CN108333600B - Coexisting unmanned aerial vehicle navigation decoy system and method - Google Patents

Abstract

The invention provides a coexisting unmanned aerial vehicle navigation decoy system and a method thereof, wherein the decoy system comprises: the satellite searching system is used for receiving a real satellite signal and analyzing the real satellite signal, and analyzed result data are transmitted to the deception signal generation control system; the deception signal generation control system is used for calculating related parameters and generating deception signals; the signal transmitting system is used for transmitting the deception signal generated by the deception signal generation control system to the target unmanned aerial vehicle, and a receiver of the target unmanned aerial vehicle captures and tracks the deception signal and the real satellite signal at the same time; and the deception signal generation control system increases the power of deception signals to strip real signals and controls the tracking loop of the target unmanned aerial vehicle. According to the method, the synchronized pseudolites and the celestial stars are generated and coexist in the target receiver, the power of the deceptive signals is gradually increased after coexistence, the noise base processed by the receiver is raised, the signal-to-noise ratio output by a correlator of the receiver is reduced, the deceptive signals gradually strip the real signals from the tracking loop by virtue of the power advantage, and then the tracking loop is controlled, so that deception on the flight direction and speed of the black-flying unmanned aerial vehicle is realized.

Description

Coexisting unmanned aerial vehicle navigation decoy system and method

Technical Field

The invention belongs to the technical field of navigation attack and defense, and particularly relates to a coexisting type unmanned aerial vehicle navigation decoy system and method.

Background

In recent years, the unmanned aerial vehicle industry has been rapidly developed, and the application of unmanned aerial vehicles is explosively grown in military or civil fields. The unmanned plane which flies for many times interferes with flight events, and causes airports with reserve landing, hundreds of flights delay and tens of thousands of passengers being blocked from traveling. Therefore, from the aspects of urban airspace security, terrorism prevention, public security maintenance and the like, a powerful control means for the unmanned aerial vehicle flying in black or malicious black is urgently needed.

At present, the control interference mode for the black unmanned aerial vehicle adopts a high-power wireless voltage interference mode mostly, because this mode is easy to operate, low in cost and far away in interference distance, but this mode can lead to the black unmanned aerial vehicle not to immediately drop after receiving the interference, and the flight direction and the place of falling after its out of control are unpredictable, and the technical problem of secondary damage can also be caused.

For the problems of uncontrollable and secondary damage, an unmanned aerial vehicle navigation decoy system is particularly important, three types of decoy interference modes are usually adopted for unmanned aerial vehicle navigation decoy, one is forward type decoy interference, the method directly receives real satellite signals, and forwards the signals after time delay and power amplification, the technology is relatively easy to realize, but the real satellite signals are directly forwarded, the forwarding path of the real satellite signals is larger than a direct path, namely the decoy signals reach a receiver later than the real signals, the receiver considers that multipath signals are directly rejected, and the deception is difficult to realize. And secondly, suppressing deception jamming, namely directly generating deception signals with the same structure as the real signals by a satellite signal simulator without the help of the real signals, wherein the deception signals are suppressed by power without considering signal synchronization, so that the receiver enters a recapture state after losing lock, and the deception signals are directly captured by the receiver due to the fact that the deception signals occupy the absolute power advantage, but the concealment of the process is poor, and the requirement on a power amplifier is high. And thirdly, synchronous generation type deception jamming, the method requires the code phase, Doppler frequency and carrier phase of deception signals to be synchronous with real signals, and the carrier phase synchronization is almost impossible in practice, because centimeter-level distance information between the target receiver antenna and the deception system transmitting antenna phase center needs to be obtained if the carrier phases of the deception signals and the real signals are aligned, so that the realization difficulty is very high for the existing measuring means. In summary, both the forwarding spoofing and the generative spoofing are to cover the satellite signal to achieve the spoofing purpose, and the described spoofing methods all face the problems of low success rate, poor concealment and high implementation difficulty.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a method and a system for realizing the quick access of a black-flying unmanned aerial vehicle to an induced signal, namely a navigation signal deception method of a coexisting unmanned aerial vehicle.

