CN111781602A - An airport runway foreign body radar monitoring system, monitoring method and monitoring device - Google Patents

Abstract

The invention relates to an airport runway foreign body radar monitoring system, a monitoring method and a monitoring device. An airport runway foreign body radar monitoring system, comprising a rotating device and a detection rotating arm device; the detection rotating arm device is installed on the rotating device, and is driven to rotate by the rotating device; the detection rotating arm device includes a transmitter , receiver, frequency synthesizer, data acquisition module, signal processing module; the frequency synthesizer is respectively connected with the transmitter and the receiver; the receiver, the data acquisition module, the signal processing module connected in sequence; the signal processing module is connected with the computing platform. Using the imaging and detection method based on the arc synthetic aperture radar system can effectively reduce the noise interference of scintillation clutter and effectively filter out possible interference items; at the same time, fully consider the height factor between the detection arm device and the target, The spatial position of the target can be determined more quickly, and the detection capability can be improved.

Description

An airport runway foreign body radar monitoring system, monitoring method and monitoring device

technical field

The invention relates to the field of radar monitoring, in particular to an airport runway foreign body radar monitoring system, a monitoring method and a monitoring device.

Background technique

Airport runway foreign objects (Foreign Object Debris, abbreviated FOD) refer to objects that should not exist on the runway and cause damage to the system or aircraft. In the flight area, any objects that may endanger the safety of the ground operation of the aircraft, such as stones, metal parts, tapes, plastic products, leaves, etc., are collectively referred to as foreign objects on the airport runway. FOD poses a serious threat to the safety of aircraft take-off and landing. The aircraft's engine can easily absorb foreign objects on the airport runway, causing it to fail. Those debris will also accumulate in the mechanical devices, which will make the aircraft unable to operate normally. The direct loss caused by FOD in the world every year is at least more than 3-4 billion US dollars, and the indirect loss is several times that of the direct loss.

According to the regulations of the International Civil Aviation Organization (ICAO), the runway needs to be inspected at least four times a day. Manual inspection takes a long time. During the inspection, the runway must be closed to reduce the traffic flow of the runway. In addition, it is affected by weather and human factors. The ability to discover is limited, and it is unable to detect the hidden dangers of operation safety caused by all FODs. Therefore, the problem of manual inspection needs to be solved by configuring an automated FOD monitoring system.

The FOD automatic monitoring system mainly adopts radar detection technology and video image processing identification technology. The monitoring system based on video image processing technology is easily affected by bad weather conditions such as rain, snow and fog, as well as strong light, night and other lighting conditions, while the monitoring system using radar technology can work around the clock and all day, and has high detection efficiency. A FOD automatic monitoring technology with broad application prospects.

At present, typical FOD monitoring radar products include the Tarsier (tarsier) tower system of QinetiQ Company of the United Kingdom, the FODetect sidelight system of Xsight Company of Israel, the FOD Finder vehicle-mounted mobile system of Trex Company of the United States, and the second institute of the Civil Aviation Administration of China. The edge light system, the tower system of the 50th Research Institute of China Electronics Technology Group, etc., have been practically used in many airports at home and abroad. However, the existing systems all use the narrow beam real-aperture antenna mechanical scanning method to image the scene. Although the technology is relatively mature, there are also principle limitations, as follows:

1. Since the irradiation time of the real aperture to the target is in the millisecond level, for "flickering" clutter such as raindrops/snow particles, leaves/grass moving on the runway, birds that occasionally stay, water splashes from raindrops on the runway, etc. Indistinguishable from still images during a scan, there is little immunity to such "flicker" clutter, temporally bursty clutter that stays in the image for the entire scan period. If suppression is to be performed, average suppression must be performed by scanning images of multiple frames, but this increases the processing time and cannot meet the real-time requirements of FOD monitoring. A typical phenomenon of “scintillation” clutter causing the degradation of detection performance is that the detection distance is greatly shortened under rain and snow conditions. CA-2016-01)", its Appendix A gives the results of the evaluation of detection equipment by the US Airport Technology Center of Excellence. The Tarsier system of QinetiQ has been tested in detail. The test results in "Performance Assessment of a Radar-BasedForeign Object Debris Detection System (DOT/FAA/AR-10/33)" show that the detection effect has decreased significantly. The main reason is that Raindrops in the air and water splashes on the ground form clutter in the radar image, which increases the image noise floor, reduces the target SNR, and greatly shortens the detection distance under the same detection performance;

