CN115902955A - Synchronous GNSS deception signal generation method and device - Google Patents
Synchronous GNSS deception signal generation method and device Download PDFInfo
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Abstract
The invention discloses a method and a device for generating a synchronous GNSS deception signal, which are used for capturing, tracking and demodulating a real GNSS signal based on a DSP module to obtain a signal parameter of the real GNSS signal; calculating the corresponding additional time delay of each satellite channel based on the spreading code period of the real GNSS signal; processing the signal parameters and the additional delay based on the FPGA module to obtain a baseband signal of the GNSS deception signal, acquiring an intermediate frequency carrier of the GNSS deception signal, and performing frequency mixing processing on the baseband signal and the intermediate frequency carrier to obtain a digital intermediate frequency signal; and performing signal processing on the digital intermediate frequency signal to obtain a regenerated GNSS deception signal. Compared with the prior art, the technical scheme of the invention calculates the additional time delay of each satellite channel through the GNSS signal spread spectrum code period so as to ensure that the GNSS deception signal and the real GNSS signal are accurately synchronized when invading the target receiver, thereby realizing hidden deception.
Description
Technical Field
The invention relates to the technical field of radio signals, in particular to a method and a device for generating a synchronous GNSS deception signal.
Background
The Global Navigation Satellite System (GNSS) has been widely applied in the fields of transportation, agriculture, forestry and fishery, hydrological monitoring, meteorological survey and forecast, communication time service, electric power scheduling, disaster relief and reduction, public safety and the like by virtue of accurate positioning, navigation and time service capabilities, serves national important infrastructure, and generates remarkable economic and social benefits. With the development of satellite navigation technology, the integrity, usability, positioning accuracy and the like of a satellite navigation system are greatly improved and perfected. Under the background that the dependence of national key infrastructure on GNSS is getting larger and larger, how to improve the safety of a satellite navigation system becomes an important issue in the navigation field. The man-made malicious interference on the user segment of the GNSS system can be mainly classified into two categories: suppressing interference and spoofing interference; the suppression interference is to suppress a jamming machine with high power to emit a single-frequency, frequency-sweeping, pseudo-code and other suppression signals so that a target receiver cannot normally work after being unlocked, the primary goal of the suppression interference is to reduce the precision of a GNSS terminal, the deception interference is to generate deception satellite signals which are highly similar to real signals or forward the real satellite signals, and the primary goal of the suppression interference is to obtain false information such as time, position, speed and the like in an unconscious state of a user receiver so as to achieve the deception purpose. In contrast, spoofing interference does not require too much power, is well concealed, and is therefore more hazardous.
In recent years, with the development of software radio technology, the flexibility of spoofing interference attack is higher and higher, and the implementation cost is lower and lower, so that a satellite navigation receiver is attacked by false satellite signals and radio interference signals, the satellite navigation receiver cannot receive satellite signals or generates wrong positioning and time service information, and the theoretical research is carried out to real application. In order to research the vulnerability of the receiver and provide a spoofing interference resistance performance evaluation and detection method for the GNSS navigation terminal, it is necessary to deeply research a spoofing interference technology, and the attention of the industry on the navigation security is improved.
In the existing GNSS spoofing technology, there are also great technical defects. For an autonomously generated deception jamming source (equivalent to a GNSS signal simulator), the operable space for the deception signal is insufficient, and the navigation information carried by the deception signal cannot be flexibly changed. For a forwarding type deception jamming source, the forwarding time delay of a deception signal cannot be a negative value and the inherent time delay of a link exists, so that the deception signal cannot be accurately synchronized with a real GNSS signal, and cannot be hidden to invade a target receiver.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the method and the device for generating the synchronous GNSS deception signal are provided, so that the GNSS deception signal and a real GNSS signal are accurately synchronized, and the concealment of the GNSS deception signal is improved.
In order to solve the above technical problem, the present invention provides a method for generating a GNSS spoofing signal in a synchronous manner, including:
acquiring, tracking and demodulating a real GNSS signal based on a DSP module to obtain signal parameters of the real GNSS signal;
acquiring a spread spectrum code period of the real GNSS signal, and calculating additional time delay corresponding to each satellite channel based on the spread spectrum code period;
processing the signal parameters and the additional delay based on an FPGA module to obtain a baseband signal of a GNSS deception signal, acquiring an intermediate frequency carrier of the GNSS deception signal, and performing frequency mixing processing on the baseband signal and the intermediate frequency carrier to obtain a digital intermediate frequency signal;
and performing signal processing on the digital intermediate frequency signal to obtain a regenerated GNSS deception signal.
In a possible implementation manner, after obtaining the intermediate frequency carrier of the GNSS spoofing signal, the method further includes:
acquiring intermediate frequency carrier frequency of the intermediate frequency carrier, and calculating additional Doppler shift of each satellite channel to one satellite channel;
and obtaining a first intermediate frequency carrier frequency of the intermediate frequency carrier based on the intermediate frequency carrier frequency and the additional Doppler shift.