To achieve the above and other related objects, the present invention provides a coexisting type drone navigation spoofing system, including:

the satellite searching system is used for receiving a real satellite signal and analyzing the real satellite signal, and analyzed result data are transmitted to the deception signal generation control system;

the deception signal generation control system is used for calculating related parameters and generating deception signals;

the signal transmitting system is used for transmitting the deception signal generated by the deception signal generation control system to the target unmanned aerial vehicle, and the target unmanned aerial vehicle simultaneously captures and tracks the deception signal and the real satellite signal;

and the deception signal generation control system increases the power of deception signals to strip real signals and controls the tracking loop of the target unmanned aerial vehicle.

Preferably, the satellite searching system comprises a GNSS time service receiver, a receiving antenna and a laser range finder,

the receiving antenna is used for receiving real satellite signals;

the GNSS time service receiver is used for demodulating and resolving a real satellite signal to obtain the signal power, the code phase, the ionosphere delay, the troposphere delay, the local coordinate of a decoy system, the signal emission time, the visible satellite number, the visible satellite elevation angle and the visible satellite azimuth angle of the real satellite signal;

the laser range finder is used for measuring the distance from the decoy system to the target unmanned aerial vehicle, and the elevation angle and the azimuth angle relative to the ground plane.

Preferably, the spoofing signal generating and controlling system comprises a DSP module and an FPGA module;

the DSP module calculates the coordinates of the current visible satellite, the geometric distance from the current visible satellite to the decoy system, the position of the target unmanned aerial vehicle, the distance from the satellite signal to the target unmanned aerial vehicle and the GNSS time for the satellite signal to reach the target unmanned aerial vehicle according to the parameter information provided by the GNNS time service receiver, the ephemeris data of the GNNS satellite and the ranging information of the laser range finder, calculates the emission time of the deception signal and the Doppler frequency shift of the deception signal according to the distance from the decoy system to the unmanned aerial vehicle, and further calculates the initial carrier phase and code phase of each visible satellite, the initial carrier frequency control word and the pseudocode frequency control word;

and the FPGA module receives the related information obtained by the calculation of the DSP module to generate a deception signal.

Preferably, the signal transmitting system includes a power amplifier control module, and the power amplifier control module compensates the spoofed signal so that the power of the spoofed signal received by the target drone is approximately equal to the power of the real satellite signal.

In order to achieve the above objects and other related objects, the present invention provides a coexisting type drone navigation decoy method, which includes the following steps:

receiving and analyzing a real satellite signal;

generating a deception signal according to the analysis result of the real satellite signal, and simultaneously capturing and tracking the deception signal and the real satellite signal by the target unmanned aerial vehicle;

and the deception signal generation control system increases the power of deception signals to strip real signals and controls the tracking loop of the target unmanned aerial vehicle.

Preferably, said analyzing the real satellite signals comprises the sub-steps of:

receiving a real satellite signal;

demodulating and resolving a real satellite signal to generate signal power, a code phase, ionosphere delay, troposphere delay, local coordinates of a decoy system, signal emission time, a visible satellite number, a visible satellite elevation angle and a visible satellite azimuth angle of the real satellite signal;

the range, elevation angle and azimuth angle of the decoy system to the target drone are measured.

Preferably, the method for generating a spoof signal includes the following substeps:

s1, obtaining the current visible star coordinate, the geometric distance between the current visible star and the decoy system, the position of the target unmanned aerial vehicle, the distance between the satellite signal and the target unmanned aerial vehicle and the GNSS time of the satellite signal reaching the target unmanned aerial vehicle according to the demodulated and resolved parameter information, the GNNS satellite ephemeris data, the measured distance between the decoy system and the target unmanned aerial vehicle and the elevation angle and the azimuth angle relative to the ground plane;

s2, calculating the emission time of the deception signal and the Doppler frequency shift of the deception signal according to the distance from the deception system to the target unmanned aerial vehicle, and further calculating the initial carrier phase and code phase of each visible satellite, the initial carrier frequency control word and the pseudo code frequency control word;

s3 generates a spoof signal based on the related information obtained in steps S1 and S2.

Preferably, the power of the spoofed signal is approximately equal to the power of the real satellite signal.

As described above, the coexisting type unmanned aerial vehicle navigation decoy system and method of the present invention have the following beneficial effects:

according to the method, the synchronized pseudolites and the celestial stars are generated and coexist in the target receiver, the power of the deceptive signals is gradually increased after coexistence, the noise base processed by the receiver is raised, the signal-to-noise ratio output by a correlator of the receiver is reduced, the deceptive signals gradually strip the real peak from the tracking loop by virtue of the power advantage, the tracking loop is further controlled, and deception on the flight direction and speed of the black-flying unmanned aerial vehicle is realized.

