System for positioning aerial sonic boom target by using earthquake monitoring station network

Abstract

The invention belongs to the technical field of aerial sonic boom target positioning, and discloses a system for positioning an aerial sonic boom target by using an earthquake monitoring station net, the system comprises stations for collecting signals, the stations are arranged in a circle with the theoretical drop point of the aerial sonic boom target as the circle center and the radius of 10km, and the stations are used for collecting the signals. A monitoring station time service uses an NTP server to carry out unified time service on stations, the stations transmit signals to a monitoring processing center in real time, the monitoring processing center transmits the collected real-time signals to a flow positioning system to carry out spectrum analysis, positioning is carried out by using a simulated annealing method after analysis, and thus the falling point position of an aerial sonic boom target is judged. According to the system, the falling point position of the air sonic boom target can be accurately judged, and the deviation precision is smaller than 50 m; therefore, the air sonic boom target drop point can be quickly judged, a decision basis is provided for quickly studying and judging drop area safety, and the method is suitable for air sonic boom target drop point judgment.

Description

Technical Field

[0001] The invention relates to the technical field of airborne sonic boom target positioning, and in particular to a system for positioning airborne sonic boom targets by utilizing a seismic monitoring network. Background Art

[0002] With the rapid development of national defense, a large number of experimental tests are also being carried out. Positioning the landing point of sonic boom targets in the air is an important task. Rapid positioning of the landing point of sonic boom targets in the air can enable timely processing of the target and take corresponding measures in advance within the range of its landing point to avoid harm.

[0003] The present invention proposes a system for locating an aerial sonic boom target using a seismic monitoring network. The system can quickly locate the landing point of the aerial sonic boom target, and the difference between the judged landing point and the actual landing point is less than 50m, so that the target can be quickly located. Summary of the invention

[0004] The present invention is intended to provide a system for locating aerial sonic boom targets using a seismic monitoring network, thereby being able to quickly determine the landing point of the aerial sonic boom target and provide a decision-making basis for quickly assessing the safety of the landing area.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] A system for locating an aerial sonic boom target using a seismic monitoring network, the system comprising a plurality of stations arranged within a circle with a radius of 10 km with a theoretical landing point of the aerial sonic boom target as the center, the plurality of stations being networked and monitored by a mobile real-time monitoring center, the plurality of stations being uniformly timed by a network NTP server, the signals detected by the stations being sent by the mobile real-time monitoring center to a mobile positioning system for wave spectrum analysis and output by a terminal, in the process of locating the aerial sonic boom target, the system can collect two groups of obvious signals at the stations, wherein the first group is an aerial sonic boom signal and the second group is a sound wave signal at the landing point of the target debris, the second group of sound wave signals is selected for positioning, and finally the landing point of the target debris is obtained by using a simulated annealing positioning method, finally the landing point of the target debris is obtained by using a simulated annealing positioning method;

[0007] The specific process of positioning using simulated annealing method includes the following steps:

[0008] S1, set C = C0, where C and C0 are the current parameters of the earthquake event and the initial earthquake catalog parameters respectively; set S0 to be the initial search range and time window length of the earthquake event location and earthquake time;

[0009] S2. For each iteration i, i = 1.. N max , where i is the iteration index and N maxis the maximum number of iterations during which the program selects a new set of model parameters C new , C new is a random neighboring value of C, the current search range S will be reduced to S = S0*(f) i Where f is the annealing rate, its value is between 0 and 1. If R(C new )<R min Or exp(R min -R(C new ) / S)>random(0,1), C new is accepted as C, and the program enters the next iteration, where R min is the minimum residual value of the previous iteration, R(C new ) is the current model parameter C new The residual value, random(0,1) randomly gives a decimal between 0 and 1, exp(R min -R(C new ) / S)>random(0,1) is a probabilistic acceptance condition to prevent the search from falling into a local minimum;

[0010] S3, model parameter space C and R of the last round of iteration min The minimum residual is the optimal parameter model and corresponding residual finally solved.