In a possible implementation manner, acquiring, tracking, and demodulating a real GNSS signal based on a DSP module to obtain a signal parameter of the real GNSS signal specifically includes:
performing filtering processing on a real GNSS signal based on a band-pass filter to obtain a GNSS filtering signal, acquiring a sine local oscillator signal generated by a local oscillator, performing signal processing on the sine local oscillator signal and the GNSS filtering signal to obtain a first intermediate frequency signal, and performing analog-to-digital conversion on the first intermediate frequency signal to obtain a first digital intermediate frequency signal;
performing parallel code phase search on the first digital intermediate frequency signal based on a DSP module to obtain a code phase estimation value and a carrier Doppler estimation value of a real GNSS signal;
simultaneously acquiring a local carrier and a spread spectrum code, and circularly adjusting the local carrier and the spread spectrum code based on a carrier ring and a code ring to obtain an adjusted first local carrier and a first spread spectrum code;
and obtaining a navigation message bit sequence based on the first digital intermediate frequency signal, the first local carrier and the first spreading code.
In a possible implementation manner, calculating, based on the spreading code period, an additional delay corresponding to each satellite channel specifically includes:
calculating and obtaining the time delay corresponding to each satellite channel, and increasing the spread spectrum code period to the time delay to obtain the additional time delay corresponding to each satellite channel, wherein the additional time delay calculation formula is as follows:
in the formula,. DELTA.tau. i In order to add a time delay to the signal,
for a first pseudorange between an ith satellite and a receiving antenna of a spoofing interferer>
Is a second pseudo-range between the ith satellite and the target spoofing point, L is a first distance between a receiving antenna of the spoofing interference source and the target spoofing point, c is the speed of light, and tau D Inherent time delay, T, of the overall link for a true GNSS signal from a spoofed interferer receive antenna to a spoofed interferer transmit antenna code Is the spreading code period of the real GNSS signal.
In a possible implementation manner, the processing the signal parameter and the additional delay based on the FPGA module to obtain a baseband signal of the GNSS spoofing signal specifically includes:
generating an initial spreading code sequence based on an FPGA module, and performing delay processing on the initial spreading code sequence based on the additional delay to generate a local spreading code sequence;
and multiplying the local spread spectrum code by the signal parameter to obtain a baseband signal of the GNSS deception signal.
In a possible implementation manner, the signal processing is performed on the digital intermediate frequency signal to obtain a regenerated GNSS spoofing signal, and the method specifically includes:
performing digital-to-analog conversion on the digital intermediate-frequency signal based on a DA module to obtain an analog intermediate-frequency signal;
multiplying the analog intermediate-frequency signal by the intermediate-frequency carrier based on a mixer to obtain a first mixing signal;
performing low-frequency filtering processing on the first mixing signal based on a band-pass filter to obtain a first filtering signal;
and performing orthogonal up-conversion processing on the first filtering signal to obtain a regenerated GNSS deception signal.
In one possible implementation manner, an additional doppler shift for each satellite channel is calculated and obtained, wherein the additional doppler shift is calculated as follows:
in the formula (I), the compound is shown in the specification,
is the movement speed of the ith satellite>
For deceiving the movement speed of the disturbance source, <' >>
In order to trick the speed into play,
is the moving speed of the target receiver; />
Unit vector representing the location of the ith satellite relative to the spoof interference source>
Unit vector representing the location of the ith satellite relative to the spoof target point, based on the location of the ith satellite in the satellite or in the satellite system>
A unit vector representing the position of the interfering source relative to the target receiver, and λ is the carrier wavelength of the GNSS signal.
The invention also provides a synchronous GNSS deception signal generation device, which comprises: the device comprises a real GNSS signal parameter acquisition module, an additional delay calculation module, a baseband signal acquisition module and a GNSS deception signal generation module;
the real GNSS signal parameter acquisition module is used for capturing, tracking and demodulating a real GNSS signal based on the DSP module to obtain a signal parameter of the real GNSS signal;
the additional delay calculating module is used for acquiring a spreading code period of the real GNSS signal and calculating the additional delay corresponding to each satellite channel based on the spreading code period;
the baseband signal acquisition module is used for processing the signal parameters and the additional delay based on the FPGA module to obtain a baseband signal of a GNSS deception signal, acquiring an intermediate frequency carrier of the GNSS deception signal, and mixing the baseband signal and the intermediate frequency carrier to obtain a digital intermediate frequency signal;
and the GNSS deception signal generation module is used for carrying out signal processing on the digital intermediate frequency signal to obtain a regenerated GNSS deception signal.
The invention provides a synchronous GNSS deception signal generation device, which also comprises: an intermediate frequency carrier frequency calculation module;
the intermediate frequency carrier frequency calculation module is used for acquiring the intermediate frequency carrier frequency of the intermediate frequency carrier and calculating the additional Doppler shift of each satellite channel to one satellite channel; and obtaining a first intermediate frequency carrier frequency of the intermediate frequency carrier based on the intermediate frequency carrier frequency and the additional Doppler shift.