Drawings

Fig. 1 is a coexisting deception jamming drone technology roadmap;

FIG. 2 is a flowchart of the fraud generation control system;

FIG. 3 is a schematic diagram of coordinate position solution for an unmanned aerial vehicle;

FIG. 4 is a block diagram of a spoofed signal initial channel state word;

FIG. 5 is a block diagram of a code NCO module structure;

FIG. 6 is a diagram of a carrier signal generation architecture;

fig. 7 is a control block diagram of the drone navigation system.

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It is to be noted that the features in the following embodiments and examples may be combined with each other without conflict.

It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention, and the components related to the present invention are only shown in the drawings rather than drawn according to the number, shape and size of the components in actual implementation, and the type, quantity and proportion of the components in actual implementation may be changed freely, and the layout of the components may be more complicated.

The embodiment provides a coexisting type unmanned aerial vehicle navigation decoy system which comprises a satellite searching system, a deception signal generation control system and a signal transmitting system.

The satellite searching system is used for receiving a real satellite signal and analyzing the real satellite signal, and analyzed result data are transmitted to the deception signal generation control system;

a spoof signal generating control system for generating a spoof signal;

the signal transmitting system is used for transmitting the deception signal generated by the deception signal generation control system to the target unmanned aerial vehicle, and the target unmanned aerial vehicle simultaneously captures and tracks the deception signal and the real satellite signal;

and the deception signal generation control system increases the power of deception signals to strip real signals and controls the tracking loop of the target unmanned aerial vehicle.

Specifically, the satellite searching system comprises a GNSS time service receiver, a laser range finder and a receiving antenna.

The receiving antenna is used for receiving real satellite signals;

the GNSS time service receiver is used for demodulating and resolving the signal power P of the real satellite signal_ACode phase

Ionospheric delay ^ I and tropospheric delay ^ T, local coordinate E (x) of decoy system₁,y₁,z₁) Time of flight t of GNSS signalⁿVisible satellite number VS_i(i 1,2.. n.,) angle of elevation of visible satellite θ_i(i ═ 1,2.. N), visible satellite azimuth_i(i＝1,2.....,N)；

The laser range finder is used for measuring the distance L from the unmanned aerial vehicle navigation decoy system to the target unmanned aerial vehicle and the elevation angle alpha relative to the ground plane₁And azimuth angle E₁。

The deception signal generation control system comprises a DSP module, an FPGA module and a D/A module, and the whole work flow is shown in figure 2.

The DSP module is used for calculating the coordinate position P (x) of the current visible star according to the parameter information provided by the star searching systemⁿ,yⁿ,zⁿ) And further calculating the geometric distance r between the current visible star and the deceptive machineⁿFurther, the position F (x, y, z) of the target unmanned aerial vehicle is calculated, so that the distance r from the satellite signal to the target unmanned aerial vehicle is calculated_nFurther, the GNSS time of the signal reaching the target drone is obtained as follows:

further calculating the signal emission time of the decoy system according to the distance L from the decoy system to the target unmanned aerial vehicle

From the free space attenuation equation:

the power compensation method is adopted to control the power amplifier control module, so that the signal power P reaching the target unmanned aerial vehicle_B≈P_ACalculating the pseudo range rho between the target unmanned aerial vehicle and each visible satellite in real time_iAnd pseudo-range rate of change +_iAnd then calculating the initial phase of the deception code, the initial phase of the deception carrier, the number of the integral digital chips, the code frequency control word and the carrier frequency control word, compiling a navigation message, calculating an invisible satellite according to the obtained current ephemeris, and taking the invisible satellite number as the satellite number of the deception signal. The spoofed satellite number, the integer chip number, and the integer millisecond delay may be combined together and referred to as the channel state. And after the relevant data of the DSP module is calculated, the channel state word is sent to the FPGA module.

The FPGA module is used for deception signal synthesis work and mainly comprises a carrier signal generation module, a pseudo code signal generation module, a navigation message reading module, a time sequence control module and a data communication module. The DSP module calculates an initial carrier phase and a pseudo code phase of a reconstructed visible satellite at an initial stage, and sends the initial carrier phase and the pseudo code phase to the FPGA channel, and after the FPGA channel receives relevant information, the FPGA channel selects a corresponding carrier signal generation module and a corresponding pseudo code signal generation module according to a satellite number and a navigation system to which the FPGA channel belongs, and then frequency control word accumulation is carried out from the calculated initial phase. The generated pseudo code signal is added with a navigation message in a mode, and then modulated onto a carrier wave, and finally a digital intermediate frequency signal is generated.