[0011] Further, the selected stations in this system are 13 and the stations are integrated short period seismometers.

[0012] Furthermore, all stations transmit data with the mobile real-time monitoring center via wireless 4G transmission.

[0013] Principle of the technical solution: The collision of a sonic boom target in the air with the ground can be roughly regarded as an explosive non-natural earthquake event, which has the following characteristics: (1) the initial motion of the P wave is upward; (2) the initial motion amplitude of the P wave is large; (3) the wave train lasts for a short time and decays quickly; (4) the time of the event can be known in advance. Therefore, the system of the present invention uses seismological methods to locate the sonic boom target in the air.

[0014] The simulated annealing positioning method in the present invention is a probabilistic algorithm for effectively solving global optimization problems. The method combines the advantages of a grid search method and a simulated annealing method. Because the aerial sonic boom target falls on the ground, the focal depth can be approximately 0 km. By observing waveform analysis, the waveform record and velocity model used for positioning are adjusted. The grid search method is used to perform a 0.1°×0.1° grid search on the theoretical landing area to find the smallest grid point, and then a finer grid is divided around the grid point. The spatial range of the search and the speed of reducing the time window length are controlled by the annealing rate. The reception probability controls whether a group of parameters are received and enter the next iteration, so as to obtain a positioning result with the best residual and reception probability.

[0015] The beneficial effect of the technical solution is that the system of the present invention can more accurately determine the landing point of the aerial sonic boom target by setting up a mobile monitoring network and processing and analyzing the signals collected by the mobile monitoring network. The positioning deviation between the landing point of the aerial sonic boom target analyzed by the system and the actual landing point of the aerial sonic boom target is less than 50m. The system of the present invention can more accurately locate the landing point of the aerial sonic boom target and provide a decision-making basis for quickly judging the safety of the landing area. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a flow chart of the system of the present invention;

[0017] Figure 2 is a spatial distribution diagram of stations of the system of the present invention;

[0018] Figure 3 The theoretical landing point map and station distribution map of the first observation preset in the embodiment of the present invention;

[0019] Figure 4 The theoretical landing point diagram and station distribution diagram of the second observation preset in the embodiment of the present invention;

[0020] Figure 5 The theoretical landing point diagram and station distribution diagram of the third observation preset in the embodiment of the present invention;

[0021] Figure 6 The theoretical landing point diagram and station distribution diagram of the fourth observation preset in the embodiment of the present invention;

[0022] Figure 7 The theoretical landing point diagram and station distribution diagram of the first observation actually performed in the embodiment of the present invention;

[0023] Figure 8 The theoretical landing point diagram and station distribution diagram of the actual second observation in the embodiment of the present invention;

[0024] Fig. 9 The theoretical landing point diagram and station distribution diagram of the third observation actually performed in the embodiment of the present invention;

[0025] Fig.10 The theoretical landing point diagram and station distribution diagram of the fourth observation actually performed in the embodiment of the present invention;

[0026] Fig.11 These are two relatively obvious groups of waveform diagrams observed by a station in an observation mission in an embodiment of the present invention; the left side is the first group, and the right side is the second group;

[0027] Fig.12 Schematic diagram of the propagation of air shock waves generated by a flying earthquake source. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments:

[0029] 1. Observation Mission Introduction

[0030] Based on the relevant information on the landing area of ​​the aerial sonic boom target, seismic monitoring technology is used to locate and recover the aerial sonic boom target near the theoretical landing point.

[0031] 2. Mobile Stand Preset Scheme

[0032] At the beginning, the mobile observation mission station installation plan adopted the plan of installing along the circumference and major and minor axes of the ellipse. That is, within the pre-calculated range of the sonic boom target in the return flight, the mobile station was installed on the circumference and major and minor axes of the ellipse with the theoretically calculated landing point as the origin and the target flight trajectory direction as the major axis. The preset plans for the first two observation missions are as follows: Figure 3 , Figure 4 shown.

