta t is the ionosphere delay, the troposphere delay and the pseudo-range deviation caused by the clock error of the GNSS satellite 1, and the ionosphere delay, the troposphere delay and the clock error of the GNSS satellite 1 are respectively corrected by utilizing an ionosphere model, a troposphere model and a satellite clock error model to obtain the second pseudo-range. Wherein (x)s(t)，ys(t)，zs(t)) is the position of the GNSS satellite 1 at time t, (x)2(t)，y2(t)，z2(t)) is the position of the ground antijam navigation receiver 3 at time t.
In some embodiments, as shown in fig. 5, step 131 may include the following sub-steps:
step 501: acquiring the receiving time of the navigation enhancement signal;
the ground anti-interference navigation receiver 3 acquires the navigation enhancement signal, and reads out the receiving time of the navigation enhancement signal according to the clock of the ground anti-interference navigation receiver 3, namely the receiving time of the navigation enhancement signal; a clock difference exists between the clock of the ground anti-interference navigation receiver 3 and the standard time, namely the clock difference of the ground anti-interference navigation receiver 3;
in some embodiments, the standard time is GPS time, BDS time, UTC time, or the like.
Step 502: acquiring a code phase of the navigation enhancement signal;
the ground anti-interference navigation receiver 3 acquires the code phase of the navigation enhancement signal after capturing and tracking the navigation enhancement signal;
the code phase of the navigation enhancement signal refers to the position of the newly received one-moment pseudo code in a whole-period pseudo code, the value of the newly received one-moment pseudo code is between 0 and L2, and the newly received one-moment pseudo code is not an integer generally, wherein L2 is the number of chips contained in the whole-period pseudo code.
Step 503: acquiring navigation messages of the navigation enhancement signal
Acquiring navigation messages of the navigation enhancement signals through synchronization and decoding; the navigation message of the navigation enhancement signal comprises time information, GNSS satellite orbit parameters, ionosphere delay and other information used for positioning, and the position and clock error of the aircraft 2 facing the sky and the forwarded navigation message of the GNSS satellite 1 can be obtained through the navigation message of the navigation enhancement signal.
The navigation messages of the navigation enhancement signal are arranged in a data stream in a frame and subframe structure, each satellite transmits the navigation messages frame by frame, and when each frame of messages is transmitted, the satellite transmits the navigation messages frame by subframe.
In some embodiments, the navigation message of the navigation enhancement signal is composed of frames, each frame is composed of subframes, each subframe is composed of words, each word is composed of bits, and each bit corresponds to a pseudo code period.
Step 504: obtaining a time of transmission of the navigation enhancement signal
Obtaining the transmitting time of the navigation enhancing signal according to the code phase of the navigation enhancing signal, wherein the calculation formula is as follows:
t(A)＝TOW2+(N2*w2+b2)×Tb2+(code_cycle2+code_ph2/code_chip2)×Tcode_cycle2
wherein t is(A)When the unit of the emission time of the navigation enhancement signal is seconds, the TOW2 is the week in units of seconds in each subframe, the w2 is the number of words in the received complete navigation message data code in the current subframe, the N2 is the number of bits contained in each word, the b2 is the number of bits received in the current word, the code _ cycle2 is the number of the received complete navigation message in the current bit, the code _ phase2 is the current code phase, and the code _ chip2 is the code phase contained in one code periodNumber of chips, Tb2Is the length of each bit in seconds, Tcode_cycle2Is the length of each code period and has the unit of seconds.
Step 505: obtaining a third pseudorange
And obtaining the third pseudorange according to the receiving time of the navigation enhancement signal, the clock error of the ground anti-interference navigation receiver 3, the transmitting time of the navigation enhancement signal and the clock error of the aircraft 2.
d＝c*[(tu2+δtu)-(t(A)+δtA)]
Where d denotes said third pseudorange, c is the speed of light, tu2For the reception time of the navigation enhancement signal, δtuFor the clock error, t, of the said ground anti-jamming navigation receiver 3(A)For enhancing the emission time of the signal, deltatAIs the clock error of the aircraft 2 facing the sky.
In some embodiments, the DOA estimation is performed by using a two-dimensional MUSIC algorithm to obtain the direction of arrival of the navigation enhancement signal, including the pitch angle theta and the azimuth angle theta of the navigation enhancement signal
Figure BDA0003392261030000121
As shown in fig. 6, step 132 may include the following sub-steps:
step 601: solving covariance matrix
In an embodiment, an array antenna is used to receive an incident signal, where the incident signal includes the navigation enhancement signal, the number of array elements of the array antenna is M, the number of signal sources is N, and then the signal expression received by the M array elements is:
X1＝AS+N
where S is a received signal, N is received noise, and a is a steering vector of mxn dimensions.
