FOD detection method, system and medium based on vehicle-mounted mobile radar
1. A FOD detection method based on a vehicle-mounted mobile radar is characterized by comprising the following steps:
1) acquiring a target echo signal reflected by a radar emission signal of an airport runway; wherein the transmission signal is an FMCW pulse signal;
2) combining target echo signals collected from a plurality of positions on a radar motion trail to form a network, and reducing clutter energy in a main beam by synthesizing a virtual large aperture;
3) in the angle-distance spectrum matrix calculation process, accurate estimation of a target angle is realized through motion self-calibration;
4) carrying out FOD detection on the calculation result of the angle-distance spectrum matrix to obtain a detection result;
in step 3), the motion self-calibration method comprises the following steps:
3.1) carrying out two-dimensional Fourier transform on the array element and the pulse two-dimensional data to obtain an angle-Doppler matrix;
3.2) carrying out target detection through angle-distance spectrum matrix calculation, and extracting corresponding target points in each array element;
3.3) obtaining the relative speed of the target point according to the position of the target point in the range-Doppler;
3.4) carrying out Fourier transform on each target point to obtain a rough estimation value of a target angle;
3.5) obtaining a speed value estimated value of the target according to the angle rough estimated value and the radial speed of the target;
3.6) splicing the data of a plurality of CPIs to form a large array, and performing motion compensation on the data among different CPIs;
3.7) accurate estimation of the target angle.
2. The FOD detection method based on vehicle-mounted mobile radar as recited in claim 1, wherein in the step 3.2), the target detection is CFAR detection.
3. The FOD detection method based on the vehicle-mounted mobile radar according to any one of claims 1-2, characterized in that in the step 2), target echo signals are subjected to deskew processing, AD sampling and distance dimension FFT processing, and then multi-beam combination is carried out to form a network.
4. The FOD detection method based on the vehicle-mounted mobile radar as claimed in any one of claims 1-2, wherein in the step 4), the calculation result is sequentially detected through a distance dimension CFAR and an angle dimension AFAR to obtain a detection result.
5. The FOD detection method based on the vehicle-mounted mobile radar as claimed in any one of claims 1-2, wherein in the step 4), the calculation result is detected through a two-dimensional CFAR to obtain a detection result.
6. An FOD detection system based on a vehicle-mounted mobile radar, which is used for executing the FOD detection method based on the vehicle-mounted mobile radar according to any one of claims 1-5, and is characterized by comprising the following steps:
the system comprises a first module, a second module and a third module, wherein the first module is used for acquiring a target echo signal of an airport runway reflected by a transmitting signal of a radar; wherein the transmission signal is an FMCW pulse signal;
the second module is used for combining target echo signals acquired from a plurality of positions on a radar motion trail to form a network, and reducing clutter energy in a main beam by synthesizing a virtual large aperture;
the third module is used for realizing accurate estimation of the target angle through motion self-calibration in the angle-distance spectrum matrix calculation process;
and the fourth module is used for carrying out FOD detection on the angle-distance spectrum matrix calculation result to obtain a detection result.
7. A computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, performs the steps of the method for on-vehicle mobile radar-based FOD detection according to any one of claims 1 to 5.
8. A computer arrangement comprising a memory and a processor, the memory having stored thereon a computer program, characterized in that the computer program, when being executed by the processor, is adapted to carry out the steps of the method for on-board mobile radar-based FOD detection according to any one of claims 1 to 5.
Background
Airport runway Foreign Objects (FOD) refer to any foreign object that does not belong to an airport but is present in the operating area of the airport and may cause damage to the airport or to the aircraft, such as stones, metal parts, adhesive tapes, newspapers, leaves, etc. Although the foreign bodies are not large in size, the foreign bodies have great influence on the normal safe operation of an airport and even form air crash events, such as a small plastic cloth is sucked into an engine to cause an air parking, and a small screw or a metal sheet or even a sharp stone can prick a tire to cause a tire burst.
Because the operation environment of the airport is complicated, the position, the time and the like of runway foreign matter invasion are difficult to estimate, and because the visual field of a crew is limited, the damage of the aircraft caused by tiny foreign matters is difficult to find in time, so that the damage of the FOD to the aircraft is huge. Conservative estimates are that direct losses due to FOD are at least $ 30-40 million worldwide each year. FOD not only causes severe direct losses, but also indirect losses such as flight delays, interrupted take-off, closed runways, etc. Statistically, the indirect loss is at least 4 times the direct loss.
