CN112327330A - Immittance platform equipment, satellite navigation countermeasure system and method - Google Patents

Abstract

The invention relates to immittance station equipment which comprises a receiving antenna array, a radio frequency front end, a digital signal processor and a transmitting antenna array, wherein the receiving antenna array, the radio frequency front end, the digital signal processor and the transmitting antenna array are sequentially connected; the digital processor comprises a signal receiver connected with the radio frequency front end, a signal buffer connected with the signal receiver, a signal enhancement processing module bidirectionally connected with the signal buffer, and a time frequency adjustment processing module connected with the signal buffer, wherein the signal buffer is connected with the transmitting antenna array; the receiving antenna array is used for receiving navigation satellite signals, the time-frequency adjusting processing module is used for applying time delay to data signals to obtain inducing signals, and the transmitting antenna array is used for sending the inducing signals to the GNSS receiver. The invention relates to a satellite navigation countermeasure system, which comprises at least 4 pieces of immittance station equipment. The invention relates to a satellite navigation countermeasure method, which utilizes a satellite navigation countermeasure system to achieve the purpose of outputting disguised position information by a GNSS receiver through suppression and induction strategies.

Description

Immittance station equipment, satellite navigation countermeasure system and method

technical field

The present invention relates to the technical field of radio satellite navigation, in particular to an immittance station device, a satellite navigation countermeasure system and a method.

Background technique

Satellite navigation and positioning technology is an important technical means to provide precise positioning in the current economic, social and military fields. In the military field, the practice of several local wars in recent decades has shown that satellite navigation system (GNSS) is an important means and key technology to achieve precision strike. At the same time, the competition and control of the navigation system and its radio signal spectrum are becoming more and more intense. With the continuous development of related technologies, navigation warfare is likely to become a new combat style in modern electronic warfare. The purpose of navigation warfare is to prevent the enemy from using GNSS in combat, and to protect the normal use of one's own side, and at the same time to prevent the navigation services outside the target area from being affected.

GNSS navigation has many advantages, but it also has significant loopholes and is prone to jamming. First, the GNSS signal transmission frequency, modulation characteristics and navigation messages are public information. Secondly, the GNSS frequency is fixed, the signal is extremely weak, and the signal power reaching the ground is generally only about -160dBW, which is 10 ^-7 to 10 ^-16 watts. Therefore, the use of electromagnetic waves with very small interference power can pose a threat to GNSS receivers with a radius of tens of kilometers or even hundreds of kilometers. Studies have shown that a GPS jammer with a transmit power of only 1 watt can make all civilian GPS receivers fail within a range of 100 kilometers, and a GPS jammer with a transmit power of 10 watts can make military receivers within a range of 10 kilometers. All machines fail. For example, in the early days of the Iraq War, GPS-guided bombs were frequently accidentally bombed by the US military, which later proved to be jammed by Iraqi GPS system signals: Iraq used a high-power GPS signal jammer purchased from Russia to successfully implement GPS jamming on the ground. .

The confrontation technology for GNSS receivers mainly includes two aspects: offense and defense. The main means of attacking GNSS receivers is electromagnetic interference, which is divided into two categories: suppressive interference and deceptive interference.

Suppressing jamming is to suppress the satellite signal at the front end of the GNSS receiver by transmitting the jamming signal, so that the GNSS receiver cannot correctly demodulate the satellite signal, so as to achieve the purpose of jamming. The advantage of this method is that the implementation principle is simple, the interference mechanism does not depend on the GNSS system, and it has good operability. Suppressing jamming can disable receivers in specific areas, but cannot achieve decoy of target location.

Deceptive jamming mainly induces the GNSS receiver to solve the wrong position and time information by transmitting false signals with the same parameters as the GNSS system. There are two technical schemes for deceptive jamming, including autonomous deception and relay deception.

In autonomous spoofing, the jammer autonomously generates a high-fidelity GNSS signal and transmits it to the target area, causing the target receiver to lock on the spoofed signal, thereby obtaining false pseudorange and positioning information. However, this method must fully grasp the GNSS signal parameters, including code structure, navigation information structure and encryption method. For example, in order to encourage the use of GNSS systems, including the American GPS system, the European Galileo navigation system, and the Chinese Beidou navigation system, the system parameters of the civil code are disclosed. This makes civilian GNSS systems vulnerable to deceptive jamming.

