Method based on ADS-B antenna configuration analysis model

Abstract

The present invention discloses a method based on an ADS-B antenna configuration analysis model, comprising the steps of: the ADS-B antenna configuration analysis model comprehensively analyzes the correlation between the number of aircraft, radar / TCAS deployment, and aircraft response / broadcast rate and the message decoding rate of directional / omnidirectional ADS-B receiving equipment, obtains an ADS-B decoding rate calculation model under directional antenna and omnidirectional antenna configuration, calculates the corresponding message decoding rate through the calculation model, uses the message decoding rate as a reference indicator for evaluating the directional / omnidirectional antenna configuration, and uses the antenna configuration corresponding to the reference indicator to provide a decision-making tool for the deployment and implementation of the ADS-B site. The present invention can provide reliable decision-making suggestions for the antenna configuration before the construction of the ADS-B site, avoiding the problem of insufficient antenna configuration causing reduced equipment performance, thereby affecting regulatory requirements, or excessive cost caused by excessive antenna configuration.

Description

Technical Field

[0001] The present invention relates to the technical field of ADS-B, and more specifically, to a method based on an ADS-B antenna configuration analysis model. Background Art

[0002] The operating frequency of ADS-B is 1090MHz. There are mainly two types of signals in this frequency band: reply signals and broadcast signals. Among them, the reply signal can be triggered by the inquiry of the ground secondary radar or the inquiry of the TCAS system equipped by other aircraft in the air; the broadcast signal is divided into DF11 and ADS-B broadcast (DF17, DF18, DF19). The update rate of ADS-B track depends on the probability of successful decoding of ADS-B message. In the actual operation scenario, ADS-B message is superimposed by the reply signal and broadcast signal of other aircraft. The higher the probability of superposition, the lower the probability of successful decoding. In the actual deployment of ADS-B sites, when the surrounding environment is complex and the number of aircraft targets is large, the successful decoding rate of ADS-B messages is improved by deploying directional antennas, but the configuration decision problem of directional antennas and omnidirectional antennas has not been solved.

[0003] At present, there is still no comprehensive theoretical model for the configuration decision of directional antennas and omnidirectional antennas when deploying ADS-B stations. Usually, the configuration is made based on the manufacturer's suggestions or user needs based on the number of surrounding targets. This method lacks scientific theoretical basis and may result in excessive configuration, resulting in cost waste, or insufficient configuration, resulting in the ADS-B decoding rate failing to meet the standard. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method based on the ADS-B antenna configuration analysis model, which can provide reliable decision-making suggestions for antenna configuration before ADS-B site construction, avoid the problem of insufficient antenna configuration causing reduced equipment performance, thereby affecting regulatory requirements, or excessive antenna configuration causing excessive costs.

[0005] The object of the present invention is achieved through the following solutions:

[0006] A method based on an ADS-B antenna configuration analysis model. The ADS-B antenna configuration analysis model comprehensively analyzes the correlation between the number of aircraft, radar / TCAS deployment, and aircraft response / broadcast rate and the message decoding rate of directional / omnidirectional ADS-B receiving equipment, and obtains an ADS-B decoding rate calculation model under directional antenna and omnidirectional antenna configuration. The corresponding message decoding rate is calculated by the calculation model, and the message decoding rate is used as a reference indicator for evaluating the directional / omnidirectional antenna configuration. The antenna configuration corresponding to the reference indicator is used to provide a decision-making tool for the deployment and implementation of ADS-B sites.

[0007] Further, the method comprises the following sub-steps:

[0008] S1, obtain the relationship between radar deployment and aircraft response;

[0009] S2, obtain the relationship between TCAS deployment status and aircraft response;

[0010] S3, obtain the number of S-mode broadcast messages;

[0011] S4, obtaining the total number of messages for a single target;

[0012] S5, obtaining an ADS-B decoding rate calculation model;

[0013] S6, obtaining model parameters, and using the model parameters to perform simulation calculation in the ADS-B decoding rate calculation model to obtain a decoding rate.

[0014] Furthermore, in step S1, the sub-steps are included: the number of reply signals of each aircraft per second is calculated as follows: AC reply: (M+N)*10*α; short S mode: N*1*α; long S mode: N*3*α; wherein M is the number of M AC mode secondary radars, N is the number of S mode secondary radars, and α is the overlap coefficient.