In order to avoid serious loss caused by foreign body detection of the airport runway, the main methods adopted at home and abroad at present are as follows:
1. manual detection: namely, related personnel are adopted to carry out timing inspection on the runway, and the domestic airport still follows the regulations formulated by the international civil aviation organization to carry out manual inspection at present. According to the regulations of International Civil Aviation Organization (ICAO), the runway needs to be detected at least 4 times in all directions every day, and the runway needs to be closed during the detection period, so that the runway time is occupied, the traffic flow is obviously reduced, and the economy of an airline operation company is influenced; moreover, human eyes are easily interfered by fatigue, blind areas, lamplight, weather and the like to generate missed picking, and small FOD targets are difficult to find, so that important potential safety hazards exist.
2. Visual image detection: and taking a picture of the field by adopting a camera, and analyzing the picture. However, due to image quality limitations, the main disadvantages are mainly the high exposure to external influences, especially light and weather, the poor detection capability for small objects at a distance, and the inability to work properly in bad weather conditions. Namely, the method based on visual image detection is too sensitive to light and climate conditions, the system robustness is poor, and the environmental adaptability is poor.
3. Radar systems based on parabolic antennas: by adopting a millimeter wave radar system and a parabolic antenna, the radar can realize scanning detection of a monitoring area by relatively narrow radar beams under the condition of cost constraint, and is an advanced technology at present. Specifically, a phased array radar system adopting a parabolic antenna realizes monitoring area scanning through a mechanical rotating antenna, the working flow of the parabolic antenna is shown in fig. 1, a radar generates a millimeter wave waveform to be transmitted, the millimeter wave waveform is transmitted to the parabolic antenna through a power amplifier, a narrow airspace beam is used for detecting a certain direction, and after a radar echo waveform is received, the narrow airspace beam and a current transmission signal are subjected to deskew processing to obtain a baseband signal for transmitting a pulse. And the radar transmits the next pulse signal, transmits a plurality of groups of signals together, performs two-dimensional Fourier transform on the echo signal, and then performs target detection in the range-Doppler unit. The target angle is the pointing angle of the current parabolic antenna, and after the detection of the direction is completed, the rotary table control system drives the rotary table to rotate, so that the target detection of the next direction is realized, and the detection of the whole airspace is realized. However, since an extremely narrow beam cannot be formed, the cost is significantly increased, a large parabolic aperture is required, and the search capability in the airspace is seriously affected.
Namely, a phased array millimeter wave radar detection system adopting a parabolic antenna can find the size of a target but is not satisfactory, especially for some scenes with harsh requirements on FOD (field of view), namely RCS (radar cross section) value, especially military airports, the RCS of the target which can be detected by the current requirement even reaches 0.01m2However, it is difficult for the current system to satisfy such a high level.
4. Vehicle-mounted FOD detection: currently, the operation mode of directly transplanting a tower-type or side-light-type real-aperture scanning FOD equipment is general, but the main problems exist:
4.1, if high-resolution imaging is required, antenna beams as narrow as possible are required, so that a large-aperture millimeter wave antenna needs to be designed and processed, the processing difficulty is high, the system is large in size and weight, and the system needs to be carried by a special vehicle;
4.2, due to the fact that a real aperture scanning mode is adopted, vehicle motion errors have great influence on imaging, the situation cannot be completely covered or the geographic registration difficulty is increased, and if a stable tripod head is equipped, the system size, weight and cost are further increased; and due to the real aperture scanning principle, the suppression capability of the flickering clutter such as raindrops in rainy and snowy days, water splash splashed on the ground and the like is poor, so that the use efficiency is seriously reduced under the severe weather condition.
In addition, when signal processing is performed, generally, a radar clutter signal is far stronger than a target signal, that is, a signal-to-noise ratio in a received echo is low, so that some FODs with small RCS cannot be detected. Therefore, in order to improve the detection performance of the FOD, the following two aspects can be used:
on one hand, the bandwidth of a transmitted signal is increased, and the increased bandwidth of the signal can reduce the width of a distance unit, so that clutter in the same distance unit with FOD is less, and the signal-to-noise ratio of an output signal is improved; however, the increased signal bandwidth can improve the FOD detection performance to a certain extent, but too large bandwidth will increase the hardware design difficulty, and meanwhile, the requirement for the sampling rate of the system will be significantly increased, thereby increasing the system cost.