The time sequence control module is used for carrying out strict counting control according to an input clock and generating timing interrupt pulses with high precision, high stability and high reliability. After the first power-on initialization is completed, the timing control module immediately generates high-precision counting and interrupt pulses and outputs all time reference signals for the whole baseband board system.

The data communication module is used for realizing data transmission between the FPGA module and the DSP module and between the FPGA module and the DA module.

The D/A module is mainly used for converting the generated digital intermediate frequency signal into an analog intermediate frequency signal.

The signal transmitting system comprises an up-conversion module, a power amplifier control module and a transmitting antenna.

The up-conversion module is used for converting the frequency of the analog intermediate frequency signal into a radio frequency signal of a corresponding frequency point.

The power amplifier control module is used for controlling the power value according to the attenuation

And calculating a power compensation value to control the power of the transmitting deception signal in time.

And the transmitting antenna is used for transmitting the radio frequency signals corresponding to the frequency points in an omnidirectional or directional manner.

According to the method, a simulation system for generating the synchronous satellite signals is established according to the received real satellite signals on the sky and the accurately calculated coordinate position of the target unmanned aerial vehicle, and the aim that the generated synchronous deceptive signals and the satellite signals on the sky coexist in the receiver to participate in positioning together instead of covering the original real satellite signals is fulfilled. According to the parameter information provided by the star searching system, the coordinate position P (x) of the current visible star is calculatedⁿ,yⁿ,zⁿ) And further calculating the geometric distance r between the current visible star and the deceptive machineⁿFurther, the position F (x, y, z) of the target unmanned aerial vehicle is calculated, so that the distance r from the satellite signal to the target unmanned aerial vehicle is calculated_nFurther, the GNSS time of the signal reaching the target drone is obtained as follows:

further calculating the signal emission time of the decoy system according to the distance L from the decoy system to the target unmanned aerial vehicle

And deceptive signal doppler shift f_u'＝f_u-f_EFAnd further calculating the initial carrier phase and code phase of each visible satellite, an initial carrier frequency control word and a pseudo code frequency control word. Combining the deception satellite number, the integral digital chip number and the integral millisecond delay together, sending the deception satellite number, the integral digital chip number and the integral millisecond delay to the FPGA module, generating deception signals by the FPGA module according to the received related information, and compensating the power of the deception signals, which is attenuated due to propagation

Make signal power P who reaches target unmanned aerial vehicle_B≈P_AThe method has the advantages that the deception signal and the real sky signal can be co-stored in the receiver after the deception signal reaches the receiver for about 3-4 s, the deception signal and the real sky signal jointly participate in positioning of the receiver, then the deception signal power is increased, the deception signal strips the real sky signal by means of the power advantage, control over a target receiver tracking loop is achieved, and deception on the direction, speed and position of the target unmanned aerial vehicle is finally achieved according to the control principle of a target unmanned aerial vehicle navigation system.

As shown in fig. 1 and fig. 2, this embodiment further provides a method for guiding and deceiving a coexisting type unmanned aerial vehicle, in which a simulation system for generating a synchronized satellite signal is established according to a high-precision time service receiver receiving an over-the-air real satellite signal and a target coordinate position accurately calculated by a DSP, and a deceptive signal for generating synchronization and an over-the-air satellite signal are mainly coexisted in the receiver instead of covering the original real satellite signal.

Specifically, the coexisting type unmanned aerial vehicle navigation decoy method specifically comprises the following steps:

firstly, according to the signal power P of the real satellite signal of the GNSS time service receiver in the satellite searching system_ACode phase

Ionospheric delay^ I and tropospheric delay ^ T, local coordinate E (x) of decoy system₁,y₁,z₁) Time of flight t of GNSS signalⁿVisible satellite number VS_i(i 1,2.. N), visible satellite elevation angle θ_i(i ═ 1,2.. N), visible satellite azimuth_i(i＝1,2.....,N)。