[0033] According to the analysis results of these two single observation missions, it was found that the positioning deviation was too large, so the preset plans for the next two observation missions were adjusted. It was planned to set up 13 sets of integrated short-period seismometers within 10 km of the theoretical landing point. The preset plans for the next two observation missions were as follows: Figure 5 , Figure 6 shown.

[0034] 3. Actual Installation of Mobile Stands

[0035] During the installation of the mobile stations, the on-site working group adjusted the installation locations of some mobile stations based on the design plan and according to factors such as the actual observation site environment, 4G signals, and the angle of the station to the theoretical landing point.

[0036] In order to provide landing point information in a timely manner, a mobile real-time monitoring center was set up at the on-site command post in the landing area of ​​the aerial sonic boom target. The mobile seismic stations set up were networked with the surrounding fixed seismic stations to realize real-time synchronous monitoring and analysis by the on-site mobile station network and Guizhou Seismic Station.

[0037] In terms of time, GPS timing was used in the first observation mission, but due to factors such as the site environment and the timing module, there was a problem of inconsistent time. Therefore, a unified timing server (NTP) was used for timing in the next three observation missions to ensure unified timing.

[0038] like Figure 7-10 Shown is the actual installation of the mobile rig for the four observation missions.

[0039] 4. Positioning methods and principles

[0040] The positioning method tried to use the Hyposat positioning method, but when this method predicted the landing point of the aerial sonic boom target, the deviation between the predicted landing point and the actual landing point was 5km±. Therefore, the positioning analysis method adopted the improved simulated annealing seismic positioning method. When positioning, because the aerial sonic boom target fell to the ground, the focal depth was located at 0km during positioning, and the waveform record and velocity model used for positioning were adjusted through waveform analysis. Then, the grid search method was used to search the target with a grid of 0.1°×0.1° to find the grid point with the smallest residual, and then a finer grid was divided around the grid point. Using the simulated annealing method, after multiple cycles of iterative calculations, the positioning result with the best residual and reception probability was obtained, and the result accuracy was at the meter level.

[0041] By performing pop analysis on the signals collected by mobile monitoring of each aerial sonic boom target and observing their waveforms, the mobile seismic station will record two groups of relatively obvious signals during the entire process of the aerial sonic boom target falling to the ground: the first group is 7-8 minutes after the launch, and the signals of this group are strong. Mobile seismic stations within 30km of the actual landing point can record clear signals; the second group is 30-60 seconds after the first group of signals are recorded. The signals of this group are weaker, and only mobile seismic stations within 5km of the actual landing point can record relatively clear signals, such as Fig.11 shown.

[0042] The analysis shows that the first group of signals is the sonic boom shock wave signal generated by the high-speed movement of the aerial sonic boom target to an altitude of 13-17 km. The generation of the air shock wave is caused by Fig.12 As shown, the signal d received by the mobile station i deployed on the ground i for:

[0043] d i =∫ s G i (R i ,F;t)ds

[0044] Among them G i is the Green function between the flying object and the ground mobile station i, R i =R i(x, y, z) is the coordinate of the mobile platform, F(x, y, z, v, t) = F0(v, t)X f (x, y, z, t) is the source function of the falling body, where X f is the spatial position of the falling object, the source time function F0 is a function of the flight speed, the integral path s is the flight trajectory of the falling object, and the Green function G between the falling object and the mobile station is i It can be expressed as:

[0045]

[0046] where |X f -R i | is the distance from the earthquake source to the mobile station, V a is the average speed of sound waves in the air. Therefore, the air shock wave observed by mobile station i is:

[0047]

[0048] It can be seen that if we want to quantitatively or qualitatively analyze the air shock wave waveform observed by the mobile station, we need to determine the source time function F(x, y, z, v, t) of the falling body, that is, we need to know the XX trajectory and instantaneous XX velocity of the X body. In addition, the speed of the falling body is relatively low before the final landing, and the shock wave generated is also small, so the shock wave signal d i It is mainly caused by the falling object during high-speed falling, and is of little help in determining the final landing point.

