A combined detection method for microwave thermal radiation and electromagnetic scattering of sea surface targets

Abstract

The present invention relates to a method for jointly detecting microwave thermal radiation and electromagnetic scattering of sea surface targets, which includes the following steps: Step 1: Use the spaceborne microwave radiation passive detection subsystem to obtain the brightness temperature image of the sea surface target, realize the wide-area search of the sea surface target, and at the same time conduct a rough classification of the target, obtain the position information of the sea surface target, and send it to the spaceborne microwave radiation active detection subsystem; Step 2: The spaceborne microwave active detection subsystem in the shutdown state, after receiving the target information from the spaceborne microwave radiation passive detection subsystem, adjusts the satellite attitude, and immediately shuts down after completing the SAR imaging of the indicated target; Step 3: Process the microwave radiation image and SAR image of the target through a fusion and mining method to realize the refined recognition and situation awareness of the target. The present invention realizes the refined recognition of sea surface targets to meet the urgent needs of all-weather, all-day, concealed detection and refined recognition of sea surface targets in the open sea and the high seas.

Description

Technical Field

[0001] The present invention relates to a method for jointly detecting microwave thermal radiation and electromagnetic scattering of sea surface targets, belonging to the field of space microwave remote sensing technology. Background Art

[0002] For the detection of important targets on the open sea and the high seas, the space-based platform is currently the best platform for detecting important targets on the open sea and the high seas due to its advantages of "standing high and seeing far". The main means of detecting sea surface targets based on the space-based platform include visible light, infrared, active radar, electronic reconnaissance, and AIS (automatic identification systems).

[0003] However, the existing detection means face major challenges for all-weather and all-day detection of sea surface targets. Space-based visible light and infrared detection means are easily affected by bad marine weather such as clouds, fog, and rainfall, and visible light can only work during the day when there is sunlight.

[0004] Space-based active radar detection means are easily affected by sea clutter, and need to actively emit signals, with high power consumption, short effective working time in orbit (about ten minutes per orbit), poor concealment, vulnerable to electromagnetic interference, and it is difficult to balance high resolution and wide swath.

[0005] Space-based electronic reconnaissance requires sea surface targets to actively emit electromagnetic signals, and it is helpless when sea surface targets are in electromagnetic silence; AIS is for sea surface targets to actively emit positioning signals, which are easily deceived and the actively emitted signals can be cut off at any time. Summary of the Invention

[0006] The technical problem solved by the present invention is: overcoming the deficiencies of the prior art, a method for jointly detecting microwave thermal radiation and electromagnetic scattering of sea surface targets is proposed. By using a space-based high-resolution microwave thermal radiation passive detection system, wide-area search and rough classification of sea surface targets are realized, guiding a high-resolution space-based active detection system (synthetic aperture radar or phased array radar) to achieve refined detection of important sea surface targets, and jointly using the microwave thermal radiation characteristics and scattering characteristics of the targets to achieve refined identification of important sea surface targets, so as to meet the urgent needs of all-weather, all-day, concealed detection and refined identification of sea surface targets on the open sea and the high seas.

[0007] The solution to solve the technology of the present invention is:

[0008] A method for jointly detecting microwave thermal radiation and electromagnetic scattering of sea surface targets, comprising the following steps:

[0009] Step 1: Use the spaceborne microwave radiation passive detection subsystem to obtain the bright temperature image of the sea surface target, realize the wide-area search of the sea surface target, and at the same time conduct a rough classification of the target, obtain the position information of the sea surface target, and send it to the spaceborne microwave radiation active detection subsystem;

[0010] Step 2: After receiving the target information from the spaceborne microwave radiation passive detection subsystem, the spaceborne microwave active detection subsystem in the shutdown state adjusts the satellite attitude, completes the SAR imaging of the indicated target, and then shuts down immediately;

[0011] Step 3: Process the microwave radiation image and SAR image of the target through a fusion and mining method to realize the refined recognition and situation awareness of the target.

[0012] Furthermore, the spaceborne microwave radiation passive detection subsystem of the sea surface target is a synthetic aperture microwave radiation passive detection system, and its array configuration adopts any one of Y-shaped, T-shaped, cross-shaped or distributed.

[0013] Furthermore, the spaceborne microwave active detection subsystem of the sea surface target is a synthetic aperture radar or a phased array radar, which can obtain high-resolution SAR imaging of the sea surface target.

[0014] Furthermore, refine the recognition of the sea surface target by establishing a complete sea surface target database or use neural network and deep learning methods to realize the refined recognition of the sea surface target.