[0015] Further, in step S2, the sub-steps are included: the number of reply signals of each aircraft per second is calculated as follows: C reply: A*1; short S mode: A / 6; long S mode: A / 8; A represents the number of aircraft in the covered airspace.

[0016] Further, in step S3, the number of S-mode broadcast messages obtained is: short S-mode: 1 time / s; long S-mode: 4 times / s.

[0017] Further, in step S4, when all aircraft are equipped with TCAS systems and M AC secondary radars and N S-mode secondary radars are deployed on the ground, for any target, the number of reply messages is calculated as follows: AC: 10*(M+N)*α+20+0; short S-mode: N*1*α+3+1; long S-mode: N*3*α+2+4.

[0018] Further, in step S5, the probability P[n] that the ground station correctly receives the ADS-B signal is calculated as follows:

[0019]

[0020] Where P num Represents the number of aircraft per second, I num represents the number of interference signals generated by each aircraft per second, λ is the antenna weighting factor, t represents the size of the time window, n represents the number of occurrences, n is 0 or 1, and 0 means that adding the corresponding interference within the time window cannot successfully decode.

[0021] Furthermore, the correct reception probability of the ADS-B signal after adding A / C mode, short S mode and long S mode interference is calculated according to the following formula:

[0022]

[0023]

[0024]

[0025] Among them, P num is the number of aircraft per second, I num1 is the number of A / C interference signals generated by each aircraft per second, I num2 is the number of short S-mode interference signals generated by each aircraft per second, I num3 is the number of long S-mode jammers generated by each aircraft per second;

[0026] If the above λ is an omnidirectional antenna 1 , 2 With λ 3 The coefficient is 1. If it is a directional antenna, the weighting factor needs to be multiplied by the multi-channel influence factor γ, γ<1;

[0027] The correct answer probability P after adding three kinds of interference is calculated according to the following formula:

[0028] p=P(A / C)*P(Short)*P(Long);

[0029] For the case of two extended intermittent oscillations per second, the probability of correctly decoding the ADS-B message at least once in n consecutive seconds is calculated according to the following formula:

[0030] p x =1-(1-p) 2*n-1 .

[0031] Further, step S6 includes the following sub-steps: after selecting the ADS-B ground station installation location, obtaining the number of A / C mode, short S mode, and long S mode interference messages generated by each target per second around the installation location through steps S1 to S4, i.e., the number of parameters I in step S5. num1 ,I num2 and I num3 By changing the number of targets and the refresh rate, the correct message decoding rate of the omnidirectional antenna and the directional antenna receiving different numbers of targets and different refresh rates is analyzed.

[0032] Further, the method comprises the following steps: after step S6, the method comprises the following steps: deploying the antenna configuration under the message decoding rate in combination with the control requirements, that is, obtaining the ADS-B site deployment implementation requirements that meet the corresponding control requirements.

[0033] The beneficial effects of the present invention include:

[0034] The present invention establishes a scientific, reasonable and complete ADS-B antenna configuration analysis model. The method based on this model can provide reliable decision-making suggestions for antenna configuration before ADS-B site construction, avoiding the problem of insufficient antenna configuration causing reduced equipment performance, thereby affecting regulatory requirements, or excessive antenna configuration causing excessive costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0036] Figure 1 Configure the model block diagram for the antenna;

[0037] Figure 2 In response to multiple responses;

[0038] Figure 3 Provide effective coverage for the airspace of a certain radar station;

[0039] Figure 4 Interrogate schematic for TCAS;

[0040] Figure 5 The correct decoding rate of the omnidirectional antenna at a refresh rate of 1 second (left) and 4 seconds (right);

[0041] Figure 6 The correct decoding rate of the four-channel directional antenna at a refresh rate of 1 second (left) and 4 seconds (right). DETAILED DESCRIPTION

[0042] All features disclosed in all embodiments in this specification, or steps in all methods or processes implicitly disclosed, except for mutually exclusive features and / or steps, can be combined and / or expanded or replaced in any manner.

[0043] like Figure 1 to Figure 6 As shown in FIG. 1 , a method based on the ADS-B antenna configuration analysis model is used. The message decoding rate is used as a direct indicator to evaluate the effect of directional / omnidirectional antennas. A model is established to study the correlation between the number of aircraft, radar / TCAS deployment, aircraft response / broadcast rate and the message decoding rate of directional / omnidirectional ADS-B receiving equipment. The model block diagram is shown in FIG. Figure 1 .

