CN212872946U

CN212872946U - Holographic imaging security inspection system

Info

Publication number: CN212872946U
Application number: CN202022056937.4U
Authority: CN
Inventors: 张建新; 黄平平; 张殿坤; 李世龙
Original assignee: Obe Terahertz Technology Beijing Co ltd
Current assignee: Obe Terahertz Technology Beijing Co ltd
Priority date: 2020-08-18
Filing date: 2020-09-18
Publication date: 2021-04-02
Anticipated expiration: 2030-09-18
Also published as: CN112162326B; CN112162327B; CN212965469U; CN213692346U; CN112131525A; CN112132002A; CN112134031B; CN112162326A; CN112132002B; CN112162328A; CN112162327A; CN112162328B; CN112131525B; CN112134031A

Abstract

The present disclosure provides a holographic imaging security inspection system. The holographic imaging security inspection system comprises: the device comprises a multi-subband modulation and demodulation device, a channel switch switching device, a distributed antenna device and a data acquisition and processing device. The multi-subband modulation and demodulation device sends a plurality of subband signals to the channel switch switching device, the channel switch switching device sends the plurality of subband signals to corresponding receiving and transmitting antenna unit combinations in the distributed antenna device through the switched channel switch combinations, the receiving and transmitting antenna unit combinations respond to the received subband signals, transmit electromagnetic wave signals to the tested object, receive the corresponding plurality of subband echo signals, send the plurality of subband echo signals to the multi-subband modulation and demodulation device through the channel switch combinations, and the multi-subband modulation and demodulation device sends the modulated plurality of subband echo signals to the data acquisition and processing device. Through the signal transceiving mechanism based on the plurality of sub-band signals, the signal processing efficiency of the holographic imaging security inspection system for the specified bandwidth is improved.

Description

Holographic imaging security inspection system

Technical Field

The disclosure relates to the technical field of safety detection, in particular to a holographic imaging safety inspection system.

Background

At present, imaging detection technology is widely used, and particularly, security imaging equipment in the security inspection field includes various types, such as a common millimeter wave human body security inspection equipment, and the millimeter wave human body security inspection equipment can effectively detect contraband articles and the like hidden at various parts of a human body under clothing coverage without directly contacting the human body of a person to be detected by using the millimeter wave imaging technology, and can extract information such as the shape, size, position and the like of a hidden target article from an image generated based on the detection. Based on words, the millimeter wave human body security inspection equipment is applied to areas with high public safety requirements, such as airports, stations, frontiers and the like.

In the detection scanning process of the existing millimeter wave human body security inspection equipment, a bandwidth signal for triggering the antenna to scan is transmitted to the antenna, and the antenna responds to the bandwidth signal to emit electromagnetic waves for scanning. However, the bandwidth signal used for triggering is a large bandwidth signal, the bandwidth frequency range of the large bandwidth signal is very wide, the large bandwidth signal is difficult to modulate, and the bandwidth frequency range corresponding to the large bandwidth signal is wide, so that the data acquisition efficiency is low, and further the efficiency of the millimeter wave human body security check equipment is low.

SUMMERY OF THE UTILITY MODEL

In view of the foregoing, the present disclosure provides a holographic imaging security inspection system. The multi-subband modulation and demodulation device in the holographic imaging security inspection system can modulate a plurality of subband signals corresponding to the specified bandwidth and demodulate a plurality of subband echo signals, and the channel switch switching device and the distributed antenna device are matched to transmit and receive various signals, so that a signal receiving and transmitting mechanism based on the plurality of subband signals is realized. The multiple sub-band signals and the corresponding multiple sub-band echo signals are matched for signal receiving and transmitting, and the signal processing efficiency aiming at the specified bandwidth is improved.

According to an aspect of the present disclosure, there is provided a holographic imaging security inspection system, comprising: the system comprises a multi-subband modulation and demodulation device, a channel switch switching device, a distributed antenna device and a data acquisition and processing device; the multi-subband modulation and demodulation device is respectively connected with the channel switch switching device and the data acquisition and processing device, and the channel switch switching device is also connected with the distributed antenna device; the multi-subband modulation and demodulation device sends a plurality of modulated subband signals to the channel switch switching device, the channel switch switching device sends the plurality of subband signals to corresponding transceiving antenna unit combinations in the distributed antenna device through the switched channel switch combinations, and the transceiving antenna unit combinations respond to the received subband signals and send electromagnetic wave signals to the tested object; the receiving and transmitting antenna unit receives a plurality of sub-band echo signals corresponding to the plurality of sub-band signals in a combined mode, and sends the plurality of sub-band echo signals to the multi-sub-band modulation and demodulation device through the channel switch in a combined mode, and the multi-sub-band modulation and demodulation device sends the plurality of modulated sub-band echo signals to the data acquisition processing device.

Optionally, in an example of the above aspect, the multi-subband modem apparatus is configured to: and when each sub-band signal is modulated, performing frequency sampling in a sub-band signal frequency interval corresponding to the sub-band signal, and modulating the sampling frequency, wherein the sampling frequency interval of the frequency sampling is determined according to the distance between the transmitting and receiving antenna unit combination of the distributed antenna device and the measured object.

Optionally, in an example of the above aspect, the multi-subband modem apparatus is configured to: when the sub-band echo signals corresponding to the sub-band signals are demodulated, the sub-band echo signals of the sub-band signals and the sub-band signals are subjected to mixing processing to obtain sub-band echo signals with specified frequencies.

Optionally, in an example of the above aspect, the distributed antenna apparatus includes antenna arrays, each antenna array including a transmit antenna element column and a receive antenna element column, each transmit antenna element column including a plurality of transmit antenna element groups, and each receive antenna element column including a plurality of receive antenna element groups.

Optionally, in one example of the above aspect, each transmit antenna element in the transmit antenna element column of each antenna array is arranged offset from each receive antenna element in the receive antenna element column in the azimuth dimension.

Optionally, in an example of the above aspect, the channel switch switching device is further configured to: determining a receiving and transmitting antenna unit combination of each time period and a corresponding relation between each receiving and transmitting antenna unit combination and each sub-band signal according to the sub-band signal and an antenna array in the distributed antenna device; and determining the channel switch combination corresponding to each time period according to the determined receiving and transmitting antenna unit combination and the corresponding relation.

Optionally, in an example of the above aspect, the channel switch switching device is further configured to: determining a sub-period included in each time period according to the number of the sub-band signals; and determining the corresponding relation between each sub-band signal and the receiving and transmitting antenna unit combination in each sub-period aiming at each time period; and determining the channel switch combination corresponding to each sub-period according to the determined corresponding relation.

Optionally, in an example of the above aspect, the number of subband signals modulated by the multi-subband modem apparatus is determined according to the number of antenna arrays in the distributed antenna apparatus and a switch control logic of the channel switch apparatus.

Optionally, in an example of the above aspect, each group of transmit antenna elements in the column of transmit antenna elements is separated by a first distance, each group of receive antenna elements in the column of receive antenna elements is separated by a second distance, where the first distance is greater than a distance between two adjacent transmit antenna elements in the group of transmit antenna elements, and the second distance is greater than a distance between two adjacent receive antenna elements in the group of receive antenna elements.

Optionally, in one example of the above aspect, the transmitting antenna unit groups and the receiving antenna unit groups in each antenna array are arranged in a staggered manner in the azimuth dimension direction.

Optionally, in an example of the above aspect, the channel switch switching device is further configured to: controlling each antenna array according to one of the following switch control logics: the antenna arrays are performed in parallel in a linear scanning manner, a portion of the antenna arrays are performed in parallel in a linear scanning manner and another portion of the antenna arrays are performed in parallel in a random scanning manner, the antenna arrays are sequentially performed in series in a linear scanning manner, a portion of the array is performed in series in a linear scanning manner and another portion is performed in series in a random scanning manner, and the antenna arrays are sequentially performed in series in a random scanning manner.

Alternatively, in one example of the above aspect, one or more partition walls are disposed on one side or both sides of the transmitting antenna unit column, and one or more partition walls are disposed on one side or both sides of the receiving antenna unit column, wherein each partition wall is formed with a choke groove.

Optionally, in one example of the above aspect, the data acquisition processing device includes a data acquisition device and a data processing device; the data acquisition device is used for synthesizing the sub-band echo signals demodulated by the multi-sub-band modulation and demodulation device to obtain bandwidth echo signals; the data processing device is used for carrying out three-dimensional imaging processing according to the bandwidth echo signals acquired from the data acquisition device and carrying out foreign matter detection processing based on three-dimensional image data.

