CN115524724B - General aviation credible space-time service method, system and medium - Google Patents
General aviation credible space-time service method, system and medium Download PDFInfo
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Abstract
The invention discloses a general aviation credible space-time service method, a system and a medium, wherein the method comprises the steps of monitoring satellite navigation signals in real time and identifying possible navigation signal abnormity; if the navigation signal is normal, the local clock is acclimated to be synchronous to the satellite navigation time, and differential enhancement information is generated and broadcasted; if the navigation signal is abnormal: for the navigation time service equipment, blocking abnormal navigation signals and generating satellite navigation signals based on a local clock; and broadcasting satellite-like navigation signals for the navigation positioning equipment so as to continuously provide navigation services. The navigation signal abnormity identification is used for judging the satellite navigation signal abnormity through a plurality of signal characteristics based on a support vector machine, so that more accurate signal abnormity judgment is provided. When the navigation signal is abnormal, the normal use of the equipment is ensured; meanwhile, the system can emit enhanced compatible satellite navigation signals to provide navigation service for the navigation aircraft.
Description
Technical Field
The invention relates to the field of satellite navigation, in particular to a general aviation credible space-time service method, a system and a medium.
Background
General aviation refers to aviation activities except military affairs, police affairs, customs seizing flight and public air transportation flight, and can be mainly divided into three types of business, such as passenger carrying type, human carrying type and other types. Global, all-weather, high-precision position or time information can be provided according to satellite navigation. While satellite navigation is in widespread use, huge potential safety hazards are buried. This makes the satellite signal highly susceptible to interference and spoofing due to the weak power of the satellite signal. Satellite navigation spoofing refers to the acquisition of spoofed signals by broadcasting false satellite signals, thereby obtaining erroneous position or time information.
In the prior art, for a spoofed signal of satellite navigation, a single index is usually adopted to identify whether a received signal is abnormal, however, in many complex spoofed signals, the identification of the spoofed signal cannot be realized by the single identification index, and therefore, the identification accuracy rate by adopting the method is low.
Disclosure of Invention
Technical problem to be solved
In order to solve the technical problems, the invention provides a method, a system and a medium for a universal aviation trusted space-time service. The method comprises the steps of establishing a navigation signal abnormity detection model through a support vector machine, and identifying navigation signal abnormity based on the model and the characteristics of received signals.
(II) technical scheme
In order to solve the technical problems and achieve the purpose of the invention, the invention is realized by the following technical scheme:
a general aviation credible space-time service method comprises the following steps:
s1: acquiring satellite navigation signals, and monitoring the satellite navigation signals in real time;
specifically, a receiver on an aircraft receives satellite navigation signals and performs signal processing;
s2: establishing a model for receiving interference navigation signals;
the signal captured and tracked by the navigation positioning receiving equipment consists of a real navigation signal, a deception jamming navigation signal and noise in a visual range;
s3: acquiring characteristic parameters of satellite navigation signals, including signal intensity, signal-to-noise ratio, signal absolute power, pseudo range, carrier phase and carrier Doppler frequency shift;
s4: establishing a navigation signal abnormity detection model;
according to the signal feature extraction result of the step S3, judging the navigation signal abnormity based on a support vector machine regression model, wherein the judgment comprises the steps of constructing a support vector machine regression model for supervised learning by utilizing regression analysis to perform mapping point segmentation on the navigation signal acquisition data space, and determining whether the navigation signal is abnormal or not;
s5: selecting a response countermeasure according to the navigation signal state detection result, if the navigation signal is normal, turning to S6, otherwise, turning to S7;
s6: the local clock is acclimated, synchronized to the satellite navigation time, and differential enhancement information is generated and broadcasted;
s7: for the navigation time service equipment, blocking an abnormal navigation signal, generating a satellite navigation signal based on a local clock, and providing signal input for the navigation time service equipment; and broadcasting satellite-like navigation signals for the navigation positioning equipment so as to continuously provide navigation services.
Further, the navigation signal abnormality is a navigation signal integrity abnormality or an interference abnormality.
Further, the differential enhancement information is at least one of pseudo-range differential information and carrier phase differential information.