And secondly, obtaining the coordinates of the current visible star, the geometric distance between the current visible star and the decoy system, the position of the target unmanned aerial vehicle, the distance from the satellite signal to the target unmanned aerial vehicle and the GNSS time of the satellite signal to the target unmanned aerial vehicle according to the demodulated and demodulated parameter information, the GNNS satellite ephemeris data, the measured distance from the decoy system to the target unmanned aerial vehicle and the elevation angle and the azimuth angle relative to the ground plane. Specifically, the second step includes the following substeps:

step 1) the DSP module is selected from the known deception system coordinate E (x)₁,y₁,z₁) And the DSP module calculates the coordinates P (x) of the current visible star according to the ephemeris parametersⁿ,yⁿ,zⁿ) (n represents the satellite number), and then the geometric distance r between the visible satellite and the decoy system is calculatedⁿIf the visible satellite 1 is present, the geometric distance between the decoy system and the visible satellite 1 is

Step 2) constructing a space rectangular coordinate system xAy by taking the E point of the decoy system as the circle center, and determining the elevation angle theta of the known visible satellite_i(i 1,2.. N), visible satellite azimuth_i(i 1,2.. N), the distance L from the decoy system to the target drone, the elevation angle α from the ground plane₁And azimuth angle E₁The included angle PEF (beta) of the plane where the visible star, the decoy system and the target unmanned aerial vehicle are located can be solved_i-α₁So that the geometric distance from the visible star to the target unmanned aerial vehicle can be obtained by the triangle cosine law as

Step 3) can be obtained from step 1) and step 2):

the coordinate position F (x, y, z) of the target drone can be solved by the least square method according to equation (1).

Step 4) the time service receiver obtains the observed quantity information of each channel after information resolving processing, obtains the navigation message of each channel satellite, and calculates the satellite signal transmitting time t with the satellite number n according to the following formulaⁿ：

In the above formula, when TOW represents the week, w represents the number of words of the navigation message data code that has been received by the current receiver channel, b represents the number of bits of the navigation message that has been received by the current channel, and c represents the number of bits of the navigation message that has been received by the current channel₁The CP represents the code phase measured value corresponding to the current channel at the moment. the pseudo-range formula of the receiver at the time t is as follows:

ρ_t＝(t-tⁿ)c₁ (3)

by reverse reasoning, with known receiver time and pseudorange, the n satellite transmission time is:

tⁿ＝t-ρ_t/c₁ (4)

step 5) calculating the transmitting time t of the satellite signal by the step 4)ⁿAnd 3) calculating the distance r from the visible satellite to the target unmanned aerial vehicle_nAnd step one, resolving ionospheric delay ^ I and tropospheric delay ^ T, and calculating GNNS time T of the number n satellite signals to the target unmanned aerial vehicle_u：

Step 6) obtaining the signal emission time t of the decoy system according to the distance L between the decoy system and the target unmanned aerial vehicle measured by the laser range finder_q：

And 7) after time service, using the UTC time as the initial synchronization time of a frame for generating satellite signals by the decoy system to start the simulation system, wherein the formula can be formed by the satellite time:

in the formula, t_qTo trick the signal transmission time, t_{s_int}Is t_uThe satellite counts an integer number of seconds at the moment, bit is the satellite bit count at the moment t, and ms is t_uTime satellite millisecond counting; v. of_chipIs t_uTime satellite spread spectrum code rate;

is t_uCounting the integral code chips of the time satellite; theta_chipIs t_uData in a time local register; width is the receiver local register width.

Further according to the deception signal emission time t calculated in the step 6)_qObtaining the initial chip number required by the navigation decoy system to simulate the current satellite

And a small digital phase theta_chip. The time of bit and ms is the integer millisecond period of delay needed by the navigation decoy system. Meanwhile, the decoy system obtains the initial phase of the carrier wave by adopting the same method, and the ionosphere accelerates the carrier wave speed and slows down the pseudo code speed, so that the pseudo range delay used by the carrier wave is different from the pseudo range delay used by the pseudo code.

Step 8) calculating the Doppler frequency shift f between the target unmanned aerial vehicle and the decoy system according to the relative motion of the target unmanned aerial vehicle and the decoy system_EFMeanwhile, calculating the distance r between the visible star and the target unmanned aerial vehicle according to the step 1)ⁿThereby calculating rⁿThe change rate of the values obtains the relative movement speed v of the target unmanned aerial vehicle and the visible star_uThe Doppler frequency f between the visible satellite and the target drone can be derived from the following formula_u：

Wherein f is_cIs the carrier reference frequency and c is the speed of light.

Further deriving the Doppler frequency f at which the spoofed signal is generated_u' is: f. of_u'＝f_u-f_EF，f_EFIndicating the doppler frequency between the spoofing system and the target drone.

