CN108957503B - Positioning and false target identification method based on ADS-B message pulse counting - Google Patents

Abstract

The invention discloses a positioning and false target identification method based on ADS-B message pulse counting, which estimates the pulse counting deviation of receiving reference aircraft ADS-B between all the interception base stations by receiving ADS-B message pulse signals transmitted by aircrafts with S-mode answering machines and the counting of leading pulses thereof through different interception base stations; and then aiming at ADS-B signals or secondary radar response signals transmitted by other aircrafts with unknown positioning information and received by the plurality of intercept base stations, a range estimation method of a containing space is adopted to effectively verify the false target. The invention can realize an MDS system based on ADS-B, does not need to synchronize time among all the reconnaissance base stations, reduces the time synchronization cost of a multipoint positioning system, effectively makes up the defects of secondary radar and ADS-B positioning, eliminates false target information and ensures civil aviation flight safety.

Description

Location and false target identification method based on ADS-B message pulse count

technical field

The invention relates to a positioning and false target identification method based on ADS-B message pulse count.

Background technique

With the rapid development of the civil aviation industry, the number of aircraft has increased significantly. In order to better ensure the safety of flight, ADS-B technology emerged as the times require, making up for the lack of secondary radar to a certain extent. However, due to technical limitations, ADS-B is not loaded on all aircraft, and ICAO is easily forged, so it is difficult for the ADS-B receiver to determine whether the target is authentic. At the same time, the current multi-point positioning system lays wired links between the receiving stations in order to solve the clock error of the receiving stations, resulting in a cost of tens of millions of yuan, and local airports cannot purchase this set of facilities.

SUMMARY OF THE INVENTION

In order to solve the deficiencies of the prior art, the object of the present invention is to provide a method for positioning and false target identification based on ADS-B message pulse count, and to solve this problem by establishing a model and programming, greatly reducing the cost and making full use of the method. The existing technical means are used to make up for the shortcomings of ADS-B technology and secondary radar, which enhances the problem of airport surface surveillance, greatly guarantees the safety of aircraft, and identifies false targets in time.

In order to achieve above-mentioned goal, the present invention adopts following technical scheme:

A method for positioning and false target identification based on ADS-B message pulse counting, characterized in that it comprises the following steps:

Step 1) The aircraft with its own S-mode transponder sends data pulses, and each detection base station calculates the start number of the preamble pulse;

Step 2) each detection base station matches the same pulse signal, and calculates the measurement error of each detection base station by counting the pulse deviation;

Step 3) introducing the measurement pulse deviation correction mechanism to accurately obtain the measurement error of each base station;

Step 4) set the threshold, compare the number of base stations of the received ADS-B signal with the threshold, if not less than the threshold, then go to step 5), otherwise, go to step 6);

Step 5) arranging the signal stations according to the star shape, simultaneously transmitting signals to the target, considering the measurement error of each base station, and generating intersections to determine the position through three unilateral curved surfaces;

Step 6) Obtain the real-time position of the target or divide the flight range by detecting the base station, and use the purpose matching verification method to eliminate false signal interference.

Aforementioned a kind of positioning and false target identification method based on ADS-B message pulse count, it is characterized in that, the concrete content of described step 1) is:

The response signal of the aircraft's own Mode S transponder is used as the signal radiation source, and each ground station is used to calculate the number of pulses before receiving the preamble of the message;

Calculate the starting number of the received preamble pulse, match the same pulse signal, and send it to the master station, the master station will process it uniformly, the ADS-B message should be pulsed from the first sent pulse with a pulse interval of 0.5 microseconds For transmission, when the detection base station receives the same message preamble, it calculates the count of the previously received pulses.

Aforementioned a kind of positioning and false target identification method based on ADS-B message pulse count, it is characterized in that, the concrete content of described step 2) is:

When receiving station i receives the preamble information, the pulse count before it is recorded as P _i , the time of target signal transmission is consistent, and the calculation starts after receiving the same initial pulse signal. Signal error, when the receiving station starts to search for the ADS-B preamble, it collects the previously received pulse signals;

ΔP_i1是各个侦收基站收到的脉冲与中心基站的脉冲数目相减，

是脉冲平均宽度，Δl是S模式应答机发出的信号自带经纬度信息，通过计算得到的带有S模式应答机的航空器到各个接收站的距离；c是脉冲传递的速度。Among them, the error between each detection base station and the central base station

ΔP _i1 is the subtraction of the pulses received by each detection base station and the pulse number of the central base station,

is the average pulse width, Δl is the latitude and longitude information of the signal sent by the Mode S transponder, and the calculated distance from the aircraft with the Mode S transponder to each receiving station; c is the speed of the pulse transmission.