On the other hand, a narrower beam is formed, the main beam becomes narrower, clutter components entering the main lobe in the same distance ring are reduced, the signal-to-noise-and-noise ratio of an output signal can be improved, and the FOD performance of detecting the weak RCS can be improved. However, to realize narrow beams, a larger parabolic aperture is required for parabolic antennas, and for phased array radar, the array is required to include more array elements, which also greatly increases the system cost.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: aiming at the problems in the prior art, the invention provides a FOD detection method, a FOD detection system and a FOD detection medium which are strong in weak target detection capability and based on a vehicle-mounted mobile radar.
In order to solve the technical problems, the technical scheme provided by the invention is as follows:
a FOD detection method based on a vehicle-mounted mobile radar comprises the following steps:
1) acquiring a target echo signal reflected by a radar emission signal of an airport runway; wherein the transmission signal is an FMCW pulse signal;
2) combining target echo signals collected from a plurality of positions on a radar motion trail to form a network, and reducing clutter energy in a main beam by synthesizing a virtual large aperture;
3) in the angle-distance spectrum matrix calculation process, accurate estimation of a target angle is realized through motion self-calibration;
4) carrying out FOD detection on the calculation result of the angle-distance spectrum matrix to obtain a detection result;
in step 3), the motion self-calibration method comprises the following steps:
3.1) carrying out two-dimensional Fourier transform on the array element and the pulse two-dimensional data to obtain an angle-Doppler matrix;
3.2) carrying out target detection through angle-distance spectrum matrix calculation, and extracting corresponding target points in each array element;
3.3) obtaining the relative speed of the target point according to the position of the target point in the range-Doppler;
3.4) carrying out Fourier transform on each target point to obtain a rough estimation value of a target angle;
3.5) obtaining a speed value estimated value of the target according to the angle rough estimated value and the radial speed of the target;
3.6) splicing the data of a plurality of CPIs to form a large array, and performing motion compensation on the data among different CPIs;
3.7) accurate estimation of the target angle.
Preferably, the target detection is CFAR detection.
Preferably, in step 2), the target echo signal is deskewed, AD sampled, distance-dimensional FFT processed, and then multi-beam combination is performed to form the network.
Preferably, in step 4), the calculation result is sequentially detected through the distance dimension CFAR and the angle dimension AFAR, so as to obtain a detection result.
Preferably, in step 4), the calculation result is detected by the two-dimensional CFAR, so as to obtain a detection result.
The invention also discloses an FOD detection system based on the vehicle-mounted mobile radar, which is used for executing the FOD detection method based on the vehicle-mounted mobile radar, and comprises the following steps:
the system comprises a first module, a second module and a third module, wherein the first module is used for acquiring a target echo signal of an airport runway reflected by a transmitting signal of a radar; wherein the transmission signal is an FMCW pulse signal;
the second module is used for combining target echo signals acquired from a plurality of positions on a radar motion trail to form a network, and reducing clutter energy in a main beam by synthesizing a virtual large aperture;
the third module is used for realizing accurate estimation of the target angle through motion self-calibration in the angle-distance spectrum matrix calculation process;
and the fourth module is used for carrying out FOD detection on the angle-distance spectrum matrix calculation result to obtain a detection result.
The invention further discloses a computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, performs the steps of the above described method for FOD detection based on a mobile radar on board a vehicle.
The invention also discloses computer equipment which comprises a memory and a processor, wherein the memory is stored with a computer program, and the computer program executes the steps of the FOD detection method based on the vehicle-mounted mobile radar when being executed by the processor.
Compared with the prior art, the invention has the advantages that:
according to the invention, a vehicle-mounted millimeter wave radar system is adopted, the motion of the radar is utilized, the data acquired by a plurality of positions of a receiving antenna on a motion track are combined, an extremely narrow beam main lobe is realized by synthesizing a virtual large aperture, the clutter energy in the main beam is reduced, the signal-to-noise ratio processed by the system is improved, and further a higher index, namely the small target detection capability is achieved; moreover, the radar system based on the moving platform needs few radar array elements, and the effect of hundreds or even thousands of array elements can be achieved through a few or more than ten array elements.
