CN115097447A - MIMO radar monitoring system and monitoring method based on MIMO radar monitoring system - Google Patents

MIMO radar monitoring system and monitoring method based on MIMO radar monitoring system Download PDF

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CN115097447A
CN115097447A CN202210707150.0A CN202210707150A CN115097447A CN 115097447 A CN115097447 A CN 115097447A CN 202210707150 A CN202210707150 A CN 202210707150A CN 115097447 A CN115097447 A CN 115097447A
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transmitting
signal
receiving
array
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王宏宇
于慧
姚迪
江志远
戴颖超
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Suzhou Science And Technology Leike Sensing Technology Co ltd
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Suzhou Science And Technology Leike Sensing Technology Co ltd
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Priority to PCT/CN2022/115405 priority patent/WO2023245862A1/en
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/88—Radar or analogous systems specially adapted for specific applications
    • G01S13/885—Radar or analogous systems specially adapted for specific applications for ground probing
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
    • G01B7/16—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring the deformation in a solid, e.g. by resistance strain gauge
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/88—Radar or analogous systems specially adapted for specific applications
    • G01S13/89—Radar or analogous systems specially adapted for specific applications for mapping or imaging
    • G01S13/90—Radar or analogous systems specially adapted for specific applications for mapping or imaging using synthetic aperture techniques, e.g. synthetic aperture radar [SAR] techniques
    • G01S13/9021—SAR image post-processing techniques
    • G01S13/9023—SAR image post-processing techniques combined with interferometric techniques
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/03—Details of HF subsystems specially adapted therefor, e.g. common to transmitter and receiver

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  • Remote Sensing (AREA)
  • Radar, Positioning & Navigation (AREA)
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  • Radar Systems Or Details Thereof (AREA)

Abstract

The invention provides an MIMO radar monitoring system and a monitoring method based on the same, belongs to the field of radar monitoring, can realize stable system calibration, and cannot influence subsequent imaging and deformation calculation. The invention discloses an MIMO radar monitoring system, which comprises a signal processor module, a frequency synthesizer module, a single power amplifier module, a transmitting switch array module, a transmitting antenna array, a receiving switch array module and a receiving antenna array, wherein the signal processor module is connected with the frequency synthesizer module; the signal processor module is connected with the frequency synthesizer module; the frequency synthesizer module is connected with the signal processor module, the single power amplifier module and the receiving switch array module, and the receiving switch array module is also connected with the receiving antenna array; the single power amplifier module is arranged between the frequency synthesizer module and the transmitting switch array module and is respectively connected with the frequency synthesizer module and the transmitting switch array module, and the transmitting switch array module is also connected with the transmitting antenna array.

Description

MIMO radar monitoring system and monitoring method based on MIMO radar monitoring system
Technical Field
The invention belongs to the technical field of radar detection, and particularly relates to an MIMO radar monitoring system and a monitoring method based on the MIMO radar monitoring system.
Background
The key of landslide disaster monitoring and early warning is high-precision surface deformation measurement, and in recent years, the side slope deformation monitoring radar is rapidly developed in the field of landslide disaster prevention and control by virtue of the advantages of high measurement precision, all-time, all-weather, large-range, continuous detection and the like. The radar is based on the technical principle of combining Synthetic Aperture Radar (SAR) high-resolution imaging with phase difference interferometry. At present, a plurality of research institutions at home and abroad develop the research on slope deformation monitoring radars, and release a plurality of radar products of a mechanical scanning synthetic aperture system, although the deformation measurement and early warning analysis on the surface of the slope landslide can be realized to a certain extent, the method is limited by the defects of monitoring precision, climate, scenes and key random numbers, and the deformation monitoring of the slope scenes with full coverage, portability, high precision and high reliability is difficult to realize simultaneously.
