Navigation deception source detection method based on array antenna direction finding

Abstract

The invention discloses a navigation deception source detection method based on array antenna direction finding, and belongs to the field of radio signal detection. According to the method, one channel and one array element of a dual-channel receiver are kept normally open, and a navigation deception signal is detected from a space signal received by the normally open array element; when a navigation deception signal is detected, the other channel of the dual-channel receiver is sequentially gated with other array elements, and the carrier phase difference of the navigation deception signal of the two channels is calculated during each gating; and finally, forming a phase difference vector by all carrier phase differences obtained by gating, performing correlation matching on the phase difference vector and the phase difference vector in the sample library, and determining the coming direction of the navigation deception signal. The method is simple, easy to implement and high in feasibility, can be widely applied to the current mainstream radio direction finding receiver, and has a relatively high engineering application prospect.

Description

Technical Field

[0001] The invention relates to the field of radio signal detection, in particular to a navigation deception source detection method based on array antenna direction finding. Background Art

[0002] With the rapid development of software radio technology, the technical approach to constructing satellite navigation spoofing signals is becoming simpler and simpler, and spoofing interference attacks on satellite navigation equipment are becoming more and more frequent. Compared with other types of radio interference, satellite navigation spoofing signals have lower power than noise and higher concealment. This makes it impossible to use traditional radio monitoring methods to warn and detect satellite navigation spoofing signals, which poses a great security risk.

[0003] At present, the method for detecting satellite navigation spoofing sources is mainly based on the amplitude comparison method, that is, using a directional antenna as a receiving antenna connected to an ordinary receiver, the directional antenna continuously scans the monitoring direction, and uses the characteristics of different gains of the directional antenna in different incident directions to determine the direction of the satellite navigation spoofing source. This method has the advantages of simple equipment composition and easy engineering implementation; but it also has the disadvantages of poor direction finding accuracy, easy to mistake the real navigation signal as a spoofing signal, and slow response speed of spoofing source detection. Summary of the invention

[0004] In view of this, the present invention proposes a navigation deception source detection method based on array antenna direction finding. The method of the present invention is simple and easy to implement in engineering. It can detect interference sources for satellite navigation deception that cannot be detected by conventional means due to low signal power, thereby improving the ability of satellite navigation countermeasures.

[0005] The object of the present invention is achieved in that:

[0006] A navigation deception source detection method based on array antenna direction finding is applied to an antenna system including a dual-channel receiver and at least three array elements; one channel of the dual-channel receiver is always connected to one array element, and the navigation deception signal is detected from the space signal received by the always-connected array element; when the navigation deception signal is detected, the other channel of the dual-channel receiver is selected with other array elements in turn, and each time the selection is performed, the carrier phase difference of the navigation deception signals of the two channels is calculated; finally, all the carrier phase differences obtained by selection are formed into a phase difference vector, and the phase difference vector is matched with the phase difference vector in a sample library for correlation, so as to determine the direction of the navigation deception signal and complete the navigation deception source detection.

[0007] Furthermore, the navigation deception signal is detected from the space signal received from the normally-on array element in a specific manner as follows:

[0008] (101) down-converting and sampling the spatial signal received by the regular array element to convert it into a digital baseband signal;

[0009] (102) searching all correlation peaks in the current code / frequency two-dimensional domain through a capture module;

[0010] (103) continuously performing signal tracking processing on the signals of each correlation peak searched by the capture module, and calculating the pseudo-range observation value corresponding to each correlation peak;

[0011] (104) According to the navigation satellite ephemeris, the real-time position of the satellite is calculated (X k ,Y k ,Z k ), k is the satellite number of the navigation satellite;

[0012] (105) Based on the known local position (X, Y, Z) of the receiver, the distance between the receiver and the navigation satellite is calculated:

[0013]

[0014] (106) The pseudo-range observations of each correlation peak are respectively compared with r k ￠Make the difference and take the modulus. If the result of a correlation peak is ≥50 meters, it is determined that a navigation deception signal is detected, and the correlation peak is the correlation peak corresponding to the navigation deception signal.