2. The azimuthal resolution of the image in real aperture imaging is determined by the antenna beam width. In order to improve the resolution, the antenna gain is very high, resulting in a strong equivalent isotropic radiated power (EIRP, which is approximately equal to the product of the transmit power and the antenna gain) ), taking the tower-type FOD system of Chengdu Saiying Company as an example, the transmit power is not less than 10dBmW, and the antenna beam width is 2.4°×0.4°, it can be calculated that the gain is about 45.3dBi, and its EIRP is higher than 55.3dBmW or 340W , although there are currently no regulations for the control of FOD radar radio radiation power, such a strong radiation energy may cause potential electromagnetic compatibility problems in the future, bring airborne equipment safety risks, or personnel health risks;

3. To achieve a very narrow beam width in the millimeter-wave frequency band, the processing accuracy of the reflective antenna is extremely high, and the real-aperture imaging also has high requirements for the positional accuracy of the turntable, resulting in a significant increase in the processing cost and the cost of the whole machine. higher.

At present, most of the technical solutions for airport runway detection are based on the working mode of narrow beam antenna real aperture mechanical scanning. The patent CN204515166U provides a FOD monitoring radar technical scheme with a synthetic aperture imaging system. Linear tracks are installed on both sides of the runway, and the car with the radar installed moves along the track to form a synthetic aperture and perform imaging. This method can obtain high-resolution images of the airport runway, and also has the advantages of the above-mentioned synthetic aperture radar system, but the construction scheme of adding tracks on both sides of the runway is complex, difficult to maintain, and difficult to pass approval. Only a few use wide-beam antennas for monitoring. The patent document with the patent number of ZL201210506514.5 discloses an airport runway foreign object detection system. The display control terminal is composed of: the transmitting and receiving antennas are connected with the radar transceiver front end through a waveguide, the radar transceiver front end is connected with a signal processor through a rotating mechanism, and the signal processor is connected with the display control terminal. Aiming at the linear frequency modulation continuous wave system, the invention realizes high distance resolution through broadband linear frequency modulation, and constructs synthetic aperture by realizing the rotation of the semi-circular track of the antenna, thereby realizing high azimuth resolution, reducing the area of the ground clutter unit, and realizing the detection of the runway. Detection of debris small objects. However, there are still many shortcomings, and the measurement results are not accurate enough.

Therefore, there are still deficiencies in the field of foreign body monitoring on the existing airport runways, which need to be improved and improved.

SUMMARY OF THE INVENTION

In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide an airport runway foreign body radar monitoring system, monitoring method and monitoring device, which can realize high-precision detection of foreign bodies on the airport runway on the basis of simple layout.

In order to achieve the above object, the present invention has adopted the following technical solutions:

An airport runway foreign body radar monitoring system, comprising a rotating device and a detection arm device; the detection arm device is installed on the rotating device, and is driven and rotated by the rotating device;

The detection arm device includes a transmitter, a receiver, a frequency synthesizer, a data acquisition module, and a signal processing module; the frequency synthesizer is respectively connected with the transmitter and the receiver; the receiver, the The data acquisition module and the signal processing module are connected in sequence;

The transmitter is connected to a transmitting antenna, and the receiver is connected to a receiving antenna; the transmitting antenna and the receiving antenna are located at the top of the detection arm device; the signal processing module is connected to a computing platform.

Preferably, in the airport runway foreign body radar monitoring system, the signal processing module is connected with the computing platform through a wired or wireless data link.

Preferably, in the airport runway foreign body radar monitoring system, the frequency synthesizer is used to generate a modulated emission waveform;

The modulated emission waveform is a linear frequency modulated continuous wave or a stepped frequency continuous wave or a pseudo-random code modulated signal.

Preferably, in the airport runway foreign body radar monitoring system, the working frequency of the modulated emission waveform is 10-300 GHz.

Preferably, in the airport runway foreign body radar monitoring system, the rotating device includes a rotating mechanism and a servo control module; the servo control module is used to drive the rotating mechanism to rotate, thereby driving the detection arm device to rotate.

An airport runway foreign body radar monitoring method using the airport runway foreign body radar monitoring system, comprising the steps of:

S1. Drive the rotating device to drive the detection arm device to rotate within a predetermined angular range at a predetermined angular velocity; at the same time, send a wide-beam radar signal to the outside at a predetermined transmission frequency through a transmitting antenna, and receive a feedback signal through a receiving antenna; Both the signal and the feedback signal are transmitted to the signal processing module in real time;

S2. The signal processing module mixes the wide-beam radar signal and the feedback signal to obtain a difference frequency signal, and then obtains the radar range image of the target;

S3. The radar range image is processed using a back projection or range Doppler algorithm to obtain a two-dimensional radar image, and a runway foreign object detection result is obtained by performing target detection on the two-dimensional radar range image.

