Detection apparatus, detection method, computer device, computer-readable storage medium, and computer program product

Abstract

A detection device, wherein the detection device comprises a target recognition unit, at least one non-linear junction detection unit, and at least one eddy current detection unit. The non-linear junction detection unit is used for acquiring non-linear features of an object to be detected, and sending the non-linear features to the target recognition unit. The eddy current detection unit is used for acquiring eddy current features of said object, and sending the eddy current features to the target recognition unit. The target recognition unit is used for performing target recognition on said object on the basis of the received non-linear features and eddy current features. The detection frequency of the eddy current detection unit is different from that of the non-linear junction detection unit, and the eddy current detection unit and the non-linear junction detection unit operate simultaneously.

Description

Detection devices, detection methods, computer equipment, computer-readable storage media, and computer program products

[0001] This application claims priority to Chinese Patent Application No. 202410920399.9, filed on July 10, 2024, entitled “Composite Through-Type Detector and Through-Type Detector”, and Chinese Patent Application No. 202510939173.8, filed on July 7, 2025, entitled “Detection Device, Detection Method and Related Equipment”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to a detection device, detection method, computer equipment, computer-readable storage medium, and computer program product. Background Technology

[0003] In recent years, data breaches have occurred frequently. Electronic storage devices such as USB drives and hard drives, electronic eavesdropping and surveillance devices such as microphones and cameras, and electronic communication devices such as mobile phones can all be exploited by criminals to steal data. For secure locations, detecting these illegal devices at entrances and exits is a crucial part of security checks; currently, this is generally done through security gates.

[0004] However, security gates (also known as metal detectors) in related technologies primarily rely on the principle of electromagnetic induction to detect metal objects. In practical applications, while these security gates can detect well-shielded electronic products such as mobile phones, USB flash drives with metal casings, and voice recorders with metal casings to a certain extent, they are prone to missing detections of certain electronic products with nonlinear nodes that lack metal casings or have poor shielding. Summary of the Invention

[0005] Therefore, it is necessary to provide a detection device, a detection method, a computer device, a computer-readable storage medium, and a computer program product.

[0006] A detection device includes: at least one nonlinear node detection unit, which acquires nonlinear features of an object to be detected and sends the nonlinear features to a target recognition unit; at least one eddy current detection unit, which acquires eddy current features of the object to be detected and sends the eddy current features to the target recognition unit; the detection frequency of the eddy current detection unit is different from that of the nonlinear node detection unit, and the eddy current detection unit and the nonlinear node detection unit operate simultaneously; the target recognition unit is used to perform target recognition on the object to be detected based on the received nonlinear features and eddy current features.

[0007] A detection method, applied to a detection device, the detection method comprising:

[0008] The nonlinear characteristics of the object to be detected obtained by the nonlinear node detection unit and the eddy current characteristics obtained by the eddy current detection unit are obtained, wherein the detection frequency of the eddy current detection unit and the detection frequency of the nonlinear node detection unit are different, and the eddy current detection unit and the nonlinear node detection unit work simultaneously.

[0009] The object to be detected is identified based on the nonlinear characteristics and the eddy current characteristics. A third aspect of the present invention provides a computer device including a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the steps of the detection method described in any of the preceding embodiments.

[0010] A computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the above-described detection method.

[0011] A computer program product includes a computer program that, when executed by a processor, implements the steps of the detection method described above.

[0012] Details of one or more embodiments of this application are set forth in the following drawings and description. Other features, objects, and advantages of the invention will become apparent from the specification, drawings, and claims. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other embodiments can be obtained from these drawings without creative effort.

[0014] Figure 1 is a schematic diagram of the detection device provided in an embodiment of the present invention;

[0015] Figure 2 is a partial cross-sectional view of a detection device provided in an embodiment of the present invention;

[0016] Figure 3 is a partial cross-sectional view of a detection device provided in another embodiment of the present invention;

[0017] Figure 4 is a schematic diagram of the specific modules of the detection device provided in an embodiment of the present invention;

[0018] Figure 5 is a schematic diagram of the principle of a nonlinear node detection unit provided in an embodiment of the present invention;

[0019] Figure 6 is a circuit diagram of a nonlinear node detection unit provided in an embodiment of the present invention;

[0020] Figure 7 is a circuit diagram of a signal generator provided in an embodiment of the present invention;

[0021] Figure 8 is a schematic diagram of the operating timing of the nonlinear node detection unit and the eddy current detection unit provided in an embodiment of the present invention;

[0022] Figure 9 is a flowchart of a detection method provided in an embodiment of the present invention;

[0023] Figure 10 is a flowchart of a detection method provided in another embodiment of the present invention. Detailed Implementation

[0024] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings. Preferred embodiments of this application are shown in the drawings. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of this application.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. The terminology used herein in the specification of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0026] The foregoing description includes examples of one or more embodiments. It is certainly impossible to describe all possible combinations of components or methods in order to describe the above embodiments, but those skilled in the art will recognize that further combinations and arrangements of the various embodiments are possible. Therefore, the embodiments described herein are intended to cover all such changes, modifications, and variations that fall within the scope of the appended claims. Furthermore, the term "comprising" as used in the specification or claims is interpreted in a manner similar to the term "including," just as "comprising" is interpreted as a conjunction in the claims. Additionally, the use of any term "or" in the specification of the claims is intended to mean "non-exclusive or."

[0027] Referring to Figure 1, this embodiment of the invention discloses a detection device. This detection device can be installed at entrances / exits of a location or other locations where such detection is needed, and is used to detect illegal equipment. The detection device of this embodiment includes: at least one nonlinear node detection unit 1, which acquires nonlinear features of the object to be detected 4 and sends the nonlinear features to a target identification unit 3; at least one eddy current detection unit 2, which acquires eddy current features of the object to be detected 4 and sends the eddy current features to the target identification unit 3. The detection frequency of the eddy current detection unit 2 is different from that of the nonlinear node detection unit 1, and the eddy current detection unit 2 and the nonlinear node detection unit 1 operate simultaneously. The target identification unit 3 is used to identify the object to be detected 4 based on the received nonlinear features and eddy current features. The nonlinear features and eddy current features can be referred to separately or jointly as feature data of the object to be detected 4.