In a possible implementation manner, the real GNSS signal parameter obtaining module is configured to capture, track and demodulate a real GNSS signal based on a DSP module, and obtain a signal parameter of the real GNSS signal, specifically includes:
performing filtering processing on a real GNSS signal based on a band-pass filter to obtain a GNSS filtering signal, acquiring a sine local oscillator signal generated by a local oscillator, performing signal processing on the sine local oscillator signal and the GNSS filtering signal to obtain a first intermediate frequency signal, and performing analog-to-digital conversion on the first intermediate frequency signal to obtain a first digital intermediate frequency signal;
performing parallel code phase search on the first digital intermediate frequency signal based on a DSP module to obtain a code phase estimation value and a carrier Doppler estimation value of a real GNSS signal;
simultaneously acquiring a local carrier and a spread spectrum code, and circularly adjusting the local carrier and the spread spectrum code based on a carrier ring and a code ring to obtain an adjusted first local carrier and a first spread spectrum code;
and obtaining a navigation message bit sequence based on the first digital intermediate frequency signal, the first local carrier and the first spreading code.
In a possible implementation manner, the additional delay calculating module is configured to calculate an additional delay corresponding to each satellite channel based on the spreading code period, and specifically includes:
calculating and obtaining the time delay corresponding to each satellite channel, and increasing the spreading code period for the time delay to obtain the additional time delay corresponding to each satellite channel, wherein the additional time delay calculation formula is as follows:
in the formula,. DELTA.tau i In order to add a time delay to the signal,
for a first pseudorange between an ith satellite and a receiving antenna of a spoofing interferer>
Is a second pseudo-range between the ith satellite and the target spoofing point, L is a first distance between a receiving antenna of the spoofing interference source and the target spoofing point, c is the speed of light, τ D Inherent time delay, T, of the overall link for a true GNSS signal from a spoofed interferer receive antenna to a spoofed interferer transmit antenna code Is the spreading code period of the real GNSS signal.
In a possible implementation manner, the baseband signal obtaining module is configured to process the signal parameter and the additional delay based on the FPGA module to obtain a baseband signal of the GNSS spoofing signal, and specifically includes:
generating an initial spread spectrum code sequence based on an FPGA module, and performing delay processing on the initial spread spectrum code sequence based on the additional delay to generate a local spread spectrum code sequence;
and multiplying the local spread spectrum code by the signal parameter to obtain a baseband signal of the GNSS deception signal.
In a possible implementation manner, the GNSS spoofing signal generating module is configured to perform signal processing on the digital intermediate frequency signal to obtain a regenerated GNSS spoofing signal, and specifically includes:
performing digital-to-analog conversion on the digital intermediate-frequency signal based on a DA module to obtain an analog intermediate-frequency signal;
multiplying the analog intermediate-frequency signal by the intermediate-frequency carrier based on a mixer to obtain a first mixing signal;
performing low-frequency filtering processing on the first mixing signal based on a band-pass filter to obtain a first filtering signal;
and performing orthogonal up-conversion processing on the first filtering signal to obtain a regenerated GNSS deception signal.
In a possible implementation manner, the intermediate frequency carrier frequency calculation module is configured to calculate and obtain an additional doppler shift for each satellite channel, where a calculation formula of the additional doppler shift is as follows:
in the formula (I), the compound is shown in the specification,
is the movement speed of the ith satellite>
For deceiving the movement speed of the disturbance source, <' >>
In order to trick the speed into play,
is the moving speed of the target receiver; />
Indicating that the ith satellite is relative to spoofingUnit vector that spoofs an interfering source location>
Unit vector representing the location of the ith satellite relative to the spoof target point, based on the location of the ith satellite in the satellite or in the satellite system>
A unit vector representing the position of the interfering source relative to the target receiver, and λ is the carrier wavelength of the GNSS signal.
The invention also provides a terminal device comprising a processor, a memory and a computer program stored in the memory and configured to be executed by the processor, wherein the processor implements the method for generating a synchronized GNSS spoofing signal as defined in any of the above when executing the computer program.
The invention also provides a computer-readable storage medium, which includes a stored computer program, wherein when the computer program runs, a device in which the computer-readable storage medium is located is controlled to execute the method for generating a GNSS spoofing signal in synchronous mode according to any item in the above description.
Compared with the prior art, the method and the device for generating the synchronous GNSS deception signal have the following beneficial effects that:
capturing, tracking and demodulating a real GNSS signal through a DSP module to obtain a signal parameter of the real GNSS signal; acquiring a spread spectrum code period of the real GNSS signal, and calculating additional time delay corresponding to each satellite channel based on the spread spectrum code period; processing the signal parameters and the additional delay based on an FPGA module to obtain a baseband signal of a GNSS deception signal, acquiring an intermediate frequency carrier of the GNSS deception signal, and performing frequency mixing processing on the baseband signal and the intermediate frequency carrier to obtain a digital intermediate frequency signal; and performing signal processing on the digital intermediate frequency signal to obtain a regenerated GNSS deception signal. Compared with the prior art, the technical scheme provided by the invention realizes reconstruction of a real GNSS signal by adopting the architecture of the FPGA module and the DSP module, regenerates a GNSS deception signal, ensures that the inherent time delay of a link is small enough, and calculates the additional time delay of each satellite channel based on the GNSS signal spreading code period so as to ensure that the spreading code phase of the deception signal and the real GNSS signal are accurately synchronized when invading a target receiver, thereby realizing the hidden deception.