[0015] Furthermore, each time the two channels are connected, the carrier phase difference of the navigation spoofing signals of the two channels is calculated, specifically in the following manner:

[0016] (201) The navigation deception signal result detected by the normally-on array element is guided to the signal received by another channel to obtain the navigation deception signal of the other channel. The navigation deception signals obtained by the two channels are S IF1 (t), S IF2 (t);

[0017] (202) generating an I branch carrier and a Q branch carrier by a carrier digitally controlled oscillator, and mixing the spoof signal of each channel with the I branch carrier and the Q branch carrier respectively;

[0018] (203) Generate a local spreading code through a spreading code digitally controlled oscillator, cross-correlate the two mixing results of each channel with the local spreading code, and then perform a complete spreading code period T on the two cross-correlation results. coh The coherent integral of

[0019] (204) performing non-coherent accumulation of the two coherent integration results of each channel, determining the locking state of the signal through a signal detector, and adjusting the carrier digital controlled oscillator and the spread spectrum code digital controlled oscillator in step (202) and step (203) according to the locking state of the signal to constitute feedback regulation;

[0020] (205) The carrier phases of the navigation spoofing signals of the two channels are respectively extracted by a carrier digitally controlled oscillator to obtain the carrier phase difference of the navigation spoofing signals of the two channels.

[0021] Furthermore, the sample library is constructed in the following manner:

[0022] For an incoming signal, the carrier phase difference between the normal array element and each selected array element is obtained, and these carrier phase differences are combined into a phase difference vector of the current signal coming downward;

[0023] The phase difference vectors of all signals are measured to form a sample library.

[0024] The present invention has the following advantages:

[0025] 1. The present invention utilizes the characteristic that the carrier phase difference of the navigation deception signal received by the array antenna is different, and performs navigation deception interference on the carrier phase difference of the received signal of each receiving element of the array antenna to estimate, thereby realizing the tracking and search of the deception signal source.

[0026] 2. The present invention adopts the method of despreading autocorrelation to realize low-power deception interference detection, and adopts the method of array antenna to estimate the direction to realize the detection of satellite navigation deception attack source.

[0027] 3. The present invention can realize the alarm and detection of deceptive signals with power lower than the noise floor, making up for the deficiency that the existing methods cannot detect deceptive signals with power lower than the noise floor.

[0028] 4. The method of the present invention is simple, easy to implement, and has strong feasibility, and can be widely used in current mainstream radio direction-finding receivers.

[0029] In summary, the present invention improves the signal-to-noise ratio by despreading the satellite navigation deception interference signal, thereby realizing the detection of navigation deception interference; the signal direction is estimated by the carrier phase difference of the signal received by the array antenna, thereby detecting the direction of the navigation deception source, and realizing the tracking and search of the navigation deception source. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A schematic diagram of an application scenario of an embodiment of the present invention;

[0031] Figure 2 A schematic diagram of the principle of the fraud signal detection and identification of the present invention;

[0032] Figure 3 It is a schematic diagram of the principle of estimating the direction of the spoofing signal of the present invention. DETAILED DESCRIPTION

[0033] The present invention will be further described below in conjunction with the accompanying drawings.

[0034] A navigation deception source detection method based on array antenna direction finding is applied to an antenna system including a dual-channel receiver and at least three array elements; one channel of the dual-channel receiver is always connected to one array element, and the navigation deception signal is detected from the space signal received by the always-connected array element; when the navigation deception signal is detected, the other channel of the dual-channel receiver is selected with other array elements in turn, and each time the selection is performed, the carrier phase difference of the navigation deception signals of the two channels is calculated; finally, all the carrier phase differences obtained by selection are formed into a phase difference vector, and the phase difference vector is matched with the phase difference vector in a sample library for correlation, so as to determine the direction of the navigation deception signal and complete the navigation deception source detection.

[0035] The following is a more specific explanation using a five-element circular antenna and a dual-channel receiver as an example:

[0036] A navigation deception source detection method based on array antenna direction finding, Figure 1 This is a schematic diagram of the application scenario of this method. Figure 1 In the process, the switching of different receiving array element signals is realized through the five-choice-two matrix, and the time-sharing reception strategy is used to realize the dual-channel collection of five-element signals, thereby realizing the spatial signal reception. In the subsequent signal processing stage, the deception signal and the real navigation signal are separated, and the incident angle of the deception signal is estimated, finally realizing the detection and search of the deception attack source.