[0028] The nonlinear node detection unit 1 can detect nonlinear nodes in the object 4 to be detected. A PN junction is a typical nonlinear node. If the electronic product lacks electromagnetic shielding or has poor shielding, the PN junction within the electronic product can generate harmonic signals under the influence of the fundamental signal emitted by the nonlinear node detection unit 1. For example, the nonlinear node detection unit 1 can emit a fundamental signal, and the nonlinear nodes in the object 4 to be detected will generate first-order harmonic signals (also called first-order harmonic signals), second-order harmonic signals, and third-order harmonic signals (also called third-order harmonic signals) under the influence of the fundamental signal. Each receiving module of the nonlinear node detection unit 1 receives, for example, the aforementioned first-order, second-order, and third-order harmonic signals and sends them to the target identification unit 3, thereby performing target identification on the object 4 to be detected. The nonlinear characteristics can be the aforementioned first-order, second-order, and third-order harmonic signals, or signals obtained after performing relevant processing (e.g., down-conversion) on the aforementioned harmonic signals. The target recognition unit 3 is used to perform target recognition on the object to be detected 4 based on the received nonlinear features and eddy current features.

[0029] For example, the target identification unit 3 may be a microcontroller, a control chip, or a chip or device capable of running a preset calculation strategy. Alternatively, the target identification unit 3 may include at least one of a microcontroller, a control chip, and a device capable of running a preset calculation strategy.

[0030] Among the related information leakage devices, some electronic products generally lack electromagnetic shielding (e.g., they lack a metal casing) or have poor electromagnetic shielding, such as USB flash drives, eavesdropping devices, and cameras. For these electronic products, the nonlinear node detection unit 1 can achieve good detection results when detecting nonlinear nodes. For electronic products with electromagnetic shielding measures or good electromagnetic shielding, such as mobile phones, tablets, and smartwatches, as long as they contain metal, the amplitude and phase characteristics of the secondary magnetic field formed by eddy currents can be utilized. Eddy current detection unit 2 can then detect these electronic products and obtain their eddy current characteristics. These eddy current characteristics include, for example, the amplitude and phase characteristics of the secondary magnetic field formed by electronic products with metal components under the detection of eddy current detection unit 2. Eddy current detection unit 2 can supplement the insufficient detection capability of nonlinear node detection unit 1 for electronic products with electromagnetic shielding. Simultaneously, nonlinear node detection unit 1 can also compensate for the inability of eddy current detection unit 2 to detect electronic products.

[0031] Furthermore, the detection frequency of eddy current detection unit 2 in the detection device is different from that of nonlinear node detection unit 1. Therefore, eddy current detection unit 2 and nonlinear node detection unit 1 will not interfere with each other, thus enabling them to operate simultaneously. The operating frequency of nonlinear node detection unit 1 refers to the frequency of the fundamental wave signal emitted by nonlinear node detection unit 1. The operating frequency of eddy current detection unit 2 refers to the frequency band of the driving signal of the transmitting coil in eddy current detection unit 2. Since the operating frequency bands of the transmitting and receiving antennas in nonlinear detection unit 1 (e.g., the frequency band of its transmitted fundamental wave signal and the frequency bands of its received first, second, and third harmonic signals) are relatively high, while the operating frequency bands of the modules in eddy current detection unit 2 (e.g., the frequency band of its transmitting coil driving signal) are relatively low, their operating frequency bands do not overlap, therefore they will not interfere with each other. Furthermore, the eddy current detection unit 2 and the nonlinear node detection unit 1 in the detection device work simultaneously, so that when the detection device detects the object to be detected 4, it can simultaneously obtain eddy current characteristics and nonlinear characteristics, and obtain as much feature data as possible in the same time period, thereby reducing the false alarm rate.

[0032] Furthermore, to expand the detection area coverage of the detection device, reduce the detection blind zone, and lower the false alarm rate, in some embodiments of the detection device, the number of nonlinear node detection units 1 on the same side panel of the detection device is two or more, and all nonlinear node detection units 1 are arranged sequentially along a set direction. This set direction can be the gravity direction. For example, when two or more nonlinear node detection units 1 are arranged sequentially along the gravity direction, the number of nonlinear node detection units 1 is increased, and the detection area corresponding to each nonlinear node detection unit 1 does not overlap at least partially in the gravity direction. This increases the coverage of the total detection area (including the detection areas corresponding to all nonlinear node detection units 1) in the gravity direction, reduces the detection blind zone in the gravity direction, and lowers the false alarm rate.

[0033] The detection device can be a walk-through detection device, such as a security gate. In other embodiments, the detection device can also be a handheld detection device. When the detection device is a walk-through detection device, it has a detection channel, and the set direction can also be the direction of gravity. The detection channel is covered by the detection area corresponding to the nonlinear node detection unit 1, which can detect the object 4 to be detected passing through the detection channel.

[0034] Furthermore, taking a security gate as an example, in some embodiments, multiple nonlinear node detection units 1 can be set on the same side panel of the detection device, and these multiple nonlinear node detection units 1 are arranged sequentially at intervals along the direction of gravity. This arrangement not only reduces the blind zone area, but also allows the algorithm to calculate which nonlinear node detection unit 1 the detected object 4 is located within, thus enabling zoned detection and obtaining the position information of the object 4, such as its height.

[0035] It should be noted that, due to the relatively fast movement speed of the person carrying the object 4 or the object 4 itself relative to the detection device, the time spent in the detection area of ​​the detection device is short. Therefore, the nonlinear node detection unit 1 must complete sampling within a sufficiently short time. In some embodiments of the detection device, two or more nonlinear node detection units 1 can operate simultaneously. Thus, two or more nonlinear node detection units 1 can detect more nonlinear node features of the object 4 within a shorter time, meaning the amount of detected data increases exponentially. This data facilitates target recognition by the target recognition unit 3 using algorithms, thereby improving detection accuracy. For example, in one embodiment, the time required for a single nonlinear node detection unit 1 to detect one frame of data is 15ms, while the time for the object 4 to pass through the detection device is 1s. Therefore, a single nonlinear node detection unit 1 can detect approximately 6 to 7 frames of data within 1 second. When there are multiple nonlinear node detection units 1, for example, eight units, approximately 42 to 49 more frames of data can be obtained compared to when only one nonlinear node detection unit 1 is working, since all nonlinear node detection units 1 operate simultaneously. In other words, increasing the number of nonlinear node detection units 1 and arranging them along a predetermined direction not only reduces the detection blind zone but also allows for the acquisition of more data.