Drawings
FIG. 1 is a flowchart illustrating a method for generating GNSS spoofing signals in a synchronous manner according to an embodiment of the present invention;
FIG. 2 is a schematic structural diagram illustrating an embodiment of a synchronous GNSS deception signal generation apparatus provided in the present invention;
fig. 3 is a schematic structural diagram of a synchronous GNSS spoofing signal generating apparatus according to still another embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without inventive step based on the embodiments of the present invention, are within the scope of protection of the present invention.
Example 1
Referring to fig. 1, fig. 1 is a schematic flowchart of an embodiment of a method for generating a synchronized GNSS spoofing signal according to the present invention, as shown in fig. 1, the method includes steps 101 to 104, specifically as follows:
step 101: and capturing, tracking and demodulating a real GNSS signal based on a DSP module to obtain signal parameters of the real GNSS signal.
In one embodiment, a real GNSS signal enters a band-pass filter through a receiving antenna, so that the band-pass filter performs filtering processing on the real GNSS signal; specifically, the band near the true GNSS signal carrier is filtered by a band-pass filter, and the band near the non-true GNSS signal carrier is filtered to obtain a GNSS filtering signal.
In one embodiment, a sinusoidal local oscillator signal generated by a local oscillator is obtained, and a GNSS filtering signal is multiplied by the sinusoidal local oscillator signal based on a mixer to obtain a mixing signal; and then, filtering the mixing signal based on a band-pass filter, filtering out a high-frequency signal component in the mixing signal to obtain a first intermediate frequency signal, and performing analog-to-digital conversion on the first intermediate frequency signal to obtain a first digital intermediate frequency signal.
In an embodiment, the first digital intermediate frequency signal is used as an input of a DSP module, and parallel code phase search is performed on the first digital intermediate frequency signal based on the DSP module, so as to complete capturing of a real GNSS signal, and obtain a code phase estimation value and a carrier doppler estimation value of the real GNSS signal.
In one embodiment, the GNSS signal acquisition process is to perform rough estimation of the code phase and carrier doppler of the GNSS signal to provide initial values for the tracking process, and tracking the GNSS signal is to perform accurate estimation of the code phase and carrier doppler.
In one embodiment, in order to complete accurate estimation of code phase and carrier doppler, a carrier loop and a code loop are required; specifically, a local carrier and a spreading code are obtained, the local carrier is circularly adjusted based on a carrier ring, and the spreading code is circularly adjusted based on a code ring, so that an adjusted first local carrier and an adjusted first spreading code are obtained.
In one embodiment, after the first digital intermediate frequency signal is multiplied by the first local carrier and the first spreading code in sequence, a navigation message bit sequence can be obtained through timing and sampling judgment, and the navigation message bit sequence is used as a parameter of the real GNSS signal.
In one embodiment, ephemeris data, i.e., satellite orbit parameters, may be obtained based on the navigation message bit sequence, thereby enabling the position of the ith satellite to be determined
Step 102: and acquiring a spread spectrum code period of the real GNSS signal, and calculating additional time delay corresponding to each satellite channel based on the spread spectrum code period.
In an embodiment, the spreading code period of the real GNSS signal is a known parameter, and takes a GPS L1CA frequency point as an example, the spreading code period is 1ms.
In one embodiment, before calculating the additional delay corresponding to the satellite channel, the relevant parameters also need to be obtained; specifically, a first pseudo range between an ith satellite and a receiving antenna of a deception jamming source is obtained, a second pseudo range between the ith satellite and a target deception point is obtained, a first distance between the receiving antenna of the deception jamming source and the target deception point is obtained, and an integral link inherent time delay of a real GNSS signal from the receiving antenna of the deception jamming source to the deception jamming transmitting antenna is obtained, wherein when the pseudo range between the ith satellite and the target is calculated, the used satellite position is the position of the ith satellite after influences of satellite clock error, ionosphere error, troposphere error, thermal noise error and the like are corrected.
In one embodiment, a first pseudorange between an i-th satellite and a receiving antenna of a spoofed interferer is computed; specifically, assume that the position of the receiving antenna of the spoofing interferer a is (x) a ,y a ,z a ) Based on the navigation message bit sequence, the position of the ith satellite is calculated as
And substituting the positions into a first pseudorange calculation formula to obtain a first pseudorange, wherein the first pseudorange calculation formula is as follows:
in one embodiment, for the calculation of the second pseudo-range between the ith satellite and the target spoofing point, specifically, the position of the target spoofing point b is assumed to be (x) b ,y b ,z b ) Calculating the position of the ith satellite based on the navigation message bit sequence
Replacing the two positions withAnd obtaining a second pseudorange in a second pseudorange calculation formula, wherein the second pseudorange calculation formula is as follows:
in one embodiment, for the calculation of the first distance between the receiving antenna of the spoofing interference source and the target spoofing point, it is specifically assumed that the position of the receiving antenna of the spoofing interference source a is (x) a ,y a ,z a ) Suppose the position of the target spoofing point b is (x) b ,y b ,z b ) Substituting the positions into a first distance calculation formula to obtain a first distance, wherein the first distance calculation formula is as follows:
in an embodiment, based on the first pseudo-range, the second pseudo-range, the first distance, the speed of light, and the inherent delay of the overall link from the spoofed interference source receiving antenna to the spoofed interference transmitting antenna, the delay corresponding to each satellite channel is obtained, and on the basis of the delay, the spreading period is added to the delay to obtain the additional delay corresponding to each satellite channel, where the additional delay calculation formula is as follows:
in the formula,. DELTA.tau. i In order to add a time delay to the signal,
for a first pseudorange between an ith satellite and a receive antenna of a spoofing interferer>
Is a second pseudorange between the ith satellite and the target spoofing point, and L is spoofing interferenceA first distance between the receiving antenna of the source and the target spoofing point, c being the speed of light, τ D Inherent time delay, T, of the overall link for a true GNSS signal from a spoofed interferer receive antenna to a spoofed interferer transmit antenna code Is the spreading code period of the true GNSS signal.