Preferably, in the airport runway foreign object radar monitoring method, in the step S2, the wide-beam radar signal s _T (t) is a linear frequency modulated continuous wave, and its generation expression is:

The feedback signal s _R (τ _m ,t,τ ₀ ,r ₀ ) is:

The target slope distance R(τ _m ) can be expressed as:

where sinβ=H/r ₀

The difference frequency signal after mixing is:

Among them, P is the target point; β is the top view angle from the radar to the target P; H is the vertical height of the antenna turntable relative to the target P; ω is the angular velocity of the antenna rotation; L is the arm length _; The distance to the target P; τ ₀ is the starting time; R(τ _m ) is the instantaneous slope distance between the radar and the target P; τ _m is the slow time, t is the fast time; K _r is the frequency modulation slope, and T _p is the pulse modulation period , f _c is the carrier frequency, and c is the speed of light.

Preferably, in the airport runway foreign object radar monitoring method, in step S3, the specific steps of target detection are:

S31, perform fast-time Fourier transform on the difference frequency signal to obtain the target echo spectrum; the formula of the Fourier transform is:

Among them, the meaning of each item is the same as the above formula, and will not be repeated;

S32, according to the corresponding relationship f=2rK _r /c between the frequency and the target distance, obtain a one-dimensional distance image of the target echo;

S33. According to the stop-and-go hypothesis, the imaging network in the polar coordinate system is delineated for the imaging area, and the radar complex scattering image I(θ, r) of the pixel point (θ, r) corresponds to the one-dimensional range image of each azimuth within the accumulation angle range. The result of phase compensation and coherent accumulation of distance values:

Among them, θ=ω(τ _m -τ ₀ ) is the azimuth angle corresponding to the image pixel (θ, r), and τ ₁ and τ ₂ are the start and end times of the radar irradiation of the pixel point (θ, r) determined by the accumulation angle, respectively;

S34 , a radar image in the form of two-dimensional polar coordinates is obtained, and a FOD detection result is obtained through constant false alarm detection.

An airport runway foreign body radar monitoring device using the airport runway foreign body radar monitoring system, comprising a rotating arm, a counterweight and a bracket; the bracket includes a base and a rotating device, and one end of the rotating device is connected to the base. The other end is equipped with the rotating arm; the rotating arm is divided into a first part and a second part through the connection point with the rotating device, the length of the first part is greater than that of the second part, and the length of the first part is longer than that of the second part. The outer end of the second part is provided with a counterweight, and the outer end of the first part is provided with an antenna bracket;

The rotating arm is adapted to install the detection rotating arm device, wherein the transmitting antenna and the receiving antenna are installed on the antenna support.

Preferably, in the airport runway foreign object radar monitoring device, the elevation angle can be adjusted between the antenna bracket and the rotating arm.

Compared with the prior art, an airport runway foreign body radar monitoring system, monitoring method and monitoring device provided by the present invention have the following beneficial effects:

1) The height and position of the monitoring system are fixed, and normal detection can be realized as long as it is constructed in the form of a side light or a tower;

2) Using the imaging and detection method based on the arc synthetic aperture radar system can effectively reduce the noise interference of scintillation clutter and effectively filter out possible interference items; at the same time, fully consider the height between the detection arm device and the target factor, the spatial position of the target can be determined more quickly, and the detection ability can be improved;

3) The antenna bracket is located at the top of the swivel arm. This position enables the transmitting antenna and the receiving antenna to form as large a circular arc aperture as possible when rotating to improve the detection resolution; at the same time, by controlling the angle of the antenna bracket, it can adapt to different detection environments. , improve the detection ability;

4) The rotation angle is flexible. The rotation angle of the detection arm device can be a fixed angle or 360°, that is, it can be rotated back and forth within a fixed angle range, or it can be rotated back and forth to achieve partial or all-round rotation. monitor.