In forwarding spoofing, the jammer first receives the satellite navigation signal, and then delays the forwarding with high fidelity, so that the spoofed receiver generates wrong pseudorange measurement values unconsciously, and finally makes the receiver solve the wrong positioning information.

This method does not need to decode information, and has a certain concealment, mainly for non-public GNSS signals. In addition to the public code for civil use, each GNSS system also has a dedicated military code navigation method. The system parameters of this method are the core technical parameters of the system, which are strictly confidential to the outside world, and it is difficult to obtain the corresponding technical information. Therefore, the autonomous spoofing jamming of military GNSS receivers does not have the conditions for realization. Taking the P code of GPS as an example, the P code is encrypted and has a period of up to 267 days. In practical application, the period of the P code is divided into 38 parts, and each part is 7 days. Each satellite uses a different part of the P-code, all with the same code length and period, but with a different structure. Cracking the P-code is extremely difficult and unrealistic. Therefore, forwarding spoofing jamming is the main technical means to deal with P codes.

Russia has developed jamming equipment for GPS receivers very early, and has used it in local hot wars including Iraq and Kosovo. In order to cope with this situation, the United States has carried out a substantial modernization and improvement of GPS. The current generation of GPS 3 series satellites has added a number of new navigation warfare features, mainly in the following points. First, a fourth civilian signal was added. Using advanced coding technologies such as Low Density Compression Coding (LDPC), it has stronger anti-interference and error correction capabilities under the same transmit power, which means that the positioning capability and availability under weak signal conditions such as shaded trees and indoors will be improved. greatly enhanced. Secondly, the signal transmission power is improved, especially for the second civil signal and the third civil signal. Third, provide higher positioning accuracy. GPS 3 satellites have higher orbit-keeping accuracy, and through technical upgrades in on-board atomic clocks, thermal control, and fully digital navigation signal generation, they can provide higher-stability positioning signals, and the user's ranging error is higher than before. The satellite has increased by more than 3 times. Fourth, improving the spot beam capability can increase the transmission power of the military code by more than 100 times in an area of several hundred kilometers, greatly enhancing the anti-jamming capability of local areas, and improving the regional combat capability qualitatively.

At present, for various interference strategies, new GNSS receivers have continuously developed corresponding anti-jamming countermeasures, that is, defense strategies of GNSS receivers, such as antenna enhancement technology, radio frequency interference detection and suppression, power anomaly detection and consistency detection, etc. With the development of these anti-jamming technologies, the original jamming technologies either fail, or their effects are greatly reduced and cannot function. Therefore, it is necessary to develop new means of navigation countermeasures. At the same time, in the navigation war, the offensive and defensive parties need to constantly play games to achieve a certain degree of equilibrium. With the improvement of the anti-jamming capability of each satellite navigation system, it is necessary to develop corresponding countermeasures.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide an immittance station device, a satellite navigation countermeasure system and a method, and the purpose of making the GNSS receiver output camouflaged position information is achieved through suppressing and inducing strategies by using the immittance station device.

The technical solution adopted by the present invention to solve the technical problem is: to provide an immittance station device, including a receiving antenna array, a radio frequency front end, a digital signal processor and a transmitting antenna array connected in sequence; A signal receiver connected to the radio frequency front end, a signal buffer connected to the signal receiver, a signal enhancement processing module bidirectionally connected to the signal buffer, and a time-frequency adjustment processing module connected to the signal buffer, so the signal buffer is connected to the transmit antenna array;

The technical solution adopted by the present invention to solve the technical problem is to provide a satellite navigation countermeasure system, which includes at least 4 sets of the above-mentioned immittance station devices deployed in the air.