Step 103: and processing the signal parameters and the additional delay based on an FPGA module to obtain a baseband signal of the GNSS deception signal, acquiring an intermediate frequency carrier of the GNSS deception signal, and performing frequency mixing processing on the baseband signal and the intermediate frequency carrier to obtain a digital intermediate frequency signal.
In an embodiment, the FPGA module generates an initial spreading code sequence according to the sampling points, and performs delay processing on the initial spreading code sequence according to the additional delay corresponding to each satellite channel calculated in step 102 to generate a local spreading sequence.
In an embodiment, the local spreading sequence is multiplied by the navigation message bit sequence based on the navigation message bit sequence calculated in step 101, so as to obtain a baseband signal of the GNSS spoofing signal.
In one embodiment, the intermediate frequency carrier of each GNSS spoofing signal is generated by a numerically controlled oscillator NCO.
In an embodiment, the intermediate frequency carrier of each path of GNSS spoofing signal is obtained, the intermediate frequency carrier frequency of the intermediate frequency carrier is also obtained, and the additional doppler shift of each satellite channel pair is added to the intermediate frequency carrier frequency to obtain a first intermediate frequency carrier frequency, and the first intermediate frequency carrier frequency is used as the final intermediate frequency carrier frequency of the intermediate frequency carrier.
In one embodiment, the calculation formula of the additional doppler shift for each satellite channel to one is as follows:
in the formula (I), the compound is shown in the specification,
motion of the ith satelliteSpeed,. Or>
For deceiving the speed of movement of the disturbance source, in combination with a signal processing unit>
In order to trick the speed into play,
is the moving speed of the target receiver; />
Unit vector representing the location of the ith satellite relative to a spoofed interfering source location, based on the location of the location in the receiver, and the location in the receiver>
A unit vector representing the location of the ith satellite relative to the spoofed target point, device for selecting or keeping>
A unit vector representing the position of the interference source relative to the target receiver, λ being the carrier wavelength of the GNSS signal.
In an embodiment, the baseband signal and the intermediate frequency carrier are further subjected to frequency mixing processing to obtain a digital intermediate frequency signal.
Step 104: and performing signal processing on the digital intermediate frequency signal to obtain a regenerated GNSS deception signal.
In one embodiment, the digital intermediate frequency signal is subjected to signal processing, specifically, digital-to-analog conversion is performed on the digital intermediate frequency signal based on a DA module to obtain an analog intermediate frequency signal; multiplying the analog intermediate-frequency signal by the intermediate-frequency carrier based on a mixer to obtain a first mixing signal; performing low-frequency filtering processing on the first mixing signal based on a band-pass filter so as to filter low-frequency components in the first mixing signal to obtain a first filtering signal; and performing quadrature up-conversion processing on the first filtering signal to obtain a regenerated GNSS deception signal, and inputting the regenerated GNSS deception signal into a power amplifier so that the power amplifier controls the power of the regenerated GNSS deception signal.
In one embodiment, the generated regenerated GNSS spoofing signal is input into a transmitting antenna through a power amplifier, so that the transmitting antenna transmits the generated regenerated GNSS spoofing signal.
Example 2
Referring to fig. 2, fig. 2 is a schematic structural diagram of an embodiment of a synchronous GNSS spoofing signal generating apparatus provided in the present invention, as shown in fig. 2, the apparatus includes a real GNSS signal parameter obtaining module 201, an additional delay calculating module 202, a baseband signal obtaining module 203, and a GNSS spoofing signal generating module 204, which are as follows:
the real GNSS signal parameter acquiring module 201 is configured to capture, track and demodulate a real GNSS signal based on a DSP module, and obtain a signal parameter of the real GNSS signal.
The additional delay calculating module 202 is configured to acquire a spreading code period of the real GNSS signal, and calculate an additional delay corresponding to each satellite channel based on the spreading code period.
The baseband signal obtaining module 203 is configured to process the signal parameter and the additional delay based on the FPGA module to obtain a baseband signal of the GNSS spoofing signal, obtain an intermediate frequency carrier of the GNSS spoofing signal, and perform frequency mixing processing on the baseband signal and the intermediate frequency carrier to obtain a digital intermediate frequency signal.
The GNSS deception signal generating module 204 is configured to perform signal processing on the digital intermediate frequency signal to obtain a regenerated GNSS deception signal.
