CN114371451A - Distance and speed dual-pulling interference resisting method based on monostatic and bistatic radar combination - Google Patents

Distance and speed dual-pulling interference resisting method based on monostatic and bistatic radar combination Download PDF

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CN114371451A
CN114371451A CN202210031106.2A CN202210031106A CN114371451A CN 114371451 A CN114371451 A CN 114371451A CN 202210031106 A CN202210031106 A CN 202210031106A CN 114371451 A CN114371451 A CN 114371451A
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radar
target
bistatic
monostatic
bistatic radar
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戴幻尧
孔德培
周瑞
石川
王建路
孙丹辉
刘冰峰
王岩
许光飞
王小森
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UNIT 63892 OF PLA
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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
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/36—Means for anti-jamming, e.g. ECCM, i.e. electronic counter-counter measures
    • 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
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/41—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00 using analysis of echo signal for target characterisation; Target signature; Target cross-section
    • G01S7/411—Identification of targets based on measurements of radar reflectivity

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Abstract

The invention belongs to the technical field of electronic countermeasure, and discloses a distance and speed resisting double-pulling interference method based on a monostatic and bistatic radar combination, which adopts a system for preventing a target from deceiving and interfering a radar, and comprises the following steps: the bistatic radar, the bistatic radar and the target position enable the bistatic radar, the bistatic radar receiver and the bistatic radar transmitter to be mutually synchronous, so that the bistatic radar receiver, the bistatic radar transmitter and the target form a triangular layout of a radar; enabling the monostatic radar and the bistatic radar to work under different frequencies, and determining Doppler frequency; when the monostatic radar and the bistatic radar receiver find that the Doppler frequency is the same, determining that interference exists, and changing the frequency of the bistatic radar transmitter to continuously monitor the speed and the position of the target. The invention has the advantages that the requirement on frequency agility is low, and the target is accurately positioned under the conditions of speed wave gate dragging and distance wave gate dragging interference.

Description

Distance and speed dual-pulling interference resisting method based on monostatic and bistatic radar combination
Technical Field
The invention belongs to the technical field of electronic countermeasure, and relates to a distance and speed resisting double-pulling interference method based on a monostatic and bistatic radar combination.
Background
In monostatic pulse radars, only one antenna acts as both transmitter and receiver (transceiver). Its operating principle is simple and it processes the echo of a transmitted pulse when it is reflected back by a target threat. Most modern radars are monostatic radars in which the radar distinguishes between transmitted and received pulses by means of a duplexer.
Bistatic radars have two separate antenna systems as transmitter and receiver, respectively. Unlike continuous wave radars, where the distance between the transmitter and receiver is small, such systems of bistatic radars are physically separated by a distance comparable to the target distance. Due to the invention of the duplexer, a pulse signal based monostatic radar is generally used as a ground based radar for military purposes. In our proposed solution, bistatic and monostatic radars are used in combination to mitigate the electronic countermeasures of deceptive jamming.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides a distance and speed resisting double-pulling interference method based on a monostatic and bistatic radar combination.
In order to achieve the purpose, the invention adopts the following technical scheme:
an anti-range-velocity dual-pulling interference system based on a monostatic and bistatic radar combination, comprising: a system for preventing targets from deceiving into radar, providing a set of monostatic radar equipped with a transmitter and a receiver; providing a bistatic radar transmitter co-located with the monostatic radar; providing a bistatic radar receiver located at a known distance from the bistatic radar transmitter such that the bistatic radar receiver, the bistatic radar transmitter and targets form a triangular layout; synchronizing the monostatic radar, the bistatic radar receiver and the bistatic radar transmitter with each other; enabling the monostatic radar and the bistatic radar to work under different frequencies; determining Doppler frequency through a monostatic radar receiver and a bistatic radar receiver, wherein the working state is as follows: when the monostatic radar receiver and the bistatic radar receiver find that the recorded Doppler frequencies are the same, determining that interference exists; calculating the distance between the monostatic radar and the target before interference; when the Doppler frequency read by the monostatic radar and the bistatic radar is the same, changing the frequency of a transmitter of the bistatic radar to continuously monitor the speed and the position of a target; where spoofing is the result of a distance or velocity wave gate tow.