At present, the MIMO radar can be used for monitoring the deformation of the side slope by virtue of the advantages of high switching speed, high reliability and the like, but the application and popularization of the MIMO deformation monitoring radar are greatly limited by the problems that the multichannel calibration is difficult, the complexity of system hardware is high, the cost is high and the like.
The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art that is already known to a person skilled in the art.
Disclosure of Invention
The invention aims to reduce the cost of edge side end units, and provides an MIMO radar monitoring system and a monitoring method based on the MIMO radar monitoring system.
In a first aspect, an embodiment of the present invention provides a MIMO radar monitoring system, including a signal processor module, a frequency synthesizer module, a single power amplifier module, a transmit switch array module, a transmit antenna array, a receive switch array module, and a receive antenna array; wherein the content of the first and second substances,
the signal processor module is connected with the frequency synthesizer module and is configured to realize the functions of time sequence control of a system, generation of an analog signal, supply of the analog signal to the frequency synthesizer module, reception of a baseband signal returned by the frequency synthesizer module, AD sampling, signal preprocessing, data storage and return;
the frequency synthesizer module is connected with the signal processor module, the single power amplifier module and the receiving switch array module, and the receiving switch array module is also connected with the receiving antenna array; the frequency synthesizer module is configured to provide a reference clock signal; receiving the analog signal sent by the signal processor module, performing up-conversion to generate a radio frequency transmitting signal, and sending the radio frequency transmitting signal to the single power amplifier module; the echo signal returned by the receiving switch array module is obtained, orthogonal down-conversion is completed, a baseband signal is generated, and the signal is amplified in power and then sent to the signal processor module;
the single power amplifier module is arranged between the frequency synthesizer module and the transmitting switch array module, and is respectively connected with the frequency synthesizer module and the transmitting switch array module, and the transmitting switch array module is also connected with the transmitting antenna array; the single power amplifier module is configured to receive the radio frequency transmitting signal output by the frequency synthesizer module, perform power amplification, and transmit the radio frequency transmitting signal to the transmitting switch array module, so that the transmitting switch array module transmits the radio frequency transmitting signal output by the single power amplifier module to the transmitting antenna array, thereby realizing time-sharing conduction of a transmitting channel.
Optionally, the transmit switch array module includes a plurality of transmit switches, and the transmit antenna array includes a plurality of transmit antennas, where one transmit switch of the plurality of transmit switches is correspondingly connected to one transmit antenna of the plurality of transmit antennas;
the receiving switch array module comprises a plurality of receiving switches, the receiving antenna array comprises a plurality of receiving antennas, and one receiving switch in the plurality of receiving switches is correspondingly connected with one receiving antenna in the plurality of receiving antennas.
Optionally, the transmit antenna array comprises M transmit antennas, and the receive antenna array comprises N receive antennas; the M transmitting antennas are evenly divided into two transmitting antenna sub-arrays which are arranged at intervals and symmetrically, the distance between every two adjacent transmitting antennas in each transmitting antenna sub-array is lambda/2, lambda is the wavelength corresponding to the central frequency, and M is an even number; n receiving antennas form a receiving antenna sub-array, and the distance between adjacent receiving antennas in the receiving antenna sub-array is M lambda/4; the receiving antenna sub array and the transmitting antenna sub array are arranged in parallel.
Optionally, the radio frequency transmission signal is a chirp continuous wave signal.
Optionally, the signal processor module includes a programmable main control chip, and a data memory, an analog-to-digital converter and a direct digital frequency synthesizer connected to the main control chip.
Optionally, the receiving switch array module includes a plurality of receiving switches and a plurality of low-noise amplifiers connected to the plurality of receiving switches, and is configured to implement the functions of time-sharing conduction of the receiving channels and low-noise amplification of the receiving signals.
In a second aspect, an embodiment of the present disclosure provides a method for monitoring based on the above MIMO radar monitoring system, including:
transmitting a microwave signal to a monitored area;
receiving echo signals reflected by the monitored area;
sampling the echo signal;
imaging the monitored area based on the sampled echo signal to obtain an image about the monitored area;
and calculating whether the monitored area sends deformation or not by using the image.