[0036] In some embodiments, the setting direction of the detection device can also be parallel to the travel direction of the detection channel, that is, the object 4 to be detected passes through each nonlinear node detection unit 1 sequentially when passing through the detection channel. Furthermore, multiple nonlinear node detection units 1 can be arranged sequentially at intervals. In this embodiment, increasing the number of nonlinear node detection units 1 in the travel direction can effectively reduce the detection blind zone of the detection channel in the travel direction, and increase the amount of data obtained, resulting in more accurate nonlinear characteristics, improved detection accuracy, and reduced false alarm rate. The specific principle is the same as in the embodiment where multiple nonlinear node detection units 1 are arranged along the direction of gravity, and will not be elaborated further here.

[0037] It should be noted that having multiple nonlinear node detection units 1 operating simultaneously may present the following two problems. For example, in a scheme where multiple nonlinear node detection units 1 with the same operating frequency are installed within a single door panel, if the operating frequencies of these nonlinear node detection units 1 are identical, it may cause problems for the processing of harmonic signals in subsequent signal processing units (such as target recognition unit 3). For instance, when different nonlinear node detection units 1 have the same operating frequency (e.g., the frequency of the emitted fundamental signal), the frequencies of the second-order and third-order harmonic signals corresponding to the fundamental signal are also the same. The target recognition unit 3 may not be able to accurately distinguish which nonlinear node detection unit 1 corresponds to the harmonic signal, thereby affecting the detection accuracy of the entire detection device.

[0038] For example, in a scheme where multiple nonlinear node detection units 1 with the same operating frequency are installed in both door panels, in addition to the problems that may occur in a single-side door panel, false alarms may also occur in the opposite door panel. Specifically, when the fundamental frequency of the nonlinear node detection unit 1 on one side of the door panel and the nonlinear node detection unit 1 on the other side of the door panel is the same, taking the left door panel as an example, the frequency of the fundamental frequency of the nonlinear node detection unit 1 on the left side of the door panel is F, while the frequency of the second harmonic signal it expects to receive is 2F. At this time, the fundamental frequency of the two different nonlinear node detection units 1 on the right side of the door panel is also F. Therefore, the frequency of the signal after the fundamental frequency of the two different nonlinear node detection units 1 on the right side of the door panel is mixed together is 2F, which happens to be the same as the frequency of the second harmonic signal that the nonlinear node detection unit 1 on the left side of the door panel expects to receive. As a result, the detection device may false alarm, thereby affecting the detection efficiency and accuracy of the entire detection device. Similarly, the same applies to the other side of the door panel. In addition, the three fundamental signals emitted by the nonlinear node detection unit 1 on one side of the door panel, after mixing, may have the same frequency as the third harmonic signal that the nonlinear detection unit 1 on the opposite side of the door panel expects to receive.

[0039] Furthermore, to enable two or more nonlinear node detection units 1 in the security gate to operate simultaneously without affecting the target identification unit 3 or the side door panel, in some embodiments of the disclosed detection device, the different nonlinear node detection units 1 on the same side door panel operate at different frequencies. Specifically, if the fundamental wave signals emitted by different nonlinear node detection units 1 to the object to be detected 4 have different frequencies, it can avoid interfering with the signal processing of the target identification unit 3 and improve detection accuracy. Moreover, it can also ensure that even if the fundamental wave signals emitted by each nonlinear node detection unit 1 mix, a signal with the same frequency as the desired second-order harmonic signal or the desired third-order harmonic signal will not be generated, effectively avoiding false alarms during subsequent signal identification and processing.

[0040] In some embodiments, multiple nonlinear node detection units 1 can be provided in both side door panels, and the operating frequencies of the different nonlinear node detection units 1 in the side door panels are also different. This scheme can further avoid mutual interference between the nonlinear node detection units 1 in the side door panels (that is, to avoid the situation where the signal obtained after fundamental frequency mixing of multiple nonlinear node detection units 1 in the opposite side door panel is mistakenly identified as a harmonic signal). Therefore, in this embodiment, all nonlinear node detection units 1 in the side door panels can work simultaneously.

[0041] Referring to Figures 4 and 5, further, in some embodiments of the detection device, the nonlinear node detection unit 1 may include: a signal transmitting module 10, a first signal receiving module 11, a second signal receiving module 12, and a third signal receiving module 13. The first signal receiving module 11, the second signal receiving module 12, and the third signal receiving module 13 are all connected to the target identification unit 3. The signal transmitting module 10 is used to transmit a fundamental wave signal, which is transmitted outward to the detection area to be detected by the detection device. When the object to be detected 4 enters the detection area, the nonlinear nodes in the object to be detected 4 generate first-order harmonic signals, second-order harmonic signals, and third-order harmonic signals under the influence of the fundamental wave signal.

[0042] The first signal receiving module 11 is used to receive the first harmonic signal generated by the object to be detected 4 based on the fundamental wave signal, and send the first harmonic signal or the signal obtained by processing the first harmonic signal to the target identification unit 3. The second signal receiving module 12 is used to receive the second harmonic signal generated by the object to be detected 4 based on the fundamental wave signal, and send the second harmonic signal or the signal obtained by processing the second harmonic signal to the target identification unit 3. The third signal receiving module 13 is used to receive the third harmonic signal generated by the object to be detected 4 based on the fundamental wave signal, and send the third harmonic signal or the signal obtained by processing the third harmonic signal to the target identification unit 3.