A distance and speed dual-dragging interference resisting method based on a monostatic and bistatic radar combination adopts a physical arrangement mode of the monostatic and the bistatic radar to enable a transmitter, a receiver and a target to form an inequilateral triangle;
assuming that information between two radar systems is intercommunicated, adopting a speed gate dragging and distance gate dragging (VGPO/RGPO) mode and a Digital Radio Frequency Memory (DRFM) technology to shift down and sample a received radio frequency signal in frequency, and then storing the obtained digital signal in a high-speed digital memory;
in order to reconstruct the stored signal, the values stored in the memory are coherently reconstructed and then shifted up in frequency, converting to the original radio frequency; RGPO spoofs the transmission characteristics of the radar system by interfering with the impulse signals generated in the bird and, in addition, locks it by the radar on the received signal with the highest received power, while the transmitted signal power at the false target frequency remains higher than the real reflected wave at all times, which makes it increasingly difficult for the radar to detect the real target; thus, the radar tends to track such ongoing signal transmissions, and interfering devices change the return signal time reflected back from the decoy; the VGPO confuses the Doppler radar system by changing the frequency or phase of a radar receiving signal, so that the visual speed of a target is changed; the specific implementation steps are as follows:
firstly, the target allows itself to be locked by the radar system, once the tracking radar detects a target displayed on its position indicator, it will set range gates on both sides of the detected target, which will filter out all signals coming from outside this limited range, for which it will increase the signal-to-noise ratio and protect the radar from the effects of out-of-sync interference pulses; the radar will focus on this distance interval of the enclosed target location and no longer monitor other targets, a condition known as a "locked condition", which may be deceived by the target breaking the lock and escaping from the window; the speed-induced interference is divided into three stages,
firstly, stopping dragging, wherein the Doppler frequency of a false target is equal to the echo frequency of a real target, and the stopping time is slightly longer than the capturing time of a speed tracking circuit;
the second stage is a dragging stage, the Doppler frequency of the false target is gradually separated from the real target, and when the interference energy is greater than the target echo, the speed tracking circuit is dragged to track the interference frequency;
the third phase is the off period, where the interfering device stops transmitting signals, and thus the target disappears on the radar. Equation (1) shows that the interfering Doppler frequency (f) is not present when the door is unlockeddj) Equal to the true Doppler frequency (f)d) Once the gate is locked, the jammer shifts its frequency to time t2Finally, the transmission of the signal is stopped, so that the target disappears;
Figure BDA0003466470710000041
where k is the separation speed in Hz/sec;
in addition to the physical isolation of the system, most of the advantages of bistatic radar are derived from the general geometry of the system, the transmitted signal must be known at the receiving end, and if the doppler shift is to be determined, the transmitted frequency must also be known;
secondly, in bistatic radar, target positioning requires total signal propagation time, quadrature angle measurement of the receiver and estimation of the transmitter position, forming a triangle consisting of transmitter-target-receiver, which is called bistatic triangle; the geometrical characteristics of bistatic and monostatic radars are used to make it a semi-multistatic radar which eliminates fraud and detects objects by a very simple method, using an arrangement comprising: m-monostatic radar position, BT-bistatic radar transmitter position;
setting M as BT, TG as target, BR as bistatic radar receiver position, and similarly, dtDistance between transmitter and target of monostatic or bistatic radar, drDistance between bistatic radar receiver and target, distance between transmitter of bistatic radar or bistatic radar and bistatic radar receiver, f1Operating frequency of monostatic radar, f2Operating frequency, f, after identification of a spoofed interference by a monostatic radar3Identifying the operating frequency after deception jamming by bistatic radar, wherein the relative speed of the target relative to the station M is v
Figure BDA0003466470710000042