Optionally, before transmitting the microwave signal to the monitored area, the method further includes:
measuring the relative amplitude and phase of each antenna of the system by using the vector network and a standard antenna, and obtaining a channel correction factor at one time; setting the echo data of the mth transmitting antenna measured by the calibration system as data tm And M is 1,2, …, M, the test echo data of the nth receiving antenna is data rn ,n＝1,2,…,N；
Calculating the relative amplitude and the relative phase of each transceiving pair by using a first formula as a correction factor, wherein the first formula is as follows:
Figure BDA0003705831610000041
optionally, the imaging the monitored region based on the sampled echo signal specifically includes:
assuming that each transmit antenna of each cycle transmits a signal:
Figure BDA0003705831610000042
wherein, T p For the modulation period, f 0 Is the radio frequency starting frequency
Figure BDA0003705831610000043
Figure BDA0003705831610000044
The system frequency modulation slope is obtained;
then, the time domain signal obtained after the down-conversion of the echo of the nth transceiver pair by the frequency synthesizer module is:
Figure BDA0003705831610000045
wherein, tau mn Delaying a target echo corresponding to the mn-th transceiving pair;
τ mn the general expression of (a) is as follows:
Figure BDA0003705831610000046
wherein (x) tm ,y tm ,z tm ) (x) coordinates of the m-th transmitting antenna rn ,y rn ,z rn ) Is the coordinate of the nth receiving antenna, (x) 0 ,y 0 ,z 0 ) The coordinates of the position of the target are obtained;
windowing and channel amplitude-phase correction are carried out on the time domain echo signals of each channel, and the channel correction factor of the mth transceiving pair is recorded as err mn And the windowing coefficient is win (t), and the echo of the mn-th channel after time domain processing is as follows:
Figure BDA0003705831610000047
for the nth echo signal
Figure BDA0003705831610000048
The distance is changed to the frequency domain from FFT, and after the amplitude is ignored:
Figure BDA0003705831610000049
and (3) azimuth back projection, wherein the imaging result can be obtained by the following formula:
Figure BDA00037058316100000410
when the monitoring system of any one of claims 1-6 is employed, τ mn The general expression of (a) is:
Figure BDA00037058316100000411
optionally, after the monitored area is imaged based on the sampled echo signal, a differential interference processing step is further included, that is, after the PS point selection, the atmospheric phase correction, and the deformation extraction step, the deformation information of each pixel point is calculated according to the deformation information calculation model.
Optionally, the deformation information calculation model is:
Figure BDA0003705831610000051
wherein, λ is the wavelength corresponding to the center frequency,
Figure BDA0003705831610000052
and d is the deformation quantity of the target in the radar sight line direction. This section is similar to the deformation monitoring radar of other systems and will not be described in detail.
Drawings
Fig. 1 is a schematic structural diagram of a MIMO radar monitoring system according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of an antenna array according to an embodiment of the present disclosure;
fig. 3 is a graph of an antenna array according to an embodiment of the present disclosure.
Detailed Description
In order to make the technical solutions of the present invention better understood, the present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
Unless defined otherwise, technical or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The use of "first," "second," and similar terms in the present application do not denote any order, quantity, or importance, but rather the terms are used to distinguish one element from another. Also, the use of the terms "a," "an," or "the" and similar referents do not denote a limitation of quantity, but rather denote the presence of at least one. The word "comprising" or "comprises", and the like, means that the element or item preceding the word comprises the element or item listed after the word and its equivalent, but does not exclude other elements or items. The terms "connected" or "coupled" and the like are not restricted to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "upper", "lower", "left", "right", and the like are used merely to indicate relative positional relationships, and when the absolute position of the object being described is changed, the relative positional relationships may also be changed accordingly.