Optionally, in an example of the above aspect, the data processing apparatus performs the three-dimensional imaging processing using a three-dimensional frequency domain energy-gathering imaging algorithm and/or a three-dimensional sparse bayesian compressed sensing imaging algorithm.

Optionally, in an example of the above aspect, the data processing apparatus is further configured to: performing orthographic projection on the three-dimensional image data to obtain a plurality of pieces of two-dimensional image data; performing segmentation processing on each two-dimensional image data according to a measured object in each two-dimensional image data so that each two-dimensional image data is segmented into at least one sub-image data aiming at the measured object; and inputting each piece of sub-image data into a trained anchor-free foreign matter detection model to obtain a foreign matter detection result aiming at the detected object, wherein the anchor-free foreign matter detection model generates a detection frame aiming at the part of the detected object included in the sub-image data based on the input sub-image data, and carries out foreign matter detection based on the generated detection frame.

Optionally, in an example of the above aspect, the data acquisition device is further configured to: performing clutter suppression processing, residual video phase correction, phase error correction and synthesis processing on the sub-band echo signals demodulated by the multi-sub-band modulation and demodulation device in sequence; and the data processing device is used for carrying out three-dimensional imaging processing according to the bandwidth echo signals obtained by the synthesis processing and carrying out foreign matter detection processing based on the three-dimensional image data.

Optionally, in an example of the above aspect, at least one of a temperature measuring device, a metal detecting device, and a three-dimensional point cloud measuring device is further included.

According to another aspect of the present disclosure, there is also provided a method of security inspection using a holographic imaging security inspection system, wherein the holographic imaging security inspection system comprises: the system comprises a multi-subband modulation and demodulation device, a channel switch switching device, a distributed antenna device and a data acquisition and processing device; the method comprises the following steps: modulating and modulating a plurality of sub-band signals corresponding to the specified bandwidth at the multi-sub-band modulation and demodulation device, and sending the modulated plurality of sub-band signals to the channel switch switching device; at the channel switch switching device, switching the corresponding channel switch combination according to the multiple sub-band signals and the time period, and sending each sub-band signal to the corresponding transceiving antenna unit combination by using each corresponding channel switch in the channel switch combination; at the receiving and transmitting antenna unit combination in the distributed antenna device, responding to the received sub-band signal, transmitting an electromagnetic wave signal to the tested object, receiving a corresponding sub-band echo signal, and feeding back the sub-band echo signal to the channel switch switching device; transmitting, at the channel switch switching device, the received subband echo signal to the multi-subband modem device; at the multi-sub-band modulation and demodulation device, demodulating the received sub-band echo signals and sending the demodulated sub-band echo signals to the data acquisition and processing device; and at the data acquisition and processing device, performing three-dimensional imaging processing according to the demodulated sub-band echo signal and performing foreign matter detection processing based on the three-dimensional image data.

Drawings

A further understanding of the nature and advantages of the present disclosure may be realized by reference to the following drawings. In the drawings, similar components or features may have the same reference numerals.

FIG. 1 illustrates a block diagram of one example of a holographic imaging security inspection system of the present disclosure.

Fig. 2 shows a schematic diagram of one example of linear scanning and random scanning of an antenna array.

Fig. 3A shows a schematic frequency-modulated wave diagram of one example of channel switch switching by the channel switch switching device in the case of two subband signals according to the present disclosure.

Fig. 3B shows a schematic frequency modulated wave diagram of an example of channel switch switching by the channel switch switching device in the case of four subband signals according to the present disclosure.

Fig. 4 shows a schematic diagram of one example of an antenna array included in the distributed antenna apparatus of the present disclosure.

Fig. 5 shows a schematic diagram of another example of an antenna array included in the distributed antenna apparatus of the present disclosure.

FIG. 6 illustrates a flow chart of one example of a method of security screening using the holographic imaging security screening system of the present disclosure.

Detailed Description

The subject matter described herein will be discussed with reference to example embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and thereby implement the subject matter described herein, and are not intended to limit the scope, applicability, or examples set forth in the claims. Changes may be made in the function and arrangement of elements discussed without departing from the scope of the disclosure. Various examples may omit, substitute, or add various procedures or components as needed. In addition, features described with respect to some examples may also be combined in other examples.

As used herein, the term "include" and its variants mean open-ended terms in the sense of "including, but not limited to. The term "based on" means "based at least in part on". The terms "one embodiment" and "an embodiment" mean "at least one embodiment". The term "another embodiment" means "at least one other embodiment". The terms "first," "second," and the like may refer to different or the same object. Other definitions, whether explicit or implicit, may be included below. The definition of a term is consistent throughout the specification unless the context clearly dictates otherwise.

As used herein, the term "couple" refers to a direct mechanical, communication, or electrical connection between two components, or an indirect mechanical, communication, or electrical connection through an intermediate component. The term "electrically connected" means that electrical communication can be made between two components for data/information exchange. Likewise, the electrical connection may refer to a direct electrical connection between two components, or an indirect electrical connection through an intermediate component. The electrical connection may be achieved in a wired manner or a wireless manner.

Millimeter wave human body security check equipment is widely used in various security check places such as airports, stations, courts and the like, and by using millimeter wave imaging technology, millimeter wave human body security check equipment can effectively detect contraband articles hidden in various parts of a human body under clothing coverage without directly contacting the human body of a person to be detected, and can extract information such as the shape, size and position of a hidden target article from an image generated based on detection. Based on words, the millimeter wave human body security inspection equipment is applied to areas with high public safety requirements, such as airports, stations, frontiers and the like.

In view of the foregoing, the present disclosure provides a holographic imaging security inspection system and a security inspection method. The multi-subband modulation and demodulation device in the holographic imaging security inspection system can modulate a plurality of subband signals corresponding to the specified bandwidth and demodulate a plurality of subband echo signals, and the channel switch switching device and the distributed antenna device are matched to transmit and receive various signals, so that a signal receiving and transmitting mechanism based on the plurality of subband signals is realized. The multiple sub-band signals and the corresponding multiple sub-band echo signals are matched for signal receiving and transmitting, and the signal processing efficiency aiming at the specified bandwidth is improved.

The holographic imaging security inspection system according to the present disclosure will be described in detail below with reference to the accompanying drawings.

Fig. 1 shows a block diagram of one example of a holographic imaging security inspection system 100 of the present disclosure.

As shown in fig. 1, the holographic imaging security inspection system 100 may include: the multi-subband modulation and demodulation device 110, the channel switch switching device 120, the distributed antenna device 130 and the data acquisition and processing device 140. The multi-subband modulation and demodulation apparatus 110 may be connected to the channel switch switching apparatus 120 and the data acquisition and processing apparatus 140, respectively, and the channel switch switching apparatus 120 may also be connected to the distributed antenna apparatus 130.

Next, the multi-subband modem 110 will be explained first.

The multi-subband modem 110 may modulate a plurality of subband signals corresponding to a designated bandwidth.

The designated bandwidth corresponds to a designated frequency range, the frequency range corresponding to the signal bandwidth of each sub-band signal belongs to the frequency range corresponding to the designated bandwidth, and the signal bandwidth corresponding to each sub-band signal may constitute the designated bandwidth. The subband signals correspond to the echo signals one by one, and the signal bandwidths of the echo signals can also form a specified bandwidth.

For example, the frequency range of the specified bandwidth is [70Hz, 90Hz ]]And obtaining 4 subband signals through modulation: r is₁(f₁)、r₂(f₂)、r₃(f₃) And r₄(f₄) Wherein r is₁(f₁) The frequency range of (1) is [70Hz, 75Hz]，r₂(f₂) The frequency range of (1) is [75Hz, 80Hz]，r₃(f₃) The frequency range of (A) is [80Hz, 85Hz]，r₄(f₄) The frequency range of (1) is [85Hz, 90Hz]. Accordingly, 4 echo signals can be obtained:

and

wherein the content of the first and second substances,

is r₁(f₁) The corresponding echo signal is then transmitted to the receiver,

the corresponding frequency ranges are 70Hz, 75Hz]，

Is r₂(f₂) The corresponding echo signal is then transmitted to the receiver,

the frequency range of (1) is [75Hz, 80Hz]，

Is r₃(f₃) The corresponding echo signal is then transmitted to the receiver,

the frequency range of (A) is [80Hz, 85Hz]，

Is r₄(f₄) The corresponding echo signal is then transmitted to the receiver,

the frequency range of (1) is [85Hz, 90Hz]。

In one example, the number of subband signals modulated by multi-subband modem 110 may be determined according to the number of antenna arrays in distributed antenna apparatus 130 and the switch control logic of channel switch 120.