And 9) after the initial carrier phase and the pseudo code phase of the deception signal are calculated in the DSP module, the phase of the deception signal at any sampling moment can be obtained by using a frequency control word. The frequency control word corresponds to the speed of the spoofed signal. The accuracy of the satellite signal doppler depends on the length of the time interval, with shorter time intervals, faster frequency control word updates, and higher accuracy in generating the spoofed signal.

Suppose a frequency control word t_s(t) update interval of Δ t, local receiver t_uA time pseudorange of

Then t_uThe time t represented by the satellite signal received at the moment_s(t) is:

local receiver t_uPseudorange at + Δ t

The time t represented by the satellite signal received at time t_s' (t) is:

t_s'(t)＝t_u+Δt-ρ_t'/c₁

then the satellite time is given by t in the Δ t time interval_s(t) is run to t_s' (t), the time interval over which the satellite time elapses is:

Δt_s＝t'_s(t)-t_s(t)＝(t_u+Δt-ρ'_t/c₁)-(t_u-ρ'_t/c₁)＝Δt-(ρ'_t-ρ_t)/c₁

time interval Δ t of satellite_sI.e. at time, Δ t_sAnd/Δ t is the velocity of the satellite signal phase. Control word K for carrier frequency in delta t time interval_{CARRIER_NCO}And a pseudo code frequency control word K_{CODE_NCO}Respectively as follows:

in the form of GNSS_RFIs the GNSS satellite system radio frequency; GNSS_codespeedPseudo code rate for GNSS satellite system; f. of_sSampling a clock for the signal; and width is the width of the FPGA register.

Step 10) the DSP reads the information resolved by the time service receiver, the GNSS satellite ephemeris data and the ranging information, and calculates the coordinates F (x, y, z) of the unmanned aerial vehicle and the emission time t of the deceptive signal_qAnd deceptive signal doppler shift f_u'＝f_u-f_EFAnd then, calculating the initial carrier phase and code phase of each visible satellite, and the initial carrier frequency control word and the pseudo code frequency control word according to the simulation initial time, the unmanned aerial vehicle coordinates and the GNSS satellite ephemeris. Meanwhile, the invisible satellite is calculated according to the obtained current ephemeris, the invisible satellite number is used as the satellite number of the deception signal, and the deception satellite number, the integral number of chips and the integral millisecond delay are combined together to be called as a channel state. The channel state structure assembly is completed, a satellite number is assembled by 0-5 bits, the number of chips is assembled by 6-15 bits, an integral millisecond delay is assembled by 16-28 bits, and the rest bits are reserved bits, and the structure is shown in figure 4. And after the DSP calculates the initialization data, the DSP sends a channel state word to the FPGA.

And step three, generating a deception signal according to the related information obtained in the step one and the step two. Specifically, the third step includes the following substeps:

step 1) the FPGA accumulates frequency control words according to initial information transmitted by the DSP through EMIF and based on an initial phase by using an FPGA working clock clk being 62MHz, obtains the phase of a deception signal, synthesizes a pseudo code and a carrier of a frequency band signal corresponding to a satellite number, generates a pseudo code signal, performs analog-to-digital addition on a navigation message, modulates the pseudo code signal and the navigation message onto the carrier, synthesizes a plurality of multi-channel signals of the same frequency band, and finally generates a multi-frequency-point digital intermediate frequency signal of the GNSS system.

And step 2) generating the deception digital intermediate frequency signal is specifically completed by a pseudo code NCO module, a carrier NCO module, a navigation message module and a signal modulation module in the FPGA module. The decoy system adopts a numerical control oscillator technology to generate a pseudo code, and the pseudo code has a chip concept, only has two states of '0' and '1', and has no amplitude value. And accumulating the frequency control words on a working clock of the FPGA module, adding 1 to a chip counter when an accumulated value overflows, inputting the value of the chip counter into a C/A code table, outputting '0' or '1' corresponding to a chip, wherein the overflow frequency of a phase accumulator is the pseudo code frequency. The pseudo code NCO module structure block diagram is shown in FIG. 5.