It should be noted that the MIMO radar monitoring system may be used for monitoring in various situations, such as monitoring landslide and debris flow, and the following embodiments are described by taking the MIMO radar monitoring system as an example for monitoring slope deformation.
The key of landslide hazard monitoring and early warning is high-precision surface deformation measurement, and in recent years, the side slope deformation monitoring radar is rapidly developed in the field of landslide hazard prevention and control by virtue of the advantages of high measurement precision, all-day, all-weather, large-range and continuous detection and the like. The radar is based on the technical principle of combining Synthetic Aperture Radar (SAR) high-resolution imaging with phase difference interferometry. At present, a plurality of research institutions at home and abroad develop the research on slope deformation monitoring radars, and release a plurality of radar products of a mechanical scanning synthetic aperture system, although the deformation measurement and early warning analysis on the surface of the slope landslide can be realized to a certain extent, the method is limited by the defects of monitoring precision, climate, scenes and key random numbers, and the deformation monitoring of the slope scenes with full coverage, portability, high precision and high reliability is difficult to realize simultaneously.
The system implementation proposed in the CN113419239A patent is a currently common implementation of MIMO radar system, but in practical application, the following two problems are mainly faced:
1) the system design is complex, the realization difficulty is high and the cost is high;
2) amplifiers are arranged in all the receiving and transmitting channels of the system, and because the amplitude-phase characteristics of a plurality of amplifiers are affected by temperature to be inconsistent, when the external environment changes, the amplitude-phase relation between multiple channels (a transmitting channel and a receiving channel) of the system changes, the multichannel correction difficulty is high, and the subsequent imaging and deformation calculation are affected.
In order to solve at least one of the above technical problems, embodiments of the present invention provide an MIMO radar monitoring system and a method for monitoring based on the MIMO radar monitoring system, and the MIMO radar monitoring system and the method for monitoring based on the MIMO radar monitoring system provided in embodiments of the present invention are described in further detail below with reference to the accompanying drawings and the detailed description.
Fig. 1 is a schematic structural diagram of a MIMO radar monitoring system according to an embodiment of the present invention, and as shown in fig. 1, the MIMO radar monitoring system includes a signal processor module 11, a frequency synthesizer module 12, a single power amplifier module 13, a transmit switch array module 14, a transmit antenna array 15, a receive switch array module 16, and a receive antenna array 17.
Specifically, the signal processor module 11 is connected to the frequency synthesizer module 12, and the signal processor module 11 is configured to implement timing control of the system, generate a wideband high-phase noise analog signal, provide the wideband high-phase noise analog signal to the frequency synthesizer module 12, and receive a baseband signal returned by the frequency synthesizer module 12 for AD sampling, signal preprocessing, data storage, and return functions.
The frequency synthesizer module 12 is connected with the signal processor module 11, the single power amplifier module 13 and the receiving switch array module 16, and the receiving switch array module 16 is further connected with the receiving antenna array 17. The frequency synthesizer module 12 is configured to provide a reference clock signal, receive the analog signal sent by the signal processor module 11 for up-conversion, generate a radio frequency transmit signal, send the radio frequency transmit signal to the single power amplifier module 13, obtain an echo signal returned by the receive switch array module 16, perform quadrature down-conversion, generate a baseband signal, and send the baseband signal to the signal processor module 11 after power amplification.
The single power amplifier module 13 is disposed between the frequency synthesizer module 12 and the transmit switch array module 14, and is respectively connected to the frequency synthesizer module 12 and the transmit switch array module 14, and the transmit switch array module 14 is further connected to the transmit antenna array 15. The single power amplifier module 13 is configured to receive the radio frequency transmission signal output by the frequency synthesizer module 12, perform power amplification, and transmit the radio frequency transmission signal to the transmit switch array module 14, so that the transmit switch array module 14 transmits the radio frequency transmission signal output by the single power amplifier module to the transmit antenna array 15, thereby implementing time-sharing conduction of a transmit channel.
Alternatively, the radio frequency transmission signal may be a chirped continuous wave signal.