[0043] In this embodiment, if the target identification unit 3 can directly receive harmonic signals (e.g., the target identification unit 3 includes a down-conversion circuit and a processor), then the first signal receiving module 11, the second signal receiving module 12, and the third signal receiving module 13 can directly send their respective received harmonic signals (such as first-order harmonic signals, second-order harmonic signals, and third-order harmonic signals) to the target identification unit 3. If the target identification unit 3 cannot directly process the harmonic signals, then the first signal receiving module 11, the second signal receiving module 12, and the third signal receiving module 13 can respectively process their received harmonic signals (e.g., down-conversion, filtering, etc.) before sending the processed signals to the target identification unit 3.

[0044] Furthermore, the connection between the three signal receiving modules and the target identification unit 3, including direct connection or indirect connection, is within the scope of protection of this application.

[0045] In a direct connection scenario, as shown in Figures 5 and 6, the first signal receiving module 11, the second signal receiving module 12, and the third signal receiving module 13 are all directly connected to the target identification unit 3. In this example, the first signal receiving module 11, the second signal receiving module 12, and the third signal receiving module 13 respectively send the received harmonic signals or signals after processing the harmonic signals to the target identification unit 3. Specifically, the first signal receiving module 11, the second signal receiving module 12, and the third signal receiving module 13 can convert their respective received harmonic signals into mid- or low-frequency signals and send these mid- or low-frequency signals to the target identification unit 3. The target identification unit 3 can, for example, perform frequency domain conversion on the received signals to obtain parameters (e.g., power) at relevant frequency points to identify the object 4 to be detected.

[0046] In an indirect connection example, as shown in Figure 4, the nonlinear node detection unit 1 includes an MCU (Microcontroller Unit). The first signal receiving module 11, the second signal receiving module 12, and the third signal receiving module 13 are all connected to the MCU, which in turn is connected to the target identification unit 3. In this example, the first signal receiving module 11, the second signal receiving module 12, and the third receiving module 13 can convert the received harmonic signals into mid- and low-frequency signals and send them to the MCU. After frequency domain conversion, the MCU obtains the parameters (e.g., power) of the relevant frequency points. These parameters represent one specific example of the nonlinear characteristics. The MCU can then send the frequency domain data to the target identification unit 3.

[0047] It should be noted that, after extensive experimentation, the inventors discovered that different harmonic signals exhibit varying degrees of sensitivity to different types of objects to be detected. For example, first-order harmonic signals are more sensitive to loosely connected metal nodes, making the first signal receiving module 11 more likely to detect them (e.g., two or more unstable overlapping metal structures, such as screws, keychains, etc.). Second-order harmonic signals are more sensitive to semiconductor targets, thus making them easier to detect. Third-order harmonic signals are more sensitive to stable metal nodes (stable and unchanging metal structures, such as steel bars inside a wall or metal eyeglasses), making them more effective at detecting stable metal nodes.

[0048] In this embodiment, by setting a first signal receiving module 11, a second signal receiving module 12, and a third signal receiving module 13, first-order harmonic signals, second-order harmonic signals, and third-order harmonic signals are received respectively. Since different harmonic signals have different sensitivities to different types of nodes, this embodiment can detect multiple types of objects to be detected, thereby reducing the false alarm rate.

[0049] Further, as shown in FIG6, in some embodiments of the detection device, the signal transmitting module 10 may include a fundamental wave signal source 101 and a transmitting processing circuit 100. The transmitting processing circuit 100 is used to generate a fundamental wave signal based on the fundamental wave signal source. The first signal receiving module 11 is used to mix the first harmonic signal and the first reference signal to obtain a first identification signal, and send the first identification signal to the target identification unit 3. The first reference signal is generated based on the fundamental wave signal source 101.

[0050] It should be noted that, in this embodiment, the input to the first signal receiving module 11 before mixing can be a first-order harmonic signal, or it can be a signal processed from the first-order harmonic signal (e.g., a more precise first-order harmonic signal). These are all within the scope of protection of this application.

[0051] The first harmonic signal is the signal returned after the fundamental signal is radiated to the nonlinear node on the object to be detected 4. Therefore, the first harmonic signal contains a non-zero frequency shift caused by the nonlinear feedback of the object to be detected 4, for example, the frequency of this non-zero frequency shift is Δf1. The first identification signal is the signal obtained by down-converting the first harmonic signal. After mixing the first harmonic signal and the first reference signal, the non-zero frequency shift of the first-order response of the object to be detected 4 caused by the nonlinear node can be obtained, which is the first identification signal. The target identification unit 3 can perform target identification based on the first identification signal.

[0052] In a specific embodiment, for a particular nonlinear node detection unit 1, the frequency of its fundamental signal is f0, the frequency of its first reference signal is f0, and the frequency of its first harmonic signal is f0+Δf1. Specifically, in order to extract the signal with frequency Δf1 carried in the first harmonic signal, a first reference signal with a frequency equal to f0 is provided during down-conversion of the first harmonic signal; that is, the frequency of the first reference signal is consistent with the frequency of the fundamental signal.

[0053] Furthermore, in the detection device provided in this embodiment of the invention, the first reference signal is generated based on the fundamental wave signal source 101, which can ensure that the frequency of the generated first reference signal is exactly the same as that of the fundamental wave signal, thereby ensuring that the frequency of the signal extracted after mixing will not be shifted, and ensuring detection accuracy.

[0054] It should be noted that if the fundamental signal and the first reference signal use different clock signals as reference clocks—for example, if the fundamental signal and the first reference signal are generated based on different crystal oscillators, and the frequencies of crystal oscillators, even within the same batch, will have slight differences—the difference between the fundamental signal and the first reference signal obtained after frequency multiplication will be amplified exponentially. Therefore, the frequency of the first identification signal obtained after the mixing operation may have a certain offset. For example, the expected value of Δf1 is 1kHz, but after mixing it may be 0.8kHz, 1.2kHz, etc., deviating from the expected 1kHz signal, which will affect the detection accuracy of the detection device.