The technical solution adopted by the present invention to solve the technical problem is to provide a satellite navigation countermeasure method, which adopts the above-mentioned satellite navigation countermeasure system, including:

Step (1): transmitting interference signals to the target area through the immittance station equipment to suppress the navigation satellite signals, so that the GNSS receiver and the navigation satellites in the target area lose lock;

Step (2): each of the immittance station equipment is directed to receive the signal of a single navigation satellite through the receiving antenna array;

Step (3): filter and enhance the navigation satellite signal received by each of the immittance station equipment through the signal enhancement processing module, and apply a pre-filter to the filtered and enhanced signal through the time-frequency adjustment processing module. Set the time delay to get the induced signal;

Step (4): each of the impedance station equipment sends the induced signal to the GNSS receiver through the transmit antenna array to change the output positioning of the GNSS receiver.

The transmit power of the interference signal in the step (1) satisfies: P _J >L _path +L _f +J _GNSS +J _th -G _J -G _r , where J _th is an anti-interference margin, and J _th <J _SIR , J _SIR is the interfering signal ratio entering the receiver, and J _SIR =J _eff -J _GNSS , J _eff is the effective interference power, and J _eff =P _J +G _J +G _r -L _path -L _f ,J _GNSS is the useful signal power, P _J is the transmission power of the jamming signal, G _J is the transmit antenna gain of the jammer, G _r is the antenna gain of the receiver, L _f is the front-end filter loss of the receiver, and L _path is the path propagation loss.

其中，δ₁为接收机V₁的时钟偏差，

为接收机在当前位置A点测量到的与导航卫星S_i间的伪距，

为接收机在诱导位置B点测量到的与导航卫星S_i间的伪距，c表示真空中光速。In the step (3), a preset time delay is applied to the filtered and enhanced signal by the time-frequency adjustment processing module, and the calculation formula of the preset time delay is:

where δ ₁ is the clock offset of receiver V ₁ ,

is the _pseudorange between the receiver and the navigation satellite Si measured by the receiver at the current position A,

is the _pseudorange between the receiver and the navigation satellite Si measured by the receiver at the induced position B point, and c represents the speed of light in vacuum.

其中，

(t)为逐步增加时延量，t为时间，Δt是为了将接收机V₁诱导至B点发送诱导信号的持续时间。In the step (3), applying a preset time delay to the filtered and enhanced signal by the time-frequency adjustment processing module, further comprising: gradually increasing the delay amount gradually, the formula is:

in,

(t) is the gradual increase of the delay amount, t is the time, and Δt is the duration for inducing the receiver V ₁ to point B to send the induced signal.

Step (5) is further included after the step (4): according to the current position and the new induced position of the GNSS receiver, the process of the step (1) to the step (4) is repeated.

In the step (1), the transmission frequency of the interference signal is consistent with the center frequency of the navigation satellite signal.

The type of the interference signal in the step (1) is wideband Gaussian noise, wideband phase frequency modulation signal or narrowband continuous wave interference signal.

beneficial effect

Compared with the prior art, the present invention has the following advantages and positive effects due to the adoption of the above-mentioned technical solution: the immittance station equipment provided by the present invention can not only effectively receive and transmit signals, but also has strong anti-interference performance; The present invention uses a satellite navigation countermeasure system constructed by multiple immittance station equipment to truly simulate the arrival direction of the navigation satellite signal, so as to prevent the induced signal from being detected and suppressed by the abnormal signal arrival angle detection module on the receiver side, thereby ensuring the induced effect; the present invention Through the precise transmission power control of the immittance station equipment in the suppression phase and the induction phase, the abnormal detection mechanism of the signal power on the receiver side is avoided, so as to ensure the induction effect; the present invention estimates the current position and the expected position of the target through the immittance station equipment. The delay amount to be applied is calculated, and the adjustment method of the gradual induction delay is adopted to gradually induce the target to deviate from the trajectory, avoiding the sudden jump of the positioning of the target receiver, so as to ensure the induction effect; Receive and transmit antenna arrays, that is, to achieve narrow beam tracking to lock the satellite to receive satellite navigation signals provided by navigation satellites in a specific direction, and to implement suppression and induction to specific areas; The alternating cycle of this process continuously consolidates and guarantees the induction effect.