Further, the identifying the possible navigation signal abnormality includes establishing a model of the received interference navigation signal, where the model is as follows:
in the formula (I), the compound is shown in the specification,
for receiving information, the flags marked A and S represent the true navigation signal and the spoofed jamming navigation signal, respectively, i represents the signal sequence, and/or>
Represents the number of received real navigation signals, is greater than>
Indicating received deception jamming navigation signalsThe number of the particles; />
Represents a slowly varying process that develops due to an instability of the receiver clock>
For channel gain, <' > based on>
For a spread-spectrum code of the navigation signal, <' >>
For navigation data transmitted by the satellite, is->
Is the frequency of the doppler frequency of the received signal,
for additive white noise, is selected>
Delay the signal transmission.
Further, the navigation signal abnormality detection model of step S4 further includes a relaxation factor and a penalty factor.
Further, the objective function of the navigation signal abnormality detection model in step S4 is:
wherein, the first and the second end of the pipe are connected with each other,
is a relaxation factor->
Is a weight coefficient, is based on>
Is a penalty factor.
Further, the establishing of the navigation signal abnormity detection model also comprises the step of determining an error penalty factor C, an RBF nuclear parameter g1 and a Sigmoid nuclear parameter g2 in the support vector machine model based on an optimized whale algorithm.
Further, the optimized whale algorithm adopts a reverse learning mechanism, and the algorithm is as follows:
wherein, the first and the second end of the pipe are connected with each other,
is broadly reversed to relieve>
For an individual in the n-dimensional space, is>
Is the dynamic upper and lower boundaries in the t-th iteration, and rand is the expansion control quantity of the dynamic boundary, and is [0, 1]]The random number of (2).
The invention also provides a general aviation credible space-time service system, which comprises: the satellite signal acquisition module is used for acquiring satellite navigation signals and monitoring the satellite navigation signals in real time;
the model modeling module of the received interference navigation signal is used for establishing an interference signal model by a real navigation signal, a deception interference navigation signal and noise in a visual range according to the tracked signal captured by the navigation positioning receiving equipment;
the satellite navigation signal characteristic parameter acquiring module is used for acquiring signal characteristic parameters for distinguishing a real satellite navigation signal and an abnormal satellite navigation signal based on the difference of the characteristics of the signals, and specifically comprises the following steps: signal strength, signal-to-noise ratio, signal absolute power, pseudo range, carrier phase, carrier doppler shift;
the navigation signal abnormity detection module is used for judging the abnormity of the navigation signal based on a support vector machine regression model according to the characteristic extraction result of the satellite navigation signal characteristic parameter acquisition module, and comprises the steps of utilizing regression analysis to realize the regression detection of the navigation signal to abnormal data, constructing the support vector machine regression model for supervised learning to perform the space mapping point segmentation of the navigation signal acquisition data, and determining whether the navigation signal is abnormal or not;
the decision selection module is used for selecting response countermeasures according to the state detection result of the navigation signal abnormality detection module, if the signal is normal, the local clock is tamed to be synchronized to the satellite navigation time, differential enhancement information is generated and broadcasted, otherwise, the abnormal navigation signal is blocked aiming at the navigation time service equipment, the satellite navigation signal is generated based on the local clock, signal input is provided for the navigation time service equipment, and the normal operation of the navigation time service equipment is ensured; and broadcasting satellite-like navigation signals for the navigation positioning equipment so as to continuously provide navigation services.
In addition, to achieve the above object, the present invention also provides a computer readable storage medium having stored thereon data encryption program instructions of the general aviation trusted spatiotemporal service method, the data protection program instructions of the general aviation trusted spatiotemporal service being executable by one or more processors to implement the steps of the general aviation trusted spatiotemporal service method as described above.
(III) advantageous effects
Compared with the prior art, the invention has the beneficial effects that:
(1) According to the method and the device, the satellite navigation signal abnormity is judged through a plurality of signal characteristics, more accurate signal abnormity judgment is provided, and the situations of misjudgment and the like caused by single index judgment are avoided.