And 3) generating a carrier signal by a carrier NCO module by adopting a DDS technology. Under the control of an FPGA working clock, firstly, an initial phase is written into a phase register by the FPGA, then frequency control words are accumulated on a phase accumulator by each working clock, the obtained phase is input into a sine query table, and a quantized amplitude value is output according to the input phase value as one phase of a sine signal corresponds to one amplitude value. Each time the accumulator overflows, a discrete sine signal is generated; the frequency is the accumulated times multiplied by the FPGA working clock period. The amplitude value is subjected to DA digital-to-analog conversion to obtain an analog sinusoidal signal, and the analog sinusoidal signal is filtered by a Low Pass Filter (LPF) to obtain a carrier signal required by us, and the carrier generation signal structure is shown in fig. 6.

And 4) the FPGA processes the navigation message by adopting ping-pong operation, the GPS and GLONASS navigation messages cannot be completely stored in the FPGA at one time due to large data volume, and the DSP encodes the GPS navigation message of two subframes or six strings of GLONASS navigation messages in advance before the FPGA formally generates signals and transmits the data to the FPGA through an EMIF bus. Since the GPS navigation message subframe lasts 6 seconds, the GLONASS navigation message string lasts 2 seconds. In order to enable the two navigation systems to share one interrupt response, the FPGA prestores two subframes of GPS navigation messages and 6 strings of GLONASS navigation messages. The FPGA clock module sends a pulse every 20ms to the DSP triggering interrupt 5 for counting navigation messages. The DSP interrupts 5 service program to count the navigation message counter NavCount, NavCount self-adding 1 means that the message propagation time is increased by 20ms, and the GEO satellite and the MEO satellite respectively count. When NavCount adds up to the message length of a subframe, NavCount sets 0, and the DSP sends the navigation message of the next subframe to the FPGA.

And 5) finally, the FPGA completes the modulation synthesis of the signal, the BDS navigation message and the NH code are modulated firstly, then the BDS navigation message and the NH code are subjected to spread spectrum modulation, then the GPS/GLONASS navigation message, the C/A code and the Meander code are modulated, and finally the BDS navigation message, the C/A code and the Meander code are modulated with a carrier to generate a digital intermediate frequency signal. In addition, navigation message reading and channel state control are also completed in the channel signal modulation module.

And 6) converting the digital baseband I, Q signal into an analog I, Q signal through a DAC (digital-to-analog converter), filtering the analog I, Q signal through a low-pass filter, mixing the analog I, Q signal with two orthogonal local oscillation signals, and then superposing the signals to convert the signals into analog intermediate frequency modulation signals. The simulated intermediate frequency modulation signal passes through the intermediate frequency filter and then is mixed with the radio frequency local oscillator to become a radio frequency modulation signal, the radio frequency modulation signal passes through the radio frequency filter to generate radio frequency signals with different frequency points, and the radio frequency modulation signal passes through the power amplifier control module to compensate the power value of signal propagation attenuation, so that the power of a deception signal received by the target unmanned aerial vehicle is approximately equal to the power of a real satellite signal, and finally the deception signal is accessed into the transmitting antenna array to.

And step four, after the deception signal is finished and the real signal jointly enters a receiver tracking loop, stripping the real signal and implementing deception on the speed, direction and position of the unmanned aerial vehicle.

The fourth step comprises the following substeps:

step 1) when a spoofing signal reaches a receiver of a target unmanned aerial vehicle, because the satellite number of the spoofing signal is different from the current visible satellite number and the spoofing signal is synchronous with the current satellite signal on the sky, the generated synchronous spoofing signal can quickly enter a receiver tracking loop and the satellite on the sky coexists in the receiver of the target unmanned aerial vehicle, a GNSS receiver generally completes positioning according to at least four satellites, a group of satellites with the best GDOP can be selected to receive the position of the receiver in the satellite selection process, and therefore the spoofing signal corresponding to the satellite with the high elevation angle can be selected to be generated. After the deception signal participates in positioning, the power of the deception signal is increased, the deception signal gradually peels off the real signal from the tracking loop by virtue of the power advantage, and finally the deception signal controls the tracking loop of the receiver.