Description of drawings

1 is a schematic diagram of an application scenario of an embodiment of the present invention;

FIG. 2 is a schematic structural diagram of an immittance table device according to an embodiment of the present invention;

Fig. 3 is the method flow chart of the embodiment of the present invention;

FIG. 4 is a schematic diagram of the cycle of the pressing and inducing process of the immittance stage equipment in the embodiment of the present invention.

Detailed ways

The present invention will be further described below in conjunction with specific embodiments. It should be understood that these examples are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

The embodiment of the present invention relates to an immittance station device, and a satellite navigation countermeasure system is composed of at least four navigation countermeasure devices (immittance station devices) deployed in the air, as shown in FIG. 1 , which is an application of the embodiment of the present invention Schematic diagram of the scene, the scene consists of three parts, namely: the navigation satellite located in space, the aerial platform composed of the UAV deployed in the air and equipped with the anti-missile equipment (the satellite navigation countermeasure system is the aerial platform), and the air platform located on the ground or GNSS receivers for navigating near-ground countermeasure areas. The navigation satellites may be GPS satellites, Beidou navigation satellites or Galileo navigation satellites. Under normal conditions, they provide navigation signals to terrestrial or near-earth GNSS receivers.

Further, the satellite navigation countermeasure system (air platform) mainly includes the immittance platform equipment installed on platforms such as unmanned aerial vehicles, aircraft, airships or hot air balloons. The main functions of the Immittance Station equipment include: First, orient upward to receive the navigation signal of a specific navigation satellite. Second, the received signal is processed, including signal quality improvement and time-frequency adjustment, to generate a high-fidelity induced signal with controllable delay. Third, the induced signal is transmitted to the designated area through a directional beam. At the same time, the immittance station equipment can complete its own high-precision positioning in real time with the help of multiple navigation satellites, and if necessary, combine the integrated navigation system composed of inertial navigation and satellite navigation to provide itself with high-precision positioning.

As shown in FIG. 2 , it is a schematic structural diagram of an immittance stage device according to an embodiment of the present invention. The immittance stage device includes a receiving antenna array connected in sequence, a radio frequency front end for performing radio frequency signal processing, a digital signal processor, and a digital signal processor. Transmitting antenna array; the two antenna arrays of the immittance station respectively have a two-layer beam structure facing the direction of the navigation satellite in the sky and the direction of the interference area downward. First, the receiving beam from the navigation satellite signal in the direction of the air can be realized The high-gain reception of satellite signals in a specific direction can isolate the interference from other directions, especially the interference from the ground or parallel airspace, so that the immittance station has a strong anti-interference ability. Secondly, the transmit beam directed towards the ground interference area is mainly used to send the induced signal to the GNSS receiver in the target area.

Further, the digital processor includes a signal receiver connected with the radio frequency front end, a signal buffer connected with the signal receiver, a signal enhancement processing module bidirectionally connected with the signal buffer, and a signal enhancement processing module connected with the signal buffer. A time-frequency adjustment processing module connected to the signal buffer, the time-frequency adjustment processing module is connected with the transmitting antenna array. The signal receiver processes the signal from the radio frequency front end and stores the signal in the signal buffer; the signal enhancement processing module performs operations such as filtering and enhancement processing on the data in the signal buffer; the time-frequency adjustment processing module According to the information such as the position of the target, the time delay applied when the signal is forwarded is calculated, and the timing of signal forwarding is controlled accordingly, and the data is taken out from the signal buffer and sent to the transmitting antenna array to complete the transmission of the induced signal.

Specifically, the immittance table device in this embodiment has the following features:

First of all, the Immittance Station equipment has the capability of mobile deployment. Immittance table equipment is installed in platforms such as UAVs in the near-Earth air. The aerial platforms where multiple immittance station devices are located can be maneuvered over and at the edge of the interference area to provide stable suppressing and inducing signals in the interference area. The maneuverably deployed immittance platform equipment provides many technical advantages: that is, the position of the aerial platform can be adjusted according to the position of the induced target, so as to achieve the best coverage of the target area; The optimal positioning layout is formed to improve the positioning accuracy.