[0015] Furthermore, the spaceborne microwave radiation passive detection subsystem of the sea surface target uses the difference in microwave thermal radiation bright temperature images between the sea surface target and the sea surface background to realize the effective detection of the sea surface target, and uses the microwave thermal radiation bright temperature characteristics of different sea surface targets to conduct a rough classification of the sea surface target.

[0016] Furthermore, the spaceborne microwave radiation passive detection subsystem of the sea surface target includes an antenna array, a receiver and a correlator.

[0017] The antenna array receives the microwave thermal radiation signals radiated from the sea surface target and the sea surface scene, and outputs the signals received by the antenna to the receiver. The receiver performs low-noise amplification, filtering, down-conversion, intermediate-frequency amplification, and intermediate-frequency filtering on the received signals, and outputs intermediate-frequency signals;

[0018] Output the intermediate-frequency signals to the correlator to complete A / D quantization, IQ separation, and pairwise cross-correlation of the signals to obtain the normalized correlation coefficient;

[0019] Through error correction and calibration of the normalized correlation coefficient, bright temperature image reconstruction, target detection and rough classification, obtain the rough position, speed and heading information of the target.

[0020] Furthermore, the spaceborne microwave active detection subsystem for sea surface targets is based on a spaceborne platform. It uses the actively transmitted signal to obtain the scattered echo of sea surface targets. Based on the ability to generate ultra-wideband linear frequency modulation signals and the ability to achieve extremely large synthetic apertures in the azimuth direction, it ensures the range and azimuth resolutions and realizes the effective detection of sea surface targets.

[0021] Furthermore, the spaceborne microwave active detection subsystem for sea surface targets includes a frequency modulation source, a system controller, a TR module, a data acquisition and processor, and an internal calibrator.

[0022] The frequency modulation source generates the required low-power linear frequency modulation signal under the control of the system controller. This signal is up-converted and power-amplified, and then supplied to the H and V polarization transmitting antennas through the RF front end of the TR module.

[0023] The antenna feeds the signal to the observation area, and the received H and V polarization reflection / scattering echoes in the observation area are sent to the receiver through the internal calibrator.

[0024] The receiver down-converts the RF echo signal to the intermediate frequency. The data acquisition and processor band-pass samples and quantizes the analog intermediate frequency signal into a digital signal, and then sends it to the data transmission subsystem after preprocessing.

[0025] The internal calibrator couples a part of the power of the transmitter into the receiver to form a closed loop, thereby realizing internal calibration, eliminating the measurement errors caused by the changes in the transceiver system, and correcting the amplitude-phase distortion errors of the transceiver system as a reference calibration signal.

[0026] The data transmission system sends the on-board raw data to the ground imaging processor for SAR imaging processing, obtains the target SAR image and position information, extracts the electromagnetic characteristic information of the scattering cross-section and scattering phase of the target, performs image display, and stores the echo and imaging data.

[0027] Furthermore, the fusion and mining method is as follows: fuse the target information and brightness temperature image obtained by the spaceborne microwave thermal radiation passive detection subsystem for sea surface targets and the target information and SAR image obtained by the spaceborne microwave active detection subsystem for sea surface targets to realize the refined recognition and situation awareness of important sea surface targets.

[0028] The beneficial effects of the present invention compared with the prior art are as follows:

[0029] (1) The present invention uses the spaceborne high-resolution microwave thermal radiation passive detection system to realize the wide-area search and rough classification of sea surface targets, and guides the high-resolution spaceborne active detection system (synthetic aperture radar) to realize the refined detection of sea surface targets.

[0030] (2) The present invention realizes the refined recognition of sea surface targets by combining the microwave thermal radiation characteristics and scattering characteristics of the targets, so as to meet the urgent needs for all-weather, all-day, concealed detection and refined recognition of sea surface targets in the open sea and the high seas. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a schematic diagram of the spaceborne microwave thermal radiation and electromagnetic scattering joint detection system for sea surface targets;

[0032] Figure 2 is the spaceborne microwave passive detection subsystem for sea surface targets;

[0033] Figure 3 is the spaceborne microwave active detection subsystem for sea surface targets;

[0034] Figure 4 is the brightness temperature image of the sea surface detected by the spaceborne microwave passive detection subsystem;

[0035] Figure 5 is the radiation brightness temperature image of a certain sea surface target after rough classification by the spaceborne microwave passive detection subsystem;

[0036] Figure 6 is the spaceborne microwave passive detection subsystem for Figure 5 the SAR image obtained by detecting the sea surface target in;

[0037] Figure 7 is to identify using the spaceborne microwave thermal radiation and electromagnetic scattering joint detection method for sea surface targets Figure 5 and Figure 6 targets. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] The present invention will be further described below in conjunction with embodiments.