In this embodiment, because the single power amplifier module 13 is disposed between the frequency synthesizer module 12 and the transmission switch array module 14, and is respectively connected to the frequency synthesizer module 12 and the transmission switch array module 14, when the external environment changes, the amplitude-phase relationship between the system transmission channels 100 and between the system reception channels 200 does not change greatly, so that stable system calibration can be realized, the subsequent imaging and deformation calculation are not affected, the system design is simplified, the cost is reduced, and the stability of the system is improved.
In some embodiments, the transmit switch array module 14 may include a plurality of transmit switches, and the transmit antenna array 15 includes a plurality of transmit antennas, wherein one transmit switch of the plurality of transmit switches is correspondingly connected to one transmit antenna of the plurality of transmit antennas. The receiving switch array module 16 includes a plurality of receiving switches, and the receiving antenna array 17 includes a plurality of receiving antennas, and one of the plurality of receiving switches is correspondingly connected to one of the plurality of receiving antennas.
In some embodiments, the antenna array comprises a transmit antenna array and a receive antenna array, wherein the transmit antenna array comprises M transmit antennas and the receive antenna array comprises N receive antennas; the M transmitting antennas are evenly divided into two groups of symmetrically arranged transmitting antenna sub-arrays at intervals, the distance between adjacent transmitting antennas in each transmitting antenna sub-array is lambda/2, lambda is the wavelength corresponding to the central frequency, and M is an even number; n receiving antennas form a receiving antenna sub-array, and the distance between adjacent receiving antennas in the receiving antenna sub-array is M lambda/4; the receiving antenna subarrays are arranged in parallel with the transmitting antenna subarrays.
For example, fig. 2 is a schematic structural diagram of an antenna array provided in the embodiment of the present disclosure, as shown in fig. 2, the antenna array includes a transmitting antenna array and a receiving antenna array, where M is 8, N is 4, the transmitting antenna array includes 8 transmitting antennas 21, and the receiving antenna array includes 4 receiving antennas 22. The 8 transmitting antennas 21 are equally divided into two symmetrically arranged transmitting antenna sub-arrays 300, the distance between adjacent transmitting antennas 21 in each transmitting antenna sub-array 300 is λ/2, and λ is the wavelength corresponding to the center frequency. The 4 receiving antennas form a receiving antenna sub-array 400, the distance between the adjacent receiving antennas 22 in the receiving antenna sub-array 400 is 2 lambda, and the receiving antenna sub-array 400 is arranged in parallel with the transmitting antenna sub-array 300. It is to be understood that the values of M and N may also be specifically selected according to the circumstances, and are not specifically limited herein.
In the embodiment, by designing the arrangement mode of the transmitting antenna array and the receiving antenna array in the above way, when the target is in the far field area of the antenna, the transmitting antenna array and the receiving antenna array can be equivalent to a uniform linear array (500) with the distance of lambda/4, so that the imaging calculation is simplified. At this time, the length of the virtual array formed between the centers of the corresponding equivalent phases is: d ═ ((MN-1) λ)/4.
In some embodiments, the signal processor module may include a programmable master control chip, and a data memory, an analog-to-digital converter, and a direct digital frequency synthesizer connected to the master control chip.
In some embodiments, the receiving switch array module includes a plurality of receiving switches and a plurality of low noise amplifiers connected to the plurality of receiving switches, and is configured to implement the functions of time-sharing conduction of the receiving channels and low noise amplification of the receiving signals.
In a second aspect, an embodiment of the present disclosure further provides a method for deformation monitoring based on a MIMO radar monitoring system, including: transmitting a microwave signal to a monitored area; receiving echo signals reflected by the monitored area; sampling the echo signal; imaging the monitored area based on the sampled echo signal to obtain an image about the monitored area; and judging whether the monitored area sends deformation or not by using the image.