The covariance matrix is:
Rxx＝X1X1 H/L
wherein L is the number of fast beats.
Step 602: and carrying out eigenvalue decomposition on the covariance matrix to respectively obtain an eigenvalue and an eigenvector.
Step 603: setting a threshold, comparing the characteristic value with the threshold, and judging the number of the incident signals as the number of the characteristic values larger than the threshold;
step 604: constructing a noise subspace according to the feature vectors, and obtaining a spatial spectrum function according to the guide vectors and the noise subspace;
step 605: two-dimensional peak value search is carried out on the space spectrum function, and the pitch angle theta and the azimuth angle of the signal can be estimated according to the position of the maximum value point
Figure BDA0003392261030000131
Fig. 7 is a schematic diagram illustrating a system for identifying deceptive jamming based on aircraft-approaching assistance according to an embodiment of the present application. As shown in fig. 7, the system includes the following components:
GNSS satellite 701: any one of four satellite navigation constellations including GPS, BDS, GLONASS and GALILEO broadcasts GNSS satellite navigation signals;
aircraft flying in air 702: receiving and processing the GNSS satellite 701, modulating a GNSS satellite navigation message together with parameters such as self position, time, motion speed and the like on the navigation enhancement signal, and broadcasting the navigation enhancement signal to a ground anti-interference navigation receiver 703, wherein the navigation enhancement signal is 15dB to 20dB higher than the signal power of the GNSS satellite navigation signal; the aircraft 2 is not interfered by the interference source 4 or can eliminate the interference of the interference source 4.
The ground anti-interference navigation receiver 703: and receiving and processing the GNSS satellite navigation signal and the navigation enhancement signal broadcasted by the GNSS satellite 701, and completing the identification of the deception jamming signal by the aid of the aircraft 702.
The interference source 704: deception jamming signals of the GNSS satellite navigation signals are broadcast to the ground anti-jamming navigation receiver 703, causing jamming to the ground anti-jamming navigation receiver.
Those skilled in the art will appreciate that those matters not described in detail in the present specification are well known in the art.
Although the present invention has been described with reference to the preferred embodiments, it is not intended to limit the present invention, and those skilled in the art can make variations and modifications of the present invention without departing from the spirit and scope of the present invention by using the methods and technical contents disclosed above.

Claims (10)

1. A deception jamming identification method based on the assistance of an air-facing aircraft is characterized by comprising the following steps:
acquiring a signal to be identified; the signal to be identified comprises a navigation signal (1) of a GNSS satellite directly acquired by the ground anti-interference navigation receiver (3) or an interference signal of an interference source (4) directly acquired by the ground anti-interference navigation receiver (3);
acquiring a navigation enhancement signal of the aircraft (2), wherein the aircraft (2) is not interfered by the interference source (4) or the interference of the interference source (4) can be eliminated;
analyzing a signal to be identified to obtain a first pseudo range of a ground anti-interference navigation receiver (3) and a GNSS satellite (1);
analyzing the navigation enhancement signal to obtain a second pseudo-range of the ground anti-interference navigation receiver (3) and the GNSS satellite (1);
calculating a difference between the first pseudorange and the second pseudorange;
and when the difference value is smaller than a preset difference value threshold value, determining the signal to be identified as the navigation signal of the GNSS satellite (1).
2. The aircraft-approaching-aircraft-assistance-based deceptive interference identification method according to claim 1, further comprising:
when the difference is larger than or equal to the difference threshold value, determining the signal to be identified as an interference signal of an interference source (4).
3. The method for identifying deceptive jamming based on aircraft-in-flight assistance according to claim 1, characterized in that the GNSS satellites (1) comprise any one of the four satellite navigation constellations GPS, BDS, GLONASS and GALILEO.
4. The aircraft-flying-aircraft-assistance-based deceptive jamming identification method according to claim 1, wherein the navigation enhancement signal is modulated using quadrature phase shift keying, and the signal format of the navigation enhancement signal is expressed as:
Figure FDA0003392261020000021
wherein P is the transmitting signal power of the aircraft (2) facing the sky, CI(t) and CQ(t) spreading codes for ranging modulated on branch I, Q, DI(t) and DQ(t) navigation messages modulated on branch I, Q, DI(t) includes the position of the aircraft (2), the clock difference, DQ(t) comprises forwarding the navigation messages of said GNSS satellites (1), f0The carrier frequency of the navigation enhancement signal of the aircraft facing the sky is represented, and t represents a time variable.