Description of drawings

1 is a structural block diagram of an airport runway foreign body radar monitoring system provided by the present invention;

Fig. 2 is the structural block diagram of the airport runway foreign body radar monitoring device provided by the present invention;

Fig. 3 is the flow chart of the airport runway foreign body radar monitoring method provided by the present invention;

4 is a schematic diagram of the meaning of each variable in the airport runway foreign body radar monitoring method provided by the present invention;

Fig. 5 is the imaging result (left) and the partial enlarged view of the target (right) obtained by applying the airport runway foreign body radar monitoring method simulation provided by the present invention;

FIG. 6 is an azimuth profile (left) and a range profile (right) for the imaging result in FIG. 5 provided by the present invention.

Detailed ways

In order to make the objectives, technical solutions and effects of the present invention clearer and clearer, the present invention will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.

Please refer to FIG. 1 to FIG. 6 together. The present invention provides an airport runway foreign object radar monitoring system, including a rotating device 1 and a detection arm device 2; the detection arm device 2 is installed on the rotating device 1, Driven to rotate by the rotating device 1;

The detection arm device 2 includes a transmitter 21, a receiver 22, a frequency synthesizer 23, a data acquisition module 24, and a signal processing module 25; the frequency synthesizer 23 is connected to the transmitter 21 and the receiver 22 respectively. connection; the receiver 22, the data acquisition module 24, and the signal processing module 25 are connected in sequence;

The transmitter 21 is externally connected to a transmitting antenna 26, and the receiver 22 is externally connected to a receiving antenna 27; the transmitting antenna 26 and the receiving antenna 27 are located at the top of the detection arm device 2; the signal processing module 25 is connected to the calculation Platform connection.

Specifically, the transmitting antenna 26 and the receiving antenna 27 are radar antennas for transmitting and receiving radar signals; the frequency synthesizer 23 is used for generating a modulated transmit waveform, that is, a preset radar signal, including but not limited to Linear Frequency Modulated Continuous Wave (FMCW), Stepped Frequency Continuous Wave (SFCW); In addition, the modulation waveform generated by the frequency synthesizer 23 is a wide-beam radar signal, its operating frequency is 10-300GHz, range resolution and ranging accuracy Depending on the band bandwidth, the larger the bandwidth, the better the range resolution. The transmitter 21 is used to power amplify the modulated transmit waveform generated by the frequency synthesizer 23 and radiate it out through the transmit antenna 26 ; the receiver 22 is used to transmit the radar echo signal fed by the receive antenna 27 After amplification, down-conversion and intermediate frequency signal conditioning (such as amplification, filtering, etc.) processing, an intermediate frequency signal is obtained, and the intermediate frequency signal is sent to the data acquisition module 24; the data acquisition module 24 converts the intermediate frequency signal into a digital signal The signal is output to the signal processing module 25. Of course, at the same time, the data acquisition module 24 synchronously converts the modulated emission waveform generated by the frequency synthesizer 23 into a digital signal and sends it to the signal processing module 25; The signal processing module 25 completes arc synthetic aperture imaging and change detection according to the modulated emission waveform and the radar echo signal, so as to realize target positioning. It should be noted that the airport runway foreign body radar monitoring system provided by the present invention uses the method of arc synthetic aperture to realize the detection of airport runway foreign bodies. Generally, the conventional method of arc aperture can be used, which is not specifically limited. The rotation device 1 drives the detection arm device 2 to rotate, thereby realizing the synthesis of the arc synthetic aperture. Here, the internal structure of the rotating device 1 is not limited, and is a commonly used rotating structure in the field, as long as the detection arm device 2 can be driven to rotate at a predetermined angular velocity, and orientation or orientation can be achieved within a certain angular orientation. Just turn it back and forth. Preferably, the transmitting antenna 26 and the receiving antenna 27 are both low-gain antennas, preferably antennas with a gain of 10-20 dBi, more preferably antennas with a gain of 12 dBi.

As a preferred solution, in this embodiment, the signal processing module 25 is connected to the computing platform through a wired or wireless data link. Specifically, after the signal processing module 25 processes the corresponding data and obtains the target positioning data, it can output the corresponding result obtained. In this embodiment, the result data is output to the computing platform through a wired or wireless data link. , for use by the computing platform. The wired data link is preferably an RJ45 network connection line; the wireless data link is preferably a WiFi network connection and a 3G/4G/5G network connection. The computing platform includes computing devices such as computers and servers, which are not specifically limited.