The channel switch 120 is configured to control the antenna units scanned in each antenna array by switching different channel switches, and the switch control logic of the channel switch 120 may include parallel control and serial control for each antenna array, where the antenna arrays may be scanned simultaneously during the parallel control, and the antenna arrays may be scanned sequentially in sequence during the serial control.

The number of sub-band signals modulated is the same as the number of antenna arrays that need to be scanned in parallel. For example, there are two antenna arrays in the distributed antenna apparatus, and the switch control logic of the channel switch apparatus controls the two antenna arrays in a parallel manner, that is, the two antenna arrays scan in parallel, so that the multi-subband modem apparatus 110 can modulate two subband signals, and the two subband signals respectively control the two antenna arrays.

After determining the number of subband signals, multi-subband modem 110 may divide the signal frequency interval of the designated bandwidth into the determined number of subband signal frequency intervals. For example, the signal frequency interval specifying the bandwidth is: 26 GHz-40 GHz, the determined number of subband signals is 2, then dividing the subband signals into two subband signal frequency intervals, which are respectively: 26GHz to 33GHz and 33GHz to 40 GHz.

Each subband signal frequency interval corresponds to one subband signal, and when each subband signal is modulated, frequency sampling is carried out in the subband signal frequency interval corresponding to the subband signal, and the sampling frequency is modulated.

For the frequency sampling of each subband signal frequency interval, the resulting sampling frequency can represent or recover the continuous frequency of the subband signal frequency interval. Therefore, under the condition of ensuring that each sub-band signal is not distorted, the data volume carried by each sub-band signal can be reduced, and the transmission efficiency is improved in the signal transmission process.

The sampling frequency interval of the frequency sampling may be determined according to the distance between the transmitting and receiving antenna unit combination of the distributed antenna apparatus 130 and the object to be measured. Specifically, the larger the distance between the transmitting/receiving antenna unit combination of the distributed antenna apparatus 130 and the measured object is, the smaller the sampling frequency interval may be; the smaller the distance between the transmitting/receiving antenna element combination of the distributed antenna apparatus 130 and the object to be measured, the larger the sampling frequency interval may be.

For example, the minimum frequency of the subband signal frequency interval is f_minIf the sampling frequency interval is Δ f, a sub-band frequency vector f consisting of sampling frequencies obtained by frequency sampling_nComprises the following steps:

wherein N represents the determined number of subband signals, N_rDenotes the number of samples for a subband signal frequency interval, round (.) denotes the rounding operator, and superscript T denotes the vector transposition. Subband frequency vector f_nEach vector element in (a) represents a sampling frequency.

For each sub-band signal frequency interval, after frequency sampling, frequency modulation processing may be performed on the sampling frequency of each sub-band signal frequency interval, so as to obtain a frequency-modulated sub-band signal. The frequency modulation modes adopted by different sub-band signal frequency intervals can be different, and the frequency modulation modes can comprise continuous wave frequency modulation, linear frequency modulation, step frequency modulation and the like.

After obtaining each modulated subband signal, the multi-subband modem 110 may correspondingly transmit each subband signal to the channel switch combination switched by the channel switch switching device 120, and transmit each subband signal to the corresponding antenna unit combination through the channel switch combination, so as to trigger the antenna unit combination to scan.

In addition, the multi-subband modem 110 may also perform demodulation processing on the subband echo signal corresponding to the subband signal.

The sub-band echo signal is a signal reflected to the receiving antenna unit by the measured object after the transmitting antenna unit in the transmitting-receiving antenna unit combination transmits an electromagnetic wave signal to the measured object. The subband echo signal is sequentially transmitted to the multi-subband modem 110 through the distributed antenna apparatus 130 and the channel switch switching apparatus 120, wherein the subband signal triggering the transmitting antenna unit to transmit the electromagnetic wave signal corresponds to the subband echo signal reflected based on the electromagnetic wave signal, and the channel switch of the channel switch switching apparatus 120 transmitting the subband echo signal is the same as the channel switch of the subband signal corresponding to the subband echo signal.

In one example, when demodulating the sub-band echo signal corresponding to each sub-band signal, the multi-sub-band modem 110 may mix the sub-band echo signal of the sub-band signal with the sub-band signal to obtain a sub-band echo signal of a specified frequency. Wherein the designated frequency may include an intermediate frequency.

The sub-band echo signals subjected to the frequency mixing processing correspond to sub-band signals, and each sub-band echo signal is obtained from the corresponding sub-band signal. Therefore, the consistency of the sub-band signals is kept during the mixing processing, and each sub-band signal is kept relatively independent in the modulation and demodulation processes and is not influenced by other sub-band signals.

By the multi-subband modulation and demodulation device 110, simultaneous multi-channel signal transmission can be realized, the signal receiving and transmitting time is saved, and the data acquisition efficiency is improved. In addition, the multi-subband modem 110 performs multi-subband signal transceiving, thereby avoiding the problems of in-band and out-of-band spurs caused by the original large-bandwidth signal generation mode and the deterioration of flatness in the signal band, which further causes the difficulty of channel signal compensation to increase. The multi-subband modem 110 modulates the multi-subband signal, so that in-band and out-of-band spurs generated by a single signal can be well suppressed, and good in-band flatness can be effectively ensured. In addition, the multi-subband modem 110 can reduce the bandwidth of a single signal by modulating the multi-subband signal, so that the linearity of the subband signal is easy to implement, and the subsequent signal compensation and imaging processing is facilitated.

The channel switch switching device 120 will be explained first.

The channel switch switching device 120 may include a plurality of channel switches, each corresponding to one antenna unit in the distributed antenna device 130. When the channel switch corresponding to the transmitting antenna unit is turned on, the transmitting antenna unit can receive the sub-band signal and can be triggered to transmit the electromagnetic wave signal. When the channel switch corresponding to the transmitting antenna unit is closed, the transmitting antenna unit cannot receive the sub-band signal and further cannot be triggered to transmit the electromagnetic wave signal. When the channel switch corresponding to the receiving antenna unit is turned on, the receiving antenna unit can be used as a receiving antenna unit corresponding to the transmitting antenna unit for receiving the sub-band echo signal. When the channel switch of the corresponding receiving antenna unit is closed, the receiving antenna unit receives the receiving antenna unit which can not be used for receiving the sub-band echo signal.

The transmitting antenna unit which is started by the channel switch and the receiving antenna unit which is started by the channel switch can form a group of receiving and transmitting antenna unit combination, and the group of receiving and transmitting antenna unit combination can perform at least one time of transmitting and receiving operation of electromagnetic wave signals, so that the channel switches corresponding to the group of receiving and transmitting antenna unit combination can be used as a switch channel when all the channel switches are started. Each switch channel corresponds to a group of transceiving antenna units and accordingly can perform at least one transmission and receiving operation of electromagnetic wave signals. And each sub-band signal is transmitted by a corresponding switch channel and triggers a corresponding transceiving antenna unit to be combined.

The channel switch 120 can independently control each antenna array, for example, control each antenna array to perform in different orders, for example, in parallel or in serial order; the scanning mode of each antenna array can be controlled to be different, for example, the antenna array can adopt a linear scanning mode or a random scanning mode.

In one example, the channel switch switching device 120 may control the respective antenna arrays in accordance with any of the following switch control logic: the antenna arrays are performed in parallel in a linear scanning manner, a portion of the antenna arrays are performed in parallel in a linear scanning manner and another portion of the antenna arrays are performed in parallel in a random scanning manner, the antenna arrays are sequentially performed in series in a linear scanning manner, a portion of the array is performed in series in a linear scanning manner and another portion is performed in series in a random scanning manner, and the antenna arrays are sequentially performed in series in a random scanning manner.