(2) The invention identifies abnormal signals based on a support vector machine, realizes signal integrity and interference identification at the same time, does not need large sample quantity, and finally determines a decision function only by a few support vectors, and the complexity of calculation depends on the number of the support vectors instead of the dimension of a sample space, thereby avoiding dimension disaster.
(3) The optimal parameter value of the support vector machine algorithm is obtained by combining the improved whale algorithm, and the convergence speed and precision of the algorithm are improved.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the application and together with the description serve to explain the application and not to limit the application. In the drawings:
FIG. 1 is a flow diagram illustrating a general aviation trusted space-time service method according to an embodiment of the present application;
fig. 2 is a schematic diagram of a navigation signal anomaly detection model according to an embodiment of the present application.
Detailed Description
The embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.
The embodiments of the present disclosure are described below with specific examples, and other advantages and effects of the present disclosure will be readily apparent to those skilled in the art from the disclosure in the specification. It is to be understood that the described embodiments are merely illustrative of some, and not restrictive, of the embodiments of the disclosure. The disclosure may be embodied or carried out in various other specific embodiments, and various modifications and changes may be made in the details within the description without departing from the spirit of the disclosure. It is to be noted that the features in the following embodiments and examples may be combined with each other without conflict. All other embodiments, which can be derived by a person skilled in the art from the embodiments disclosed herein without making any creative effort, shall fall within the protection scope of the present disclosure.
It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present disclosure, and the drawings only show the components related to the present disclosure rather than the number, shape and size of the components in actual implementation, and the type, amount and ratio of the components in actual implementation may be changed arbitrarily, and the layout of the components may be more complicated.
Referring to fig. 1, a general aviation trusted space-time service method includes the following steps:
s1: and acquiring satellite navigation signals, and monitoring the satellite navigation signals in real time.
Specifically, a receiver on an aircraft receives satellite navigation signals and performs signal processing; the signal processing includes filtering.
S2: establishing a model for receiving interference navigation signals
The navigation positioning receiving equipment captures the tracked signals, real navigation signals, deception jamming navigation signals and noise in a visual range, and a model of the received jamming navigation signals is as follows:
in the formula (I), the compound is shown in the specification,
for receiving information, flags marked A and S respectively representing a real navigation signal and a deception jamming navigation signal, i representing a signal sequence, and->
Represents the number of received real navigation signals, is greater than>
Indicating the number of received spoofed jamming navigation signals; />
Represents a slowly varying process that develops due to an instability of the receiver clock>
For channel gain, <' > based on>
For a spread-spectrum code of the navigation signal, <' >>
For navigation data transmitted by the satellite, is->
Is the frequency of the doppler frequency of the received signal,
for additive white noise, is selected>
The signal transmission is delayed.
S3: obtaining satellite navigation signal characteristic parameters
Acquiring signal characteristic parameters for distinguishing a real satellite navigation signal and an abnormal satellite navigation signal based on the difference of the characteristics of the signals, specifically comprising the following steps: signal strength, signal-to-noise ratio, signal absolute power, pseudorange, carrier phase, carrier doppler shift.
The abnormal satellite navigation signal includes at least one of a navigation signal integrity abnormality or an interference abnormality. The signal integrity includes signal anomalies caused by ringing, ground bounce, distortion, signal loss, and noise in the power supply; the interference anomalies also include spoofing interference.
(1) Signal strength
The satellite signal is subjected to a series of attenuations from transmitting to reaching the receiver antenna array, meanwhile, the movement of the satellite itself can also affect the strength of the satellite signal, and the slight changes of the satellite signal caused by the attenuations and the influences are smooth and have no abrupt change. However, for the spoofed interference navigation signal, the signal source of the spoofed interference navigation signal needs a larger signal power than the real navigation signal, so if the observation value is found to have a sudden change, the spoofed interference signal is considered to be possibly present.
(2) Signal to noise ratio
For real navigation signals, its structureIn the case that the noise bandwidth of the environment is mostly within the signal bandwidth and there is background noise outside the signal bandwidth, since the real navigation signal power is relatively stable, the signal-to-noise ratio will decrease when the background noise increases. For the interference navigation signal, the total power of the interference signal in the received signal is set as
：
The above-mentioned
For disturbing the navigation signal power>
To disturb the navigation signal quality.