[0049] The second group of signals will have two types of wave overlap, such as Fig.11 As shown in the figure, one is the wave generated by the impact, and the other is the acoustic signal. The second group of signals is weaker, and only mobile seismometers within 5km of the actual landing point can record relatively clear signals. Analysis shows that this may be due to the relatively low speed of the airborne sonic boom target, or because the impact of the ground can be equivalent to a vertical single force source, causing the excited seismic wave energy to radiate mainly downward, and the energy propagated laterally is not particularly strong, so it is necessary to conduct more intensified observations of the landing area. Analysis shows that the landing point of the airborne sonic boom target should be located using the acoustic signal recorded by the second group of signals recorded by the observation.

[0050] 5. Positioning Results and Analysis

[0051] The technicians used the mobile observation system to obtain the analysis results about 20 minutes after the sonic boom target landed in the air. In these two observation missions, 13 integrated short-period mobile seismometers were set up in a circle with a radius of 10km with the theoretical landing point as the center. The stations of this system are distributed as follows: Figure 2As shown; in the positioning process, the acoustic wave signal recorded by the second group of signals is selected for positioning, and the positioning method used is the simulated annealing method. That is, the observation system and positioning method proposed by the present invention are used in both observation tasks. The flow chart of the observation system of the present invention is as follows Figure 1 The results are shown in Table 1:

[0052] Table 1 Mobile observation positioning results

[0053]

[0054] After field investigation of the sonic boom target landing area, the positioning results of the two mobile observation missions were within 50m of the actual landing point of the sonic boom target. In these two observation missions, the high-precision positioning results quickly provided by the system of the present invention were used to provide earthquake science and technology services and support in improving XX recovery efficiency and preventing and resolving risks.

[0055] The above is only an embodiment of the present invention, and the common knowledge such as the known specific technical solutions or characteristics in the solution is not described in detail here. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the technical solution of the present invention, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A system for locating aerial sonic boom targets using a seismic monitoring network, characterized in that: The system includes a number of stations set within a circle with a radius of 10 km, with the theoretical landing point of the aerial sonic boom target as the center. The stations are networked to form a mobile network, and the mobile real-time monitoring center monitors the mobile network in real time. The stations are all uniformly timed by the network NTP server. The signals detected by the stations are sent by the mobile real-time monitoring center to the mobile positioning system for wave spectrum analysis and output by the terminal. During the positioning of the aerial sonic boom target, the station can collect two groups of obvious signals, the first group of which is the aerial sonic boom signal, and the second group is the target wreckage landing point sound wave signal. The second group of sound wave signals is selected for positioning, and finally the target wreckage landing point is obtained by using the simulated annealing positioning method. The specific process of positioning using simulated annealing method includes the following steps: S1, set C = C0, where C and C0 are the current parameters of the earthquake event and the initial earthquake catalog parameters respectively; set S0 to be the initial search range and time window length of the earthquake event location and earthquake time; S2. For each iteration i, i = 1.. N max , where i is the iteration index and N max is the maximum number of iterations during which the program selects a new set of model parameters C new , C new is a random neighboring value of C, the current search range S will be reduced to S = S0*(f) i Where f is the annealing rate, its value is between 0 and 1. If R(C new )<R min Or exp(R min -R(C new ) / S)>random(0,1), C new is accepted as C, and the program enters the next iteration, where R min is the minimum residual value of the previous iteration, R(C new ) is the current model parameter C new The residual value, random(0,1) randomly gives a decimal between 0 and 1, exp(R min -R(C new ) / S)>random(0,1) is a probabilistic acceptance condition to prevent the search from falling into a local minimum; S3, model parameter space C and R of the last round of iteration min The minimum residual is the optimal parameter model and corresponding residual finally solved.

2. A system for locating aerial sonic boom targets using a seismic monitoring network according to claim 1, characterized in that: There are 13 stations selected in this system, and the stations are integrated short-period seismometers.

3. The system for locating aerial sonic boom targets using a seismic monitoring network according to claim 1, characterized in that: The stations all transmit data with the mobile real-time monitoring center via wireless 4G transmission.

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