Step 2) utilizing the characteristic that the unmanned aerial vehicle needs GNSS observation value to correct inertial navigation, the navigation system of the unmanned aerial vehicle controls as shown in figure 5, and the initial speed (v) of the simulated target in the decoy system is set_x＝1,v_y＝0,v_z0), the coordinate position received by the receiver on the unmanned aerial vehicle takes the current coordinate position F (x, y, z) as a starting point and moves in the east direction at the speed of 1m/s, however, the unmanned aerial vehicle can correct the state of the unmanned aerial vehicle according to the change of the received coordinate, the unmanned aerial vehicle control holder can guide the unmanned aerial vehicle to fly in the west direction (the opposite direction) at the speed of 1m/s to correct the state of the unmanned aerial vehicle, and the unmanned aerial vehicle precisely hovers by using the principle, so that the deception on the speed and the position of the unmanned aerial vehicle is realized, therefore, the deception system can simulate a dynamic scene, the deception unmanned aerial vehicle can be tricked to fly in the corresponding direction, and the deception unmanned aerial vehicle is guided to be.

The parameter information provided by the star searching system of the invention is used for calculating the coordinate position P (x) of the current visible starⁿ,yⁿ,zⁿ) And further calculating the geometric distance r between the current visible star and the deceptive machineⁿFurther, the position F (x, y, z) of the target unmanned aerial vehicle is calculated, so that the distance r from the satellite signal to the target unmanned aerial vehicle is calculated_nFurther, the GNSS time of the signal reaching the target drone is obtained as follows:

further calculating the signal emission time of the decoy system according to the distance L from the decoy system to the target unmanned aerial vehicle

And deceptive signal doppler shift f_u'＝f_u-f_EFAnd further calculating the initial carrier phase and code phase of each visible satellite, an initial carrier frequency control word and a pseudo code frequency control word. Combining the deception satellite number, the integral digital number and the integral millisecond delay together, sending the deception satellite number, the integral digital number and the integral millisecond delay to the FPGA module, generating deception signals by the FPGA module according to the received related information, compensating the power of the deception signals due to propagation attenuation, and enabling the signal power P reaching the target unmanned aerial vehicle_B≈P_AAnd the deception signal and the real signal on the sky can coexist in the receiver after reaching the receiver for about 3-4 s, the power of the deception signal is increased, the deception signal strips the real signal by virtue of the power advantage, so that the control on a tracking loop of the target receiver is achieved, and the deception on the direction, the speed and the position of the unmanned aerial vehicle is finally realized according to the control principle of the unmanned aerial vehicle navigation system.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.

Claims (2)

1. A coexisting unmanned aerial vehicle navigation trapping method is characterized by comprising the following steps:

receiving and analyzing a real satellite signal;

generating a deception signal according to the analysis result of the real satellite signal, and simultaneously capturing and tracking the deception signal and the real satellite signal by a receiver of the target unmanned aerial vehicle;

a deception signal generation control system increases deception signal power to strip real signals and controls a tracking loop of the target unmanned aerial vehicle;

the analyzing of the real satellite signal comprises the following substeps:

receiving a real satellite signal;

demodulating and resolving a real satellite signal to generate signal power, a code phase, ionosphere delay, troposphere delay, local coordinates of a decoy system, GNSS signal emission time, a visible satellite number, a visible satellite elevation angle and a visible satellite azimuth angle of the real satellite signal;

measuring the distance from the decoy system to the target unmanned aerial vehicle, and the elevation angle and the azimuth angle relative to the ground plane;

the method for generating the deception signal comprises the following substeps:

s1, obtaining the current visible star coordinate, the geometric distance between the current visible star and the decoy system, the position of the target unmanned aerial vehicle, the distance between the satellite signal and the target unmanned aerial vehicle and the GNSS time of the satellite signal reaching the target unmanned aerial vehicle according to the demodulated and resolved parameter information, the GNNS satellite ephemeris data, the measured distance between the decoy system and the target unmanned aerial vehicle and the elevation angle and the azimuth angle relative to the ground plane; calculating an initial carrier phase and a code phase of each visible satellite and an initial carrier frequency control word and a pseudo code frequency control word according to the simulation initial time, the unmanned aerial vehicle coordinates and the GNSS satellite ephemeris, meanwhile, calculating an invisible satellite according to the obtained current ephemeris, taking the invisible satellite number as the satellite number of a deception signal, and combining the deception satellite number, the integral number of chips and the integral millisecond delay together to be called as a channel state;

s2, calculating the emission time of the deception signal and the Doppler frequency shift of the deception signal according to the distance from the deception system to the target unmanned aerial vehicle, and further calculating the initial carrier phase and code phase of each visible satellite, the initial carrier frequency control word and the pseudo code frequency control word;

s3 generates a spoof signal based on the related information obtained in steps S1 and S2.

2. The method of claim 1, wherein the power of the spoofed signal is approximately equal to the power of the real satellite signal.

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