JP2000131430A - Method and system for suppressing false radar image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the generation of false images based on reflective bodies in a radar device. SOLUTION: Two targets having the same airplane number which occur due to a false image are detected from target data detected by an SSR target detecting part 3. Next, by computing a time difference Δt within radar scan in which the two targets are detected on the basis of one time of the targets, the locations of the targets at the other same time is predicted and computed through the use of past track data to obtain the distance data of the two targets. Then, through the use of the fact that a false target by reflected waves is present at a location farther than a true target by direct waves, the target farther in distance among the two targets is determined as a false target to suppress the false image.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air traffic control radar, and more particularly, to a radar false image suppressing method and method for suppressing a false image caused by reflection from a building or the like existing around the radar.

[0002]

2. Description of the Related Art In recent years, large buildings such as terminal buildings have been increasing at airports, and the radio wave environment has been deteriorating. In an air traffic control radar, a false image may appear due to such a reflection object, even though the target does not exist, as if the target were present at the azimuth and position. The occurrence of such false images is a very serious problem in control operation.

FIG. 3 is a diagram for explaining a mechanism of generating a false image on a radar scope. In the figure, if a reflector 11 such as a building exists near the radar 10,
When the radar 10 detects the direction of the reflector 11, the radio wave reflected by the reflector 11 is radiated in a different direction (false image area 14), and the true target (true target) A exists in the false image area 14. The reflected wave 13 reflected by the target A is reflected again by the reflector 11 and returns to the radar 10. When such a reflection phenomenon occurs, a false image A ′ due to the reflected wave 13 of the true target A is displayed in the radar detection direction (false image generation area 15) on the radar scope. That is, the target existing in the false image area appears as a false image in the false image generation area.

As described above, when the true target A such as a target machine enters the false image area 14 determined from the positional relationship between the radar 10 and the reflecting object 11 and the direction of the reflecting surface, the false image A ′ due to the reflected wave 13 becomes It appears as if it exists behind the reflector 11. If this false image phenomenon occurs in the air traffic control radar, it is extremely difficult for the controller to determine which of the two targets with the same beacon code is the true target on the radar scope. As a result, the aircraft A may be guided in a dangerous direction.

For this reason, various measures for suppressing a false image have conventionally been devised. As a countermeasure against false images, it is essentially not to generate false images themselves. For example,
Reflectors such as buildings have a lower elevation angle as viewed from radar than aircraft flying in the sky, so methods such as sharpening the vertical pattern of the antenna and weakening the radiated power to the reflector have been adopted. I have. However, it is difficult to sharpen the vertical plane directivity pattern extremely, so there is a limit to this method.

For this reason, as a countermeasure against false images, a method has been devised in which even if a false image is generated, it is determined whether the false image is true or false by using the characteristics of the false image and the occurrence of the false image is eliminated by processing on a circuit. ing. For example, a scheme has been devised in which a false image passing through a reflection path has a relatively lower received signal level than a true target due to a direct wave, thereby suppressing the false image. However, if the area of the reflecting object is large and the reflecting surface is good, a reception signal level equivalent to the true target is obtained, and it may not be possible to determine the authenticity.

Therefore, as another method, the position of the reflecting object, the direction of the reflecting surface, and the like are input in advance as data, and a false image is generated from the relationship between the false image region and the false image generation region as shown in FIG. A method of calculating an expected area and determining whether the area is true or false is adopted.

FIG. 4 is a block diagram showing this method.
A secondary surveillance radar (SSR: secondary) having an antenna 1, an SSR transmission / reception unit 2, an SSR target detection unit 3, and an instruction unit 5.
y surveillanc radar), the same beacon detecting unit 100, the false image area determining unit 106, and the false image erasing unit 4 are provided, and data such as the position of the reflecting object and the direction of the reflecting surface is input to the false image area determining unit 106 in advance. In addition, the reflected wave of the same beacon detected by the same beacon detection unit 100 is configured so that the false image area determination unit 106 determines the authenticity.

However, in order to adopt the method shown in FIG. 4, it is necessary to input reflected object data to the false image area determination unit 106 in advance. As such data, simply building data on a map is not sufficient, and it is necessary to collect reflector data by a flight test or the like and then further analyze the reflector data to obtain detailed data in all directions. A lot of effort and time was needed to investigate and obtain reflector data. Moreover, it is actually impossible to acquire all the reflection object data, and the false image cannot be suppressed in an area where the reflection object data cannot be set.

[0010]

SUMMARY OF THE INVENTION In order to suppress false images,
An important issue is how to reliably discriminate between true and false targets. As described above, a difference between the reception signal level of the true / false target and a method of predicting a false image occurrence region from the reflection object data in advance have been devised, but none of these measures is sufficient, and the reflection object There were problems such as requiring much labor and time to obtain data.

(Object) It is an object of the present invention to provide a radar false image suppressing method and method capable of automatically and accurately detecting and suppressing a false image.