Taking the two antenna arrays 121 and 122 as an example, the channel switch 120 may control the antenna arrays 121 and 122 to perform the scanning operation in parallel, at this time, the antenna arrays 121 and 122 perform the scanning operation simultaneously, and the scanning modes of the antenna arrays 121 and 122 may be the same, that is, both the scanning modes are linear scanning or random scanning; it may also be different, i.e. one antenna array in a linear scanning manner and the other antenna array in a random scanning manner.

The channel switch 120 may further control the antenna arrays 121 and 122 to sequentially and serially perform the scanning operation, in this case, the antenna array 121 may perform the antenna array 122 first, or the antenna array 122 may perform the antenna array 121 first and then perform the scanning operation. In this case, the antenna arrays 121 and 122 may be scanned in the same manner, i.e., both in a linear scanning manner or in a random scanning manner; it may also be different, i.e. one antenna array is in a linear scanning mode and the other antenna array is in a random scanning mode

When the antenna array scans in a linear scanning mode, equivalent sampling points formed by the combination of the receiving and transmitting antenna units are uniformly distributed, and when the antenna array scans in a random scanning mode, the equivalent sampling points formed by the combination of the receiving and transmitting antenna units are non-uniformly distributed. The equivalent sampling point formed by the transceiving antenna unit combination can be the geometric center position of the transmitting antenna unit and the receiving antenna unit in the transceiving antenna unit combination. The equivalent sampling points of the transceiving antenna element combinations in the same antenna array can be located on the same straight line.

Fig. 2 shows a schematic diagram of one example 200 of linear scanning and random scanning of the antenna array of the present disclosure.

The channel switch switching device 120 in the holographic imaging security inspection system shown in fig. 2 includes two antenna arrays 121 and 122, wherein the antenna array 121 adopts a linear scanning manner, and the antenna array 122 adopts a random scanning manner. The equivalent sampling points formed by scanning with the linear scanning antenna array 121 are uniformly distributed, as shown on the left side of the cylinder in fig. 2. The equivalent sampling points formed by scanning with the randomly scanned antenna array 122 are not uniformly distributed, as shown on the right side of the cylinder in fig. 2.

The combination of antenna elements selected by the channel switch switching device 120 in different time periods may be different, i.e., the switch channels turned on in different time periods may be different. Based on this, the channel switch switching device 120 can switch the corresponding channel switch combination according to the plurality of subband signals and the time period, so as to select the transceiving antenna unit combination corresponding to the channel switch combination for scanning in the time period.

And the channel switches in the switched channel switch combination are turned on in corresponding time periods, and each subband signal is transmitted to the corresponding antenna unit through the corresponding channel switch so as to trigger the corresponding antenna unit to scan.

Each time period corresponds to at least one group of transceiving antenna unit combination, and the corresponding transceiving antenna unit combination is triggered to scan in the time period. The combination of the transmit and receive antenna elements for different time periods may be different.

For each time period, the time period may be divided into a plurality of sub-periods according to the number of sub-band signals. In each sub-period, each sub-band signal triggers the corresponding antenna unit combination to perform parallel scanning. In different sub-periods belonging to the same time period, the antenna unit combinations corresponding to the same sub-band signal may be different.

The channel switch switching device 120 may further determine the transceiving antenna unit combination of each time period according to the subband signal and the antenna array in the distributed antenna device, and the corresponding relationship between each transceiving antenna unit combination and each subband signal.

Each subband signal is used for triggering the corresponding receiving and transmitting antenna unit combination to carry out scanning operation. When each antenna array in the distributed antenna device scans serially, only one antenna array performs the scanning operation at each time, and the determined transceiving antenna unit combination is the same as the number of the sub-band signals.

When the number of antenna arrays in parallel in the distributed antenna apparatus includes at least two, the same number of combinations of transmit/receive antenna elements may be determined from each antenna array, and the sum of the determined combinations of transmit/receive antenna elements in all antenna arrays is the same as the number of subband signals.

After determining the transceiving antenna unit combination corresponding to each time period and the corresponding relationship between the transceiving antenna unit combination and each subband signal, the channel switch switching device 120 may determine the channel switch combination corresponding to each time period. And according to the corresponding relationship between the combination of the transmitting and receiving antenna units and the sub-band signals and the corresponding relationship between the combination of the switching channels and the combination of the transmitting and receiving antenna units, the sub-band signals can be transmitted to the corresponding combination of the transmitting and receiving antenna units by using the corresponding switching channels, and then the combination of the transmitting and receiving antenna units is triggered to carry out scanning operation in the current period.

Further, the channel switch switching means may determine the number of sub-periods included in each time period according to the number of sub-band signals, the determined number of sub-periods included in each time period being the same as the number of sub-band signals.

Then, for each time period, the corresponding relationship between the respective subband signals and the transceiving antenna unit combinations in each sub-period within the time period can be determined. In the same time period, the corresponding combinations of the transmit-receive antenna units in different sub-periods of the same sub-band signal may be different. Based on this, the channel switch combination corresponding to each sub-period can be determined according to the determined corresponding relationship between each sub-band signal and the transceiving antenna unit combination in each sub-period. In each sub-period, the sub-band signal, the channel switch combination and the transceiving antenna unit combination are in a corresponding relationship, and the switch channel formed by each channel switch combination is used for transmitting the corresponding sub-band signal to the corresponding transceiving antenna unit combination. In different sub-periods, the corresponding relationship among the sub-band signals, the combination of the channel switches and the combination of the transmitting and receiving antenna units is different.

As shown in fig. 3A, the frequency intervals corresponding to the two subband signals modulated by the multi-subband modem are f₁And f₂The distributed antenna device comprises two antenna arrays: TR1 and TR2, and the two antenna arrays are scanned in parallel, a transceiver antenna element combination is determined from each antenna array for each time period, such that a transceiver antenna element combination in each of the two antenna arrays performs the scanning operation during each time period.

The first time period may include two sub-periods per time period according to the number of sub-band signals, as shown in fig. 3A, and the two sub-periods included in the first time period are: 0-1/2 Δ t and 1/2 Δ t- Δ t.

During the first time period at, the transceiver antenna element combination triggered to scan in antenna array TR1 includes transmit antenna elements TR1-T1 and receive antenna elements TR1-R1, and correspondingly, the transceiver antenna element combination triggered to scan in antenna array TR2 includes transmit antenna elements TR2-T1 and receive antenna elements TR 2-R1.

Wherein, in the first sub-period (0-1/2 Δ T), the antenna elements TR1-T1 and TR1-R1 form a transmit-receive antenna element combination responsive to f₁Antenna elements TR2-T1 and TR2-R1 are combined in response to f₂The subband signal of (a); during the second sub-period (1/2 Δ T- Δ T), the antenna elements TR1-T1 and TR1-R1 form a transmit-receive antenna element combination responsive to f₂Antenna elements TR2-T1 and TR2-R1 are combined in response to f₁Of the sub-band signal.

During a second time period (at-2 at), a transceiver antenna element combination triggered to scan in antenna array TR1 includes transmit antenna elements TR1-T1 and receive antenna elements TR1-R2, and accordingly, a transceiver antenna element combination triggered to scan in antenna array TR2 includes transmit antenna elements TR2-T1 and receive antenna elements TR 2-R2.

Wherein during a first sub-period (Δ T-3/2 Δ T) of the second time period, the transmit-receive antenna element combination of antenna elements TR1-T1 and TR1-R2 is responsive to f₁Antenna elements TR2-T1 and TR2-R2 are combined in response to f₂The subband signal of (a); during the second sub-period (3/2 Δ T-2 Δ T), the antenna elements TR1-T1 and TR1-R2 form a transmit-receive antenna element combination responsive to f₂Antenna elements TR2-T1 and TR2-R2 are combined in response to f₁Of the sub-band signal.

As shown in fig. 3B, the frequency intervals corresponding to the four subband signals modulated by the multi-subband modem are f₁、f₂、f₃And f₄The distributed antenna device comprises two antenna arrays: TR1 and TR2, and the two antenna arrays are scanned in parallel, two combinations of transceiver antenna elements are determined from each antenna array for each time period, such that two combinations of transceiver antenna elements in each of the two antenna arrays perform the scanning operation during each time period.

Four sub-periods may be included per time period according to the number of sub-band signals, and as shown in fig. 3B, the first time period includes two sub-periods: 0-1/4 Δ t, 1/4 Δ t-2/4 Δ t, 2/4 Δ t-3/4 Δ t and 3/4 Δ t- Δ t.