The embodiment of the invention provides a synchronous GNSS deception signal generation device, which further comprises: an intermediate frequency carrier frequency calculation block 205; fig. 3 is a schematic structural diagram of a synchronous GNSS deception signal generating apparatus according to another embodiment of the present invention.
In an embodiment, the intermediate frequency carrier frequency calculating module 205 is configured to obtain an intermediate frequency carrier frequency of the intermediate frequency carrier, and calculate an additional doppler shift for each satellite channel; and obtaining a first intermediate frequency carrier frequency of the intermediate frequency carrier based on the intermediate frequency carrier frequency and the additional Doppler shift.
In an embodiment, the real GNSS signal parameter obtaining module 201 is configured to perform capturing, tracking and demodulating on a real GNSS signal based on a DSP module to obtain a signal parameter of the real GNSS signal, and specifically includes: performing filtering processing on a real GNSS signal based on a band-pass filter to obtain a GNSS filtering signal, acquiring a sine local oscillator signal generated by a local oscillator, performing signal processing on the sine local oscillator signal and the GNSS filtering signal to obtain a first intermediate frequency signal, and performing analog-to-digital conversion on the first intermediate frequency signal to obtain a first digital intermediate frequency signal; performing parallel code phase search on the first digital intermediate frequency signal based on a DSP module to obtain a code phase estimation value and a carrier Doppler estimation value of a real GNSS signal; simultaneously acquiring a local carrier and a spread spectrum code, and circularly adjusting the local carrier and the spread spectrum code based on a carrier ring and a code ring to obtain an adjusted first local carrier and a first spread spectrum code; and obtaining a navigation message bit sequence based on the first digital intermediate frequency signal, the first local carrier and the first spreading code.
In an embodiment, the additional delay calculating module 202 is configured to calculate an additional delay corresponding to each satellite channel based on the spreading code period, and specifically includes: calculating and obtaining the time delay corresponding to each satellite channel, and increasing the spread spectrum code period to the time delay to obtain the additional time delay corresponding to each satellite channel, wherein the additional time delay calculation formula is as follows:
in the formula,. DELTA.tau i In order to add a time delay to the signal,
for a first pseudorange between an ith satellite and a receive antenna of a spoofing interferer>
Is a second pseudo-range between the ith satellite and the target spoofing point, L is a first distance between a receiving antenna of the spoofing interference source and the target spoofing point, c is the speed of light, τ D Inherent time delay, T, of the overall link for a true GNSS signal from a spoofed interferer receive antenna to a spoofed interferer transmit antenna code Is the spreading code period of the real GNSS signal.
In an embodiment, the baseband signal obtaining module 203 is configured to process the signal parameter and the additional delay based on an FPGA module to obtain a baseband signal of a GNSS spoofing signal, and specifically includes: generating an initial spreading code sequence based on an FPGA module, and performing delay processing on the initial spreading code sequence based on the additional delay to generate a local spreading code sequence; and multiplying the local spread spectrum code by the signal parameter to obtain a baseband signal of the GNSS deception signal.
In an embodiment, the GNSS spoofing signal generating module 204 is configured to perform signal processing on the digital intermediate frequency signal to obtain a regenerated GNSS spoofing signal, and specifically includes: performing digital-to-analog conversion on the digital intermediate frequency signal based on a DA module to obtain an analog intermediate frequency signal; multiplying the analog intermediate-frequency signal by the intermediate-frequency carrier based on a mixer to obtain a first mixing signal; carrying out low-frequency filtering processing on the first mixing signal based on a band-pass filter to obtain a first filtering signal; and performing orthogonal up-conversion processing on the first filtering signal to obtain a regenerated GNSS deception signal.
In an embodiment, the intermediate frequency carrier frequency calculating module 205 is configured to calculate and obtain an additional doppler shift for each satellite channel, where a calculation formula of the additional doppler shift is as follows:
in the formula (I), the compound is shown in the specification,
is the movement speed of the ith satellite>
For deceiving the movement speed of the disturbance source, <' >>
In order to trick the speed into play,
is the moving speed of the target receiver; />
Unit vector representing the location of the ith satellite relative to the spoof interference source>
Unit vector representing the location of the ith satellite relative to the spoof target point, based on the location of the ith satellite in the satellite or in the satellite system>
A unit vector representing the position of the interference source relative to the target receiver, λ being the carrier wavelength of the GNSS signal.
It can be clearly understood by those skilled in the art that, for convenience and simplicity of description, the specific working process of the apparatus described above may refer to the corresponding process in the foregoing method embodiment, and details are not described herein.
It should be noted that the above embodiment of the synchronized GNSS spoofing signal generating apparatus is merely illustrative, wherein the modules illustrated as separate components may or may not be physically separate, and the components displayed as modules may or may not be physical units, that is, may be located in one place, or may also be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment.
On the basis of the above-mentioned embodiment of the synchronized GNSS spoofing signal generating method, another embodiment of the present invention provides a synchronized GNSS spoofing signal generating terminal device, which includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, and when the processor executes the computer program, the synchronized GNSS spoofing signal generating method according to any one of the embodiments of the present invention is implemented.