[0037] like Figure 2 As shown, in the stage of detecting and identifying navigation deception signals, the following steps are performed:

[0038] (101) down-converting and sampling the spatial signal received by the regular array element to convert it into a digital baseband signal;

[0039] (102) searching all correlation peaks in the current code / frequency two-dimensional domain through a capture module. If there are two or more correlation peaks, it can be determined that a navigation deception signal currently exists;

[0040] (103) Continue to perform signal tracking processing on the signals of each correlation peak searched by the capture module, and calculate the pseudo-range observation value corresponding to each correlation peak; in this example, there are two correlation peaks, and the corresponding two pseudo-range observation values ​​r are calculated. k,1 , r k,2 ;

[0041] (104) According to the navigation satellite ephemeris, the real-time position of the satellite is calculated (X k ,Y k ,Z k ), k is the satellite number of the satellite;

[0042] (105) Based on the known local position (X, Y, Z) of the receiver, the distance between the receiver and the navigation satellite is calculated:

[0043]

[0044] (106) The two pseudo-range observations r k,1 、r k,2 Respectively with r k ￠Make the difference and take the modulus. If one of the results is ≥50 meters, the signal corresponding to the result is the navigation deception signal.

[0045] In the above process, the receiver realizes the despreading processing of the digital baseband signal through the capture process, and improves the signal-to-noise ratio of the real navigation signal and the spoofing signal with power below the noise floor to above the noise floor; the receiver realizes the accurate estimation of the carrier phase of the spoofing signal and the real navigation signal through the tracking process to obtain the maximum de-amplification gain; the receiver continuously performs telegram demodulation through the tracking loop to obtain pseudo-range observations and navigation satellite ephemeris information.

[0046] Next, you need to switch each antenna element in turn and perform the following steps (such as Figure 3 shown):

[0047] (201) The carrier NCO (numerically controlled oscillator) generates the carriers of the in-phase branch (I branch) and the quadrature branch (Q branch), and converts the two-way spoofing signal S received by the dual-channel receiver into IF1 (t), S IF2 (t) mixing with the carriers of the I branch and the Q branch respectively;

[0048] (202) cross-correlating the four mixing results with the local spreading code generated by the spreading code NCO;

[0049] (203) The four cross-correlation results are coherently integrated for one complete spread spectrum code period, and the period time is T coh ;

[0050] (204) performing non-coherent accumulation on the I and Q branches of the received signal of each channel, determining the locking state of the signal through a signal detector, and adjusting the carrier NCO and the spread spectrum code NCO according to the locking state of the signal;

[0051] (205) The carrier phases of the two signals are extracted respectively through the carrier NCO, and a difference operation is performed to obtain the carrier phase difference of the two signals. The specific process is:

[0052] (20501) Read the carrier phase of the dual channel receive signal.

[0053] (20502) Since the two signal receiving antennas are very close to each other and the antenna gains are basically the same, the carrier phase difference of the two signals can be obtained by dividing the two signals:

[0054] S IF1 / IF2 =expj(f IF1 -f IF2 )

[0055] The carrier phase difference of the spoofing signal is j1=f IF1 -f IF2 .

[0056] The above method makes full use of the correlation gain of the spread spectrum code and improves the direction finding sensitivity of the receiver.

[0057] Repeat the above steps (201)-(205) until four carrier phase differences are obtained, and the four carrier phase differences are combined into a phase difference vector:

[0058]

[0059] In order to realize navigation deception signal direction finding, this method needs to establish a database containing the phase difference vectors of each signal direction in advance. The phase difference vector of each signal direction is:

[0060]

[0061] Where i is the incident angle of the navigation deception signal;

[0062] Then, the phase difference vector formed by the navigation spoofing signal received by the array antenna in real time in step (5) is matched with each phase difference vector in the sample library, and the phase difference correlation is calculated:

[0063]

[0064] Finally, find r i The maximum value r in the vector max , the angle i corresponding to the subscript max is the incident angle of the current navigation deception signal.