[0039] As Figures 1-3 shown, the spaceborne microwave thermal radiation and electromagnetic scattering joint detection system for sea surface targets includes a spaceborne microwave passive detection subsystem for sea surface targets and a spaceborne microwave active detection subsystem for sea surface targets.

[0040] The spaceborne microwave thermal radiation passive detection subsystem for sea surface targets adopts the synthetic aperture microwave radiation passive detection technology to obtain as high a spatial resolution as possible. The spaceborne microwave thermal radiation passive detection technology for sea surface targets mainly realizes the effective detection of sea surface targets by using the difference in the microwave thermal radiation brightness temperature images between sea surface targets and sea surface backgrounds, and realizes the rough classification of sea surface targets by using the microwave thermal radiation brightness temperature characteristics of different sea surface targets. The hardware of the spaceborne microwave thermal radiation passive detection subsystem for sea surface targets mainly consists of an antenna array, a receiver channel, a correlation processor and a control power distributor, and the software processing flow includes error correction and calibration, brightness temperature image reconstruction, target detection and rough classification.

[0041] For the space-based passive microwave thermal radiation detection subsystem of sea surface targets, first, the antenna array receives the microwave thermal radiation signals radiated from sea surface targets and sea surface scenes; subsequently, the signals received by the antenna are output to the receiver, and the receiver performs low-noise amplification, filtering, down-conversion, intermediate-frequency amplification, and intermediate-frequency filtering on the received signals and outputs intermediate-frequency signals; then, the intermediate-frequency signals are output to the correlator to complete A / D quantization, IQ separation, and pairwise cross-correlation of signals to obtain the normalized correlation coefficient; finally, by performing error correction and calibration on the normalized correlation coefficient, bright temperature image reconstruction, target detection and rough classification, important information such as the rough position, speed, and heading of the target is obtained.

[0042] The space-based active microwave detection subsystem of sea surface targets mainly uses synthetic aperture radar detection technology. It is mainly based on a spaceborne platform and uses the actively transmitted signals to obtain the scattered echoes of sea surface targets. Based on the ability to generate ultra-wideband linear frequency modulation signals and the ability to achieve an extremely large synthetic aperture in the azimuth direction, it ensures the range and azimuth resolutions and realizes the effective detection of sea surface targets. The hardware of the system consists of a data processor, a radio frequency channel, an internal calibrator, a TR module, and an SAR antenna. Among them, the data processor includes a control power distributor, a frequency modulation source, a collector and a memory; the radio frequency channel includes a frequency source, an up-converter, and a down-converter; the internal calibrator includes multiple electronic switches and mainly completes the switching of transmitted signals, received signals, and internal calibration signals; the TR module includes a power amplifier, a circulator, and a coupler, and the SAR antenna includes an H polarization module and a V polarization module.

[0043] For the space-based active microwave detection subsystem of sea surface targets, first, the frequency modulation source generates the required low-power linear frequency modulation signal under the control of the system controller. This signal is up-converted and power-amplified and supplied to the H and V polarization transmitting antennas through the radio frequency front end of the TR module.

[0044] The antenna feeds the signal to the observation area, and then the received H and V polarization reflection / scattering echoes in the observation area are sent to the receiver through the calibration unit. The receiver down-converts the radio frequency echo signal to the intermediate frequency, and the data acquisition and processor band-pass samples and quantizes the analog intermediate frequency signal into a digital signal, and then sends it to the data transmission subsystem after preprocessing.

[0045] The internal calibrator couples a part of the power of the transmitter into the receiver to form a closed loop, thereby realizing internal calibration, eliminating the measurement errors caused by the changes of the transceiver system, and using it as a reference calibration signal to correct the amplitude-phase distortion errors of the transceiver system.

[0046] Then, the original data on the aircraft is sent to the ground imaging processor for SAR imaging processing to obtain information such as the target SAR image and position, and extract key electromagnetic characteristic information such as the scattering cross-section and scattering phase of the target for image display. Finally, the echoes and imaging data are stored and managed.

[0047] The combined detection method of microwave thermal radiation and electromagnetic scattering for sea surface targets is as follows:

[0048] Step 1: Utilize the spaceborne microwave thermal radiation passive detection subsystem of sea surface targets, which has the ability of wide-area stealth detection, to achieve wide-area search of sea surface targets, obtain important information such as the rough position, target heading, and target speed of sea surface targets, and at the same time achieve rough classification of sea surface targets based on the microwave thermal radiation brightness temperature characteristics of sea surface targets. The spaceborne microwave radiation thermal radiation passive detection subsystem of sea surface targets transmits the rough position, heading, speed and other important information of the important sea surface targets obtained by rough classification to the spaceborne microwave active detection subsystem of sea surface targets through the inter-satellite link to instruct it to conduct a detailed inspection.