[0055] Specifically, in some embodiments of the detection device disclosed, as shown in FIG6, the fundamental wave signal source 101 may specifically include a first signal generator L01 and a power divider F1. The input terminal of the first signal generator L01 is connected to the target identification unit 3, the output terminal of the first signal generator L01 is connected to the input terminal of the power divider F1, the first output terminal of the power divider F1 is connected to the transmission processing circuit 100, and the second output terminal of the power divider F1 is connected to the first signal receiving module 11. The first signal generator L01 is used to generate a local oscillator signal under the control of the target identification unit 3. The power divider F1 is used to distribute the power of the local oscillator signal to multiple output ports. For example, the power of the local oscillator signal generated by the signal generator L01 can be equally divided and sent to the transmission processing circuit 100 through the first output terminal and to the first signal receiving module 11 through the second output terminal, respectively, to form a fundamental wave signal and a first reference signal. In this embodiment, the fundamental signal and the first reference signal are from the same source, that is, they are both signals generated by the first signal generator L01. Therefore, the frequencies of the fundamental signal and the first reference signal can be guaranteed to be completely consistent, which enables the first signal receiving module 11 to accurately extract the required signal and ensure detection accuracy.

[0056] As shown in Figure 6, the transmission processing circuit 100 may include a first amplifier A0, a transmission filter Z0, and a transmission antenna TX, which are sequentially electrically connected to the first output terminal of the power divider F1. The transmission filter Z0 filters out harmonic components carried in the fundamental signal. The first amplifier A0 increases the signal power, ensuring effective signal transmission.

[0057] Additionally, the first signal receiving module 11 includes a first mixer M1, a first receiving antenna RX1, a first filter Z1, and a first receiving amplifier A1, which are electrically connected in sequence. The first receiving amplifier A1 is electrically connected to the first mixer M1, and the first mixer M1 is connected to the second output terminal of the power divider F1. A first filter Z1 is provided at the front end of the first mixer M1 to allow signals in the target frequency band (i.e., first harmonic signals) to pass through while blocking interference and noise. The first receiving amplifier A1 is also provided to enhance signal strength with minimal noise introduction, providing a high-quality input signal to the first mixer M1.

[0058] Furthermore, in some embodiments of the detection device, the second signal receiving module 12 is used to mix the second harmonic signal and the second reference signal to obtain a second identification signal, and then send the second identification signal to the target identification unit 3. The third signal receiving module 13 is used to mix the third harmonic signal and the third reference signal to obtain a third identification signal, and then send the third identification signal to the target identification unit 3. The fundamental signal source 101, the signal source of the second reference signal, and the signal source of the third reference signal all reference the same clock signal.

[0059] In this embodiment, the input to the second signal receiving module 12 before mixing can be a second-order harmonic signal, or a signal processed from the second-order harmonic signal (e.g., a more precise second-order harmonic signal). Similarly, the input to the third signal receiving module 13 before mixing can be a third-order harmonic signal, or a signal processed from the third-order harmonic signal (e.g., a more precise third-order harmonic signal). These are all within the scope of this application.

[0060] For a certain nonlinear node detection unit 1, the frequency of its fundamental signal is f0, and the frequency of its second harmonic signal is 2f0 + Δf2. To extract the signal with frequency Δf2 carried in the second harmonic signal, a second reference signal with a frequency equal to 2f0 is provided during the down-conversion of the second harmonic signal; that is, the frequency of the second reference signal is twice the frequency of the fundamental signal. The frequency of the third reference signal is equal to 3f0, and its principle is the same as that of the first and second reference signals, so it will not be elaborated further here.

[0061] In addition, since the fundamental signal source 101, the signal source of the first reference signal, the signal source of the second reference signal, and the signal source of the third reference signal all refer to the same clock signal, it can be guaranteed that the frequency of the second reference signal is always twice the frequency of the fundamental signal, and that the frequency of the third reference signal is always three times the frequency of the fundamental signal. This ensures that the signal obtained after down-conversion is the signal of the desired frequency, and that the frequency of the obtained signals (e.g., the first identification signal, the second identification signal, and the third identification signal) will not deviate, thereby improving the detection accuracy of the detection device.

[0062] In some embodiments of the detection device disclosed, as shown in FIG6, the second signal receiving module 12 may include a second mixer M2, a second signal generator L02 (i.e., the signal source of the second reference signal), and a second receiving antenna RX2, a second filter Z2, and a second receiving amplifier A2 connected in sequence. The first input terminal of the second mixer M2 is connected to the second signal generator L02, the second input terminal of the second mixer M2 is connected to the second receiving amplifier A2, and the output terminal of the second mixer M2 is connected to the target identification unit 3. The second mixer M2 is used to mix the second reference signal from the second signal generator L02 and the signal processed by the second harmonic signal from the second receiving amplifier A2 to output the second identification signal to the target identification unit 3. The second receiving amplifier A2 is electrically connected to the second mixer M2. The second filter Z2 has the same function as the first filter Z1, and the function of the second receiving amplifier A2 is the same as that of the first receiving amplifier A1, which will not be described in detail here.

[0063] In some embodiments of the detection device, the third signal receiving module 13 includes a third mixer M3, a third signal generator L03 (i.e., the signal source of the third reference signal), and a third receiving antenna RX3, a third filter Z3, and a third receiving amplifier A3 connected in sequence. The first input terminal of the third mixer M3 is connected to the third signal generator L03, the second input terminal of the third mixer M3 is connected to the third receiving amplifier A3, and the output terminal of the third mixer M3 is connected to the target identification unit 3. The third mixer M3 is used to mix the third reference signal from the third signal generator L03 and the signal processed from the third receiving amplifier A3 (after processing the third harmonic signal) to output a third identification signal to the target identification unit 3. The third receiving amplifier A3 is electrically connected to the third mixer M3. The third filter Z3 has the same function as the first filter Z1, and the third receiving amplifier A3 has the same function as the first receiving amplifier A1; these details will not be elaborated further here.