[0065] In summary, the present invention uses the method of despreading autocorrelation to improve the signal-to-noise ratio of the navigation deception signal, making its signal-to-noise ratio higher than the noise floor, thereby realizing the discovery and warning of the deception signal; further, the method of using the array antenna to estimate the direction realizes the detection of the satellite navigation deception attack source. The method of the present invention is simple and easy to implement in engineering. It solves the problem that low-power satellite navigation deception signals cannot be detected by existing radio detection equipment, lays a technical foundation for the development of satellite navigation deception interference monitoring equipment, and has a high prospect for engineering application.

Claims

1. A method for detecting navigation deception sources based on array antenna direction finding, characterized in that: The invention is applied to an antenna system including a dual-channel receiver and at least three array elements; one channel of the dual-channel receiver is always connected to one array element, and the navigation deception signal is detected from the space signal received by the always-connected array element; when the navigation deception signal is detected, the other channel of the dual-channel receiver is selected with other array elements in turn, and each time the selection is performed, the carrier phase difference of the navigation deception signals of the two channels is calculated; finally, all the carrier phase differences obtained by selection are formed into a phase difference vector, and the phase difference vector is matched with the phase difference vector in the sample library for correlation, so as to determine the direction of the navigation deception signal and complete the detection of the navigation deception source.

2. The method for detecting a navigation deception source based on array antenna direction finding according to claim 1, characterized in that: The specific method of detecting the navigation deception signal from the space signal received by the normally-on array element is as follows: (101) down-converting and sampling the spatial signal received by the regular array element to convert it into a digital baseband signal; (102) searching all correlation peaks in the current code / frequency two-dimensional domain through a capture module; (103) continuously performing signal tracking processing on the signals of each correlation peak searched by the capture module, and calculating the pseudo-range observation value corresponding to each correlation peak; (104) According to the navigation satellite ephemeris, the real-time position of the satellite is calculated (X k ,Y k ,Z k ), k is the satellite number of the navigation satellite; (105) Based on the known local position (X, Y, Z) of the receiver, the distance between the receiver and the navigation satellite is calculated: (106) The pseudo-range observations of each correlation peak are respectively compared with r k ￠Make the difference and take the modulus. If the result of a correlation peak is ≥50 meters, it is determined that a navigation deception signal is detected, and the correlation peak is the correlation peak corresponding to the navigation deception signal.

3. The method for detecting navigation deception sources based on array antenna direction finding according to claim 1, characterized in that: Each time the two channels are connected, the carrier phase difference of the navigation spoofing signals of the two channels is calculated as follows: (201) The navigation deception signal result detected by the normally-on array element is guided to the signal received by another channel to obtain the navigation deception signal of the other channel. The navigation deception signals obtained by the two channels are S IF1 (t), S IF2 (t); (202) generating an I branch carrier and a Q branch carrier by a carrier digitally controlled oscillator, and mixing the spoof signal of each channel with the I branch carrier and the Q branch carrier respectively; (203) Generate a local spreading code through a spreading code digitally controlled oscillator, cross-correlate the two mixing results of each channel with the local spreading code, and then perform a complete spreading code period T on the two cross-correlation results. coh The coherent integral of (204) performing non-coherent accumulation of the two coherent integration results of each channel, determining the locking state of the signal through a signal detector, and adjusting the carrier digital controlled oscillator and the spread spectrum code digital controlled oscillator in step (202) and step (203) according to the locking state of the signal to constitute feedback regulation; (205) The carrier phases of the navigation spoofing signals of the two channels are respectively extracted by a carrier digitally controlled oscillator to obtain the carrier phase difference of the navigation spoofing signals of the two channels.

4. The method for detecting navigation deception sources based on array antenna direction finding according to claim 1, characterized in that: The sample library is constructed as follows: For an incoming signal, the carrier phase difference between the normal array element and each selected array element is obtained, and these carrier phase differences are combined into a phase difference vector of the current signal coming downward; The phase difference vectors of all signals are measured to form a sample library.

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