Illustratively, the computer program may be partitioned in this embodiment into one or more modules that are stored in the memory and executed by the processor to implement the invention. The one or more modules may be a series of computer program instruction segments capable of performing specific functions, which are used for describing the execution process of the computer program in the synchronized GNSS spoofing signal generating terminal device.
The synchronous GNSS deception signal generation terminal device can be a desktop computer, a notebook computer, a palm computer, a cloud server and other computing devices. The synchronized GNSS spoofing signal generating terminal device may include, but is not limited to, a processor, a memory.
The Processor may be a Central Processing Unit (CPU), other general purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), an off-the-shelf Programmable Gate Array (FPGA) or other Programmable logic device, discrete Gate or transistor logic, discrete hardware components, etc. The general purpose processor may be a microprocessor or the processor may be any conventional processor, etc., and the processor is a control center of the synchronous GNSS spoofing signal generating terminal device, and various interfaces and lines are used to connect various parts of the entire synchronous GNSS spoofing signal generating terminal device.
The memory may be configured to store the computer program and/or module, and the processor may implement various functions of the synchronized GNSS spoofing signal generating terminal device by executing or executing the computer program and/or module stored in the memory and calling data stored in the memory. The memory may mainly include a storage program area and a storage data area, wherein the storage program area may store an operating system, an application program required for at least one function, and the like; the storage data area may store data created according to the use of the mobile phone, and the like. In addition, the memory may include high speed random access memory, and may also include non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) Card, a Flash memory Card (Flash Card), at least one magnetic disk storage device, a Flash memory device, or other volatile solid state storage device.
On the basis of the above embodiment of the method for generating a synchronized GNSS spoofed signal, another embodiment of the present invention provides a storage medium, where the storage medium includes a stored computer program, where when the computer program runs, a device on which the storage medium is located is controlled to execute the method for generating a synchronized GNSS spoofed signal according to any one of the embodiments of the present invention.
In this embodiment, the storage medium is a computer-readable storage medium, and the computer program includes computer program code, which may be in source code form, object code form, executable file or some intermediate form, and so on. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, usb disk, removable hard disk, magnetic disk, optical disk, computer Memory, read-Only Memory (ROM), random Access Memory (RAM), electrical carrier wave signals, telecommunications signals, software distribution medium, and the like. It should be noted that the computer readable medium may contain content that is subject to appropriate increase or decrease as required by legislation and patent practice in jurisdictions, for example, in some jurisdictions, computer readable media does not include electrical carrier signals and telecommunications signals as is required by legislation and patent practice.
In summary, the present invention provides a method and an apparatus for generating a GNSS spoofing signal in a synchronous manner, wherein a DSP module is used to capture, track and demodulate a real GNSS signal to obtain a signal parameter of the real GNSS signal; acquiring a spread spectrum code period of the real GNSS signal, and calculating additional time delay corresponding to each satellite channel based on the spread spectrum code period; processing the signal parameters and the additional delay based on an FPGA module to obtain a baseband signal of a GNSS deception signal, acquiring an intermediate frequency carrier of the GNSS deception signal, and performing frequency mixing processing on the baseband signal and the intermediate frequency carrier to obtain a digital intermediate frequency signal; and performing signal processing on the digital intermediate frequency signal to obtain a regenerated GNSS deception signal. Compared with the prior art, the technical scheme provided by the invention realizes reconstruction of a real GNSS signal by adopting the architecture of the FPGA module and the DSP module, regenerates a GNSS deception signal, ensures that the inherent time delay of a link is small enough, and calculates the additional time delay of each satellite channel based on the GNSS signal spreading code period so as to ensure that the spreading code phase of the deception signal and the real GNSS signal are accurately synchronized when invading a target receiver, thereby realizing hidden deception.
The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and substitutions can be made without departing from the technical principle of the present invention, and these modifications and substitutions should also be regarded as the protection scope of the present invention.
Claims (10)
1. A method for generating a synchronized GNSS spoofing signal, comprising:
acquiring, tracking and demodulating a real GNSS signal based on a DSP module to obtain signal parameters of the real GNSS signal;
acquiring a spread spectrum code period of the real GNSS signal, and calculating additional time delay corresponding to each satellite channel based on the spread spectrum code period;
processing the signal parameters and the additional delay based on an FPGA module to obtain a baseband signal of a GNSS deception signal, acquiring an intermediate frequency carrier of the GNSS deception signal, and performing frequency mixing processing on the baseband signal and the intermediate frequency carrier to obtain a digital intermediate frequency signal;
and performing signal processing on the digital intermediate frequency signal to obtain a regenerated GNSS deception signal.
2. A method as recited in claim 1, wherein obtaining an intermediate frequency carrier of the GNSS spoofed signal further comprises:
acquiring intermediate frequency carrier frequency of the intermediate frequency carrier, and calculating additional Doppler shift of each satellite channel to one satellite channel;
and obtaining a first intermediate frequency carrier frequency of the intermediate frequency carrier based on the intermediate frequency carrier frequency and the additional Doppler shift.