In this embodiment, deformation monitoring is performed by using a monitoring system based on MIMO radar, and since the single power amplifier module 13 is disposed between the frequency synthesizer module 12 and the transmission switch array module 14 and is connected to the frequency synthesizer module 12 and the transmission switch array module 14, when an external environment changes, the amplitude-phase relationship between the transmission channels 100 and between the reception channels 200 of the system does not change, so that stable system calibration can be achieved, and subsequent imaging and deformation calculation are not affected. Meanwhile, since the transmit switch array module does not include a power amplification module, amplitude-phase characteristics between the transmit channels 100 are highly consistent and switching speed is fast.
In some embodiments, for MIMO imaging systems, amplitude phase disparity between multiple channels directly affects the imaging performance. Therefore, the amplitude and phase consistency calibration of multiple channels is required before the step of transmitting the microwave signal to the monitored area. Based on above-mentioned based on MIMO radar monitoring system, owing to share the power amplifier, the amplitude and phase uniformity between the multichannel is mainly influenced by the inside cable of system and switch, receives the influence of outside temperature less, consequently accessible once only calibrates outward and generates fixed channel correction factor, and concrete step is as follows:
(1) measuring the relative amplitude and phase of each antenna of the system by using the vector network and a standard antenna; setting the echo data of the mth transmitting antenna measured by the calibration system as data tm And M is 1,2, …, M, the test echo data of the nth receiving antenna is data rn ,n＝1,2,…,N；
(2) Calculating the relative amplitude and the relative phase of each transceiving pair by using a first formula as a correction factor, wherein the first formula is as follows:
Figure BDA0003705831610000091
(represents the channel correction factor for the mn-th transceive pair).
In some embodiments, imaging the monitored region based on the sampled echo signals specifically includes:
a coordinate system as shown in fig. 3 is established and the transmit antenna array comprising the transmit antennas 21, the receive antenna array comprising the receive antennas 22 and the equivalent linear array comprising the equivalent phase center 23 are placed in the coordinate system, wherein the equivalent phase center 23 is located on the X-axis.
Assuming that each transmit antenna 21 of each cycle transmits a signal:
Figure BDA0003705831610000101
wherein, T p For the modulation period, f 0 Is the starting frequency of radio frequency
Figure BDA0003705831610000102
Figure BDA0003705831610000103
The system frequency modulation slope is obtained;
then, the time domain signal obtained after the down-conversion of the echo of the nth transceiver pair by the frequency synthesizer module is:
Figure BDA0003705831610000104
wherein, tau mn Delaying a corresponding target echo for the nth receiving and transmitting pair;
τ mn the general expression of (a) is as follows:
Figure BDA0003705831610000105
wherein (x) tm ,y tm ,z tm ) Is the coordinate of the mth transmitting antenna, (x) rn ,y rn ,z rn ) Is the coordinate of the nth receiving antenna, (x) 0 ,y 0 ,z 0 ) The coordinates of the position of the target are obtained;
windowing and channel amplitude-phase correction are carried out on the time domain echo signals of each channel, and the channel correction factor of the mth transceiving pair is recorded as err mn And the windowing coefficient is win (t), and the echo of the mn-th channel after time domain processing is as follows:
Figure BDA0003705831610000106
for the nth echo signal
Figure BDA0003705831610000107
The distance is changed to the frequency domain from FFT, and after the amplitude is ignored:
Figure BDA0003705831610000108
and (3) azimuth back projection, wherein the imaging result can be obtained by the following formula:
Figure BDA0003705831610000109
when the monitoring system of any one of claims 1-6 is employed, τ mn The general expression of (a) is:
Figure BDA00037058316100001010
in particular, when the distance of the target from the antenna array satisfies the far-field condition, i.e., the distance of the target from the antenna array is greater than
Figure BDA0003705831610000111
When (D is the distance between the equivalent phase centers 23 and λ is the wavelength), τ can be determined mn Simplified to
Figure BDA0003705831610000112
Figure BDA0003705831610000113
Wherein x is mn To be located on the X-axis, centered on the origin, at azimuthal intervals of
Figure BDA0003705831610000114
A uniform linear array of (a).