Second, the immittance station equipment has the ability to adaptively receive specific satellite signals. Immittance station equipment is equipped with a large-scale antenna array facing the sky. By adaptively adjusting the beamforming of the weight coefficient vector of the antenna element, a receiving beam facing a specific direction is formed to realize the reception of radio signals in a specific direction. By using this method, the receiving antenna of the immittance station equipment can be directed to a specific navigation satellite, not only high-gain satellite signals can be obtained, but also radio interference from other directions can be isolated, which greatly enhances the immittance station to receive high-fidelity navigation satellites signal capability.

Third, the immittance station equipment has its own positioning ability. Immittance station equipment needs to accurately determine its own position in real time in order to realize the positioning and induction of the target receiver. Using the above-mentioned large-scale antenna array beamforming receiving technology, the immittance station equipment can calculate high-precision position information from the navigation satellite signals. At the same time, the combined navigation of inertial navigation and satellite navigation can also provide high-precision, high-output frequency positioning information.

This embodiment also relates to a satellite navigation countermeasure method, as shown in FIG. 3 , which is a flowchart of the method according to the embodiment of the present invention, which specifically includes:

Step (1): Signal suppression. The GNSS receiver in the specific area loses lock with the navigation satellite by transmitting the jamming signal of preset frequency and power to the specific area, and the GNSS receiver starts to search for the satellite signal again. . Typically, the signal suppression duration may be 1 to 5 minutes.

Described step (1) is described in detail below:

The type of the interference signal may be broadband Gaussian noise, or a broadband phase frequency modulated signal, or a narrowband continuous wave interference signal. When the frequency of the strong interference signal is the same as the center frequency of the GNSS signal, it will cause the pulse signal to jump, causing the receiver to fail to identify the satellite signal, and the receiver cannot capture, track, or lock the satellite signal. When the frequencies are not the same, due to the frequency selectivity of the front-end circuit of the receiver, only the interference signal close to the center frequency of the GNSS signal can enter the receiver, resulting in in-band and out-of-band interference. At this time, the effect of interference to the GNSS signal is not only related to the frequency and pulse width of the interfering signal, but also to the initial phase angle.

Preferably, the transmission frequency of the interference signal is consistent with the center frequency of the GNSS signal.

The transmission _power of the _interference signal should be determined according to the following method. the maximum value of the interference), namely:

J _SIR > J _th

The anti-interference margin J _th has different values according to the characteristics of different signals of different systems. For example, for the civil code (C/A code) of GPS, the anti-interference margin is below 30dB, which is generally considered to be 25dB, which is expressed as J _th,CA =25. For the P code of GPS, the anti-jamming margin is about 43dB, which is expressed as J _th,P =25.

The interference signal ratio can be obtained by calculating the effective interference power _Jeff and the useful GNSS signal power J _GNSS respectively. In the logarithmic domain, there are:

J _SIR = J _eff - J _GNSS

The useful GNSS signal power has different values according to different systems and different signals. For example, for a GPS system, the ground received power level of L1C is about -155.5dBW, and the power level of C/A code is about -158.5dBW.

For the effective interference power, it can be determined by the following formula:

J _eff =P _J +G _J +G _r -L _path -L _f

Among them, P _J is the transmit power of the interfering signal, G _J is the transmit antenna gain of the impedance station equipment, Gr is the antenna gain of the receiver, _{L f} is the front-end filter loss of the receiver, and L _path is the path propagation loss.

According to the formula J _SIR >J _th , J _SIR =J _eff -J _GNSS and J _eff =P _J +G _J +G _r -L _path -L _f , the transmit power P _J of the interference signal can be obtained:

P _J >L _path +L _f +J _GNSS +J _th -G _J -G _r

Further, when the interference signal is transmitted to the same area by a plurality of immittance station devices, the transmit power of a single immittance station device can be correspondingly reduced.

Step (2): Narrow beam reception of specific navigation satellite signals. Each of the immittance station devices is directed to receive the signal of a single specific navigation satellite through the receiving antenna array.

Immittance station equipment uses a directional receiving antenna to aim at a specific navigation satellite and receive the navigation signal of a single navigation satellite.

The immittance station equipment uses the unencrypted ephemeris to obtain the position of the navigation satellites, and allocates the navigation satellites to be received according to the target position and the layout of each immittance station equipment.