The monostatic radar transceiver and the bistatic radar transmitter are located at the same position at site M, and the monostatic radar and the bistatic radar are configured to operate in a synchronous mode; in the normal working mode without electron pair anti-interference, the transmitter of the bistatic radar keeps a silent state, becauseThe receiver on the bistatic radar works at double frequencies and is responsible for receiving scattered echoes, namely f, of the signal transmitted by the monostatic radar1(ii) a The working frequency band of the monostatic radar is different from that of the bistatic radar, and the monostatic radar is used for reducing blocking type interference and influencing the bistatic radar; if a monostatic radar is disturbed by noise, the bistatic radar receiver corresponding to it will be able to identify the disturbance on it: the method comprises the following specific steps:
first, two parameters α and d are calculated, respectivelytIn the position of these three objects: the transmitter, the receiver and the target of the bistatic radar form an inequilateral triangle together, the cosine law is applied to the triangle to calculate the distance from the target to the receiver, and the cosine law is applied again by using the calculated parameters to obtain the included angle beta between the target and the bistatic radar; therefore, even if the wave gate dragging effect exists, the bistatic radar can calculate the position of the target;
when the jamming device waits for the range gate to be locked, the monostatic radar calculates the distance d by receiving the initial echotAnd an angle α;
calculating the distance dr by knowing the distance D, applying a cosine law to a receiver of the bistatic radar, which always receives the target echo irradiated by the station M, and obtaining the following equation by means of the cosine law:
dr 2＝dt 2+D2-2dtDcosα (4)
where alpha and d aretCalculating the distance between the bistatic radar receiver and the target through the station M before being effectively deceived, and calculating the distance between the bistatic radar receiver and the target through equation (4);
when the gate is locked and the jammer spoofs site M, BT transmits a signal and BR receives the frequency associated with BT, the BR is still able to not only identify the jammer but also locate the target despite site M being spoofed;
calculating beta by other forms of the law of cosines
Figure BDA0003466470710000061
When a real target exists, the Doppler frequency measured by the two receivers is different, and when the real target exists, the Doppler frequency measured by the two stations is equal to fdj；
Without interference from the electron pair, the measured Doppler frequency of the monostatic radar is
Figure BDA0003466470710000062
Measured by a bistatic radar receiver at a Doppler frequency of
Figure BDA0003466470710000063
Under the condition of speed deception interference, the initial distance is locked at the beginning, and the distance from a transmitter to a target and an angle corresponding to the position of the transmitter and the position of the target are calculated by the single-base radar; at time t1Calculating these quantities; the time is the time at which the true doppler frequency of the original doppler frequency is transmitted; however, when the target starts spoofing, the doppler frequencies of the two stations may be the same, but the positions of the two radar tracks will be different.
A method for resisting range-speed double-towing interference based on a monostatic radar combination is characterized in that a radar tracks and locks a false target, and when an interference pod covers an area including a station M and a station BR, Doppler frequencies of the two stations are the same; when the interfering pod does not cover such a large area, the positions tracked by stations M and BR will be different; at this point, the bistatic radar transmitter begins operating at a different operating frequency f3The frequency of the transmitted signal is switched to f after the monostatic radar is delayed2(ii) a The system will switch the transmitter frequency only after detecting interference at two physically different locations, thus affecting the continuation backThe frequency agility disadvantage of coherence between waves is also solved; where the bistatic radar transmitter remains in silent mode without electronic pair interference, and only starts transmitting signals when station M starts to interfere, at which point station M switches frequencies and starts to operate at different frequencies, and from now on both stations BT and M start transmitting signals simultaneously and transmit synchronously, and it further makes it difficult to simultaneously interfere 3 different frequencies for the target.