Correspondingly, the present invention also provides an airport runway foreign body radar monitoring system using the airport runway foreign body radar monitoring system, comprising a rotating arm 10, a counterweight 30 and a bracket 20; the bracket 20 includes a base 202 and a rotating Device 1, one end of the rotating device 1 is connected to the base 202, and the other end is equipped with the rotating arm 10; the rotating arm 10 is divided into a first part and a second part through the connection point with the rotating device 1 part, the length of the first part is longer than that of the second part, and the outer end of the second part is equipped with a counterweight, so that the center of gravity of the rotating arm is as close as possible to the connection position with the rotating mechanism, The top of the outer end of the first part is provided with an antenna bracket 101; the detection arm device 2 is internally arranged in the arm 10, and the arm 10 has an external communication interface, so that the detection arm device 2. It can be communicated and connected with the background computing platform; the rotating device 1 is arranged in the bracket 20, and is used to drive the rotating arm 10 to rotate;

The rotating arm 10 is adapted to install the detecting rotating arm 10 device, wherein the transmitting antenna 26 and the receiving antenna 27 are installed on the antenna bracket 101 .

Specifically, the transmitting antenna 26 and the receiving antenna 27 are installed on the antenna support 101 and irradiate in a direction away from the axis of the rotating structure, which is the first part of the rotating arm 10 in this embodiment. The outer end; the antenna bracket 101 is installed on the outer end of the swivel arm 10, and the adjustment of the pitch angle can be automatically or manually controlled; the rotating mechanism 11 can be a pulse motor, or other motors and a rotation limit device are combined to install , the specific implementation is a common technical means in the field, and is not limited; the rotating device 1 drives the rotating arm 10 to rotate around the axis of the rotating device 1 . The counterweight 30 is used to transfer the center of gravity of the rotating arm 10 to the position of the axis of the rotating structure, and the wall surface is swayed positively. The rotating device 1 is installed on the base 202, and the base 202 is fixed on an iron frame or a cement table. The height of the installation position of the base 202 is not limited, and is set according to the installation requirements of the specific site. . Meanwhile, the longer the arm 10 is, the higher the azimuth resolution, that is, the better the target azimuth resolution. The radar monitoring device provided by the present invention can be installed in a tower type or a side lamp type, and the working principle is the same, as long as different operating frequencies and the length of the jib 10 are set according to the requirements, the details are as follows:

When a tower-type equipment is formed, a longer arm is generally used according to the range of the area to be detected. At this time, the circular arc generated at this time has a longer aperture and higher angular resolution, which is suitable for long-distance detection of FOD targets;

When the edge light type equipment is formed, it is generally used to detect the area according to the need, using a shorter arm and a higher working frequency, the overall size of the equipment is smaller, and it is suitable for installation on both sides of the runway.

As a preferred solution, in this embodiment, the elevation angle between the antenna support 20 and the rotating arm 10 can be adjusted. That is, the antenna bracket 20 can adjust the elevation angle within a certain angle range at the installation position, and the adjustable range is 0-90°, and the preferred elevation angles are 0°, 45°, and 90°. In the case of accurate detection, a wider range of detection is performed. The elevation angle is the angle formed by the antenna body and the plane perpendicular to the ground above the antenna installation position.

Preferably, the base 202 is a telescopic device, and the height can be adjusted according to the instructions of the computing platform. At the same time, after determining the final height of the bracket 20 , the computing platform transmits the height data to the signal processing module 25 .

As a preferred solution, in this embodiment, the rotating device 1 includes a rotating mechanism 11 and a servo control module 12; the servo control module 12 is used to drive the rotating mechanism 11 to rotate, thereby driving the detection arm device 2 to rotate .

As a preferred solution, in this embodiment, the servo control module 12 can be built in the base 202 for controlling the rotation mechanism 11 to operate normally.

Specifically, the servo control module 12 is preferably an MCU (Microcontroller Unit; Micro Control Unit), which can drive the rotating mechanism 11 to work according to a predetermined or instructed, and drive the rotating arm 10 to rotate according to a predetermined angular range and angular velocity, while determining The detection duration within a certain detection range, whether to stop, etc.; preferably, the servo control module 12 is connected to the computing platform, and drives the rotating structure to work according to the instructions of the computing platform. The rotating mechanism 11 includes a rotating motor (preferably a DC motor or a pulse motor), a rotating connector (for connecting with the rotating arm 10, and rotating to drive the rotating arm 10 to rotate), and a limiting device (for limiting the rotating arm 10). 10 rotation range, rotation within a fixed angle range or 360° rotation), cooperate with the drive arm 10 to rotate. Here, it should be noted that, in terms of the detection accuracy of the target, the slower the angular velocity of the rotating arm 10 is, the longer the two radar antennas in the same direction stay, because the residual object will stay for a short time. After disappearing, the accurate distinction of the persistent object or the target object can be achieved.