Aforementioned a kind of positioning and false target identification method based on ADS-B message pulse count, it is characterized in that, the concrete content of described step 3) is:

其中，Y_i是第i次观测到的基站之间脉冲计数差值，X_i是人为赋予的第i个观测值的权重，根据与预测期的观察值的距离给予权数值，越接近的观察值给予越小的权数值，所有的权数值的和加起来等于1；观测值的总数为n；The weighted moving average method is used to correct the systematic error, and the specific formula is as follows:

Among them, Yi is the pulse count difference between base stations observed in the _i -th time, and Xi is the artificially assigned weight of the _i -th observation value. The weight is given according to the distance from the observation value in the prediction period. The closer the observation value is, the closer the observation value is. The value is given a smaller weight value, and the sum of all weight values is equal to 1; the total number of observations is n;

Define the set {Y ₁ , Y ₂ , Y ₃ , ..., Y ₁₀₀ }, where the latest observation value ΔP _i1 is defined as Y ₁ , Y ₁₀₀ is removed from the set, and the numbers of the subscripts of all other values are increased One;

Different weights are given to different observations. Larger weights are given to observations close to the forecast period, and smaller weights are given to observations farther away from the forecast period.

将每次新得到的Y₁₀₁反馈到主站中，作为ΔP_i1。The aforementioned method for positioning and false target identification based on ADS-B message pulse counting is characterized in that, the defined weight is e- ⁱ , and the actual value obtained each time by calculating is represented by Y ₁₀₁ ,

The newly obtained Y ₁₀₁ is fed back to the master station each time as ΔP _i1 .

The aforementioned method for positioning and false target identification based on ADS-B message pulse counting is characterized in that the threshold is set to 4 in the step 4).

Aforementioned a kind of positioning and false target identification method based on ADS-B message pulse count, it is characterized in that, the concrete content of described step 5) is:

Using the method of multi-point positioning to determine the real-time position of other flying targets requires at least four detection base stations to form three unilateral hyperboloids to generate intersection points; build a model and incorporate the measurement errors of each receiving station obtained in step 3) into Model calculation, calculate the target position through the method of multi-point positioning.

The aforementioned a kind of positioning and false target identification method based on ADS-B message pulse count, is characterized in that, comprises the steps:

t_1i等于各个侦收基站收到地理信息未知的航空器的时间减去各个侦收基站与主站的测量误差，即t_1i＝T_1i-Δε_1i，其中，T_1i是i基站与主站接收同一信号的显示的时间差，Δε_1i是步骤2)中计算得到的i基站与主站的测量误差；Step 51) Since the multi-point positioning in the three-dimensional space requires at least four base stations, the receiving stations are arranged in a star shape: the main station is in the middle, and the connections between the other three secondary stations and the main station are selected to form a star shape, Set the position coordinates of the master station as (x ₁ , y ₁ , z ₁ ), and assume that the spatial position coordinates are (x, y, z); Ri is the distance from the _ith detection base station to the target signal, i=1, 2, 3, 4, R _1i represents the distance difference between the target signal reaching the primary station and the i-th secondary station, expressed by the equation:

t _1i is equal to the time when each reconnaissance base station receives the aircraft whose geographic information is unknown minus the measurement error between each reconnaissance base station and the master station, that is, t _1i =T _1i -Δε _1i , where T _1i is the reception time between the i base station and the master station The displayed time difference of the same signal, Δε _1i is the measurement error between the i base station and the master station calculated in step 2);

Step 52) Randomly set the initial position (x ₀ , y ₀ , z ₀ ) of the target at a position that is not more than 200km away from the main station;