[0044] 1. Obtaining the relationship between radar deployment and aircraft responses

[0045] At present, the typical AC mode secondary radar beam scanning cycle is 4s, and the interrogation repetition frequency is 150Hz--450Hz. According to the beam width of 8m antenna 3dB with a maximum beam width of 2.7°, the time an aircraft stays in a beam is approximately: (2.7° / 360°)×4s=30ms. The corresponding number of interrogations is between 4.5--13.5 times (generally in actual operation, each aircraft is calculated as 10 times according to the airspace operation scenario). If there are M AC mode secondary radars in the effective airspace, it is calculated as 10*M AC replies per second for each aircraft.

[0046] For Mode S interrogation, there are two methods: all-call and roll call, depending on the radar settings and the actual aircraft operation. For all-call, the DF11 format is used for reply, and for roll call interrogation, it is related to the specific interrogation strategy of the secondary radar. Considering the typical situation, the calculation is performed according to the distribution of 1 short and 3 long per second.

[0047] Since radar coverage will not completely overlap, in actual discussion, the present invention multiplies a certain overlap coefficient α (the overlap coefficient is determined according to the ratio of repeated coverage), such as Figure 2 Multiple responses will only be made when multiple radars are deployed within the coverage area.

[0048] Taking the A / C mode reply signal as an example, assuming that there are n secondary radars near the ground station (where the number of A / C mode secondary radars is M and the number of S mode secondary radars is N), their overlap coefficients with the ADS-B ground station coverage airspace are α and 1 , α 2 ...α n .

[0049] Among them, α x =O x ×C x (x=1,2,…n),O x is the overlap ratio between other radars and the coverage of the locally deployed ground station (i.e., Figure 2 The ratio of the overlapping volume of the two cones to the monitoring range of the local ground station is a purely mathematical process, and the detailed calculation process is not listed here. x The actual effective coverage rate of the airspace signal around the locally deployed ground station can be obtained through professional analysis software. Figure 3 This is the actual effective coverage of the signal at an airspace altitude of 10,000 meters above a radar station with a coverage range of 370 kilometers. When the altitude decreases, the coverage will deteriorate.

[0050] Assuming that the number of targets in the airspace covered by the ground station is A and the targets are evenly distributed, the effective A / C responses generated by each radar interrogation are A·α 1 ·10,A·α 2 ·10...A·α n ·10, the total number of responses from targets in the airspace is A·α 1 ·10+A·α 2 ·10+...A·α 2 10, the average number of responses per target per second is α 1 10+α 2 ·10+...α n ·10=(α 1 +α 2 +...α n )·10, for the sake of simplicity, the present invention uses α (i.e. the final overlap coefficient) instead, and we can get α=(α 1 +α 2 +...α n ) / n=(α 1 +α 2 +...α n ) / (M+N), the number of reply signals per aircraft per second can be obtained as follows:

[0051] AC response: (M+N)*10*α

[0052] Short S mode: N*1*α

[0053] Long S mode: N*3*α

[0054] (II) Obtaining the relationship between TCAS deployment and aircraft responses

[0055] According to the airspace operation scenario, the TCAS system has three response modes: C mode, DF0 (S mode short) and DF16 (S mode long). According to the TCAS operation rules, TCAS monitors aircraft in the surrounding airspace. TCAS divides the horizontal plane into 4 quadrants, and uses a quiet call to inquire in each quadrant (it can control the response of aircraft within a certain distance ring), such as Figure 1-4 shown.

[0056] According to the RTCA / DO185 standard, under normal circumstances, when an aircraft flies according to the civil aviation control interval (that is, no TCAS alert is generated), TCAS generates 24 C-mode inquiries (quiet call mode, the same below) in quadrant 1, 15 C-mode inquiries in quadrant 3, and 20 C-mode inquiries each in quadrants 2 and 4.

[0057] For each target, an S-mode UFO interrogation (roll call) is generated every 6 seconds, and an S-mode long interrogation (broadcast interrogation) is generated every 8 seconds. Therefore, it can be assumed that there are A aircraft in the typical coverage airspace, and each aircraft generates the following number of replies:

[0058] C answer: A*1

[0059] Short S mode: A / 6

[0060] Long S mode: A / 8

[0061] Since the TCAS standard requires that it only monitors, tracks and warns targets within the nearby airspace (80KM), the upper limit requirement is 50, and the display upper limit requirement is 30. In actual operation, the number of monitored targets is generally 20. Therefore, the present invention calculates according to 20, and the AC mode responses generated by TCAS are about 20, the short S mode responses are about 3 times, and the long S mode responses are about 2 times.