3. The method as claimed in claim 1, wherein the step of acquiring, tracking and demodulating the true GNSS signal based on the DSP module to obtain the signal parameter of the true GNSS signal comprises:
performing filtering processing on a real GNSS signal based on a band-pass filter to obtain a GNSS filtering signal, acquiring a sine local oscillator signal generated by a local oscillator, performing signal processing on the sine local oscillator signal and the GNSS filtering signal to obtain a first intermediate frequency signal, and performing analog-to-digital conversion on the first intermediate frequency signal to obtain a first digital intermediate frequency signal;
performing parallel code phase search on the first digital intermediate frequency signal based on a DSP module to obtain a code phase estimation value and a carrier Doppler estimation value of a real GNSS signal;
simultaneously acquiring a local carrier and a spread spectrum code, and circularly adjusting the local carrier and the spread spectrum code based on a carrier ring and a code ring to obtain an adjusted first local carrier and a first spread spectrum code;
and obtaining a navigation message bit sequence based on the first digital intermediate frequency signal, the first local carrier and the first spreading code.
4. The method for generating a synchronized GNSS spoofed signal of claim 1, wherein calculating the additional delay corresponding to each satellite channel based on the spreading code period specifically comprises:
calculating and obtaining the time delay corresponding to each satellite channel, and increasing the spread spectrum code period to the time delay to obtain the additional time delay corresponding to each satellite channel, wherein the additional time delay calculation formula is as follows:
in the formula,. DELTA.tau. i In order to add a time delay to the signal,
for a first pseudorange between an ith satellite and a receiving antenna of a spoofing interferer>
Is a second pseudo-range between the ith satellite and the target spoofing point, L is a first distance between a receiving antenna of the spoofing interference source and the target spoofing point, c is the speed of light, τ D Inherent time delay, T, of the overall link for a true GNSS signal from a spoofed interferer receive antenna to a spoofed interferer transmit antenna code Is the spreading code period of the true GNSS signal.
5. The method for generating a synchronized GNSS spoofing signal according to claim 1, wherein the processing of the signal parameter and the additional delay based on the FPGA module obtains a baseband signal of the GNSS spoofing signal, specifically comprising:
generating an initial spread spectrum code sequence based on an FPGA module, and performing delay processing on the initial spread spectrum code sequence based on the additional delay to generate a local spread spectrum code sequence;
and multiplying the local spread spectrum code by the signal parameter to obtain a baseband signal of the GNSS deception signal.
6. The method for generating a synchronized GNSS spoofed signal of claim 1, wherein the step of performing signal processing on the digital intermediate frequency signal to obtain a regenerated GNSS spoofed signal comprises:
performing digital-to-analog conversion on the digital intermediate frequency signal based on a DA module to obtain an analog intermediate frequency signal;
multiplying the analog intermediate-frequency signal by the intermediate-frequency carrier based on a mixer to obtain a first mixing signal;
carrying out low-frequency filtering processing on the first mixing signal based on a band-pass filter to obtain a first filtering signal;
and performing orthogonal up-conversion processing on the first filtering signal to obtain a regenerated GNSS deception signal.
7. A method for generating GNSS spoofing signals in synchronous mode according to claim 2, wherein an additional doppler bias is calculated and obtained for each satellite channel, wherein said additional doppler bias is calculated as follows:
in the formula (I), the compound is shown in the specification,
is the movement speed of the ith satellite>
For deceiving the speed of movement of the disturbance source, in combination with a signal processing unit>
For deceiving the speed, <' > or>
Is the moving speed of the target receiver; />
To show the ith satelliteUnit vector which a star represents relative to the location of a deception jamming source>
Unit vector representing the location of the ith satellite relative to the spoof target point, based on the location of the ith satellite in the satellite or in the satellite system>
A unit vector representing the position of the interference source relative to the target receiver, λ being the carrier wavelength of the GNSS signal.
8. A synchronized GNSS spoofing signal generating apparatus, comprising: the device comprises a real GNSS signal parameter acquisition module, an additional delay calculation module, a baseband signal acquisition module and a GNSS deception signal generation module;
the real GNSS signal parameter acquisition module is used for capturing, tracking and demodulating a real GNSS signal based on the DSP module to obtain signal parameters of the real GNSS signal;
the additional delay calculation module is used for acquiring a spread spectrum code period of the real GNSS signal and calculating the additional delay corresponding to each satellite channel based on the spread spectrum code period;
the baseband signal acquisition module is used for processing the signal parameters and the additional delay based on the FPGA module to obtain a baseband signal of a GNSS deception signal, acquiring an intermediate frequency carrier of the GNSS deception signal, and mixing the baseband signal and the intermediate frequency carrier to obtain a digital intermediate frequency signal;
and the GNSS deception signal generation module is used for carrying out signal processing on the digital intermediate frequency signal to obtain a regenerated GNSS deception signal.
9. A terminal device comprising a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, the processor when executing the computer program implementing a synchronized GNSS spoofing signal generating method of any of claims 1-7.
10. A computer-readable storage medium, comprising a stored computer program, wherein when the computer program is run, the computer-readable storage medium is controlled at a device to perform the method of generating a synchronized GNSS spoofing signal of any one of claims 1-7.
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| CN116359949B (en) * | 2023-05-31 | 2023-09-15 | 湖南跨线桥航天科技有限公司 | GPS M code signal regeneration method based on spread spectrum code blind estimation |
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