During the first time period at, one transceiver antenna element combination triggered for scanning in the antenna array TR1 comprises transmit antenna elements TR1-T1 and receive antenna elements TR1-R1, another transceiver antenna element combination comprises transmit antenna elements TR1-T2 and receive antenna elements TR1-R2, correspondingly, one transceiver antenna element combination triggered for scanning in the antenna array TR2 comprises transmit antenna elements TR2-T1 and receive antenna elements TR2-R1, and another transceiver antenna element combination comprises transmit antenna elements TR2-T2 and receive antenna elements TR 2-R2.

Wherein, in the first sub-period (0-1/4 Δ T), the antenna elements TR1-T1 and TR1-R1 form a transmit-receive antenna element combination responsive to f₁Antenna elements TR1-T2 and TR1-R2 are combined in response to f₂Of the sub-band signal. The antenna elements TR2-T1 and TR2-R1 constitute a transceiver antenna element combination responsive to f₃Antenna elements TR2-T2 and TR2-R2 are combined in response to f₄Of the sub-band signal.

During the second sub-period (1/4 Δ T-2/4 Δ T), the antenna elements TR1-T1 and TR1-R1 form a transceiver antenna element combination responsive to f₂Sub-band signal of (2), antenna units TR1-T2 and TR1-R2Antenna element combination response to f₃Of the sub-band signal. The antenna elements TR2-T1 and TR2-R1 constitute a transceiver antenna element combination responsive to f₄Antenna elements TR2-T2 and TR2-R2 are combined in response to f₁Of the sub-band signal.

In the third sub-period (2/4 Δ T-3/4 Δ T), the antenna elements TR1-T1 and TR1-R1 form a transceiver antenna element combination responsive to f₃Antenna elements TR1-T2 and TR1-R2 are combined in response to f₄Of the sub-band signal. The antenna elements TR2-T1 and TR2-R1 constitute a transceiver antenna element combination responsive to f₁Antenna elements TR2-T2 and TR2-R2 are combined in response to f₂Of the sub-band signal.

During the fourth sub-period (3/4 Δ T- Δ T), the combination of transmit and receive antenna elements TR1-T1 and TR1-R1 is responsive to f₄Antenna elements TR1-T2 and TR1-R2 are combined in response to f₁Of the sub-band signal. The antenna elements TR2-T1 and TR2-R1 constitute a transceiver antenna element combination responsive to f₂Antenna elements TR2-T2 and TR2-R2 are combined in response to f₃Of the sub-band signal.

The distributed antenna apparatus 130 will be explained below.

The distributed antenna apparatus 130 may include a plurality of transmitting antenna units and a plurality of receiving antenna units, and one transmitting antenna unit and one receiving antenna unit may form a transmitting and receiving antenna unit combination, and each transmitting and receiving antenna unit combination may scan the object to be tested in response to the received subband signal, that is, the transmitting antenna unit in the transmitting and receiving antenna unit combination may transmit an electromagnetic wave signal to the object to be tested, and the receiving antenna unit may receive a corresponding subband echo signal. In one example, the electromagnetic wave signals transmitted by the transceiving antenna units in the holographic imaging security inspection system 100 may include radar signals, and the radar signals may include signals in microwave, millimeter wave, terahertz wave, and other frequency bands.

In one example of the present disclosure, the transmitting antenna unit and the receiving antenna unit in the distributed antenna apparatus are arranged in an antenna array manner, and the distributed antenna apparatus may include at least one antenna array, each antenna array including a transmitting antenna unit column and a receiving antenna unit column, each transmitting antenna unit column including a plurality of transmitting antenna unit groups, and each receiving antenna unit column including a plurality of receiving antenna unit groups.

In one example, the individual transmit antenna elements in the column of transmit antenna elements may be arranged uniformly, i.e., with the same spacing between the individual transmit antenna elements. The individual receive antenna elements in the column of receive antenna elements may be arranged uniformly, i.e., with the same spacing between the individual receive antenna elements.

In another example, the respective transmit antenna elements in the transmit antenna element column are arranged in groups, and the transmit antenna element column may include a plurality of transmit antenna element groups, each of which may include a first specified number of transmit antenna elements. Each of the receiving antenna elements in the receiving antenna element column may be arranged in groups, and the receiving antenna element column may include a plurality of receiving antenna element groups, and each of the receiving antenna element groups may include a second specified number of receiving antenna elements. The first designated number and the second designated number may be different or the same.

In this example, the spacing between adjacent transmit antenna elements in the group of transmit antenna elements and the spacing between adjacent receive antenna elements in the group of receive antenna elements may be specified. For example, the spacing between adjacent receiving antenna elements in the receiving antenna element group may be k times the operating wavelength, k may take a value between 0.75 and 1.2, and the spacing between adjacent transmitting antenna elements in the transmitting antenna element group may be twice the spacing between adjacent receiving antenna elements in the receiving antenna element group.

In one example, the respective groups of transmit antenna elements in the column of transmit antenna elements may be spaced apart by a first distance, which may be greater than a spacing between two adjacent transmit antenna elements in the group of transmit antenna elements. Each receiving antenna unit group in the receiving antenna unit column may be spaced by a second distance, and the second distance may be greater than a distance between two adjacent receiving antenna units in the receiving antenna unit group.

The first distance and the second distance may be specified. For example, the first distance may be twice the spacing between adjacent receive antenna elements in the group of receive antenna elements. The second distance may be seven times a spacing between adjacent ones of the receive antenna elements in the group of receive antenna elements.

In this example, the transmitting antenna element groups and the receiving antenna element groups are arranged in a spaced manner, and the number of antenna elements is reduced on the basis that the transmission and reception of electromagnetic wave signals by the transmitting and receiving antenna element combinations can be realized.

Each transmitting antenna unit in the transmitting antenna unit column in each antenna array and each receiving antenna unit in the receiving antenna unit column are arranged in a staggered mode in the azimuth dimension direction. Can realize minimum sampling interval like this, through this kind of dislocation arrangement, realize receiving and dispatching branch and put, increase the isolation between the receiving and dispatching, promote the formation of image dynamic range of security installations, and then promote image quality, strengthen the foreign matter detectability of security installations to the human body surface.

Further, the transmitting antenna unit group and the receiving antenna unit group in each antenna array are arranged in a staggered manner in the direction of the azimuth dimension. The receiving and sending are equivalent in the same pitching dimension direction, and non-uniform signals in the direction of the azimuth dimension are avoided. In one arrangement, the distance between two adjacent transmitting antenna unit groups may be greater than the length of one receiving antenna unit group, and the distance between two adjacent receiving antenna unit groups may be greater than the length of one transmitting antenna unit group.

In addition, the column spacing between the transmit antenna element columns and the receive antenna element columns in each antenna array may be determined according to the antenna polarization of the transmit antenna elements and the receive antenna elements. The antenna polarization modes of the transmitting antenna unit and the receiving antenna unit can adopt vertical polarization, horizontal polarization, left-hand circular polarization, right-hand circular polarization, elliptical circular polarization and the like.

The same antenna polarization mode adopted by the transmitting antenna unit and the same antenna polarization mode adopted by the receiving antenna unit can be called as the same polarization, the different antenna polarization modes adopted by the transmitting antenna unit and the different antenna polarization modes adopted by the receiving antenna unit can be called as the cross polarization, and the column spacing corresponding to the same polarization mode can be set to be larger, so that the problem of the same polarization coupling can be avoided. The column pitch corresponding to the same polarization mode may be greater than the column pitch corresponding to the cross polarization mode. For example, the column pitch corresponding to the same polarization mode may be m times the operating wavelength, m may take a value between 2 and 10, the column pitch corresponding to the cross polarization mode may be n times the operating wavelength, and n may take a value between 0 and 6.

Based on the arrangement of the transmitting antenna units and the receiving antenna units in the antenna array, the transmitting antenna units in the transmitting antenna unit column and the receiving antenna units in the receiving antenna unit column may form a transceiving antenna unit combination.

In one example, for each antenna array, the transceiver antenna element combination may be composed of a transmitting antenna element in a transmitting antenna element group and a receiving antenna element in an adjacent corresponding receiving antenna element group, an equivalent sampling point is formed by the transmitting and receiving combinations, signals are acquired at different equivalent sampling points, the doppler bandwidth acquisition of a relative target is realized, and then the resolution imaging in the dimension is realized. In this example, the group of receiving antenna elements that is displaced from and closest to the transmitting antenna element is the group of receiving antenna elements that correspond adjacent to the transmitting antenna element.