Due to the adoption of the technical scheme, the invention has the following advantages:
a method for resisting double-towing interference of distance and speed based on a monostatic and bistatic radar combination adopts a system for preventing targets from deceiving and interfering radars, and comprises the following steps: the bistatic radar, the bistatic radar and the target position enable the bistatic radar, the bistatic radar receiver and the bistatic radar transmitter to be mutually synchronous, and the bistatic radar receiver, the bistatic radar transmitter and the target form a triangular layout; enabling the monostatic radar and the bistatic radar to work under different frequencies; determining Doppler frequency through a monostatic radar receiver and a bistatic radar receiver, wherein the working state is as follows: when the monostatic radar receiver and the bistatic radar receiver find that the recorded Doppler frequencies are the same, determining that interference exists; and when the Doppler frequency read by the monostatic radar and the bistatic radar is the same, changing the frequency of the transmitter of the bistatic radar to continuously monitor the speed and the position of the target. The invention has the advantages that the requirement on frequency agility is low, and the target is accurately positioned under the conditions of speed wave gate dragging and distance wave gate dragging (VGPO/RGPO) interference.
Drawings
Figure 1 shows a proposed arrangement using both monostatic and bistatic radar arrangements.
Figure 2 shows a doppler shift versus azimuth angle.
Figure 3 shows the signal to noise ratio over distance product for a bistatic radar operating at a frequency of 1GHz to maintain a transmit power of 1.5MW and a base line length of 20 km.
Figure 4 shows the signal to noise ratio over distance product for a monostatic radar operating at a frequency of 1GHz to maintain a transmit power of 1.5MW and an interference bandwidth of 10 MHz.
Fig. 5 shows a series of steps if the target attempts to spoof the radar through VGPO/RGPO.
Detailed Description
As shown in fig. 1, 2, 3, 4, and 5, a method for resisting range-velocity double-pulling interference based on a monostatic and bistatic radar combination is an innovative scheme of a monostatic and bistatic radar, and the physical arrangement of the method enables a transmitter, a receiver, and a target to form a scalene triangle.
It is assumed that the information between the two radar systems is intercommunicated. The advantage of using this scheme is that it has low frequency agility requirements and locates the target accurately in the case of velocity and distance gate pull (VGPO/RGPO) disturbances.
To implement spoofing interference, two ways, velocity-gate pulling and distance-gate pulling (VGPO/RGPO) are generally used. With the advent of Digital Radio Frequency Memories (DRFM), these spoofing techniques have become increasingly effective in interfering with radar. Therefore, these techniques have been used in large numbers by the offending parties in recent years.
Electronic countermeasure refers to a system that interferes with the proper functioning of the radar. DRFM is a technique for storing radio frequency and microwave signals using high-speed sampling and digital memory. It is becoming a common technique for implementing decoy electronic countermeasure systems. Today, most fighters are equipped with jamming pods with DRFM technology.
The technique may down shift the received radio frequency signal in frequency, sample it, and store the resulting digital signal in a high speed digital memory. To reconstruct the stored signal, the values stored in the memory are coherently reconstructed and then shifted up in frequency to the original radio frequency.
RGPO uses impulse signals generated in interfering pods to spoof the transmission characteristics of the radar system. Furthermore, it becomes increasingly difficult for the radar to detect real targets, since the radar locks it to the received signal with the highest received power, while the transmitted signal power at the false target frequency remains higher than the real reflected wave at all times. Therefore, radar tends to track such ongoing signal transmissions. Once this is achieved, the interfering device may alter the return signal time reflected back from the decoy.
The VGPO confuses the doppler radar system by changing the frequency or phase of the radar received signal, thereby changing the apparent velocity of the target.
First, the target allows itself to be locked by the radar system. Once the tracking radar detects an object displayed on its position indicator, it will place range gates on both sides of the detected object. The distance gate will filter out all signals coming from outside this limited range. For this reason it increases the signal-to-noise ratio and protects the radar from out of sync interference pulses. The radar will focus on this distance interval of the enclosed target locations and no longer monitor other targets. This state is referred to as a "locked state". However, such a range gate may be fooled by the target breaking the lock and thereby escaping the window.