利用加权最小二乘法解算目标位置偏差为：

其中，R_i′表示假设的目标初始位置(x₀，y₀，z₀)与各个基站之间的距离；Q是表示各基站中实践测量单元引入的相对误差，各个基站的固有误差相同；Step 53) carry out Taylor expansion of the formula in step 51), and remove the components above the second order to obtain: Ψ=h _t -G _t d, wherein each matrix vector is expressed as follows:

Using the weighted least squares method to solve the target position deviation is:

Wherein, R _i ' represents the distance between the assumed initial position of the target (x ₀ , y ₀ , z ₀ ) and each base station; Q is the relative error introduced by the actual measurement unit in each base station, and the inherent errors of each base station are the same;

Step 54) Substitute the initial position into (x ₀ , y ₀ , z ₀ ) to calculate the distance (x _n , y _n , z _n ), calculate the position deviation, set the threshold to ε=150m, when |x _n − x ₀ |+|y _n -y ₀ |+|z _n -z ₀ |<ε, end the calculation and feed back the results (x _n , y _n , z _n ); if not satisfied, in the next calculation, Let (x _n , _yn , z _n )=(x _n +Δx ₀ , _yn +Δy ₀ , z _n +Δz ₀ ) repeat the calculation;

Step 55) Convert (x _n , y _n , z _n ) coordinates into latitude and longitude coordinates, and compare it with the position information in the self-contained ADS-B message to determine whether it is a valid target.

Aforementioned a kind of positioning and false target identification method based on ADS-B message pulse count, it is characterized in that, the concrete content of described step 6) is:

a) When multiple detection base stations receive the target signal, use the multi-point positioning method to calculate the target real-time position (x _n , y _n , z _n ), and then compare it with the position information in the ADS-B message sent by the target, determine whether the target is a false signal;

其中，Δε是两个侦收基站对于同一个飞行目标的相对脉冲计数，

是脉冲平均宽度，(x_a,y_a,z_a)与(x_b,y_b,z_b)是两个侦收基站的位置坐标对应的经纬高度，(x_k,y_k,z_k)是飞行目标自带的经纬高度信息，ΔP是事先设定的脉冲数目偏差，用来估算包容空间，判断航空器位置范围的基准；b) When the detection base station has poor reception or the base station crashes, use the correlation function to find the correlation between the aircraft movement and the ADS-B message intention. The formula is as follows:

Among them, Δε is the relative pulse count of two reconnaissance base stations for the same flying target,

is the average pulse width, (x _a , y _a , z _a ) and (x _b , y _b , z _b ) are the latitude and longitude heights corresponding to the position coordinates of the two detecting base stations, (x _k , y _k , z _k ) is the longitude, latitude and altitude information of the flight target, and ΔP is the preset pulse number deviation, which is used to estimate the containment space and the benchmark for judging the position range of the aircraft;

By substituting the latitude and longitude altitude of the aircraft into the formula, the distance error between the position detected by the multi-point positioning system and the position information of the ADS-B message is determined. If the position information of the aircraft is displayed in the set distance band Within the range, it is considered to be a valid target; if the location information shows that it is not within the range, it is considered to be a false target.

The beneficial effects achieved by the present invention: taking the aircraft with its own S-mode transponder as the existing condition, the clock error between each receiving station can be calculated effectively without installing a wired link; Instead, the error is incorporated into the mathematical model as a known variable by means of programming, and finally the real-time position of the aircraft is obtained by continuous induction. This method greatly saves the cost of building a multi-point positioning system, effectively guarantees the monitoring of flying targets around the airport, and makes up for the shortage of secondary radar and ADS-B monitoring.

Description of drawings

Fig. 1 is the general schematic flow chart of the present invention;

Fig. 2 is the pulse count distribution of different detection base stations receiving the same ADS-B signal;

Fig. 3 is the schematic diagram of the distance difference of base station receiving reference aircraft;

FIG. 4 is a schematic diagram of a base station arrangement.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings. The following examples are only used to illustrate the technical solutions of the present invention more clearly, and cannot be used to limit the protection scope of the present invention.