Fig. 4 shows a schematic diagram of one example 400 of an antenna array included in a distributed antenna apparatus of the present disclosure.

As shown in fig. 4, the distributed antenna apparatus includes antenna arrays 121 and 122, and the arrangement of antenna elements in the two antenna arrays is the same. Only the antenna array 121 will be described below. The X-axis shown in fig. 4 represents the azimuth dimension direction, and the Z-axis represents the pitch dimension direction, i.e., the generatrix direction of the cylindrical surface.

"TR 1-T1, TR1-T2, TR1-T3, TR 1-T4" are one transmit antenna element group (hereinafter referred to as a first transmit antenna element group), and "TR 1-T5, TR1-T6, TR1-T7, TR 1-T8" are the other transmit antenna element group (hereinafter referred to as a second transmit antenna element group). "TR 1-R1, TR 1-R2" is one receiving antenna element group (hereinafter referred to as a first receiving antenna element group), "TR 1-R3, TR 1-R4" is another receiving antenna element group (hereinafter referred to as a second receiving antenna element group), and "TR 1-R5, TR 1-R6" is another receiving antenna element group (hereinafter referred to as a third receiving antenna element group).

The first transmitting antenna unit group and the second transmitting antenna unit group in the transmitting antenna unit row and the first receiving antenna unit group, the second receiving antenna unit group and the third receiving antenna unit group in the receiving antenna unit row are arranged in a staggered mode in the direction of the azimuth dimension. That is, each antenna element group is aligned with a gap between two antenna element groups of another column in the azimuth dimension direction, specifically, each transmitting antenna element group is aligned with a gap between two adjacent receiving antenna element groups in the receiving antenna element column, and each receiving antenna element group is aligned with a gap between two adjacent transmitting antenna element groups in the transmitting antenna element column in the azimuth dimension direction.

The distance "d _ Trans 2" between adjacent groups of transmit antenna elements is greater than the distance "d _ Trans 1" between adjacent transmit antenna elements in a group of transmit antenna elements, and the distance "d _ Receiv 2" between adjacent groups of receive antenna elements is greater than the distance "d _ Receiv 1" between adjacent receive antenna elements in a group of receive antenna elements. The distance between the transmitting antenna unit group and the adjacent receiving antenna unit group in the Z direction is "d _ TrRe 1", so that the transmitting antenna unit group and the receiving antenna unit group are arranged in a staggered manner, and each transmitting antenna unit and each receiving antenna unit are arranged in a staggered manner.

The first transmitting antenna unit group and the first receiving antenna unit group and the second receiving antenna unit group are adjacently corresponding, so that the transmitting antenna units in the first transmitting antenna unit group and the 'TR 1-R1, TR 1-R2' in the first receiving antenna unit group and the 'TR 1-R3, TR 1-R4' in the second receiving antenna unit group respectively form a transceiving antenna unit combination. Correspondingly, the second transmitting antenna unit group and the second receiving antenna unit group and the third receiving antenna unit group are adjacent and corresponding,

in one example, one or more partition walls are disposed on one or both sides of the transmitting antenna element column, and one or more partition walls are disposed on one or both sides of the receiving antenna element column, wherein each partition wall is formed with a choke groove.

Fig. 5 shows a schematic diagram of another example of an antenna array of the present disclosure.

As shown in fig. 5, the X-axis direction represents the azimuth dimension direction, and the Z-axis direction represents the pitch dimension direction. Two sides of the transmitting antenna unit column are respectively provided with a separation wall, and two sides of the receiving antenna unit column are also respectively provided with a separation wall. Each partition wall is formed with a choke groove, and may have a number of choke grooves, wherein the number of choke grooves may be referred to as a number of choke groove stages. Specifically, the choke groove may be formed on a side surface of the partition wall, and may extend in a length direction and a width direction of the partition wall.

The choke groove may have an opening recessed from a side surface of the partition wall, wherein the opening may extend in a width direction of the partition wall, and the opening may have a certain shape (e.g., a rectangular shape) in a cross section of the choke groove perpendicular to a length direction of the partition wall. The opening has a groove width and a groove depth, and the groove width and the groove depth of the choke groove may be approximately equal to a quarter wavelength of an operating frequency corresponding to the choke groove, in order to achieve better performance, such as attenuation of large fluctuations in the transmission distribution characteristics of the transmitting antenna unit due to the surrounding receiving antenna unit, the choke groove, and the metal floor.

In this example, by providing the isolation wall and the choke groove formed in the isolation wall, the isolation requirement value of the transmit-receive antenna array can be effectively increased in a wide frequency band range, so that the imaging quality and the detection effect of the imaging device are improved, and the requirement of the imaging system on size compactness is further met.

The data acquisition and processing device 140 will be explained below.

The data acquisition processing device 140 may receive the demodulated subband echo signals from the subband modulation and demodulation device 110, and perform three-dimensional imaging processing on the demodulated subband echo signals and foreign object detection processing based on the three-dimensional image data.

In particular, the data acquisition and processing device may comprise a data acquisition device and a data processing device. The data acquisition device can be used for synthesizing the sub-band echo signals demodulated by the multi-sub-band modulation and demodulation device to obtain bandwidth echo signals, and the data processing device is used for performing three-dimensional imaging processing according to the bandwidth echo signals acquired from the data acquisition device and performing foreign matter detection processing based on three-dimensional image data.

In one example, the data acquisition device may sequentially perform clutter suppression processing, residual video phase correction, phase error correction, and synthesis processing on the sub-band echo signals demodulated by the multi-sub-band modulation and demodulation device.

Specifically, the data acquisition device may acquire the demodulated subband echo signal from the subband modulation and demodulation device, and in this example, the subband echo signal demodulated by the subband modulation and demodulation device may be used as the first subband echo signal. The plurality of first sub-band echo signals are echo signals of a plurality of corresponding sub-band signals, the first sub-band echo signals correspond to the sub-band signals one to one, the plurality of sub-band signals correspond to a designated bandwidth, and correspondingly, the plurality of first sub-band echo signals also correspond to the designated bandwidth.

Then, Fourier transform is carried out on the obtained multiple first sub-band echo signals to obtain multiple second sub-band echo signals of a time domain; clutter in each second sub-band echo signal is suppressed, wherein the clutter in each second sub-band echo signal includes phase-directed primary and secondary frequency components that the second sub-band echo signal generates with other second sub-band echo signals. And then carrying out residual video phase correction on each second sub-band echo signal after the suppression processing.

Determining a reference sub-band echo signal from a plurality of second sub-band echo signals subjected to residual video phase correction, calculating phase errors of the reference sub-band echo signal and each of other second sub-band echo signals except the reference sub-band echo signal in the plurality of second sub-band echo signals, and determining a compensation factor corresponding to each of the other second sub-band echo signals based on the phase error of the second sub-band echo signal; and correcting the second sub-band echo signals based on the second sub-band echo signals and the corresponding compensation factors so as to enable the phases of the second sub-band echo signals to be consistent.

And performing inverse Fourier transform on the second sub-band echo signal after the phase error correction and the reference sub-band echo signal to obtain a third sub-band echo signal of the frequency domain. And synthesizing the third sub-band echo signals after the Fourier inverse transformation to obtain a bandwidth echo signal.

In one example, the data processing apparatus may also perform three-dimensional imaging processing using a three-dimensional frequency domain energy-gathering imaging algorithm and/or a three-dimensional sparse bayesian compressed sensing imaging algorithm.

When the antenna array adopts a linear scanning mode, a three-dimensional frequency domain energy gathering imaging algorithm can be used for carrying out three-dimensional imaging processing on data obtained by the linear scanning mode.

In particular, the data processing device may acquire a bandwidth echo signal from the data acquisition device, the acquired bandwidth echo signal being based on a cylindrical coordinate system.

And determining a phase correction coefficient and an amplitude correction coefficient corresponding to the environment temperature information from the corresponding relation of the temperature and the amplitude and phase correction coefficients, and performing amplitude and phase correction processing on the acquired bandwidth echo signal according to the environment temperature information, the phase correction coefficient and the amplitude correction coefficient.

And respectively carrying out Fourier transform on the bandwidth echo signals after amplitude and phase correction in the pitch dimension direction and the cylinder rotation angle direction to obtain second bandwidth echo signals of a frequency domain.