Immittance station equipment in the air platform uses narrow beams to align satellites to receive and separate out specific signals from individual navigation satellites.

In principle, only more than 4 sets of immittance station equipment are needed to separate the signals of more than 4 satellites, and the ambiguity of the angle of arrival can be eliminated by directional filtering.

Step (3): time-frequency adjustment. The signal enhancement processing module filters and enhances the navigation satellite signals received by each immittance station device, and applies a preset time delay to the filtered and enhanced signals through the time-frequency adjustment processing module, get the induction signal.

Described step (3) is described in detail below:

The purpose of filtering and enhancing the navigation satellite signal is to filter out other signals other than the selected satellite signal as much as possible and enhance the selected satellite signal.

表示接收机在A点测量到的与卫星S_i(1≤i≤4)间的信号传播时长，

表示接收机在A点测量到的与卫星S_i(1≤i≤4)间的伪距，

表示接收机V₁在B点时与卫星S_i(1≤i≤4)间的信号传播时长，

表示接收机在B点时与卫星S_i(1≤i≤4)间的伪距。This embodiment is particularly critical for determining the amount of time delay that needs to be applied. There are four immittance station devices, namely Q ₁ , Q ₂ , Q ₃ and Q ₄ , corresponding to four satellites S ₁ , S ₂ , and Q 4 , respectively. _S3 and _S4 ,

represents the signal propagation time between the receiver and the satellite Si ( _1≤i≤4 ) measured by the receiver at point A,

represents the pseudorange between the receiver and the satellite Si ( _1≤i≤4 ) measured by the receiver at point A,

represents the signal propagation time between the receiver V ₁ at point B and the satellite Si ( _1≤i≤4 ),

Indicates the pseudorange between the receiver and the satellite Si ( _1≤i≤4 ) when the receiver is at point B.

According to the GNSS positioning principle, in order to make the output positioning of the receiver at point A become point B, the delay amount that needs to be applied to the satellite signal is determined by the following formula:

Among them, δ ₁ is the clock deviation of the receiver V ₁ , which has the same effect on each satellite and does not affect the positioning result during positioning. δ ₁ can be fixed as a small constant in the calculation.

Further, in order to avoid sudden and large jumps in the navigation and positioning results of the GNSS receiver, it is necessary to gradually adjust the time-frequency parameters in an imperceptible way to gradually induce the target to deviate from the trajectory. In order to implement the induction gradually, it is not possible to apply such a large amount of delay to the satellite signal to be retransmitted at one time. Assuming that the receiver is to be induced to point B after Δt seconds, the retransmission can be gradually increased after the induction phase starts. Delay amount, the formula is:

Step (4): Inducing signal transmission. Each of the immittance station devices transmits the induced signal to the GNSS receiver through the transmit antenna array to change the output positioning of the GNSS receiver.

After the step (1) is carried out for a period of time, typically such as 1 to 5 minutes, the target in the target area will lose lock with the GNSS satellite signal, and enter the stage of re-searching for the satellite model.

At this time, the data processed in the steps (2) and (3) are sent to the target area with a certain power in the form of a very narrow beam to suppress or precisely align the area. In this way, the inducing signal is emitted downward to achieve the purpose of inducing the target to deviate from the true trajectory.

The step (2), step (3) and step (4) constitute an induction process. Generally, the duration of induction can be 5 to 10 minutes.

As shown in FIG. 4, it is a schematic diagram of the suppression and induction process cycle of the immittance station equipment in the embodiment of the present invention. In order to consolidate and guarantee the induction of the target receiver in the area, when it is necessary to start the interference to the target receiver in the area , deploy the aerial platform over the designated area, and then each device enters the suppression and induction cycle. When the induction process lasts for a period of time, in order to consolidate the results of the induction, signal suppression can be implemented again, and then based on the current position of the target and the new the induction position, recalculate the induction time delay, and conduct induction again. This cycle alternates until the navigation confrontation task is completed.