The invention adopts a millimeter wave synthetic aperture radar system of linear frequency modulation continuous waves in consideration of the cost and the product maturity. The attenuation of millimeter waves is small when the millimeter waves are transmitted by utilizing an atmospheric window (when the millimeter waves and the submillimeter waves are transmitted in the atmosphere, certain frequency with minimum attenuation caused by resonance absorption of gas molecules) and the influence of natural light and a thermal radiation source is small. The millimeter wave radar is not influenced by weather and illumination, and has excellent all-weather and all-day working capacity. In which a frequency modulated continuous wave radar (FMCW) detects a distance and a speed of an object by calculating a frequency difference between a chirp-modulated transmission signal and a reception signal. FMCW millimeter wave radar may reduce the complexity of signal processing compared to typical pulse doppler radar, since the bandwidth of the received difference frequency signal may be reduced by a significant amount. Compared with other sensors for special application, the FMCW millimeter wave radar has the advantages of low false alarm rate, high distance resolution, low transmitting power, low cost, simple structure and the like.
In addition, sar (synthetic Aperture radar), a microwave active imaging radar with extremely high resolution; the SAR realizes high-resolution microwave imaging by utilizing a synthetic aperture principle, and has various characteristics of all-time, all-weather, high resolution, large breadth and the like. Because the synthetic aperture radar antenna aperture is not related to the antenna size but related to the antenna beam width, the azimuth resolution is not limited by the antenna physical aperture, and extremely high imaging resolution is realized by synthesizing a large virtual synthetic aperture; due to the characteristics of the SAR system, the method has a good effect of inhibiting 'flickering' clutter formed on the runway in severe weather.
The FOD detection method based on the vehicle-mounted mobile radar carries out automatic motion compensation through a self-calibration method, does not need a high-precision positioning system, overcomes the difficult problem that the traditional SAR synthetic aperture radar needs a high-precision positioning system and a complex compensation algorithm, and enables the radar system to be more stable and the cost to be greatly reduced in practical application.
Drawings
Fig. 1 is a flowchart of a method for processing a parabolic antenna in the prior art.
Fig. 2 is a diagram of an embodiment of the present invention in a vehicle-mounted mobile radar.
FIG. 3 is a schematic diagram of echoes of a target signal and a clutter signal according to the present invention.
FIG. 4 is a flow chart of an embodiment of a detection method of the present invention.
FIG. 5 is a flow chart of an embodiment of a self-calibration method of the present invention.
Detailed Description
The invention is further described below with reference to the figures and the specific embodiments of the description.
As shown in fig. 2 and 4, the FOD detection method based on the vehicle-mounted mobile radar of the present embodiment includes the steps of:
1) acquiring a target echo signal reflected by a radar emission signal of an airport runway; wherein the transmission signal is an FMCW pulse signal;
2) combining target echo signals collected from a plurality of positions on a radar motion trail to form a network, and reducing clutter energy in a main beam by synthesizing a virtual large aperture;
3) in the angle-distance spectrum matrix calculation process, accurate estimation of a target angle is realized through motion self-calibration;
4) and carrying out FOD detection on the calculation result of the angle-distance spectrum matrix to obtain a detection result.
According to the invention, a vehicle-mounted millimeter wave radar system is adopted, the motion of the radar is utilized, the data acquired by a plurality of positions of a receiving antenna on a motion track are combined, an extremely narrow beam main lobe is realized by synthesizing a virtual large aperture, the clutter energy in the main beam is reduced, the signal-to-noise ratio processed by the system is improved, and further a higher index, namely the small target detection capability is achieved; moreover, the radar system based on the moving platform needs few radar array elements, and the effect of hundreds or even thousands of array elements can be achieved through a few or more than ten array elements.