Experiments show that the background noise increases with the increase of the total power of the interference signal, and the signal-to-noise ratio of the real navigation signal is continuously reduced because the power of the real navigation signal is almost unchanged.
So as to distinguish the real navigation signal from the interference navigation signal according to the difference of the signal-to-noise ratio, wherein the signal-to-noise ratio is expressed as follows:
the above-mentioned
、/>
Respectively signal power and noise power.
(3) Absolute power of signal
When the interference signal is detected by the SNR of the signal, if the SNR of the interference is not greater than the set monitoring threshold but exceeds the SNR of the true signal, the detection method is no longer effective. In addition, several interference parties add additional noise to the signal to make the noise floor of the correlator larger, so that the interference signal has a relatively stable SNR, and the method using the SNR as the detection standard cannot achieve the effect. Therefore, an absolute power detection method is also needed, and the result is not affected by the change of the background noise caused by the correlation process, so that the method has better robustness. The method is simple in implementation mode, effective for forwarding interference with relatively large signal power, and a special hardware device needs to be added to the radio frequency front end.
(4) Pseudorange
The pseudorange refers to the approximate distance from the ground receiver to the satellite in the satellite navigation positioning process, and is defined as:
wherein the content of the first and second substances,
is pseudorange, c is light speed, ->
Is the receiver clock at time t, < >>
Is the satellite signal transmission time.
The pseudorange is extremely important for receiver positioning solution as can be seen from the pseudorange positioning principle of a satellite navigation system, and the pseudorange measurement value must be estimated for successfully deceiving a receiver from the deception jamming analysis. Signals with abnormal integrity can also be identified through pseudo-range calculation.
(5) Carrier phase
The carrier phase refers to a measurement of the phase of the satellite signal received by the reference station at the same reception time with respect to the phase of the carrier signal generated by the receiver, and is defined as:
the above-mentioned
Is a carrier phase measurement value>
Duplicating the phase of the carrier signal for the receiver>
Is the phase of the satellite carrier signal received by the receiver.
The ranging code is actually the ranging code phase, and the interference source mainly influences the carrier frequency and code phase value determination of the capturing loop and the tracking loop of the carrier phase value, which has great influence on the observation of the carrier phase required by high-precision positioning.
(6) Carrier doppler shift
When relative motion exists between the emission source and the receiver, the emission source emission information frequency received by the receiver is different from the emission source emission information frequency, the phenomenon is called Doppler effect, the difference between the reception frequency and the emission frequency is Doppler frequency shift, and the carrier Doppler frequency shift is defined as:
wherein the content of the first and second substances,
representing a carrier doppler shift; />
Representing receiver velocity and satellite velocity, respectively; />
Represents a unit observation vector of the satellite at the receiver; />
Representing the carrier wavelength.
S4: establishing a navigation signal abnormity detection model
According to the signal feature extraction result, a support vector machine is combined to judge the navigation signal abnormity, and the navigation signal abnormity is further judged based on a support vector machine regression model, wherein the navigation signal abnormity judgment comprises that the navigation signal regression detection abnormal data is realized by using regression analysis, a supervised learning support vector machine regression model is constructed to carry out navigation signal acquisition data space mapping point segmentation, and whether the navigation signal is abnormal or not is determined;
let the plane equation of the classification line be:
in the formula: w weight coefficient, b offset value.
Further, a relaxation factor and a penalty factor C are introduced. The relaxation factor
Which satisfies:
the objective function is:
thereby converting the problem into a convex quadratic programming optimization problem.
Wherein the content of the first and second substances,
：
And (3) carrying out monitoring navigation signal classification by using a support vector machine model:
setting the ratio of the training set to the test set to be 6: 4, randomly selecting a normal navigation signal and an abnormal navigation signal as training samples to train, and taking the residual sample data as a test sample. And determining an error penalty factor C in the SVM, and setting RBF kernel parameters g1, polynomial and Sigmoid kernel parameters g2. The parameters C, g1 and g2 have important significance for optimizing the performance of the SVM.