Speed-pulling interference refers to speed spoofing, which can be divided into three phases. The first is the stop towing phase. At this stage, the doppler frequency of the false target is equal to the echo frequency of the real target. The stop time is slightly longer than the capture time of the speed tracking circuit. The second phase is called the towing phase. The doppler frequency of the decoy gradually separates from the real target. When the interference energy is larger than the target echo, the speed tracking circuit is dragged to track the interference frequency. The third phase is the off period. At this stage, the interfering device stops transmitting signals, and thus the target disappears on the radar. Equation (1) shows that the interfering Doppler frequency (f) is not present when the door is unlockeddj) Equal to the true Doppler frequency (f)d) But once the gate is locked the jammer shifts its frequency to time t2Eventually, the transmission of the signal is stopped, and thus the target disappears.
Figure BDA0003466470710000101
Where k is the separation speed in Hz/sec.
In addition to the physical isolation of the system, most of the advantages of bistatic radar stem from the general geometry of the system. At the receiving end, the transmitted signal must be known. If the doppler shift is to be determined, the transmit frequency must also be known.
In bistatic radar, target location requires total signal propagation time, quadrature angle measurements of the receiver, and an estimate of the transmitter position, forming a triangle of transmitter-target-receiver, referred to as a bistatic triangle. The scheme utilizes the geometrical characteristic structures of the bistatic radar and the monostatic radar, so that the bistatic radar becomes a semi-multistatic radar, and the radar can eliminate cheating and detect a target by a very simple method. The arrangement adopted is shown in figure 1.
The following is a description of the different symbols used in fig. 1.
M-monostatic radar position, BT-bistatic radar transmitter position, in this scheme configuration, set M-BT, TG-target, BR-bistatic radar receiver position, and similarly: dtDistance between monostatic radar (transmitter of bistatic radar) and target, drDistance between bistatic radar receiver and target, distance between bistatic radar (transmitter of bistatic radar) and bistatic radar receiver, f1Operating frequency of monostatic radar, f2The monostatic radar identifies the operating frequency after a spoofing disturbance. f. of3The bistatic radar identifies the operating frequency after the spoofing interference. The relative velocity of the target with respect to the station M is v
Figure BDA0003466470710000102
The monostatic radar transceiver and the bistatic radar transmitter are co-located with each other at site M. In the configuration scheme, the monostatic radar and the bistatic radar work in a synchronous mode. Bistatic radar in normal working mode without electronic pair anti-interferenceThe transmitter(s) of (1) is (are) kept silent (and therefore do not generate any energy consumption), while the receiver(s) on the bistatic radar (operating with dual frequencies) is (are) responsible for receiving the scattered echo of the signal(s) transmitted by the monostatic radar, i.e. f1. The operating band of the monostatic radar should be different from that of the bistatic radar as it will reduce the effect of jamming (which is the most effective type of noise interference for bistatic radar) on the bistatic radar. If the monostatic radar is disturbed by noise, the bistatic radar receiver corresponding thereto will be able to identify the disturbance being made thereto.
First, two parameters α and d are calculated, respectivelytWe will use these two parameters to calculate the parameters of the bistatic radar. The positions of these three objects, i.e. the transmitter and receiver of the bistatic radar and the target, now together form a scalene triangle similar to that shown in fig. 1. The cosine law is applied to the triangle to calculate the distance from the target to the receiver, and the calculated parameters are used to apply the cosine law again to obtain the included angle beta between the target and the bistatic radar. Therefore, even if there is a gate dragging effect, the bistatic radar can calculate the position of the target.
When the jamming device waits for the range gate to be locked, the monostatic radar calculates the distance d by receiving the initial echotAnd an angle alpha. The distance D is known and therefore, in order to calculate the distance dr, the cosine law is applied at the receiver of the bistatic radar, which always receives the target echo illuminated by the station M. With the aid of the cosine law, the following equation can be derived:
dr 2＝dt 2+D2-2dtD cosα (4)
(where. alpha. and dtCan be computed by site M before being effectively spoofed).