[0064] The second-order local oscillator signal generated by the second signal generator L02 serves as the second reference signal input to the second mixer M2. Since the second-order harmonic signal is the signal returned after the fundamental signal is sent to the nonlinear node on the object to be detected 4, it contains a non-zero frequency shift in the second-order response generated by the nonlinear feedback of the object to be detected 4. The frequency of this non-zero frequency shift is Δf2. The frequency of the second-order harmonic signal is 2f0 + Δf2. Because mixing is required to extract the signal with frequency Δf2, the frequency of the signal output from the second signal generator L02 (the second reference signal) is set to 2Δf0. After mixing the second-order harmonic signal and the second reference signal, the non-zero frequency shift of the second-order response generated by the nonlinear node on the object to be detected 4 can be obtained, which is the second identification signal. Furthermore, since the second signal generator L02 and the first signal generator L01 both reference the same clock signal, the frequency of the second reference signal can be guaranteed to be equal to 2f0, thus ensuring that a signal with frequency Δf2 can be obtained after frequency conversion, improving detection accuracy.

[0065] In this specific embodiment, the third-order local oscillator signal generated by the third signal generator L03 is the third reference signal input to the third mixer M3. Since the third-order harmonic signal is the signal returned after the fundamental signal is sent to the nonlinear node on the object to be detected 4, it contains a non-zero frequency shift of the third-order response generated by the nonlinear feedback of the object to be detected 4. The frequency of this non-zero frequency shift is Δf3. The frequency of the third-order harmonic signal is 3f0 + Δf3. Since mixing is required to extract the signal with frequency Δf3, the frequency of the signal output by the third signal generator L03 (the third reference signal) is set to 3Δf0. After mixing the third-order harmonic signal and the third reference signal, the non-zero frequency shift of the third-order response generated by the nonlinear node on the object to be detected 4 can be obtained, which is the third identification signal. Furthermore, since the third signal generator L03 and the first signal generator L01 both reference the same clock signal, it is guaranteed that the frequency of the third reference signal is equal to 3f0, thereby ensuring that a signal with a frequency of Δf3 can be obtained after frequency conversion, thus improving the detection accuracy.

[0066] Specifically, referring to Figure 7, in some embodiments of the detection device, the first signal generator L01, the second signal generator L02, and the third signal generator L03 can be, for example, phase-locked loops, i.e., all are loops formed by a phase detector, a loop filter, a voltage-controlled oscillator (VCO), and a frequency divider. Taking the first signal generator L01 as an example, the first signal generator L01 includes a first phase detector PD1, a first loop filter LF1, and a first VCO1 connected in sequence, and also includes a first frequency divider FD1 connected between the first phase detector PD1 and the first VCO1. The second signal generator L02 includes a second phase detector PD2, a second loop filter LF2, and a second VCO2 connected in sequence, and also includes a second frequency divider FD2 connected between the second phase detector PD2 and the second VCO2. The third signal generator L03 includes a third phase detector PD3, a third loop filter LF3, and a third voltage-controlled oscillator VCO3 connected in sequence, and a third frequency divider FD3 connected between the third phase detector PD3 and the third voltage-controlled oscillator VCO3. The first signal generator L01, the second signal generator L02, and the third signal generator L03 adjust their frequency division ratios through the first frequency divider FD1, the second frequency divider FD2, and the third frequency divider FD3, respectively. The first phase detector PD1, the second phase detector PD2, and the third phase detector PD3 are all connected to a crystal oscillator X1. The crystal oscillator X1 is the clock signal that the three signal generators use as a common reference. As shown in Figure 7, the first signal generator L01, the second signal generator L02, and the third signal generator L03 all reference the same clock (e.g., the same crystal oscillator signal), which ensures that the fundamental signal, the first reference signal, the second reference signal, and the third reference signal are in the same timing sequence, thus ensuring that the frequency of the signal obtained after mixing will not deviate and improving detection accuracy.

[0067] Furthermore, the frequency of the fundamental wave signal is similar to that of the first harmonic signal. Therefore, the frequency of the fundamental wave signal may fall within the bandwidth of the first receiving antenna (the aforementioned first receiving antenna RX1). If the transmitting antenna TX in the signal transmitting module 10 of the detection device and the first receiving antenna RX1 in the first signal receiving module 11 are too close, the fundamental wave signal may be received by the first receiving antenna RX1, resulting in a false alarm. To prevent interference between the antennas of the signal transmitting module 10 and the first receiving module 11, the distance between them can be increased as much as possible.

[0068] Therefore, in the detection device disclosed in this embodiment, the antenna of the second signal receiving module 12 (i.e., the second receiving antenna RX2) and / or the antenna of the third signal receiving module 13 (i.e., the third receiving antenna RX3) are disposed between the antenna of the signal transmitting module 10 (i.e., the transmitting antenna TX) and the antenna of the first signal receiving module 11. Thus, while rationally arranging all components within a limited space, the distance between the transmitting antenna TX and the first receiving antenna RX1 is maximized, thereby improving the isolation between the transmitting antenna TX and the first receiving antenna RX1 and reducing the false alarm rate.

[0069] For example, referring to Figure 2, for ease of observation, the outer shell of one side panel of the detection device is cut open to expose part of the internal structure. Figure 2 shows the overall structure and part of the internal structure of the detection device, which includes the signal transmitting module 10, the first signal receiving module 11, the second signal receiving module 12, and the third signal receiving module 13 in the nonlinear node detection unit 1. It can be seen that the antennas of the second signal receiving module 12 and the third signal receiving module 13 are positioned between the antenna of the signal transmitting module 10 and the antenna of the first signal receiving module 11. That is, the distance between the antenna of the signal transmitting module 10 and the antenna of the first signal receiving module 11 is relatively large, which can reduce the probability that the fundamental wave signal is received by the first signal receiving module 11, thereby reducing the false alarm rate.

[0070] Figure 3 shows the overall structure and part of the internal structure of a detection device that includes only the nonlinear node detection unit 1. In some application scenarios, the detection device may only include the nonlinear node detection unit 1. In this embodiment, as shown in Figure 3, the antennas of the second signal receiving module 12 and the third signal receiving module 13 are also arranged between the antenna of the signal transmitting module 10 and the antenna of the first signal receiving module 11, which can reduce the false alarm rate. The principle is the same as that of the aforementioned embodiment and will not be described in detail here.