[0062] (III) Obtaining the number of S-mode broadcast messages

[0063] Mode S broadcasts mainly include DF11 and DF17. According to the current transponder configuration, the number of broadcasts for each target is:

[0064] Short S mode: 1 time / s;

[0065] Long S mode: 4 times / s (mainly including position, speed, and identity messages).

[0066] (IV) Obtaining the total number of messages for a single target

[0067] According to steps (1) to (3), in a typical high-density airspace, when all aircraft are equipped with TCAS systems and have broadcast capabilities, and M AC secondary radars and N S-mode secondary radars are deployed on the ground, the number of reply messages for any target is:

[0068] AC: 10*(M+N)*α+20+0

[0069] Short S mode: N*1*α+3+1

[0070] Long S mode: N*3*α+2+4

[0071] (V) Obtaining the ADS-B decoding rate calculation model

[0072] Since the transponder broadcast signals of all aircraft in the airspace are generated completely randomly, the present invention introduces the following model to calculate the probability that the ground station can correctly receive the ADS-B signal:

[0073] The calculation formula is:

[0074] Where P num Represents the number of aircraft, I num represents the number of interference signals generated by each aircraft per second, λ is the antenna weighting factor; t represents the size of the time window. The time windows of A / C mode, short S mode and long S mode are different. The time window sizes are shown in Table 1; n represents the number of occurrences, n is 0 or 1, and 0 means that the corresponding interference cannot be successfully decoded within the time window.

[0075] The correct reception probability of the ADS-B signal after adding A / C mode, short S and long S mode interference is:

[0076]

[0077]

[0078]

[0079] P num is the number of aircraft per second, I num1 is the number of A / C interference signals generated by each aircraft per second, I num2 is the number of short S-mode interference signals generated by each aircraft per second, I num3 is the number of long S-mode jammers generated by each aircraft per second.

[0080] If the above λ is an omnidirectional antenna1 , 2 With λ 3 The coefficient is 1. If it is a directional antenna, the weighting factor needs to be multiplied by the multi-channel influence factor α (α<1). The more channels there are, the smaller the value of α is. For example, the value of α for four channels is 0.60. Then the probability of correct response after adding three interferences is p=P(A / C)*P(Short)*P(Long). For the case of two extended intermittent oscillations per second, the probability of correctly decoding the ADS-B message at least once in n consecutive seconds is: p x =1-(1-p) 2*n-1 .

[0081] (VI) Model parameter acquisition and simulation

[0082] After the ADS-B ground station installation location is selected, the number of A / C mode, short S mode, and long S mode interference messages generated by each target per second around the installation location can be obtained through steps (1) to (4), that is, parameter I in step (5). num1 ,I num2 and I num3 For example, the present invention selects site 1 and site 2, analyzes the types and quantities of radars around them, and calculates the multiple coverage coefficient α, so as to obtain the number of A / C mode, short S mode and long S mode interference messages, as shown in Table 2.

[0083] By changing the number of targets and the refresh rate, the correct decoding rate of the omnidirectional antenna and the directional antenna receiving different numbers of targets and different refresh rates can be analyzed. Figure 5 That is, the correct decoding rate of the omnidirectional antenna at 1 second refresh rate and 4 second refresh rate obtained by using the model parameters in Table 2, Figure 6 That is, the correct decoding rate of the four-channel directional antenna at 1 second refresh rate and 4 second refresh rate obtained by using the model parameters in Table 2.

[0084] According to the antenna configuration analysis model obtained from the surrounding environment and the regulatory requirements, the antenna configuration requirements that meet the corresponding regulatory requirements can be obtained.

[0085] Table 1 Time window

[0086] A / C S short S long Time window 20.3us 64us 120us Allowed interruption times 1 0 0

[0087] Table 2 Model parameter settings

[0088]

[0089] The parts not involved in the present invention are the same as the prior art or can be implemented by using the prior art.

[0090] The above technical solution is only one implementation mode of the present invention. For those skilled in the art, it is easy to make various types of improvements or modifications based on the application methods and principles disclosed in the present invention, and it is not limited to the method described in the above specific implementation mode of the present invention. Therefore, the method described above is only preferred and does not have a restrictive meaning.