[0049] Step 2: The spaceborne microwave active detection subsystem of sea surface targets remains silent without emitting any signals when it does not receive any instructions. When receiving the position information of the sea surface target transmitted by the spaceborne microwave active detection subsystem of sea surface targets, the satellite platform of the spaceborne microwave active detection subsystem of sea surface targets calculates the best detection plan for the sea surface target, and the spaceborne microwave active detection subsystem of sea surface targets immediately powers on and sequentially realizes effective detection of the sea surface target according to the planned detection route plan, obtains the high-resolution SAR image of the sea surface target, obtains the position information of important targets, etc., and immediately powers off after detection.

[0050] Step 3: Integrate the target information and brightness temperature image obtained by the spaceborne microwave thermal radiation passive detection subsystem of sea surface targets and the target information and SAR image obtained by the spaceborne microwave active detection subsystem of sea surface targets to achieve refined recognition and situation awareness of important sea surface targets. Thus, ultimately achieve effective detection and refined recognition of sea surface targets in the open sea and ocean under harsh marine environments such as low visibility and complex sea conditions.

[0051] Example of the combined detection method of microwave thermal radiation and electromagnetic scattering for sea surface targets

[0052] Step 1: The spaceborne microwave radiation passive detection subsystem passively receives the microwave thermal radiation signal of the sea surface, conducts wide-area search of the sea surface, obtains the microwave radiation brightness temperature image of the sea surface target, as shown in Figure 4 ; At the same time, the spaceborne microwave radiation passive detection subsystem uses the target rough classification method to conduct rough classification of the sea surface target, extracts the microwave radiation brightness temperature image of the target of interest, as shown in Figure 5 ; At the same time, obtain key information such as the position, heading, and speed of the target, and send the relevant information to the spaceborne microwave active detection subsystem.

[0053] Step 2: When the spaceborne microwave active detection subsystem does not receive the target information from the spaceborne microwave passive detection subsystem, it remains in the shutdown state all the time. After receiving the target information sent by the spaceborne microwave passive detection subsystem, the satellite adjusts its attitude to align with the direction where the sea surface target is located, turns on the active radar, emits detection signals, and obtains a high-resolution SAR image of the target, as Figure 6 shown; after completing the active imaging tasks for all sensitive targets, the active detection system immediately shuts down.

[0054] Step 3: Utilize the microwave thermal radiation brightness temperature image of the sea surface target obtained by the spaceborne microwave passive detection subsystem and the SAR image of the sea surface target obtained by the spaceborne microwave active detection means to mine the information of the microwave thermal radiation brightness temperature image and SAR image of the sea surface target, including important information such as the aspect ratio of the target, the quantitatively determined brightness temperature information of the target, and the SAR image of the target, so as to achieve the refined recognition and situation awareness of the sea surface target. For example, through the in-depth mining of the Figure 5 microwave radiation brightness temperature image and the Figure 6 SAR image, it is identified that the target is an oil tanker target on the sea surface, as Figure 7 shown.

[0055] The above-mentioned spaceborne microwave thermal radiation and electromagnetic scattering joint detection system and method for sea surface targets conceived by the present invention can provide a new and feasible technical approach for the all-weather, all-day, and stealthy detection and refined recognition of sea surface targets in the open sea and the high seas.

[0056] Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modification, equivalent change, and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention all fall within the protection scope of the technical solution of the present invention.

Claims

1. A combined detection method for microwave thermal radiation and electromagnetic scattering of sea surface targets, characterized in that, it includes the following steps: Step 1: Use the spaceborne microwave radiation passive detection subsystem to obtain the bright temperature image of the sea surface target, that is, the microwave radiation image, to achieve wide-area search of the sea surface target, obtain the sea surface target acquired by the spaceborne microwave thermal radiation passive detection subsystem, and at the same time conduct rough classification of the target, obtain the position information of the sea surface target, denoted as the target information acquired by the spaceborne microwave thermal radiation passive detection subsystem, and send it to the spaceborne microwave active detection subsystem; Step 2: The spaceborne microwave active detection subsystem in the shutdown state, after receiving the target information acquired by the spaceborne microwave radiation passive detection subsystem, as the target information acquired by the spaceborne microwave active detection subsystem, adjusts the satellite attitude, completes SAR imaging of the indicated target, obtains the SAR image, and then immediately shuts down; Step 3: Process the microwave radiation image and SAR image of the target through a fusion and mining method to achieve refined recognition and situation awareness of the target.