Further, the method determines an error penalty factor C and RBF nuclear parameters g1 and Sigmoid nuclear parameters g2 based on an optimized whale algorithm.
The objective function is the accuracy of the support vector machine model.
The optimized whale algorithm comprises three stages of surrounding predation, soaking net attack and searching foraging.
Encompassing the predation process:
the process of surrounding the target and preying on the prey by each whale is to continuously update the position of the whale according to the position of the current prey, which can be expressed as follows:
where, t represents the current iteration,
is thatThe position vector of the current best solution, which is updated with the iterative process,
is the location vector of the search agent, is->
To update the position>
Is a distance vector->
And &>
Is a coefficient vector, whose calculation formula is as follows:
wherein the content of the first and second substances,
is a random vector, is->
For the iteration coefficients, the following are expressed:
based on the iteration coefficient, the acceleration of the algorithm in the early stage of the iteration is realized
Speed of change of (2)And the change speed of the algorithm is slowed down in the later iteration stage, so that the algorithm iteration speed is accelerated, and the optimization accuracy of the algorithm is enhanced.
The bubble network attack process:
updating the spiral: when a whale individual searches for a prey, the position of the prey is adjusted by adopting a spiral ascending strategy, and the model is as follows:
When the bubble net attack is adopted when | A | ≦ 1, the probability of each of 50% is taken when performing the shrink wrap-around and the spiral update, and the shrink wrap-around is performed when p <0.5, otherwise the spiral update is performed, and the mathematical model thereof is as follows:
searching for foraging:
in contrast to the contracting and wrapping phase, when | A | >1 randomly selects an individual in the population to seek the best, no longer following the reference whale, as follows:
wherein
For the position of the randomly selected individual vector, w is the inertial weight.
The inertia weight w adopts a self-adaptive inertia weight strategy:
the above-mentioned
Is the maximum number of iterations.
Optionally, a reverse learning mechanism is adopted, in a conventional whale algorithm, whale individuals are guided by current optimal individuals, position comparison is carried out on the whale individuals and the distances between the whale individuals and the whale individuals, the whale individuals are updated and gradually get close to the optimal individuals, and when the positions of the optimal individuals are not the global optimal solution, the individuals are guided to the local optimal solution, so that the algorithm is early. The invention introduces a reverse learning mechanism to enhance the exploration capability of individuals on the surrounding space, and the algorithm is as follows:
wherein the content of the first and second substances,
for generalized inverse solution>
For an individual in the n-dimensional space, is>
Is the dynamic upper and lower boundaries in the t-th iteration, and rand is the expansion control quantity of the dynamic boundary, and is [0, 1]]The random number of (2).
The search range of the dynamic change of the generalized backward learning boundary value is small, and the convergence speed can be accelerated.
The optimal values of the parameters C and g1, g2 are determined according to the optimized whale algorithm described above.
S5: and selecting a response strategy according to the navigation signal state detection result. If the navigation signal is normal, go to S6, otherwise go to S7
S6: and (4) domesticating the local clock, synchronizing the local clock to the satellite navigation time, generating differential enhancement information and broadcasting the differential enhancement information.
The differential enhancement information is at least one of pseudo-range differential information and carrier phase differential information, and the satellite navigation equipment receives the differential enhancement information so as to improve the positioning accuracy.
S7: for the navigation time service equipment, an abnormal navigation signal is blocked, a satellite navigation signal is generated based on a local clock, signal input is provided for the navigation time service equipment, and the normal operation of the navigation time service equipment is ensured; and aiming at the navigation positioning equipment, broadcasting a satellite-like navigation signal so as to continuously provide navigation service.
The satellite-like navigation signal may be at least one of a compatible signal that complies with a satellite signal specification, a fully newly designed radio ranging signal. The satellite-like navigation signal is received according to different signal types, and the software and/or hardware of the navigation positioning receiving equipment needs to be adapted and adjusted.