[0091] In addition to the above examples, those skilled in the art may obtain other embodiments based on the above disclosure or by using the knowledge or technology in the relevant field to make changes. The features of each embodiment may be interchangeable or replaced. The changes and modifications made by those skilled in the art do not depart from the spirit and scope of the present invention, and should be within the scope of protection of the claims attached to the present invention.

Claims

1. A method based on an ADS-B antenna configuration analysis model, characterized in that: The ADS-B antenna configuration analysis model comprehensively analyzes the correlation between the number of aircraft, radar / TCAS deployment, and aircraft response / broadcast rate and the message decoding rate of directional / omnidirectional ADS-B receiving equipment, and obtains an ADS-B decoding rate calculation model under directional antenna and omnidirectional antenna configuration. The corresponding message decoding rate is calculated by the calculation model, and the message decoding rate is used as a reference indicator for evaluating the directional / omnidirectional antenna configuration. The antenna configuration corresponding to the reference indicator is used to provide a decision-making tool for the deployment and implementation of ADS-B sites. Includes sub-steps: S1, obtain the relationship between radar deployment and aircraft response; S2, obtain the relationship between TCAS deployment status and aircraft response; S3, obtain the number of S-mode broadcast messages; S4, obtaining the total number of messages for a single target; S5, obtaining an ADS-B decoding rate calculation model; S6, obtaining model parameters, and using the model parameters to perform simulation calculation in the ADS-B decoding rate calculation model to obtain a decoding rate; In step S1, the sub-steps are included: the number of reply signals of each aircraft per second is calculated as follows: AC reply: (M+N)*10*α; short S mode: N*1*α; long S mode: N*3*α; where M is the number of AC mode secondary radars, N is the number of S mode secondary radars, and α is the overlap coefficient; In step S2, the sub-steps are included: the number of reply signals of each aircraft per second is calculated as follows: C reply: A*1; short S mode: A / 6; long S mode: A / 8; A represents the number of aircraft in the covered airspace; In step S5, the probability of the ground station correctly receiving the ADS-B signal is calculated as follows: : In the formula, Represents the number of aircraft per second, Represents the number of interference signals generated by each aircraft per second, is the antenna weighting factor, t represents the size of the time window, n represents the number of occurrences, n is 0 or 1, and 0 represents that adding corresponding interference within the time window cannot successfully decode.

2. The method based on the ADS-B antenna configuration analysis model according to claim 1, characterized in that: In step S3, the number of S-mode broadcast messages obtained is: short S-mode: 1 time / s; long S-mode: 4 times / s.

3. The method based on the ADS-B antenna configuration analysis model according to claim 1, characterized in that: In step S4, when all aircraft are equipped with TCAS systems and M AC secondary radars and N S-mode secondary radars are deployed on the ground, for any target, the number of reply messages is calculated as follows: AC: 10*(M+N)*α+20+0; short S-mode: N*1*α+3+1; long S-mode: N*3*α+2+4.

4. The method based on the ADS-B antenna configuration analysis model according to claim 1, characterized in that: The correct reception probability of the ADS-B signal after adding A / C mode, short S mode and long S mode interference is calculated according to the following formula: ； ； ； in, is the number of aircraft per second, is the number of A / C interference signals generated by each aircraft per second, is the number of short S-mode jammers generated by each aircraft per second, is the number of long S-mode jammers generated by each aircraft per second; If the above is an omnidirectional antenna , and The coefficient is 1. If it is a directional antenna, this weighting factor needs to be multiplied by the multi-channel influence factor. , ; The probability of correct answer after adding three kinds of interference is calculated according to the following formula P for: ； For the case of two extended intermittent oscillations per second, the probability of correctly decoding the ADS-B message at least once in n consecutive seconds is calculated according to the following formula: 。 5. The method based on the ADS-B antenna configuration analysis model according to claim 4, characterized in that: Step S6 includes the following sub-steps: after selecting the ADS-B ground station installation location, obtaining the number of A / C mode, short S mode, and long S mode interference messages generated by each target per second around the installation location through steps S1 to S4, i.e., the parameter in step S5. , and By changing the number of targets and the refresh rate, the correct message decoding rate of the omnidirectional antenna and the directional antenna receiving different numbers of targets and different refresh rates is analyzed.

6. The method based on the ADS-B antenna configuration analysis model according to claim 5, characterized in that: The method comprises the following steps: after step S6, the method comprises the following steps: utilizing the antenna configuration under the message decoding rate and combining it with the regulatory requirements for deployment, that is, obtaining the ADS-B site deployment implementation requirements that meet the corresponding regulatory requirements.

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