[0012]

A radar false image suppression method according to the present invention is a radar false image suppression method for suppressing false images of an air traffic control radar, in which two target data having the same aircraft number are detected. Calculating the time difference between two targets in one radar scan, predicting the position of the target at the same time based on one time of the target from the calculated time difference, and calculating the distance data of the two targets at the same time. The distance data of the two targets is calculated, and the larger distance data is set as a false target, and the data of the false target is deleted.

The radar false image suppression method according to the present invention is a radar false image suppression method for suppressing false images of an air traffic control radar, wherein an SSR target detection unit for detecting target data from a reflected wave, and an identical aircraft based on the target data. An identical beacon detector for detecting two targets having numbers, a scan difference calculator for calculating the time difference between two targets detected in one radar scan, and the other based on one time of the target based on the calculated time difference A predicted position calculation unit that predicts a target position at the same time, a distance comparison unit that compares two target distance data at the same time, a true / false determination unit that determines a larger distance as a false target, A false image erasing unit for erasing false target data from the output of the SSR target detection unit based on the determination result of the true / false determination unit.

(Action) The true / false judgment is made by utilizing that the radio wave propagation distance of the false image generated by passing through the reflection path is always longer than the distance of the direct wave to the true target at the time of the false image occurrence. . Radar distance is compared after increasing the accuracy of the distance data of two targets at the same time by predicting the position of the other target from the past track data based on either of the true and false targets. To determine the true target data and the false target data to suppress the false target data.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Description of Configuration) Next, an embodiment of a method and system for suppressing radar false image of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of the false image suppressing method and system according to the present embodiment. Similar to the radar shown in FIG. 4, the same beacon is detected by a secondary surveillance radar (SSR) having an antenna 1, an SSR transmission / reception unit 2, an SSR target detection unit 3, a false image elimination unit 4, and an instruction unit 5. Unit 100 and track management unit 10
1, the scan difference calculation unit 102, and the predicted position calculation unit 10
3, a distance comparison unit 104, and a true / false determination unit 105. The functional outline of each unit of the present embodiment is as follows.

The antenna 1 repeatedly emits a pulsed radar transmission wave output from the SSR transmission / reception unit 2 while scanning the detection range, receives the reflected waves from the transponder of the aircraft, and sends the reflected wave to the SSR transmission / reception unit 2. Output. The SSR transmission / reception unit 2 outputs a transmission wave signal and a reflection wave signal corresponding to the transmission wave and the reflection wave to the SSR target detection unit 3. The SSR target detection unit 3 detects a transponder-specific aircraft number (referred to as “beacon code”) included in the reflected wave as target information (target data) from the transmitted wave signal and the reflected wave signal, and A time difference from the reflected wave signal and the azimuth of the antenna are detected, and distance data and azimuth data (referred to as "position data") to the target are calculated and output. Same beacon detector 100
Extracts the position data of the same beacon code, detects the position data of the same beacon code shifted in time within one radar scan, and then detects the track management unit 101, the scan difference calculation unit 102, the distance comparison unit 104, and the authenticity. Judgment unit 10
5 to output various signals based on the detection information to perform control.

A track management unit 101 manages track data based on past position data of a true target, and sends track data specified by a request for position data from the same beacon detection unit 100 to a predicted position calculation unit 103. Output. When the same beacon detection unit 100 detects two position data of the same beacon code, the scan difference calculation unit 102 calculates time data corresponding to the scan difference of the antenna 1 from each position data. The predicted position calculating unit 103 predicts a true (or false) target by inputting position data having the same beacon code as the wake data and the time data based on the scan difference. The distance comparing unit 104 compares the distance data of the false target with the distance data of the true target to calculate data of the magnitude relation of the distance. The authenticity determination unit 105 determines which of the two position data detected by the same beacon detection unit 100 corresponds to a true (or false) target. The false image erasing unit 4 erases the information of the false target from the information such as the position data to be displayed from the SSR target detecting unit 3 based on the determination result, and eliminates the display of the false target on the display unit 5.

(Explanation of Operation) Next, as an operation example of this embodiment, an example of suppressing a false image by a single target will be described. FIG. 2 is a diagram showing the position data and the positional relationship between the true target and the false target in this operation example. The radar 10 has a reflector 11 in which a false image area 24 is formed. When the true target A passes through the false image area 24, a false target B is formed in the false image generation area 25 formed by the reflector 11. This shows a situation in which a false image is generated.

In the present embodiment, the past track data (r-2, θ-2) (r-1, θ-1) of the true target A is stored in the track management unit 10.
1 is stored and managed. In this operation example, of the two position data having the same beacon code, the position data that is earlier in time is the true target A (rO, θ0), and the later data is the false target B (rO1, θ01). The false target B (rO1, θ
The actual position A ′ (rO2, θ02) of the true target A in the false image area at the same point in time when 01) is detected is a predicted value based on the wake data and is calculated by the predicted position calculation unit 103.