And filtering the phase which changes nonlinearly in the cylindrical three-dimensional coordinate direction in the Fourier transformed second bandwidth echo signal by using a nonlinear phase matching filter function to obtain a third bandwidth echo signal comprising the phase which changes linearly in the cylindrical three-dimensional coordinate direction, and performing inverse Fourier transform on the phase-filtered third bandwidth echo signal to obtain three-dimensional cylindrical imaging data based on a cylindrical coordinate system.

Wherein, the nonlinear phase matching filter function can be obtained according to the following modes: firstly, generating a function based on the cylindrical rotation angle according to the aperture of the antenna unit in the cylindrical rotation angle direction, and performing Fourier transform on the generated function to obtain a first nonlinear phase matching filter function based on the cylindrical rotation angle; then, determining a first nonlinear phase matching filter function based on the cylindrical surface rotation angle and a second nonlinear phase matching filter function based on the cylindrical surface radius and the pitching dimensional direction coordinate; and obtaining a nonlinear phase matching filter function based on the cylindrical rotation angle, the cylindrical radius and the pitching dimensional direction coordinate according to the first nonlinear phase matching filter function and the second nonlinear phase matching filter function.

When the antenna array adopts a random scanning mode, a three-dimensional sparse Bayesian compressed sensing imaging algorithm can be used for carrying out three-dimensional imaging processing on data obtained by the random scanning mode.

Specifically, the echo signals obtained by the random scanning mode can be expressed in the form of a matrix vector equation:

the matrix G is an observation matrix of M × L dimensions. According to the compressed sensing reconstruction theory, when the number of observation samples M is smaller than the number L of elements of the radar reflectivity coefficient vector to be solved, the matrix vector equation can be solved through a compressed sensing reconstruction algorithm based on L-1 norm minimization.

In particular, according to the compressed sensing theory, it is possible to convert

The sparse decomposition is expressed as

Wherein the content of the first and second substances,

representing a one-dimensional gaussian noise vector, D is a sparse basis matrix with dimensions lxl,

and substituting the coefficient vector representing the sparse decomposition into the matrix vector equation:

matrix array

Wherein the matrix

Still a one-dimensional gaussian noise vector. The sparse decomposition coefficient vector can be obtained by the way that the l-1 norm is minimized and solved

Further, the estimated value of (2) is obtained according to the sparse decomposition expression, and the radar reflectivity coefficient vector after the three-dimensional space resolution unit is subdivided, namely the resolution is improved

An estimate of (d).

By using the three-dimensional sparse Bayesian compressed sensing imaging algorithm, the influence of motion errors in the motion process of the antenna array can be effectively inhibited.

In one example, the data processing apparatus may be further operable to: carrying out orthographic projection on the three-dimensional image data to obtain a plurality of pieces of two-dimensional image data, and dividing each piece of two-dimensional image data into a plurality of pieces of sub-image data according to each part of the measured object according to a specified division rule, wherein each piece of sub-image data comprises at least one part of the measured object; and inputting each piece of sub-image data into the trained anchor-free foreign matter detection model to obtain a foreign matter detection result for the detected object, wherein the anchor-free foreign matter detection model generates a detection frame for the part of the detected object included in the sub-image data based on the input each piece of sub-image data, and performs foreign matter detection based on the generated detection frame.

The data processing apparatus may be further operable to: before each sub-image data is input into the anchor-free foreign matter detection model, the sub-image data which are obtained by segmentation and comprise the same position can be classified to be used as a sub-image set, wherein each sub-image set corresponds to at least one position, and each position corresponds to one sub-image set; inputting the obtained sub-image sets into a non-anchor point foreign matter detection model to obtain first foreign matter detection results for the parts corresponding to the sub-image sets; and the anchor-free foreign matter detection model obtains a foreign matter detection result aiming at the detected object according to the first foreign matter detection result of each sub-image set.

In addition, the anchor-free foreign object detection model may be a neural network model including a multilayer neural network, and may be obtained according to the following model training method. The following processes are executed in a loop until a loop end condition is satisfied:

inputting a training sample image including a training target into a current anchor-free foreign matter detection model to obtain a feature vector generated by each layer of neural network and aiming at the training target; determining a prediction detection frame of each layer of neural network according to the real detection frame; dividing the image represented by the feature vector by using a prediction detection frame to obtain a foreground feature vector for representing a foreground image area; classifying and predicting the foreground characteristic vector of each layer of neural network by using a classifier to obtain a predicted value of each foreground characteristic vector aiming at a real classification label; carrying out statistical regression processing on the foreground characteristic vectors of each layer of neural network by using a regression network to obtain the position information of the prediction detection frame; judging whether the cycle ending condition is met or not according to the position information and the predicted value of the prediction detection frame; if not, adjusting the model parameters of the current anchor-free foreign matter detection model according to a loss function, and taking the adjusted anchor-free foreign matter detection model as the current anchor-free foreign matter detection model in the next cycle process.

In one example of the present disclosure, the holographic imaging security inspection system may further include at least one of a temperature measurement device, a metal detection device, and a three-dimensional point cloud measurement device.

The temperature measurement device can provide temperature measurement data, and the temperature measurement data can be used for correcting data to be subjected to three-dimensional imaging processing so as to improve the accuracy of the three-dimensional imaging data.

The metal detection device can provide metal detection data, and the metal detection data can be combined with a detection result of foreign matter detection processing based on three-dimensional image data to obtain a foreign matter detection result of the holographic imaging security inspection system.

The three-dimensional point cloud measuring device can provide three-dimensional point cloud data of a detected object, and the holographic imaging security inspection system can fuse and display the three-dimensional point cloud data, the three-dimensional image data and a foreign matter detection result so as to accurately determine the position of the detected foreign matter.

The three-dimensional point cloud measuring device may include a plurality of image pickup apparatuses that can photograph the measured object from a plurality of angles. The three-dimensional point cloud measuring device adopts an optical camera shooting measuring technology to carry out real-scene three-dimensional modeling on the measured object. In order to avoid dead zones of the cameras, the angular difference between images captured by two adjacent cameras can be kept smaller than a first angle, for example, 15 °, and the overlapping angle is larger than a second angle, for example, 60 °.

The holographic imaging security inspection system can further comprise a servo motion control device, and the servo motion control device can control the distributed antenna device or the structure where the distributed antenna device is located to move. The servo motion control means may comprise servo controllers, motors, actuators, etc.

FIG. 6 illustrates a flow chart of one example of a method 600 of security screening using a holographic imaging security screening system of the present disclosure.

The method is performed by a holographic imaging security inspection system, which may include: the device comprises a multi-subband modulation and demodulation device, a channel switch switching device, a distributed antenna device and a data acquisition and processing device.

As shown in fig. 6, the multi-subband modem apparatus may modulate a plurality of subband signals corresponding to a designated bandwidth and transmit the modulated plurality of subband signals to the channel switch apparatus at 610.

At 620, the channel switch switching device may switch the corresponding channel switch combination according to the plurality of subband signals and the time period, and transmit each subband signal to the corresponding transceiving antenna unit combination using each corresponding channel switch in the channel switch combination.

At 630, a transceiver antenna element assembly in the distributed antenna apparatus may transmit an electromagnetic wave signal to the measurand in response to receiving the sub-band signal, receive a corresponding sub-band echo signal reflected back from the measurand, and feed the sub-band echo signal back to the channel switch switching apparatus.

At 640, the channel switch switching device may send the received subband echo signals to the multi-subband modem device.

At 650, the multi-subband modem may demodulate the received subband echo signal and send the demodulated subband echo signal to the data acquisition and processing device.

At 660, the data acquisition processing device may perform three-dimensional imaging processing from the demodulated sub-band echo signals and foreign object detection processing based on the three-dimensional image data.

By the security inspection method, the multi-subband modulation and demodulation device in the holographic imaging security inspection system can modulate a plurality of subband signals corresponding to the specified bandwidth, and the channel switch switching device and the distributed antenna device are matched to transmit and receive the subband signals, so that the multiple subband signals and the corresponding multiple subband echo signals are used for signal transceiving aiming at the specified bandwidth, and a signal transceiving mechanism based on the multiple subband signals is formed. The signal transceiving mechanism based on the multi-subband signal improves the signal processing efficiency for the designated bandwidth.