Equation (4) may calculate the distance between the bistatic radar receiver and the target. Now, when the gate is locked and the jammer spoofs site M, BT transmits a signal and BR receives the frequency associated with BT. At this point, the BR is still able to not only identify the interference, but also locate the target, despite the station M being spoofed.
We can also calculate β using other forms of the cosine law
Figure BDA0003466470710000121
When a real target is present, the doppler frequencies measured by the two receivers will be different. However, if it is a velocity spoofing interference, the Doppler frequency measured by both stations will be equal to fdj。
Without interference from the electron pair, the measured Doppler frequency of the monostatic radar is
Figure BDA0003466470710000122
Measured by a bistatic radar receiver at a Doppler frequency of
Figure BDA0003466470710000123
Figure 2 shows the calculated doppler shift for a certain target (speed of 800 km/h of running speed). The numerical calculation result shows that the Doppler frequency shift of the bistatic radar is 8.2473e-001KHz for the azimuth angle of 30 degrees; the doppler shift of the bistatic radar is-1.6537 e-001KHz for an azimuth of 120.
Figure 3 shows a signal-to-noise ratio corresponding to an undisturbed bistatic receiver. Wherein the signal-to-noise ratio also corresponds to a monostatic radar that is disturbed by the target threat noise, as shown in figure 4.
In the case of speed spoofing interference, the initial distance is initially locked. The monostatic radar calculates the distance from the transmitter to the target and the angle corresponding to the position of the transmitter and the position of the target. At time t1Calculating these quantities; this time is the time at which the original doppler frequency (true doppler frequency) is transmitted. However, when the target starts to cheat, there are many two sitesThe doppler frequencies may be the same but the positions of the two radar tracks will be different.
At the moment the radar tracking circuit is locked onto the false target, if the interfering bird covers an area including stations M and BR, the doppler frequencies of both stations will be the same. If the interfering pods do not cover such a large area, the positions tracked by stations M and BR will be different. At this point, the bistatic radar transmitter begins operating at a different operating frequency f3And transmitting the signal. The monostatic radar will switch the frequency to f after a certain delay2. In our proposed method, the system switches the transmitter frequency only after detecting interference at two physically different locations. Thus, the frequency agility disadvantage affecting the coherence between successive echoes is also solved.
The bistatic radar transmitter remains in silent mode without electronic pair interference and only starts transmitting signals when station M starts to interfere. At this point, station M switches frequencies and starts operating at a different frequency, and from now on stations BT and M both start transmitting signals simultaneously (transmit synchronization), and it further creates difficulties targeting simultaneous interference at 3 different frequencies.

Claims (3)

1. A distance and speed resistant double-pulling interference system based on a monostatic and bistatic radar combination is characterized in that: the method comprises the following steps: a system for preventing targets from deceiving into radar, providing a set of monostatic radar equipped with a transmitter and a receiver; providing a bistatic radar transmitter co-located with the monostatic radar; providing a bistatic radar receiver located at a known distance from the bistatic radar transmitter such that the bistatic radar receiver, the bistatic radar transmitter and targets form a triangular layout; synchronizing the monostatic radar, the bistatic radar receiver and the bistatic radar transmitter with each other; enabling the monostatic radar and the bistatic radar to work under different frequencies; determining Doppler frequency through a monostatic radar receiver and a bistatic radar receiver, wherein the working state is as follows: when the monostatic radar receiver and the bistatic radar receiver find that the recorded Doppler frequencies are the same, determining that interference exists; calculating the distance between the monostatic radar and the target before interference; when the Doppler frequency read by the monostatic radar and the bistatic radar is the same, changing the frequency of a transmitter of the bistatic radar to continuously monitor the speed and the position of a target; where spoofing is the result of a distance or velocity wave gate tow.