This method adopts the aircraft equipped with the S-mode transponder to automatically broadcast the data pulse signal. The ground detection base station collects the ADS-B message pulse signal of the reference aircraft and calculates the starting number of the preamble pulse, and matches the same pulse signal. The information is uniformly sent to the central base station for processing. The master station corrects the counting deviation through the weighted moving average method, and establishes a model to obtain the measurement error between each detection base station and the central base station through calculation. When there are enough base stations for multi-point positioning, each reconnaissance base station sends an inquiry signal to other aircraft whose positioning information is unknown, and performs false target recognition and multi-point positioning on the aircraft through the feedback signal. When the number of base stations is less than the required requirements for multi-point positioning, based on the calculated positioning information, the range estimation method of the contained space can effectively verify the false target. The letters in the drawings are defined as follows: ΔP ₂₁ is the difference in pulse counts received by base station No. 2 and base station No. 1, and ΔP ₃₁ is the difference in pulse count received by base station No. 3 and base station No. 1. L ₁ is the distance between the aircraft with its own Mode S transponder and base station 1; Li is the distance between the aircraft with its own Mode S transponder and base station _i . BS _i is the code name of the i-th base station.

As shown in Figure 1, it includes the following steps:

Step 1. In daily life, when each receiving base station performs multi-point positioning on an aircraft with unknown geographic location information, the final positioning result deviates greatly due to clock errors. The invention provides a method for greatly reducing the cost without laying and fixing the synchronization time difference of optical cables. The response signal sent by the aircraft's own Mode S transponder is used as the signal radiation source, and each ground detection base station starts to count the number of pulses before receiving the preamble of the message. Calculate the starting number of the received preamble pulse, match the same pulse signal, and send it to the master station, and the master station will process it uniformly. Figure 2 shows the receiving conditions of the same ADS-B message pulse signal and its preamble at different detection base stations.

ΔP_i1是各个侦收基站收到的脉冲与中心基站的脉冲数目相减，

是脉冲平均宽度，Δl是S模式应答机发出的信号自带经纬度信息，通过计算得到的S模式应答机到各个接收站的距离；c是脉冲传递的速度，即光速。Step 2, when the master station receives the pulses with the same preamble signal matched by each detecting base station, the following formula is used to calculate:

ΔP _i1 is the subtraction of the pulses received by each detection base station and the pulse number of the central base station,

is the average pulse width, Δl is the longitude and latitude information of the signal sent by the S-mode transponder, and the calculated distance from the S-mode transponder to each receiving station; c is the speed of pulse transmission, that is, the speed of light.

此时各个侦收基站与主站的距离站位如图3所示，此时的距离Δl_i1就是用l₁-l_i，脉冲数的差值ΔP_i1等于步骤3中通过公式计算出来的Y₁₀₁。Therefore, the measurement error between each detection base station and the master station at this time is

At this time, the distance between each detection base station and the master station is shown in Figure 3. The distance Δl _i1 at this time is l ₁ -l _i , and the difference in the number of pulses ΔP _i1 is equal to the Y calculated by the formula in step 3. ₁₀₁ .

Step 3: As time goes on, the number of target measurements increases, and the error of the entire system will increase linearly with time. To address the growing problem of bias, we employ a weighted moving average method to correct for systematic errors. The specific formula is as follows:

We define a set {Y ₁ , Y ₂ , Y ₃ , ..., Y ₁₀₀ }, where the latest observation ΔP _i1 is defined as Y ₁ , Y ₁₀₀ is excluded from the set, and all other values are subscripted numbers All add one. We give different weights to different observations, giving larger weights to observations close to the forecast period, and correspondingly smaller weights to observations farther away from the forecast period, since the sum of all weights adds up To be equal to 1, so we might as well define the weight as e ^-x .

将每次新得到的Y₁₀₁反馈到主站中，成为步骤2中计算各个侦收基站与主站测量误差的参数。So by calculation, the value we actually get every time is represented by Y ₁₀₁ ,

The Y ₁₀₁ newly obtained each time is fed back to the master station, which becomes the parameter for calculating the measurement error between each detection base station and the master station in step 2.

Referring to step 2, we put the calculated pulse deviation into the calculation formula to calculate the measurement error of the detection base station. During the measurement process, if there is a large difference between the measurement value and the previous measurement value, we generally think that a certain receiving base station does not receive a signal or the system crashes, and we should discard {Y ₁ , Y ₂ , Y ₃ , ..., Y ₁₀₀ }, re-include the observations and start the calculation again.