5. The aircraft-airborne-aircraft-assistance-based deceptive jamming identification method according to claim 1, wherein the analyzing the signal to be identified to obtain a first pseudo-range of the ground anti-jamming navigation receiver (3) and the GNSS satellite (1) comprises:
acquiring the receiving time of the signal to be identified;
acquiring the code phase of the signal to be identified through acquisition and tracking;
acquiring navigation messages of the signals to be identified through synchronization and decoding; the navigation message of the signal to be identified comprises time information, GNSS satellite (1) operation orbit parameters and ionosphere delay, and the position and clock error of the GNSS satellite (1) can be obtained through the navigation message of the signal to be identified;
obtaining the transmitting time of the signal to be identified according to the code phase of the signal to be identified;
and obtaining the first pseudorange according to the receiving time of the signal to be identified, the clock error of the ground anti-interference navigation receiver (3), the transmitting time of the signal to be identified and the clock error of the GNSS satellite (1).
6. The aircraft-airborne-aircraft-assistance-based deceptive jamming identification method according to claim 1, wherein the parsing the navigation enhancement signal to obtain a second pseudorange between the ground anti-jamming navigation receiver (3) and the GNSS satellite (1) comprises:
analyzing the navigation enhancement signal to obtain the position of the aircraft (2) and a third pseudo range of the ground anti-interference navigation receiver (3) and the aircraft (2);
acquiring the direction of arrival of the navigation enhancement signal by adopting a DOA estimation algorithm;
obtaining the position of the ground anti-interference navigation receiver (3) according to the direction of arrival of the navigation enhancement signal, the position of the aircraft (2) and a third pseudo range of the ground anti-interference navigation receiver (3) and the aircraft (2);
estimating the position of the GNSS satellite (1) according to the navigation message for forwarding the GNSS satellite (1);
and calculating to obtain the second pseudo-range according to the position of the ground anti-interference navigation receiver (3) and the position of the GNSS satellite (1).
7. The aircraft-flying-aircraft-assistance-based deceptive interference identification method according to claim 6, wherein the obtaining the direction of arrival of the navigation enhancement signal using the DOA estimation algorithm comprises:
acquiring the direction of arrival of the navigation enhancement signal by adopting a multi-signal classification algorithm, wherein the direction of arrival of the navigation enhancement signal comprises a pitch angle theta and an azimuth angle of the navigation enhancement signal
Figure FDA0003392261020000031
8. The aircraft-flying-aircraft-assistance-based deception jamming identification method according to claim 6, characterized in that the calculation of the position of the aircraft (2) flying in flight and the third pseudorange between the ground anti-jamming navigation receiver (3) and the aircraft flying in flight (2) comprises:
acquiring the receiving time of the navigation enhancement signal;
acquiring a code phase of the navigation enhancement signal through acquisition and tracking;
acquiring navigation messages of the navigation enhancement signals through synchronization and decoding; wherein the message of the navigation enhancement signal comprises the position and clock error of the aircraft (2) and the forwarded navigation message of the GNSS satellite (1);
obtaining the transmitting time of the navigation enhancing signal according to the code phase of the navigation enhancing signal; and
and obtaining the third pseudorange according to the receiving time of the navigation enhancement signal, the clock error of the ground anti-interference navigation receiver (3), the transmitting time of the navigation enhancement signal and the clock error of the aircraft (2).
9. The aircraft-on-air-vehicle-assistance-based deception jamming identification method according to claim 1, characterized in that the jamming source (4) is disposed within a set range of the ground anti-jamming navigation receiver (3), the jamming source (4) being used to generate deception jamming signals.
10. Deception jamming identification system based on face supplementary empty aircraft, its characterized in that includes: the system comprises a GNSS satellite (1), an aircraft (2) and a ground anti-interference navigation receiver (3), which are in communication connection with each other; wherein the ground anti-jamming navigation receiver (3) identifies the signal to be identified by using the deceptive jamming identification method of any one of claims 1 to 9.
CN202111467802.XA 2021-12-03 2021-12-03 Deception jamming identification method and system based on auxiliary of aircraft Pending CN114200485A (en)

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