The invention adopts a millimeter wave synthetic aperture radar system of linear frequency modulation continuous waves in consideration of the cost and the product maturity. The attenuation of millimeter waves is small when the millimeter waves are transmitted by utilizing an atmospheric window (when the millimeter waves and the submillimeter waves are transmitted in the atmosphere, certain frequency with minimum attenuation caused by resonance absorption of gas molecules) and the influence of natural light and a thermal radiation source is small. The millimeter wave radar is not influenced by weather and illumination, and has excellent all-weather and all-day working capacity. In which a frequency modulated continuous wave radar (FMCW) detects a distance and a speed of an object by calculating a frequency difference between a chirp-modulated transmission signal and a reception signal. FMCW millimeter wave radar may reduce the complexity of signal processing compared to typical pulse doppler radar, since the bandwidth of the received difference frequency signal may be reduced by a significant amount. Compared with other sensors for special application, the FMCW millimeter wave radar has the advantages of low false alarm rate, high distance resolution, low transmitting power, low cost, simple structure and the like.
In addition, sar (synthetic Aperture radar), a microwave active imaging radar with extremely high resolution; the SAR realizes high-resolution microwave imaging by utilizing a synthetic aperture principle, and has various characteristics of all-time, all-weather, high resolution, large breadth and the like. Because the synthetic aperture radar antenna aperture is not related to the antenna size but related to the antenna beam width, the azimuth resolution is not limited by the antenna physical aperture, and extremely high imaging resolution is realized by synthesizing a large virtual synthetic aperture; due to the characteristics of the SAR system, the method has a good effect of inhibiting 'flickering' clutter formed on the runway in severe weather.
The FOD detection method based on the vehicle-mounted mobile radar carries out automatic motion compensation through a self-calibration method, does not need a high-precision positioning system, overcomes the difficult problem that the traditional SAR synthetic aperture radar needs a high-precision positioning system and a complex compensation algorithm, and enables the radar system to be more stable and the cost to be greatly reduced in practical application.
In a specific embodiment, in step 3), the motion self-calibration method includes the steps of:
3.1) carrying out two-dimensional Fourier transform on the array element and the pulse two-dimensional data to obtain an angle-Doppler matrix;
3.2) carrying out target detection through angle-distance spectrum matrix calculation, and extracting corresponding target points in each array element;
3.3) obtaining the relative speed of the target point according to the position of the target point in the range-Doppler;
3.4) carrying out Fourier transform on each target point to obtain a rough estimation value of a target angle;
3.5) obtaining a speed value estimated value of the target according to the angle rough estimated value and the radial speed of the target;
3.6) splicing the data of a plurality of CPIs to form a large array, and performing motion compensation on the data among different CPIs;
3.7) accurate estimation of the target angle.
The motion self-calibration method is simple and convenient to operate. Of course, in practical application, if a positioning system is adopted, the speed of the radar can be accurately obtained, and meanwhile, a certain amount of calculation can be saved by combining the motion self-calibration method in the invention.
In a specific embodiment, in step 2), the target echo signal is deskewed, AD sampled, distance-dimensional FFT processed, and then multi-beam combination is performed to form the network. Wherein the SAR is capable of obtaining high range-wise resolution by transmitting a frequency modulated signal of large temporal-bandwidth order.
In a specific embodiment, in the step 4), the calculation result is sequentially detected through the distance dimension CFAR and the angle dimension CFAR to obtain a detection result; or detecting the calculation result through the two-dimensional CFAR to obtain a detection result.
The above invention is further illustrated below with reference to a specific embodiment:
as shown in fig. 2, the radar is installed on a vehicle, and is installed in a front side direction, the moving direction of the vehicle is parallel to a runway, and the radar needs to detect the FOD in the runway. The wide beam antenna with small size is adopted, the system has small volume and weight, so the system has good adaptability, can be directly installed on the existing FOD disposal vehicle in an airport, does not need to be provided with a special vehicle, and has low comprehensive use cost.