The embodiment of the invention also provides a general aviation credible space-time service system, which comprises the following steps:
the satellite signal acquisition module is used for acquiring satellite navigation signals and monitoring the satellite navigation signals in real time;
the model modeling module of the received interference navigation signal is used for establishing an interference signal model by a real navigation signal, a deception interference navigation signal and noise in a visual range according to the tracked signal captured by the navigation positioning receiving equipment; the received interference signal model is as follows:
in the formula，
For receiving information, the flags marked A and S represent the true navigation signal and the spoofed jamming navigation signal, respectively, i represents the signal sequence, and/or>
Represents the number of received real navigation signals, is greater than>
Indicating the number of received spoofed jamming navigation signals; />
Represents a slowly varying process that develops due to an instability of the receiver clock>
Is the channel gain->
For a spread-spectrum code of the navigation signal, <' >>
For navigation data transmitted by a satellite>
Is the frequency of the doppler frequency and is,
for additive white noise, is selected>
Delay the signal transmission.
The satellite navigation signal characteristic parameter acquiring module is used for acquiring signal characteristic parameters for distinguishing a real satellite navigation signal and an abnormal satellite navigation signal based on the difference of the characteristics of the signals, and specifically comprises the following steps: signal strength, signal-to-noise ratio, signal absolute power, pseudorange, carrier phase, carrier doppler shift.
The navigation signal abnormity detection module is used for judging the abnormity of the navigation signal based on a support vector machine regression model according to the characteristic extraction result of the satellite navigation signal characteristic parameter acquisition module, and comprises the steps of realizing the regression detection of the abnormal data of the navigation signal by using regression analysis, constructing a support vector machine regression model for supervised learning, carrying out the space mapping point segmentation of the navigation signal acquisition data and determining whether the navigation signal is abnormal or not;
the decision selection module is used for selecting response countermeasures according to the state detection result of the navigation signal abnormality detection module, if the signal is normal, the local clock is tamed to be synchronized to the satellite navigation time, differential enhancement information is generated and broadcasted, otherwise, the abnormal navigation signal is blocked aiming at the navigation time service equipment, the satellite navigation signal is generated based on the local clock, signal input is provided for the navigation time service equipment, and the normal operation of the navigation time service equipment is ensured; and broadcasting satellite-like navigation signals for the navigation positioning equipment so as to continuously provide navigation services.
Furthermore, an embodiment of the present invention also provides a computer-readable storage medium, on which data encryption program instructions of the general aviation trusted space-time service method are stored, the general aviation trusted space-time service program instructions being executable by one or more processors to implement the steps of the general aviation trusted space-time service method as described above.
The above-mentioned embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solution of the present invention made by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.
Claims (10)
1. A general aviation credible space-time service method is characterized by comprising the following steps:
s1: acquiring satellite navigation signals, and monitoring the satellite navigation signals in real time;
specifically, a receiver on an aircraft receives satellite navigation signals and performs signal processing;
s2: establishing a model for receiving interference navigation signals;
the signal captured and tracked by the navigation positioning receiving equipment consists of a real navigation signal, a deception jamming navigation signal and noise in a visual range;
s3: acquiring characteristic parameters of satellite navigation signals, including signal intensity, signal-to-noise ratio, signal absolute power, pseudo range, carrier phase and carrier Doppler frequency shift;
s4: establishing a navigation signal abnormity detection model;
according to the signal feature extraction result of the step S3, carrying out navigation signal abnormity judgment based on a support vector machine regression model, wherein the navigation signal abnormity judgment comprises the steps of utilizing regression analysis to realize navigation signal regression detection abnormal data, constructing a support vector machine regression model for supervised learning to carry out navigation signal acquisition data space mapping point segmentation, and determining whether the navigation signal is abnormal or not;
s5: selecting a response strategy according to the navigation signal state detection result, if the navigation signal is normal, turning to S6, otherwise, turning to S7;
s6: the local clock is acclimated to be synchronous to the satellite navigation time, and differential enhancement information is generated and broadcasted;
s7: for the navigation time service equipment, blocking abnormal navigation signals, generating satellite navigation signals based on a local clock, and providing signal input for the navigation time service equipment; and broadcasting satellite-like navigation signals for the navigation positioning equipment so as to continuously provide navigation services.