Correspondingly, please refer to FIG. 3 to FIG. 4 emphatically, the present invention provides an airport runway foreign body radar monitoring method using the airport runway foreign body radar monitoring system, including the steps:

S1, drive the rotating device 1 to drive the detection arm device 2 to rotate within a predetermined angular range at a predetermined angular velocity; at the same time, send the wide-beam radar signal to the outside through the transmitting antenna 26 at a predetermined transmitting frequency, and receive the feedback signal through the receiving antenna 27; Both the wide-beam radar signal and the feedback signal are transmitted to the signal processing module 25 in real time;

S2. The signal processing module 25 mixes the wide-beam radar signal and the feedback signal to obtain a difference frequency signal, and then obtains the radar range image of the target;

S3. The radar range image is processed using a back projection or range Doppler algorithm to obtain a two-dimensional radar image, and a runway foreign object detection result is obtained by performing target detection on the two-dimensional radar range image.

Specifically, the operation of mixing the wide-beam radar signal and the feedback signal may be a common operation process in the art, or other mixing technologies may be used, which is not specifically limited;

As a preferred solution, in this embodiment, the frequency synthesizer is used to generate a modulated transmit waveform;

The modulated emission waveform is a linear frequency modulated continuous wave or a stepped frequency continuous wave or a pseudo-random code modulated signal. The three modulation emission waveforms described herein are all commonly used modulation waveforms in the art, and will not be described in detail.

As a preferred solution, in this embodiment, the operating frequency of the modulated emission waveform is 10-300 GHz

As a preferred solution, in this embodiment, in the step S2, the wide-beam radar signal s _T (t) is a chirp continuous wave, and its generation expression is:

The feedback signal s _R (τ _m ,t,τ ₀ ,r ₀ ) is:

The target slope distance R(τ _m ) can be expressed as:

where sinβ=H/r ₀

The difference frequency signal after mixing is:

Among them, P is the target point; β is the top view angle from the radar to the target P; H is the vertical height of the antenna turntable (that is, the detection arm device) relative to the target P; ω is the angular velocity of the antenna rotation; L is the arm length; r ₀ is the distance from the center of the rotation axis of the arm to the target P; τ ₀ is the starting time; R(τ _m ) is the instantaneous slope distance between the radar and the target P; τ _m is the slow time, t is the fast time; k _r is the frequency modulation slope , T _p represents the pulse modulation period, f _c represents the carrier frequency, R(τ _m ) represents the real distance of the target, and c represents the speed of light. It should be noted that, in the monitoring method provided by the present invention, the vertical height of the detection arm device relative to the target P is fully considered, the three-dimensional spatial position of the target can be determined more accurately, and the positioning accuracy can be improved. The conventional FOD detection radar imaging measurement method does not introduce the height parameter of the detection arm device, which will cause a distance error, so that the phase of the obtained two-dimensional radar image does not match the actual, resulting in defocusing of the image, which in turn causes signal noise. The ratio decreases, which affects the detection of weak targets. For example, when the height of the tower-type radar monitoring device is 5 meters, the distance error to the target at 150 meters is 83 mm, which is much larger than the phase error required by the two-dimensional radar image, which is less than 1/8 wavelength (relative to 90~ The W-band signal of 110GHz is 0.375mm); when the height parameter of the radar monitoring device is introduced into the measurement method, and the control height error is controlled to 1 cm (easy to achieve when using laser ranging), the error of the target distance is less than 0.333 mm, to meet the imaging accuracy requirements.

表示距离所对应的相位

其中第二项

表示回波的多普勒效应，这是进行方位向脉压所必须处理的，第三项

是解线性调频方法所特有，称为剩余视频相位，两者均需在成像过程中进行补偿。In the above mixing calculation process, in one cycle of the beat frequency signal, R(τ _m ) is a constant, and the first term in the beat frequency signal formula

represents the phase corresponding to the distance

the second of which

Represents the Doppler effect of the echo, which must be dealt with for the azimuth pulse pressure, the third term

is specific to the dechirp method and is called residual video phase, both of which need to be compensated during the imaging process.