[0071] In some embodiments of the detection device disclosed, as shown in FIG6, the first signal receiving module 11 further includes a first capacitor C1 and a first analog-to-digital converter (ADC) 11, and a first mixer M1 is connected to the target identification unit 3 through the first capacitor C1 and the first ADC 11. The second signal receiving module 12 further includes a second capacitor C2 and a second ADC 12, and a second mixer M2 is connected to the target identification unit 3 through the second capacitor C2 and the second ADC 12. The third signal receiving module 11 further includes a third capacitor C3 and a third ADC 13, and a third mixer M3 is connected to the target identification unit 3 through the third capacitor C3 and the third ADC 13. The first signal receiving module 11 further includes a fourth receiving amplifier A4, and a power divider F1 is connected to the first mixer M1 through the fourth receiving amplifier A4.

[0072] It should be noted that, ideally, a mixer can mix the input signal and convert it to a set frequency band. That is, ideally, the frequency of the mixed signal should be within the set frequency band. However, in practical applications, due to the inherent hardware characteristics of the mixer, the input signal may be directly coupled to the output signal. For example, in Figure 6, the first reference signal output by the power divider F1 and the processed first harmonic signal received by the first mixer M1 may both be directly coupled to the output signal of the first mixer M1 (in this case, these signals are equivalent to interference signals).

[0073] In one embodiment, as shown in FIG6, the first signal receiving module 11 further includes a fourth filter Z4, a fifth amplifier A5, and a fifth filter Z5 connected in sequence. The fourth filter Z4 is also connected to the first mixer M1. The fourth filter Z4 is used to filter out interference signals carried in the signal output by the first mixer M1. Furthermore, the first mixer M1 mixes second-order harmonic signals, which reduces the power of the output signal to some extent. Therefore, the fifth amplifier A5 is provided after the fourth filter Z4 to improve the signal power and ensure that the signal can be effectively transmitted to the target identification unit 3.

[0074] Furthermore, the fourth filter Z4 may not be able to completely filter out interference signals carried in the signal. Therefore, in order to avoid the influence of interference signals, a fifth filter Z5 can be set between the fifth amplifier A5 and the target recognition unit 3 to improve signal quality.

[0075] The connection relationships and functions of the sixth filter Z6, the sixth amplifier A6, and the seventh filter Z7 in the second signal receiving module 12 are the same as those in the previous embodiments, and will not be described in detail here. The connection relationships and functions of the eighth filter Z8, the seventh amplifier A7, and the ninth filter Z9 in the third signal receiving module 13 are the same as those in the previous embodiments, and will not be described in detail here.

[0076] In some embodiments, as shown in FIG4, the MCU may include a three-channel synchronous sampling module 14, a data buffer 15, and a USB 16. The target recognition unit 3 includes an algorithm module 31 and an application module 32. The algorithm module 31 is used to perform target classification and recognition, and the application module 32 is used for alarm indication, UI display, and peripheral management. The three-channel synchronous sampling module 14, the data buffer 15, and the USB 16 constitute a nonlinear processing module. In some embodiments, the nonlinear node detection unit 1 may not include this nonlinear processing module; the signal transmission module 10, the first signal receiving module 11, the second signal receiving module 12, and the third signal receiving module 13 are directly connected to the target recognition unit 3.

[0077] Referring to Figure 4, further, in some embodiments of the detection device, the eddy current detection unit 2 may include: a control chip 21 and a digital-to-analog converter 26, a transmitting unit 24, and a magnetic field generating module 22 connected in sequence. The digital-to-analog converter 26 is also connected to the control chip 21. The eddy current detection unit 2 also includes one or more receiving channels, each receiving channel including a sensing module 23, a receiving unit 25, and an analog-to-digital converter 27 connected in sequence. The analog-to-digital converter 27 is connected to the control chip 21.

[0078] The magnetic field generating module 22 actively generates a primary magnetic field, the range of which at least covers the detection area. The sensing module 23 senses the magnetic field at its location and generates a corresponding induced electromotive force (EMF). The control chip 21 sends a command to the magnetic field generating module 22 to generate a primary magnetic field and also receives the induced EMF sent by the sensing module 23. When the object to be detected 4 in the detection area is a conductive object, the object to be detected 4 will generate a secondary magnetic field under the influence of the primary magnetic field. This secondary magnetic field interacts with the primary magnetic field generated by the magnetic field generating module 22, causing a change in the magnetic field at the location of the sensing module 23 and generating a changed induced EMF. The control chip 21 receives this changed induced EMF and performs data processing such as comparing it with the induced EMF in the original state, thereby identifying the object to be detected 4.

[0079] Furthermore, the control chip 21 can be a field-programmable gate array (FPGA) module. The FPGA module outputs a drive signal, which is converted from digital to analog by a digital-to-analog converter (DAC) 26 and amplified by the transmitting unit 24 before being sent to the magnetic field generation module 22 to generate an alternating magnetic field. Specifically, the FPGA module can also be used to obtain the eddy current characteristics (e.g., spectral data) of the object to be detected 4 based on the received induced electromotive force (EMF), and send the eddy current characteristics to the target identification unit 3. The magnetic field generation module 22 generates an alternating magnetic field (original magnetic field) when an alternating current is applied; at this time, the sensing module 23 has no induced EMF. When the object to be detected 4 is a conductive component (e.g., metal), the object to be detected 4 will generate an induced current under the influence of the original magnetic field. The magnetic field generated by the induced current will interact with the original magnetic field, causing a change in the original magnetic field. At this time, the sensing module 23 can output an induced EMF. The induced electromotive force (EMF) is processed by the receiving unit 23 and then transmitted to the control chip 21 via the analog-to-digital converter 27. The control chip 21 further processes the data, such as performing a fast Fourier transform, and then transmits it to the target recognition unit 3. The target recognition unit 3 processes and analyzes the induced EMF output by the sensing module 23, enabling the detection of the target object 4, including metallic components or electronic devices with metal casings. The magnetic field generating module 22 can be a transmitting coil, and the sensing module 23 can be a receiving coil.