The radar transmits a chirp signal, the radar signal is reflected by a target, i.e. the FOD, and a large number of ground clutter signals are received at the same time, as shown in fig. 3; the method has the advantages that an extremely narrow beam main lobe is realized by synthesizing a virtual large aperture, clutter energy in a main beam is reduced, the signal-to-noise-and-noise ratio after system processing is improved, and a higher index, namely small target detection capability, is further achieved;
further, the high-precision platform is not practical for the application of the vehicle-mounted radar, and especially for the high-frequency band, such as the 94GHz band, it is difficult for the vehicle-mounted FOD radar system to achieve such high positioning precision, and the invention adopts a self-calibration method based on target cognition, which avoids the problem, and the self-calibration method has the specific flow:
(1) distance-doppler matrix calculation: the array element and pulse two-dimensional data are subjected to two-dimensional Fourier transform to obtain an angle-Doppler matrix, and the step is similar to the application of an automobile radar;
(2) target detection: CFAR detection can be used, with or without discrimination of the target, detection being performed in this step;
(3) extracting corresponding target points in each array element: extracting the same position points of the distance-Doppler matrix corresponding to each array element, wherein the position points correspond to the same target;
(4) determining the relative velocity v of the radar and the targetr: according to the position of the target point in the range-Doppler, the relative speed of the target can be obtained;
(5) the target angle is roughly estimated for the first time: fourier transformation is carried out on each corresponding point, so that a rough estimation value of a target angle can be obtained, and the target detection and parameter estimation can be completed by the traditional automobile radar;
(6) calculating the equivalent speed of the radar: according to the angle and the radial speed of the target, a speed value estimation value of the target can be obtained;
(7) synthesizing a plurality of CPI data to form a large array;
(8) data motion compensation between different CPIs;
(9) and accurately estimating the target angle.
In step (6), the calculation process of the radar equivalent speed is as follows: according to the relative speed v of radar and targetrAnd approximate estimates for the targetThe estimated value of the radar along the moving direction of the vehicle can be calculated，。
In one CPI, the relative displacement of the radar along the direction of travel of the vehicle can be expressed as:
wherein T isCPITime, d, representing a CPICPIIndicating the displacement of motion within one CPI.
In step (7), data x of the CPIs are combinedCPIAnd (4) splicing to form a large array. Depending on the speed of the radar and the length of a CPI time, the equivalent large array formed may have overlapping array elements or may be a sparse array.
In step (8), due to the different data transmission times of the different CPIs, due to the relative motion and TCPISuch that a part of the phase difference of the data between different CPIs is caused by motion and needs to be compensated for, the phase shift value due to motion within one CPI isThe echoes of the pulses in the CPI are compensated in turn, and the phase of the compensation of the m-th pulse isWherein M is the number of the pulse, the value range is 1 … M, and M is the number of all the transmitted pulses.
The invention also discloses an FOD detection system based on the vehicle-mounted mobile radar, which is used for executing the FOD detection method based on the vehicle-mounted mobile radar, and comprises the following steps:
the system comprises a first module, a second module and a third module, wherein the first module is used for acquiring a target echo signal of an airport runway reflected by a transmitting signal of a radar; wherein the transmission signal is an FMCW pulse signal;
the second module is used for combining target echo signals acquired from a plurality of positions on a radar motion trail to form a network, and reducing clutter energy in a main beam by synthesizing a virtual large aperture;
the third module is used for realizing accurate estimation of the target angle through motion self-calibration in the angle-distance spectrum matrix calculation process;
and the fourth module is used for carrying out FOD detection on the angle-distance spectrum matrix calculation result to obtain a detection result.
The invention further discloses a computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, performs the steps of the above described method for FOD detection based on a mobile radar on board a vehicle. The invention also discloses computer equipment which comprises a memory and a processor, wherein the memory is stored with a computer program, and the computer program executes the steps of the FOD detection method based on the vehicle-mounted mobile radar when being executed by the processor.
All or part of the flow of the method of the embodiments may be implemented by a computer program, which may be stored in a computer-readable storage medium and executed by a processor, to implement the steps of the embodiments of the methods. Wherein the computer program comprises computer program code, which may be in the form of source code, object code, an executable file or some intermediate form, etc. The computer readable medium may include: any entity or device capable of carrying computer program code, recording medium, U.S. disk, removable hard disk, magnetic disk, optical disk, computer Memory, Read-Only Memory (ROM), Random Access Memory (RAM), electrical carrier wave signals, telecommunications signals, software distribution media, and the like. The memory may be used to store computer programs and/or modules, and the processor may perform various functions by executing or executing the computer programs and/or modules stored in the memory, as well as by invoking data stored in the memory. The memory may include high speed random access memory, and may also include non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) Card, a Flash memory Card (Flash Card), at least one magnetic disk storage device, a Flash memory device, or other volatile solid state storage device.
The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above-mentioned embodiments, and all technical solutions belonging to the idea of the present invention belong to the protection scope of the present invention. It should be noted that modifications and embellishments within the scope of the invention may be made by those skilled in the art without departing from the principle of the invention.