As a preferred solution, in this embodiment, in step S3, the specific steps of target detection are:

S31, perform fast-time Fourier transform on the difference frequency signal to obtain the target echo spectrum; the formula of the Fourier transform is:

Among them, each factor in the formula is consistent with the content represented in the above formula, and will not be repeated;

S32, according to the corresponding relationship f=2rK _r /c between the frequency and the target distance, obtain a one-dimensional distance image of the target echo;

S33. According to the stop-and-go hypothesis, the imaging network in the polar coordinate system is delineated for the imaging area, and the radar complex scattering image I(θ, r) of the pixel point (θ, r) corresponds to the one-dimensional range image of each azimuth within the accumulation angle range. The result of phase compensation and coherent accumulation of distance values:

Among them, θ=ω(τ _m -τ ₀ ) is the azimuth angle corresponding to the image pixel (θ, r), and τ ₁ and τ ₂ are the start and end times of the radar irradiation of the pixel point (θ, r) determined by the accumulation angle, respectively;

S34 , a radar image in the form of two-dimensional polar coordinates is obtained, and a FOD detection result is obtained through constant false alarm (CFAR) detection. The constant false alarm detection is a commonly used detection method in the field, and is not limited.

Please refer to Fig. 5-Fig. 6 emphatically, among them, the setting parameters of the simulated airport runway foreign object radar monitoring system are shown in Table 1:

Table 1 Circular synthetic aperture FOD monitoring radar parameters

project index Frequency Range 94～96GHz bandwidth 2GHz Arm radius 0.1 meters Arm speed 2 seconds/week radar repetition rate 1kHz Antenna beamwidth (3dB) 40°×6°(azimuth x pitch) Antenna gain 21dBi transmit power 0.2W Receiver noise figure Not more than 9dB maximum target distance 100 metres target scattering intensity -40dB㎡

The obtained imaging results are shown in Figure 5 and Figure 6, and the imaging indicators that can be obtained are shown in Table 2:

Table 2 Arc synthetic aperture FOD monitoring radar simulation imaging index

project index Distance Resolution (Windowed) 0.1 meters Distance accuracy 0.003m Azimuth resolution 1.36° Azimuth resolution (at maximum distance) 2.37 meters Azimuth accuracy 0.045° Positioning accuracy (at maximum distance) 0.08m Receiver sensitivity -94dBmW target signal-to-noise ratio 33dBc

To sum up, the use of the arc synthetic aperture imaging system in the foreign object radar monitoring method of the airport runway provided by the present invention is a method by moving the low-gain antenna along a certain trajectory, and using the synthetic aperture imaging algorithm to make the real aperture antenna on the trajectory "virtual". " is a method to achieve high-resolution imaging with a synthetic aperture size up to the trajectory length. Has the following technical effects:

1. For "flicker" clutter, the use of arc synthetic aperture imaging is to coherently stack hundreds to thousands of image sequences, and the clutter energy of several frames of images that appear in "flicker" clutter is suppressed and will not form. "Noise" in the image, so it has a good suppression effect on "flicker" clutter, and it can be expected that it will be significantly better than the conventional real aperture scanning system in terms of environmental adaptability;

2. Low-gain antennas help to reduce EIRP (equivalent isotropically radiated power), so that it is easy to meet future electromagnetic compatibility and human safety requirements. For example, if an antenna with a gain of 12dBi is used, the above 10dBm transmit power is still used. , its EIRP is 160mW, which is even lower than most mobile phone radiation;

3. The price of low-gain antennas is low, and the average accumulation characteristics of synthetic aperture imaging make the requirement for the repeatability of the turntable not high (simulation found that the positioning position jitter does not exceed 20% of the stepping angle, and the imaging has no deterioration effect), so it can be Reduce manufacturing and maintenance costs.

It can be understood that for those of ordinary skill in the art, equivalent replacements or changes can be made according to the technical solutions of the present invention and the inventive concept thereof, and all these changes or replacements should belong to the protection scope of the appended claims of the present invention.

Claims (10)

1. A radar monitoring system for foreign matters on an airport runway is characterized by comprising a rotating device and a detection rotating arm device; the detection rotating arm device is arranged on the rotating device and is driven to rotate by the rotating device;

the detection rotating arm device comprises a transmitter, a receiver, a frequency synthesizer, a data acquisition module and a signal processing module; the frequency synthesizer is respectively connected with the transmitter and the receiver; the receiver, the data acquisition module and the signal processing module are sequentially connected;

the transmitter is externally connected with a transmitting antenna, and the receiver is externally connected with a receiving antenna; the transmitting antenna and the receiving antenna are positioned at the top end of the detection rotating arm device; the signal processing module is connected with the computing platform.