Each device included in the holographic imaging security inspection system of the present disclosure may be implemented by hardware, software, or a combination of hardware and software. The software implementation is taken as an example, and is formed by reading corresponding computer program instructions in the storage into the memory for operation through the processor of the device where the software implementation is located as a logical means. In the present disclosure, the respective devices included in the holographic imaging security inspection system may be implemented with electronic equipment, for example.

The electronic device may include at least one processor, a memory (e.g., a non-volatile memory), a memory, and a communication interface, and the at least one processor, the memory, and the communication interface are connected together via a bus. The at least one processor executes at least one computer-readable instruction (i.e., the above-described elements implemented in software) stored or encoded in memory.

In one embodiment, computer-executable instructions are stored in the memory that, when executed, cause the at least one processor to perform the various operations and functions of the various apparatus described above.

It should be understood that the computer-executable instructions stored in the memory, when executed, cause the at least one processor to perform the various operations and functions described above in the various embodiments of the present disclosure.

According to one embodiment, a program product, such as a machine-readable medium, is provided. A machine-readable medium may have instructions (i.e., elements described above as being implemented in software) that, when executed by a machine, cause the machine to perform various operations and functions described above in various embodiments of the present disclosure.

Specifically, a system or apparatus may be provided which is provided with a readable storage medium on which software program code implementing the functions of any of the above embodiments is stored, and causes a computer or processor of the system or apparatus to read out and execute instructions stored in the readable storage medium.

In this case, the program code itself read from the readable medium can realize the functions of any of the above embodiments, and thus the machine-readable code and the readable storage medium storing the machine-readable code constitute a part of the present invention.

Computer program code required for the operation of various portions of the present specification may be written in any one or more programming languages, including an object oriented programming language such as Java, Scala, Smalltalk, Eiffel, JADE, Emerald, C + +, C #, VB, NET, Python, and the like, a conventional programming language such as C, Visual Basic 2003, Perl, COBOL 2002, PHP, and ABAP, a dynamic programming language such as Python, Ruby, and Groovy, or other programming languages. The program code may execute on the user's computer, or on the user's computer as a stand-alone software package, or partially on the user's computer and partially on a remote computer, or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user's computer through any network format, such as a Local Area Network (LAN) or a Wide Area Network (WAN), or the connection may be made to an external computer (for example, through the Internet), or in a cloud computing environment, or as a service, such as a software as a service (SaaS).

Examples of the readable storage medium include floppy disks, hard disks, magneto-optical disks, optical disks (e.g., CD-ROMs, CD-R, CD-RWs, DVD-ROMs, DVD-RAMs, DVD-RWs), magnetic tapes, nonvolatile memory cards, and ROMs. Alternatively, the program code may be downloaded from a server computer or from the cloud via a communications network.

The foregoing description has been directed to specific embodiments of this disclosure. Other embodiments are within the scope of the following claims. In some cases, the actions or steps recited in the claims may be performed in a different order than in the embodiments and still achieve desirable results. In addition, the processes depicted in the accompanying figures do not necessarily require the particular order shown, or sequential order, to achieve desirable results. In some embodiments, multitasking and parallel processing may also be possible or may be advantageous.

Not all steps and elements in the above flows and system structure diagrams are necessary, and some steps or elements may be omitted according to actual needs. The execution order of the steps is not fixed, and can be determined as required. The apparatus structures described in the above embodiments may be physical structures or logical structures, that is, some units may be implemented by the same physical entity, or some units may be implemented by a plurality of physical entities, or some units may be implemented by some components in a plurality of independent devices.

The term "exemplary" used throughout this specification means "serving as an example, instance, or illustration," and does not mean "preferred" or "advantageous" over other embodiments. The detailed description includes specific details for the purpose of providing an understanding of the described technology. However, the techniques may be practiced without these specific details. In some instances, well-known structures and devices are shown in block diagram form in order to avoid obscuring the concepts of the described embodiments.

Alternative embodiments of the present disclosure are described in detail with reference to the drawings, however, the embodiments of the present disclosure are not limited to the specific details in the embodiments, and various simple modifications may be made to the technical solutions of the embodiments of the present disclosure within the technical concept of the embodiments of the present disclosure, and the simple modifications all belong to the protective scope of the embodiments of the present disclosure.

The previous description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A holographic imaging security inspection system, comprising: the system comprises a multi-subband modulation and demodulation device, a channel switch switching device, a distributed antenna device and a data acquisition and processing device;

the multi-subband modulation and demodulation device is respectively connected with the channel switch switching device and the data acquisition and processing device, and the channel switch switching device is also connected with the distributed antenna device;

the multi-subband modulation and demodulation device sends a plurality of modulated subband signals to the channel switch switching device, the channel switch switching device sends the plurality of subband signals to corresponding transceiving antenna unit combinations in the distributed antenna device through the switched channel switch combinations, and the transceiving antenna unit combinations respond to the received subband signals and send electromagnetic wave signals to the tested object;

the receiving and transmitting antenna unit receives a plurality of sub-band echo signals corresponding to the plurality of sub-band signals in a combined mode, and sends the plurality of sub-band echo signals to the multi-sub-band modulation and demodulation device through the channel switch in a combined mode, and the multi-sub-band modulation and demodulation device sends the plurality of modulated sub-band echo signals to the data acquisition processing device.

2. The holographic imaging security inspection system of claim 1, wherein the distributed antenna arrangement comprises an antenna array, each antenna array comprising a transmit antenna element column and a receive antenna element column, each transmit antenna element column comprising a plurality of transmit antenna element groups, and each receive antenna element column comprising a plurality of receive antenna element groups.

3. The holographic imaging security inspection system of claim 2, wherein each group of transmit antenna elements in the column of transmit antenna elements is spaced apart a first distance and each group of receive antenna elements in the column of receive antenna elements is spaced apart a second distance,

the first distance is greater than the distance between two adjacent transmitting antenna units in the transmitting antenna unit group, and the second distance is greater than the distance between two adjacent receiving antenna units in the receiving antenna unit group.

4. The holographic imaging security inspection system of claim 3, wherein the groups of transmit antenna elements and the groups of receive antenna elements in each antenna array are offset in the azimuth dimension.

5. The holographic imaging security inspection system of claim 2, wherein one or more isolation walls are disposed on one or both sides of the transmitting antenna unit column and one or more isolation walls are disposed on one or both sides of the receiving antenna unit column, wherein each isolation wall is formed with a choke groove.

6. The holographic imaging security inspection system of claim 2, wherein the respective transmit antenna elements in the column of transmit antenna elements in each antenna array are offset from the respective receive antenna elements in the column of receive antenna elements in the azimuth dimension.

7. The holographic imaging security inspection system of claim 1, further comprising at least one of a temperature measurement device, a metal detection device, and a three-dimensional point cloud measurement device.

8. The holographic imaging security inspection system of claim 1, wherein the multi-subband modem means is to: when each sub-band signal is modulated, frequency sampling is carried out in the sub-band signal frequency interval corresponding to the sub-band signal, and the sampling frequency is modulated,

wherein, the sampling frequency interval of the frequency sampling is determined according to the distance between the transmitting and receiving antenna unit combination of the distributed antenna device and the measured object.

9. The holographic imaging security inspection system of claim 1, wherein the channel switch switching device is to:

determining a receiving and transmitting antenna unit combination of each time period and a corresponding relation between each receiving and transmitting antenna unit combination and each sub-band signal according to the sub-band signal and an antenna array in the distributed antenna device; and

and determining the channel switch combination corresponding to each time period according to the determined receiving and transmitting antenna unit combination and the corresponding relation.

10. The holographic imaging security inspection system of claim 1, wherein the channel switch switching device is further configured to:

determining a sub-period included in each time period according to the number of the sub-band signals;

determining the corresponding relation between each sub-band signal and the receiving and transmitting antenna unit combination in each sub-period aiming at each time period; and

and determining the channel switch combination corresponding to each sub-period according to the determined corresponding relation.

11. The holographic imaging security inspection system of claim 1, wherein the data acquisition processing device comprises a data acquisition device and a data processing device;

the multi-subband modulation and demodulation device sends demodulated subband echo signals to the data acquisition device, the data acquisition device synthesizes the received subband echo signals into bandwidth echo signals and sends the bandwidth echo signals to the data processing device, and the data processing device carries out three-dimensional imaging processing according to the bandwidth echo signals and carries out foreign matter detection processing based on three-dimensional image data.