Step 4, according to the detection result of step 3, we use the method of multi-point positioning to determine other flying targets, and judge whether it is a valid target and its real-time position. For this purpose, we set at least four reconnaissance base stations to form three unilateral hyperboloids to generate intersections.

A model is established, the clock errors of each receiving station obtained in step 3 are incorporated into the model calculation, and the target position is calculated by the method of multi-point positioning. Select the next step according to the number of base stations that have received signals.

Step 5, if the number of received base stations is not less than 4, the specific implementation process is as follows:

t_1i等于各个侦收基站收到地理信息未知的航空器的时间减去各个侦收基站与主站的测量误差，即t_1i＝T_1i-Δε_1i，其中，T_1i是i基站与主站接收同一信号的显示的时间差，Δε_1i是步骤2)中计算得到的i基站与主站的测量误差；Step 51) Since the multi-point positioning in the three-dimensional space requires at least four base stations, the receiving stations are arranged in a star shape: the main station is in the middle, and the connections between the other three secondary stations and the main station are selected to form a star shape, Set the position coordinates of the master station as (x ₁ , y ₁ , z ₁ ), and assume that the spatial position coordinates are (x, y, z); Ri is the distance from the _ith detection base station to the target signal, i=1, 2, 3, 4, R _1i represents the distance difference between the target signal reaching the primary station and the i-th secondary station, expressed by the equation:

t _1i is equal to the time when each reconnaissance base station receives the aircraft whose geographic information is unknown minus the measurement error between each reconnaissance base station and the master station, that is, t _1i =T _1i -Δε _1i , where T _1i is the reception time between the i base station and the master station The displayed time difference of the same signal, Δε _1i is the measurement error between the i base station and the master station calculated in step 2);

Step 52) Randomly set the initial position (x ₀ , y ₀ , z ₀ ) of the target at a position that is not more than 200km away from the main station;

Step 53) Perform Taylor expansion on the above formula, and remove the components above the second order to obtain: Ψ=h _t -G _t d. Each matrix vector is expressed as follows:

Using weighted least squares (WLS) to solve the target position deviation is:

Among them, R _i ′ represents the distance between the assumed initial position of the target (x ₀ , y ₀ , z ₀ ) and each base station; c _represents the speed of pulse transmission in space, that is, the speed of light; The time to the aircraft with unknown geographic information minus the measurement error of each detection base station and the main station; Q is the relative error introduced by the actual measurement unit in each base station. Generally, we think that the inherent error of each base station is the same.

Step 54) We substitute the initial position into (x ₀ , y ₀ , z ₀ ) to calculate the distance, and then calculate the position deviation, we set the threshold to ε=150m, when |Δx|+|Δy|+|Δz| <ε, end the calculation and feed back the results (x _n , _yn , z _n ); if not satisfied, repeat the calculation.

Step 6, when the number of received base stations is less than 4, in order to identify the authenticity of the ADS-B message, eliminate the interference of false flying targets to the monitoring station, and use the method of purpose matching verification to determine the authenticity of the message.

a) When multiple detection base stations receive the target signal, use the multi-point positioning method to calculate the target real-time position (x _n , y _n , z _n ), and then compare it with the position information in the ADS-B message sent by the target, determine whether the target is a false signal;

其中，Δε是两个侦收基站对于同一个飞行目标的相对脉冲计数，

是脉冲平均宽度，(x_a,y_a,z_a)与(x_b,y_b,z_b)是两个侦收基站的位置坐标对应的经纬高度，(x_k,y_k,z_k)是飞行目标自带的经纬高度信息，ΔP是事先设定的脉冲数目偏差，用来估算包容空间，判断航空器位置范围的基准；b) When the detection base station has poor reception or the base station crashes, use the correlation function to find the correlation between the aircraft movement and the ADS-B message intention. The formula is as follows:

Among them, Δε is the relative pulse count of two reconnaissance base stations for the same flying target,

is the average pulse width, (x _a , y _a , z _a ) and (x _b , y _b , z _b ) are the latitude and longitude heights corresponding to the position coordinates of the two detecting base stations, (x _k , y _k , z _k ) is the longitude, latitude and altitude information of the flight target, and ΔP is the preset pulse number deviation, which is used to estimate the containment space and the benchmark for judging the position range of the aircraft;

By substituting the latitude and longitude altitude of the aircraft into the formula calculation, the distance error between the position detected by the multi-point positioning system and the position information carried in the ADS-B message is determined. If the position information of the aircraft is displayed within the range we set, it is considered to be a valid target; if the position information is displayed not within the range, it is considered to be a false target.