2. The method of claim 1, wherein the method is based on monostatic and bistatic radar combination and is characterized in that: adopting physical arrangement modes of monostatic and bistatic radars to enable a transmitter, a receiver and a target to form an inequilateral triangle;
assuming that information between two radar systems is intercommunicated, adopting a speed gate dragging and distance gate dragging (VGPO/RGPO) mode and a Digital Radio Frequency Memory (DRFM) technology to shift down and sample a received radio frequency signal in frequency, and then storing the obtained digital signal in a high-speed digital memory;
in order to reconstruct the stored signal, the values stored in the memory are coherently reconstructed and then shifted up in frequency, converting to the original radio frequency; RGPO spoofs the transmission characteristics of the radar system by interfering with the impulse signals generated in the bird and, in addition, locks it by the radar on the received signal with the highest received power, while the transmitted signal power at the false target frequency remains higher than the real reflected wave at all times, which makes it increasingly difficult for the radar to detect the real target; thus, the radar tends to track such ongoing signal transmissions, and interfering devices change the return signal time reflected back from the decoy; the VGPO confuses the Doppler radar system by changing the frequency or phase of a radar receiving signal, so that the visual speed of a target is changed; the specific implementation steps are as follows:
firstly, the target allows itself to be locked by the radar system, once the tracking radar detects a target displayed on its position indicator, it will set range gates on both sides of the detected target, which will filter out all signals coming from outside this limited range, for which it will increase the signal-to-noise ratio and protect the radar from the effects of out-of-sync interference pulses; the radar will focus on this distance interval of the enclosed target location and no longer monitor other targets, a condition known as a "locked condition", which may be deceived by the target breaking the lock and escaping from the window; the speed-induced interference is divided into three stages,
firstly, stopping dragging, wherein the Doppler frequency of a false target is equal to the echo frequency of a real target, and the stopping time is slightly longer than the capturing time of a speed tracking circuit;
the second stage is a dragging stage, the Doppler frequency of the false target is gradually separated from the real target, and when the interference energy is greater than the target echo, the speed tracking circuit is dragged to track the interference frequency;
the third phase is a shutdown phase, in which the interfering device stops transmitting signals, and therefore the target disappears on the radar; equation (1) shows that the interfering Doppler frequency (f) is not present when the door is unlockeddj) Equal to the true Doppler frequency (f)d) Once the gate is locked, the jammer shifts its frequency to time t2Finally, the transmission of the signal is stopped, so that the target disappears;
Figure FDA0003466470700000031
where k is the separation speed in Hz/sec;
in addition to the physical isolation of the system, most of the advantages of bistatic radar are derived from the general geometry of the system, the transmitted signal must be known at the receiving end, and if the doppler shift is to be determined, the transmitted frequency must also be known;
secondly, in bistatic radar, target positioning requires total signal propagation time, quadrature angle measurement of the receiver and estimation of the transmitter position, forming a triangle consisting of transmitter-target-receiver, which is called bistatic triangle; the geometrical characteristics of bistatic and monostatic radars are used to make it a semi-multistatic radar which eliminates fraud and detects objects by a very simple method, using an arrangement comprising: m-monostatic radar position, BT-bistatic radar transmitter position;
setting M as BT, TG as target, BR as bistatic radar receiver position, and similarly, dtDistance between transmitter and target of monostatic or bistatic radar, drDistance between bistatic radar receiver and target, distance between transmitter of bistatic radar or bistatic radar and bistatic radar receiver, f1Operating frequency of monostatic radar, f2Operating frequency, f, after identification of a spoofed interference by a monostatic radar3Operating frequency after identification of deception jamming by bistatic radar, the relative speed of the target to the station M being
Figure FDA0003466470700000032