In this embodiment, in the above manner, when the target is located in the near field, the problem of high grating lobes can be avoided by refining the model, and when the target is located in the far field, the system model can be simplified on the premise of maintaining the imaging quality, and the computation amount can be reduced.
In some embodiments, after imaging the monitored area based on the sampled echo signal, a differential interference processing step is further included, that is, after the PS point selection, the atmospheric phase correction, and the deformation extraction step, the deformation information of each pixel point is calculated according to the deformation information calculation model.
Optionally, the deformation information calculation model is:
Figure BDA0003705831610000115
wherein, λ is the wavelength corresponding to the central frequency,
Figure BDA0003705831610000116
and d is the deformation quantity of the target in the radar sight line direction. This section is similar to the deformation monitoring radar of other systems and will not be described in detail.
It will be understood that the above embodiments are merely exemplary embodiments taken to illustrate the principles of the present invention, which is not limited thereto. It will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the spirit and substance of the invention, and these modifications and improvements are also considered to be within the scope of the invention.

Claims (11)

1. A MIMO radar monitoring system is characterized by comprising a signal processor module, a frequency synthesizer module, a single power amplifier module, a transmitting switch array module, a transmitting antenna array, a receiving switch array module and a receiving antenna array; wherein the content of the first and second substances,
the signal processor module is connected with the frequency synthesizer module and is configured to realize the functions of time sequence control of a system, generation of analog signals for the frequency synthesizer module, reception of baseband signals returned by the frequency synthesizer module, AD sampling, signal preprocessing, data storage and return;
the frequency synthesizer module is connected with the signal processor module, the single power amplifier module and the receiving switch array module, and the receiving switch array module is also connected with the receiving antenna array; the frequency synthesizer module is configured to provide a reference clock signal; receiving the analog signal sent by the signal processor module, performing up-conversion to generate a radio frequency transmitting signal, and sending the radio frequency transmitting signal to the single power amplifier module; the echo signal returned by the receiving switch array module is obtained, orthogonal down-conversion is completed, a baseband signal is generated, and the signal is amplified in power and then sent to the signal processor module;
the single power amplifier module is arranged between the frequency synthesizer module and the transmitting switch array module, and is respectively connected with the frequency synthesizer module and the transmitting switch array module, and the transmitting switch array module is also connected with the transmitting antenna array; the single power amplifier module is configured to receive the radio frequency transmitting signal output by the frequency synthesizer module for power amplification and transmit the radio frequency transmitting signal to the transmitting switch array module, so that the transmitting switch array module transmits the radio frequency transmitting signal output by the single power amplifier module to the transmitting antenna array, and time-sharing conduction of a transmitting channel is realized.
2. The MIMO radar monitoring system of claim 1, wherein the transmit switch array module includes a plurality of transmit switches, and the transmit antenna array includes a plurality of transmit antennas, wherein one of the plurality of transmit switches is connected to one of the plurality of transmit antennas;
the receiving switch array module comprises a plurality of receiving switches, the receiving antenna array comprises a plurality of receiving antennas, and one of the plurality of receiving switches is correspondingly connected with one of the plurality of receiving antennas.
3. The MIMO radar monitoring system of claim 2, wherein the transmit antenna array includes M transmit antennas and the receive antenna array includes N receive antennas; the M transmitting antennas are evenly divided into two transmitting antenna sub-arrays which are arranged at intervals and symmetrically, the distance between every two adjacent transmitting antennas in each transmitting antenna sub-array is lambda/2, lambda is the wavelength corresponding to the central frequency, and M is an even number; n receiving antennas form a receiving antenna sub-array, and the distance between adjacent receiving antennas in the receiving antenna sub-array is M lambda/4; the receiving antenna sub array and the transmitting antenna sub array are arranged in parallel.