Final result: If it is the case of a, convert the coordinates of (x _n , y _n , z _n ) into latitude and longitude coordinates according to the calculation, and then compare it with the location information in the ADS-B message that comes with it to use Determine if it is a valid target.

If it is the case of b, we obtain the pulse deviation Y ₁₀₁ of the detection base station and the main station through step 3 and the measurement error of each detection base station and the main station in step 2, and obtain the random detection base station and the main station for the same flight The relative pulse count Δε of the target is calculated by substituting the longitude, latitude and altitude coordinates of the aircraft into the formula to see if it is in the containment space we stipulate. If it is, the judgment is a valid target, if not, the judgment is a false target.

The above are only the preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, without departing from the technical principles of the present invention, several improvements and modifications can be made. These improvements and modifications It should also be regarded as the protection scope of the present invention.

Claims (6)

1. a kind of positioning and false target identification method based on ADS-B message pulse count, is characterized in that, comprises the steps: Step 1) The aircraft with its own S-mode transponder sends data pulses, and each detection base station calculates the start number of the preamble pulse; Step 2) each detection base station matches the same pulse signal, and calculates the measurement error of each detection base station by counting the pulse deviation; Step 3) introduce the measurement pulse deviation correction mechanism to accurately obtain the measurement error of each detection base station; Step 4) set the threshold value, compare the number of base stations for detection of the received ADS-B signal with the threshold value, if not less than the threshold value, then go to step 5), otherwise, go to step 6); Step 5) arranging the detection base stations according to a star shape, and simultaneously transmitting signals to the target, considering the measurement error of each detection base station, and generating intersections to determine the position through three unilateral curved surfaces; Step 6) obtain the target real-time position or divide the flight range by detecting the base station, and use the purpose matching verification method to eliminate false signal interference; The specific content of the step 2) is: The pulse count before the detection base station i receives the preamble pulse is recorded as P _i , the time of the target signal transmission is consistent, and the calculation starts after receiving the same initial pulse signal. Receive pulse signal error, when the detection base station starts to search for the ADS-B preamble, collect the previously received pulse signal; Among them, the error between each detection base station and the master station

ΔP _i1 is the subtraction of the pulses received by each detection base station from the pulse count of the master station,

is the average pulse width, Δl is the longitude and latitude information of the signal sent by the S-mode transponder, and the calculated distance from the aircraft with the S-mode transponder to each detection base station; c is the speed of pulse transmission; The specific content of the step 3) is: The weighted moving average method is used to correct the measurement error, and the specific formula is as follows:

Among them, Yu is the pulse count difference between the base stations observed at the _u -th time, and _Xu is the artificially assigned weight of the u-th observation value. The weight is given according to the distance from the observation value in the prediction period. Observations are given greater weights, and the sum of all weights is equal to 1; the total number of observations is n; Define the latest observed value ΔP _i1 as Y _n+1 ; Different weights are given to different observations. A larger weight is given to observations close to the forecast period, and a smaller weight is given to observations farther away from the forecast period. 2. a kind of positioning and false target identification method based on ADS-B message pulse count according to claim 1, is characterized in that, the concrete content of described step 1) is: The response signal of the aircraft's own Mode S transponder is used as the signal radiation source, and each ground detection base station starts to count the previous pulse count from the receipt of the message preamble; Calculate the starting number of the received preamble pulse, match the same pulse signal, and send it to the master station, the master station will process it uniformly, the ADS-B message should be pulsed from the first sent pulse with a pulse interval of 0.5 microseconds For transmission, when the detection base station receives the same message preamble, it calculates the count of the previously received pulses. 3. a kind of positioning and false target identification method based on ADS-B message pulse count according to claim 1, is characterized in that, in described step 4), the threshold value is set to 4. 4. a kind of positioning and false target identification method based on ADS-B message pulse count according to claim 3, is characterized in that, the concrete content of described step 5) is: Using the method of multi-point positioning to determine the real-time position of other aircraft requires at least four reconnaissance base stations to form three unilateral hyperboloids to generate intersection points; build a model and incorporate the measurement errors of each reconnaissance base station obtained in step 3) into Model calculation, calculate the target position through the method of multi-point positioning. 5. a kind of positioning and false target identification method based on ADS-B message pulse count according to claim 4, is characterized in that, described step 5) specifically comprises the steps: Step 51) Since the multi-point positioning in the three-dimensional space requires at least four detection base stations, the detection base stations are arranged in a star shape: the main station is in the middle, and the connections between the other three secondary stations and the main station are selected to form a Star shape, set the position coordinates of the master station as (x ₁ , y ₁ , z ₁ ), assuming that the position coordinates of the aircraft with unknown geographic information are (x, y, z); R _i is the ith detection base station to the target The distance of the signal, i=1, 2, 3, 4, R _1i represents the distance difference between the target signal reaching the primary station and the i-th secondary station, expressed by the equation:

R ₁ -R _i =ct _1i =R _1i , i=2, 3, 4; t _1i =T _1i -Δε _1i , where T _1i is the displayed time difference between the i-th secondary station and the primary station receiving the same signal, and Δε _1i is the measurement of the i-th secondary station and the primary station calculated in step 2). Error; c is the speed of pulse transmission, that is, the speed of light; Step 52) Randomly set the initial position (x ₀ , y ₀ , z ₀ ) of the target at a position that is not more than 200km away from the main station; Step 53) carry out Taylor expansion of the formula in step 51), remove the components above the second order to obtain: Ψ=h _t -G _t d, wherein each matrix vector is expressed as follows:

Using the weighted least squares method to solve the target position deviation is:

where R′ _i represents the distance between the assumed initial position of the target (x ₀ , y ₀ , z ₀ ) and each sensing base station; Q is the relative error introduced by the actual measurement unit in each reconnaissance base station, and the inherent error of each reconnaissance base station is the same; Step 54) Substitute the initial position (x ₀ , y ₀ , z ₀ ) into the formula to calculate the distance, calculate the position deviation, set the threshold to ε=150m, when |Δx ₀ |+|Δy ₀ |+|Δz ₀ | <ε, end the calculation and feed back the result (x, y, z); if not satisfied, in the next calculation, let (x ₀ , y ₀ , z ₀ )=(x ₀ +Δx ₀ , y ₀ + Δy ₀ , z ₀ +Δz ₀ ) repeat the calculation; Step 55) Convert the (x, y, z) coordinates into latitude and longitude coordinates, and compare it with the position information in the self-contained ADS-B message to determine whether it is a valid target. 6. a kind of positioning and false target identification method based on ADS-B message pulse count according to claim 1, is characterized in that, the concrete content of described step 6) is: a) When multiple detection base stations receive the target signal, use the multi-point positioning method to calculate the target real-time position (x, y, z), and then compare it with the position information in the ADS-B message sent by the target to determine the target. whether it is a false signal; b) When the detection base station is not well received or the detection base station crashes, use the correlation function to find the correlation between the aircraft movement and the ADS-B message intention. The formula is as follows:

in,

is the average pulse width, (x _a , y _a , za _a ) and (x _b , y _b , z _b ) are the latitude and longitude heights corresponding to the position coordinates of the two detecting base stations, (x _k , y _k , z _k ) is the longitude, latitude and altitude information that comes with the aircraft, and ΔP is the preset pulse count deviation, which is used to estimate the containment space and the benchmark for judging the position range of the aircraft; By substituting the latitude and longitude altitude of the aircraft into the formula, the distance error between the position detected by the multi-point positioning system and the position information of the ADS-B message is determined. If the position information of the aircraft is displayed in the set distance band Within the range, it is considered to be a valid target; if the location information shows that it is not within the range, it is considered to be a false target.

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