The same beacon detector 100 detects and outputs position data (r), azimuth data (θ), beacon code, and the like from the aircraft information sent from the SSR target detector 3. Now, the same beacon detector 100 detects the true target A data (rO, θ0) by the direct wave 22,
Further, after a certain period of time within one radar scan, radio waves are emitted in the direction of the reflecting object 11 (θ01), and the second target data B (θ) having the same beacon code as the true target A due to the reflected wave 23
01, θ01), the same beacon detection unit 100 sends the position data to the scan difference calculation unit 102 and outputs a wake data request signal to the wake management unit 101. The scan difference calculation unit 102 outputs the azimuth data A (θ
0), B (θ01) and the antenna rotation period ω,
Is detected at the time difference Δt (= ω (θ01−θ0) / 360)
°). Based on the time difference Δt obtained from the scan difference calculation unit 102, the predicted position calculation unit 103 calculates the past track data (r) of the target A transferred from the track management unit 101.
-2, θ-2) (r-1, θ-1) to the position (r02,
θ02).

The distance comparing section 104 is provided with the predicted position calculating section 10.
The distance is compared from the distance data A (r02) of the target A 'predicted and calculated in Step 3 and the distance data B (r01) of the target B sent from the same beacon detector 100, and r02 <r01 is detected. Is transferred to the authenticity determination unit 105. The authenticity determination unit 105 uses the fact that the distance of the radio wave propagation of the false image that occurs via the reflection path is always longer than the distance of the radio wave propagation of the true target at the time of the false image occurrence, and determines whether the authenticity is true or false. Determine. That is, based on the result compared by the distance comparison unit 104, the target A determines whether the target is a true target and the target B is a false target, and outputs the result to the false image erasing unit 4, and outputs the result to the false image erasing unit 4.
Then, the data of the false image B is erased according to the determination result.

This operation is the same when two targets having the same beacon code, the true target A (r1, θ1) and the false target B (r11, θ11), are detected.
When (r11, θ11) occurs, the prediction calculation of the true target position data is performed, and the target B (r11, θ1) is determined by comparing the two.
1) is determined as a false target and is suppressed. That is, the process is performed until the true target A passes through the false image area.

As described above, in this embodiment, in order to accurately compare the distance of the target data of the same beacon code to be processed, the position is predicted and calculated from the past track data, and the more accurate distance at the same time is calculated. Are compared, and a genuineness determination is made to determine whether the distance is false from the magnitude of the distance, and the false image is reliably erased. By calculating a time difference within a radar scan in which two true and false targets are detected, the position of the target at one and the same time of the other target is predicted and calculated using past wake data. Find distance data of two targets.

In the present embodiment, the wake data of the true target is used to predict the distance data at the same time. However, the wake data of the false target is created to predict the distance data of the false target. It is clear that this may be done.

[0026]

As described above, the radar false image suppression method and system of the present invention focus on the fact that a false image passing through a reflector is generated more distantly than a true target due to a direct wave. Since the distance data of two targets is configured to be accurately measured and determined, a false image can be reliably detected and suppressed. In addition, since there is no need to collect and input reflected object data, it is possible to realize excellent false image suppression with less burden on pre-operations due to changes in the radio wave environment and changes in the radar installation position. Is possible.

[0027]

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a diagram for explaining position data and a positional relationship between a true target and a false target.

FIG. 3 is a diagram for explaining a mechanism of generation of a false image.

FIG. 4 is a diagram showing a configuration example of a conventional system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Antenna 2 SSR transmission / reception part 3 SSR target detection part 4 False image elimination part 5 Instruction part 100 Same beacon detection part 101 Track management part 102 Scan difference calculation part 103 Prediction position calculation part 104 Distance comparison part 105 True / false judgment part

Claims (5)

[Claims] In a radar false image suppression method for suppressing false images of an air traffic control radar, when two target data having the same aircraft number are detected, a time difference between two targets in one radar scan is calculated. The position of the target at the same time is predicted based on one time of the target from the calculated time difference, the distance data of the two targets at the same time is calculated, and the distance data of the two targets is compared. A radar false image suppression method, characterized in that data with a larger data is set as a false target and the data of the false target is deleted. 2. The radar false image suppression method according to claim 1, wherein the prediction of the position of the other target is performed based on past wake data of the other target. 3. An SSR target detection unit for detecting target data from a reflected wave in a radar false image suppression method for suppressing false images of an air traffic control radar,
An identical beacon detector that detects two targets having the same aircraft number from the target data, a scan difference calculator that calculates a time difference between two targets detected in one radar scan, and a target A predicted position calculating unit for predicting a target position at the same time on the basis of one time, a distance comparing unit for comparing distance data of two targets at the same time, and determining a larger distance as a false target A radar false image suppression system, comprising: a true / false determination unit; and a false image elimination unit that erases false target data from the output of the SSR target detection unit based on the determination result of the true / false determination unit. 4. A trajectory management unit that stores past trajectory data from the target data, wherein the predicted position calculation unit calculates one of the targets based on the wake data of the wake management unit and the time difference of the scan difference calculation unit. 4. The method according to claim 3, wherein the position of the target at the same other time is predicted based on the time.
The described radar false image suppression method. 5. The apparatus according to claim 1, wherein the scan difference calculating section detects the detected 2
5. The radar false image suppression method according to claim 3, wherein a time difference is calculated from the azimuth information of the two targets.