4. The MIMO radar monitoring system of any one of claims 1-3, wherein the radio frequency transmit signal is a chirp continuous wave signal.
5. The MIMO radar monitoring system of any one of claims 1-3, wherein the signal processor module comprises a programmable master control chip, and a data memory, an analog-to-digital converter, and a direct digital frequency synthesizer coupled to the master control chip.
6. The MIMO radar monitoring system of any one of claims 1-3, wherein the receive switch array module comprises a plurality of receive switches and a plurality of low noise amplifiers connected to the plurality of receive switches, for performing time-sharing conduction on the receive channels and low noise amplification on the receive signals.
7. A method for monitoring based on the MIMO radar monitoring system of any one of claims 1-6, comprising:
transmitting a microwave signal to a monitored area;
receiving echo signals reflected by the monitored area;
sampling the echo signal;
imaging the monitored area based on the sampled echo signal to obtain an image about the monitored area;
and judging whether the monitored area deforms or not by using the image.
8. The method of claim 7, wherein prior to transmitting the microwave signal to the monitored area, further comprising:
measuring the relative amplitude and phase of each antenna of the system by using the vector network and a standard antenna, and obtaining a channel correction factor at one time; setting the echo data of the mth transmitting antenna measured by the calibration system as data tm And M is 1,2, …, M, the test echo data of the nth receiving antenna is data rn ,n＝1,2,…,N；
Calculating to obtain the relative amplitude and the relative phase of each transceiving pair as correction factors through a first formula, wherein the first formula is as follows:
Figure FDA0003705831600000031
9. the monitoring method according to claim 8, wherein the imaging the monitored region based on the sampled echo signals specifically comprises:
assuming that each transmit antenna of each cycle transmits a signal:
Figure FDA0003705831600000032
wherein, T p For modulation period, f 0 Is the starting frequency of radio frequency
Figure FDA0003705831600000033
Figure FDA0003705831600000034
The system frequency modulation slope is obtained;
then, the time domain signal obtained after the down-conversion of the echo of the nth transceiver pair by the frequency synthesizer module is:
Figure FDA0003705831600000035
wherein, tau mn Delaying a corresponding target echo for the nth receiving and transmitting pair;
τ mn the general expression of (a) is as follows:
Figure FDA0003705831600000036
wherein (x) tm ,y tm ,z tm ) Is the coordinate of the mth transmitting antenna, (x) rn ,y rn ,z rn ) Is the coordinate of the nth receiving antenna, (x) 0 ,y 0 ,z 0 ) The coordinates of the position of the target are obtained;
windowing and channel amplitude-phase correction are carried out on the time domain echo signals of each channel, and the channel correction factor of the mth transceiving pair is recorded as err mn And the windowing coefficient is win (t), and the echo of the mn-th channel after time domain processing is as follows:
Figure FDA0003705831600000037
Figure FDA0003705831600000041
for the mth echo signal
Figure FDA0003705831600000042
The distance is changed to the frequency domain from FFT, and after the amplitude is ignored:
Figure FDA0003705831600000043
and (3) azimuth back projection, wherein the imaging result can be obtained by the following formula:
Figure FDA0003705831600000044
when the monitoring system of any one of claims 1-6 is employed, τ mn The general expression of (a) is:
Figure FDA0003705831600000045
10. the monitoring method according to claim 9, wherein after imaging the monitored area based on the sampled echo signal, the method further comprises a differential interference processing step, namely after the steps of PS point selection, atmospheric phase correction and deformation extraction, deformation information of each pixel point is calculated according to the deformation information calculation model.
11. The monitoring method according to claim 10, wherein the deformation information calculation model is:
Figure FDA0003705831600000046
wherein, λ is the wavelength corresponding to the central frequency,
Figure FDA0003705831600000047
and d is the deformation quantity of the target in the radar sight line direction. This section is similar to the deformation monitoring radar of other systems and will not be described in detail.
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