2. The universal aviation trusted space-time service method according to claim 1, wherein said navigation signal anomaly is a navigation signal integrity anomaly or an interference anomaly.
3. The universal aviation trusted space-time service method according to claim 1, wherein the differential enhancement information is at least one of pseudorange differential information and carrier-phase differential information.
4. The general aviation trusted space-time service method according to claim 1, wherein the step S2 further comprises establishing a model of the received interference navigation signal, the model being as follows:
where r (t) is the received information, marked with a and S to represent the true navigation signal and the spoofed interfering navigation signal, respectively, i represents the signal sequence, L 1 Indicating the number of received real navigation signals, L 2 Indicating a number of received spoofed jamming navigation signals; α (t) represents a slowly varying process due to receiver clock instability, A (t) is the channel gain, c (t) is the spreading code of the navigation signal, d (t) is the navigation data transmitted by the satellite, f (t) is the channel gain, d (t) is the navigation data transmitted by the satellite d Is the Doppler frequency, w (t) is additive white noise, and τ is the signal transmission delay.
5. The general aviation trusted space-time service method according to claim 4, wherein the navigation signal anomaly detection model of step S4 further comprises a relaxation factor and a penalty factor.
6. The general aviation trusted space-time service method according to claim 4, wherein the objective function of the navigation signal anomaly detection model of the step S4 is as follows:
wherein, mu i Is a relaxation factor, w is a weight coefficient, and C is a penalty factor.
7. The general aviation trusted space-time service method as claimed in claim 6, wherein the establishing of the navigation signal anomaly detection model further comprises determining an error penalty factor C and RBF kernel parameters g1 and Sigmoid kernel parameters g2 in a support vector machine model based on an optimized whale algorithm.
8. The general aviation trusted space-time service method as claimed in claim 7, wherein said optimized whale algorithm employs a reverse learning mechanism, and the algorithm is as follows:
wherein the content of the first and second substances,
is a generalized inverse solution, x id Is an individual of n-dimensional space, up (t) and do (t) are dynamic upper and lower boundaries in the t-th iteration, and rand is the expansion control quantity of the dynamic boundary, and is [0, 1]]The random number of (2).
9. A system based on the general aviation trusted space-time service method according to any one of claims 1 to 8, comprising:
the satellite signal acquisition module is used for acquiring satellite navigation signals and monitoring the satellite navigation signals in real time;
the interference signal model modeling module is used for building an interference signal model by using a real navigation signal, a deception interference navigation signal and noise in a visual range according to the tracked signal captured by the navigation positioning receiving equipment;
the satellite navigation signal characteristic parameter acquiring module is used for acquiring signal characteristic parameters for distinguishing a real satellite navigation signal and an abnormal satellite navigation signal based on the difference of the characteristics of the signals, and specifically comprises the following steps: signal strength, signal-to-noise ratio, signal absolute power, pseudo range, carrier phase, carrier doppler shift;
the navigation signal abnormity detection module is used for judging the abnormity of the navigation signal through a support vector machine regression model according to the characteristic extraction result of the satellite navigation signal characteristic parameter acquisition module, the navigation signal abnormity detection data is realized through regression analysis, the support vector machine regression model for supervised learning is further constructed for carrying out navigation signal acquisition data space mapping point segmentation, and whether the navigation signal is abnormal or not is determined;
the decision selection module is used for selecting response countermeasures according to the state detection result of the navigation signal abnormality detection module, if the signal is normal, the local clock is tamed to be synchronized to the satellite navigation time, differential enhancement information is generated and broadcasted, otherwise, the abnormal navigation signal is blocked aiming at the navigation time service equipment, the satellite navigation signal is generated based on the local clock, signal input is provided for the navigation time service equipment, and the normal operation of the navigation time service equipment is ensured; and aiming at the navigation positioning equipment, broadcasting a satellite-like navigation signal so as to continuously provide navigation service.
10. A computer readable storage medium having stored thereon data encryption program instructions of a general aviation trusted spatiotemporal service method, the data protection program instructions of the general aviation trusted spatiotemporal service being executable by one or more processors to implement the steps of the general aviation trusted spatiotemporal service method as claimed in any one of claims 1 to 8.
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