The monostatic radar transceiver and the bistatic radar transmitter are located at the same position at site M, and the monostatic radar and the bistatic radar are configured to operate in a synchronous mode; in the normal working mode without electron pair and interference resistance, the transmitter of the bistatic radar keeps a silent state, so no energy consumption is generated, and the receiver on the bistatic radar works at double frequencies and is responsible for receiving the scattered echo of the signal transmitted by the monostatic radar, namely f1(ii) a The working frequency band of the monostatic radar is different from that of the bistatic radar, and the monostatic radar is used for reducing blocking type interference and influencing the bistatic radar; if a monostatic radar is disturbed by noise, the bistatic radar receiver corresponding to it will be able to identify the disturbance on it: the method comprises the following specific steps:
first, two parameters α and d are calculated, respectivelytIn the position of these three objects: the transmitter and receiver of bistatic radar and target together form a scalene triangle, and the cosine law is applied to the triangle to calculate the target to receiverThe distance is calculated, and the cosine law is applied again to obtain the included angle beta between the target and the bistatic radar; therefore, even if the wave gate dragging effect exists, the bistatic radar can calculate the position of the target;
when the jamming device waits for the range gate to be locked, the monostatic radar calculates the distance d by receiving the initial echotAnd an angle α;
calculating the distance dr by knowing the distance D, applying a cosine law to a receiver of the bistatic radar, which always receives the target echo irradiated by the station M, and obtaining the following equation by means of the cosine law:
dr 2＝dc 2+D2-2dtD cosα (4)
where alpha and d aretCalculating the distance between the bistatic radar receiver and the target through the station M before being effectively deceived, and calculating the distance between the bistatic radar receiver and the target through equation (4);
when the gate is locked and the jammer spoofs site M, BT transmits a signal and BR receives the frequency associated with BT, the BR is still able to not only identify the jammer but also locate the target despite site M being spoofed;
calculating beta by other forms of the law of cosines
Figure FDA0003466470700000051
When a real target exists, the Doppler frequency measured by the two receivers is different, and when the real target exists, the Doppler frequency measured by the two stations is equal to fdj；
Without interference from the electron pair, the measured Doppler frequency of the monostatic radar is
Figure FDA0003466470700000052
Measured by a bistatic radar receiver at a Doppler frequency of
Figure FDA0003466470700000053
Under the condition of speed deception interference, the initial distance is locked at the beginning, and the distance from a transmitter to a target and an angle corresponding to the position of the transmitter and the position of the target are calculated by the single-base radar; at time t1Calculating these quantities; the time is the time at which the true doppler frequency of the original doppler frequency is transmitted; however, when the target starts spoofing, the doppler frequencies of the two stations may be the same, but the positions of the two radar tracks will be different.
3. The method of claim 2, wherein the method is based on monostatic and bistatic radar combination for resisting range-velocity double-pull interference, and comprises the following steps: the radar tracking locks the false target, when the interference pod covers the area including the station M and the BR, the Doppler frequency of the two stations is the same; when the interfering pod does not cover such a large area, the positions tracked by stations M and BR will be different; at this point, the bistatic radar transmitter begins operating at a different operating frequency f3The frequency of the transmitted signal is switched to f after the monostatic radar is delayed2(ii) a Only after detecting interference at two physically different locations, the system will switch the frequency of the transmitter, thus the frequency agility disadvantage affecting the coherence between successive echoes is also solved; where the bistatic radar transmitter remains in silent mode without electronic pair interference, and only starts transmitting signals when station M starts to interfere, at which point station M switches frequencies and starts to operate at different frequencies, and from now on both stations BT and M start transmitting signals simultaneously and transmit synchronously, and it further makes it difficult to simultaneously interfere 3 different frequencies for the target.
CN202210031106.2A 2022-01-12 2022-01-12 Distance and speed dual-pulling interference resisting method based on monostatic and bistatic radar combination Pending CN114371451A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116840804A (en) * 2023-08-28 2023-10-03 中国人民解放军空军预警学院 Speed false target suppression method and device based on dual carrier frequency pulse

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116840804A (en) * 2023-08-28 2023-10-03 中国人民解放军空军预警学院 Speed false target suppression method and device based on dual carrier frequency pulse
CN116840804B (en) * 2023-08-28 2023-11-10 中国人民解放军空军预警学院 Speed false target suppression method and device based on dual carrier frequency pulse

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