2. An airport runway foreign object radar monitoring system as claimed in claim 1 wherein the signal processing module is connected to the computing platform by a wired or wireless data link.

3. An airport runway foreign object radar monitoring system as claimed in claim 1 wherein the frequency synthesizer is adapted to generate a modulated transmit waveform;

the modulation emission waveform is a linear frequency modulation continuous wave or a stepping frequency continuous wave or a pseudo random code modulation signal.

4. The radar monitoring system for foreign matter on airport runways of claim 3, wherein the operating frequency of said modulated transmit waveform is 10-300 GHz.

5. An airport runway foreign object radar monitoring system as claimed in claim 1 wherein the rotating means includes a rotating mechanism and a servo control module; the servo control module is used for driving the rotating mechanism to rotate so as to drive the detection rotating arm device to rotate.

6. An airport runway foreign object radar monitoring method using the airport runway foreign object radar monitoring system of any of claims 1-5, comprising the steps of:

s1, driving the rotating device to drive the detection rotating arm device to rotate in a preset angle range at a preset angular speed; meanwhile, a wide-beam radar signal is transmitted outwards through a transmitting antenna at a preset transmitting frequency, and a feedback signal is received through a receiving antenna; transmitting the wide-beam radar signal and the feedback signal to a signal processing module in real time;

s2, the signal processing module mixes the wide-beam radar signal with the feedback signal to obtain a difference frequency signal, and then a radar range profile of a target object is obtained;

and S3, processing the radar range profile by using a back projection or a range-Doppler algorithm to obtain a two-dimensional radar image, and performing target detection on the two-dimensional radar range profile to obtain a runway foreign matter detection result.

7. The radar monitoring method for foreign objects on airport runways according to claim 6, wherein in said step S2, said wide beam radar signal S_T(t) is a chirped continuous wave, which yields the expression:

the feedback signal s_R(τ_m,t,τ₀,r₀) Comprises the following steps:

target slope distance R (tau)_m) Can be expressed as:

wherein sin β ═ H/r₀

The difference frequency signal after frequency mixing is:

wherein P is a target point, β is a depression angle from the radar to the target P, H is a vertical height of the antenna turntable relative to the target P, omega is an angular velocity of the antenna rotation, L is a length of a rotating arm, r₀The distance from the center of the rotating shaft of the rotating arm to the target P; tau is₀Is the starting time; r (tau)_m) Is the instantaneous slope distance of the radar and the target P; tau is_mIs slow time, t is fast time; k_rRepresenting the chirp rate, T_pRepresenting the pulse modulation period, f_cRepresenting the carrier frequency and c the speed of light.

8. The radar monitoring method for foreign objects on airport runways according to claim 6, wherein in step S3, the specific steps of target detection are:

s31, carrying out fast time Fourier transform on the difference frequency signal to obtain a target echo frequency spectrum;

s32, obtaining a correspondence f-2 rK between the frequency and the target distance_rObtaining a one-dimensional range profile of the target echo;

s33, according to the stop-go hypothesis, an imaging network under a polar coordinate system is defined for an imaging area, and the radar complex scattering image I (theta, r) of a pixel point (theta, r) is a result of coherent accumulation after phase compensation is carried out on corresponding distance values of each azimuth one-dimensional distance image in an accumulation angle range:

where θ ═ ω (τ)_m-τ₀) Is the azimuth angle, tau, corresponding to the image pixel (theta, r)₁And τ₂Radar irradiation start-stop moments of the pixel points (theta, r) determined for the accumulation angles respectively;

and S34, obtaining a radar image in a two-dimensional polar coordinate form, and obtaining an FOD detection result through constant false alarm detection.

9. An airport runway foreign object radar monitoring device using the airport runway foreign object radar monitoring system of any of claims 1-5, comprising a radial arm, a weight block and a bracket; the bracket comprises a base and a rotating device, one end of the rotating device is connected with the base, and the other end of the rotating device is provided with the rotating arm; the swing arm is divided into a first part and a second part through a connection point of the swing arm and the rotating device, the length of the first part is larger than that of the second part, a counterweight is arranged at the outer end of the second part, and an antenna bracket is arranged at the outer end of the first part;

the spiral arm is matched with the detection spiral arm device, wherein the transmitting antenna and the receiving antenna are arranged on the antenna bracket.

10. An airport runway foreign object radar monitoring device as claimed in claim 9 wherein the elevation angle between the antenna mount and the radial arm is adjustable.

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