It can be seen that the immittance station equipment provided by the present invention can not only effectively receive and transmit signals, but also have strong anti-jamming performance; the satellite navigation countermeasure system and the satellite navigation countermeasure method provided by the present invention can suppress and induce the strategy. To achieve the purpose of making the GNSS receiver output camouflaged position information, it can effectively counter the anti-jamming strategy of the GNSS receiver in the military and aerospace fields.

Claims (9)

1. A immittance platform device is characterized by comprising a receiving antenna array, a radio frequency front end, a digital signal processor and a transmitting antenna array which are sequentially connected; the digital processor comprises a signal receiver connected with the radio frequency front end, a signal buffer connected with the signal receiver, a signal enhancement processing module bidirectionally connected with the signal buffer, and a time frequency adjustment processing module connected with the signal buffer, wherein the signal buffer is connected with the transmitting antenna array;

the receiving antenna array is used for receiving navigation satellite signals, the signal receiver is used for processing data signals from a radio frequency front end and storing the processed data signals into the signal buffer, the signal enhancement processing module is used for filtering and enhancing the data signals in the signal buffer, the time-frequency adjustment processing module is used for applying time delay to the filtered and enhanced data signals to obtain induced signals, and the transmitting antenna array is used for transmitting the induced signals to a GNSS receiver in a target area.

2. A satellite navigation countermeasure system comprising at least 4 immittance station apparatus as claimed in claim 1 deployed in the air.

3. A satellite navigation countermeasure method, characterized in that the satellite navigation countermeasure system of claim 2 is employed, comprising:

step (1): transmitting an interference signal to a target area through the immittance platform equipment to suppress a navigation satellite signal, so that a GNSS receiver and a navigation satellite in the target area are unlocked;

step (2): each of the immittance station devices directionally receives signals of a single navigation satellite through the receiving antenna array;

and (3): filtering and enhancing the navigation satellite signals received by each piece of immittance station equipment through the signal enhancement processing module, and applying a preset time delay to the filtered and enhanced signals through the time-frequency adjustment processing module to obtain induced signals;

and (4): each of the admittance station devices sends the induction signal to a GNSS receiver through the transmit antenna array to change an output position of the GNSS receiver.

4. The satellite navigation countermeasure method of claim 3, wherein the transmission power of the interference signal in step (1) satisfies: p_J＞L_path+L_f+J_GNSS+J_th-G_J-G_rWherein, J_thFor a margin against interference, and J_th＜J_SIR，J_SIRIs the interference signal ratio into the receiver, and J_SIR＝J_eff-J_GNSS，J_effIs effective interference power, and J_eff＝P_J+G_J+G_r-L_path-L_f，J_GNSSFor useful signal power, P_JFor transmitting power for interfering signals, G_JFor jammers transmitting antenna gain, G_rFor the antenna gain of the receiver, L_fFor receiver front-end filter loss, L_pathIs the path propagation loss.

5. The satellite navigation countermeasure method according to claim 3, wherein in step (3), the filtered and enhanced signal is subjected to a preset time delay by the time-frequency adjustment processing module, and the preset time delay is calculated by:

wherein, delta₁For receiver V₁The clock skew of (a) is determined,

measured for the receiver at the current position a and navigation satellite S_iThe pseudo-range between the two,

measured for receiver at induced position B and navigation satellite S_iThe pseudoranges between, c represents the speed of light in vacuum.

6. The satellite navigation countermeasure method of claim 5, wherein the step (3) of applying a preset time delay to the filtered and enhanced signal by the time-frequency adjustment processing module further comprises: progressively increasing the amount of delay by the formula:

wherein,

to increase the amount of delay step by step, t is the time, Δ t is for the receiver V₁The duration of the induction signal sent by point B.

7. The satellite navigation countermeasure method of claim 3, characterized in that the step (4) is followed by a step (5): and (4) circulating the processes from the step (1) to the step (4) according to the current position and the new induced position of the GNSS receiver.

8. The satellite navigation countermeasure method of claim 3, wherein the transmission frequency of the interference signal in step (1) coincides with the center frequency of the navigation satellite signal.

9. The satellite navigation countermeasure method of claim 3, wherein the type of the interference signal in step (1) is a wideband Gaussian noise, a wideband phase frequency modulation signal or a narrowband continuous wave interference signal.

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