2. A combined detection method for microwave thermal radiation and electromagnetic scattering of sea surface targets according to claim 1, characterized in that, the spaceborne microwave radiation passive detection subsystem of the sea surface target is a synthetic aperture microwave radiation passive detection system, and its array configuration adopts any one of Y-shaped or T-shaped or cross-shaped or distributed.

3. A combined detection method for microwave thermal radiation and electromagnetic scattering of sea surface targets according to claim 1, characterized in that, the spaceborne microwave active detection subsystem of the sea surface target is a synthetic aperture radar or a phased array radar, which is used to obtain high-resolution SAR imaging of the sea surface target.

4. A combined detection method for microwave thermal radiation and electromagnetic scattering of sea surface targets according to claim 1, characterized in that, refined recognition of sea surface targets is achieved by establishing a complete sea surface target database or by using methods of neural network and deep learning.

5. A combined detection method for microwave thermal radiation and electromagnetic scattering of sea surface targets according to claim 1 or 2, characterized in that, the spaceborne microwave radiation passive detection subsystem of the sea surface target uses the difference in microwave thermal radiation bright temperature images between the sea surface target and the sea surface background to achieve effective detection of the sea surface target, and uses the microwave thermal radiation bright temperature characteristics of different sea surface targets to achieve rough classification of the sea surface target.

6. A combined detection method for microwave thermal radiation and electromagnetic scattering of sea surface targets according to claim 1 or 2, characterized in that, the spaceborne microwave radiation passive detection subsystem of the sea surface target includes an antenna array, a receiver and a correlator, the antenna array receives the microwave thermal radiation signals radiated from the sea surface target and the sea surface scene, outputs the signals received by the antenna to the receiver, and the receiver performs low-noise amplification, filtering, down-conversion, intermediate-frequency amplification, and intermediate-frequency filtering on the received signals, and outputs intermediate-frequency signals; output the intermediate-frequency signals to the correlator, complete A / D quantization, IQ separation, and pairwise cross-correlation of the signals to obtain the normalized correlation coefficient; through error correction and calibration, bright temperature image reconstruction, target detection and rough classification of the normalized correlation coefficient, obtain the rough position, speed and heading information of the target.

7. A method for jointly detecting microwave thermal radiation and electromagnetic scattering of sea surface targets according to claim 1 or 3, characterized in that, The spaceborne microwave active detection subsystem of sea surface targets is based on a spaceborne platform, uses the actively transmitted signal to obtain the scattered echo of sea surface targets, and ensures the range and azimuth resolutions based on the ability to generate ultra-wideband linear frequency modulation signals and the ability to achieve ultra-large synthetic aperture in the azimuth direction, so as to effectively detect sea surface targets.

8. A method for jointly detecting microwave thermal radiation and electromagnetic scattering of sea surface targets according to claim 1 or 3, characterized in that, The spaceborne microwave active detection subsystem of sea surface targets includes a frequency modulation source, a system controller, a TR component, a data acquisition and processor, and an internal calibrator. The frequency modulation source generates the required low-power linear frequency modulation signal under the control of the system controller. This signal is up-converted and power-amplified, and then supplied to the H and V polarization transmitting antennas through the RF front end of the TR component. The antenna feeds the signal to the observation area, and sends the received H and V polarization reflection / scattering echoes in the observation area to the receiver through the internal calibrator. The receiver down-converts the RF echo signal to the intermediate frequency. The data acquisition and processor band-pass samples and quantizes the analog intermediate frequency signal into a digital signal, and then sends it to the data transmission subsystem after preprocessing. The internal calibrator couples a part of the transmitter power into the receiver to form a closed loop, thereby realizing internal calibration, eliminating the measurement error caused by the change of the transceiver system, and correcting the amplitude-phase distortion error of the transceiver system as a reference calibration signal. The data transmission system sends the on-board raw data to the ground imaging processor for SAR imaging processing, obtains the target SAR image and position information, extracts the electromagnetic characteristic information of the scattering cross section and scattering phase of the target, performs image display, and stores the echo and imaging data.

9. A method for jointly detecting microwave thermal radiation and electromagnetic scattering of sea surface targets according to claim 1, characterized in that, The fusion and mining method is: fusing the target information and brightness temperature image obtained by the spaceborne microwave thermal radiation passive detection subsystem of sea surface targets and the target information and SAR image obtained by the spaceborne microwave active detection subsystem of sea surface targets to realize the refined recognition and situation awareness of important sea surface targets.

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