[0080] Furthermore, the magnetic field generating module 22 can be correspondingly set with the sensing module 23, and the sensing module 23 can be a single coil (not shown in the figure) or a double coil (as shown in Figure 2). In a specific embodiment, the detection device is a security gate, and the number of receiving coils of the eddy current detection unit 2 can be 12 pairs, with 6 pairs of receiving coils evenly arranged along the direction of gravity on each side of the door panel.

[0081] In some embodiments, the control chip 21 includes a Fourier calculation module U29, which is used to perform Fourier transform on the data received from the analog-to-digital converter ADC 27. The control chip 21 is also used for mode control (e.g., switching between multiple operating modes, controlling different transmitting coils to be energized in different operating modes) and determining the transmission sequence (i.e., outputting a drive signal to cause the magnetic field generating module 22 to generate an alternating magnetic field).

[0082] Referring to Figure 8, the figure shows the timing diagram of the operation of an eddy current detection unit 2 and a nonlinear node detection unit 1 (using the first nonlinear node detection unit A and the second nonlinear node detection unit B as examples). As can be seen from the aforementioned embodiments, since the eddy current detection unit 2 and the nonlinear node detection unit 1 operate at different frequencies, they can operate simultaneously to reduce the false negative rate. Their operating times can overlap without affecting each other. Furthermore, it can be seen that the first nonlinear node detection unit A and the second nonlinear node detection unit B shown in Figure 8 operate simultaneously, meaning that the amount of detection data obtained can be increased by setting multiple nonlinear node detection units 1 within the same time period.

[0083] The idle time of eddy current detection unit 2, the first nonlinear node detection unit A, and the second nonlinear node detection unit B in each working cycle is 10ms. The working time of the transmitting coil and the receiving coil of eddy current detection unit 2 in each working cycle is 14ms, that is, each working cycle of eddy current detection unit 2 is 24ms. When the transmitting coil is working, the receiving coil works synchronously, forming a complete excitation-induction cycle. The working time of the first nonlinear node detection unit A and the second nonlinear node detection unit B is the same. The working time of their transmitting antenna and receiving antenna in each working cycle is 5ms, and in this embodiment, the nonlinear node detection unit 1 drives three receiving antennas to work simultaneously in a single working time. The transmitting antenna TX of the first nonlinear node detection unit A and the second nonlinear node detection unit B are respectively set in their signal transmitting module 10. The receiving antennas of the first nonlinear node detection unit A and the second nonlinear node detection unit B include their respective first receiving antenna RX1, second receiving antenna RX2, and third receiving antenna RX3. The first receiving antenna RX1, the second receiving antenna RX2, and the third receiving antenna RX3 are respectively disposed in their corresponding first signal receiving module 11, second signal receiving module 12, and third signal receiving module 13.

[0084] Therefore, in this embodiment, the eddy current detection unit 2 and all the nonlinear node detection units 1 can operate simultaneously. Although the time it takes for the object 4 to pass through the detection device is short, usually 1 second, both the eddy current detection unit 2 and the nonlinear node detection unit 1 can collect enough data within this time period, thereby improving the detection accuracy.

[0085] Referring to Figures 9 and 10, this embodiment of the invention also discloses a detection method. This detection method can be applied to the detection device disclosed in the above embodiments, and can also be applied to other detection devices equipped with a nonlinear node detection unit 1 and an eddy current detection unit 2. The detection method includes:

[0086] S10. Obtain the nonlinear characteristics of the object 4 to be detected obtained by the nonlinear node detection unit 1 and the eddy current characteristics obtained by the eddy current detection unit 2, wherein the detection frequency of the eddy current detection unit 2 is different from that of the nonlinear node detection unit 1, and the eddy current detection unit 2 and the nonlinear node detection unit 1 work simultaneously.

[0087] S20. Target identification is performed on the object to be detected 4 based on nonlinear and eddy current characteristics.

[0088] In some embodiments, the detection method can be applied to the detection device in any of the foregoing embodiments and executed by the target identification unit 3 in the detection device.

[0089] It should be noted that the nonlinear characteristics of the object 4 to be detected obtained by the nonlinear node detection unit 1 may include harmonic signals (e.g., first-order, second-order, and third-order harmonic signals). Eddy current characteristics may include parameters such as phase and amplitude. In one embodiment, the target recognition unit 3 can use the amplitude of the harmonic signals to perform target recognition of the object 4 to be detected. For example, the judgment can be made by determining the amplitude relationship between the second-order and third-order harmonic signals.

[0090] In one embodiment, when the amplitude of the second harmonic signal is greater than the amplitude of the third harmonic signal, the object to be detected 4 is determined to have a nonlinear node, and a first identification result is obtained. The target identification unit 3 can use parameters such as phase and amplitude to perform target identification on the object to be detected 4. For example, if the amplitude is determined to be greater than a set threshold, the object to be detected 4 is determined to be a mobile phone, and a second identification result is obtained. At this time, the target identification unit 3 can output the first identification result and the second identification result respectively, or it can obtain a comprehensive identification result based on the first identification result and the second identification result and output it.

[0091] In another embodiment, the target recognition unit 3 can simultaneously make a comprehensive judgment based on the nonlinear characteristics and eddy current characteristics of the object to be detected 4, i.e., perform target recognition. Specifically, in some embodiments of the detection method, the step of recognizing the object to be detected 4 based on the nonlinear characteristics and eddy current characteristics includes: if the eddy current characteristics are determined to match the characteristics of a mobile phone, i.e., the phase and amplitude are within the threshold range corresponding to a mobile phone, and the nonlinear characteristics are weak, then the object to be detected 4 can be considered to be a mobile phone. If the eddy current characteristics are determined to be weak, and the nonlinear characteristics are strong, then the object to be detected 4 is considered to be an electronic product other than a mobile phone.

[0092] In some embodiments, the detection method can also be applied to other detection devices that include computing processing functions (e.g., a processing chip), and executed by the processing chip in the detection device. Alternatively, the detection method can also be performed by a human.

[0093] It should be noted that the eddy current detection unit 2 is affected by two factors during detection. First, there may be metal components in the nonlinear node detection unit 1, especially when nonlinear node detection units 1 are set in both side panels. For any eddy current detection unit 2, the metal components in the nonlinear node detection unit 1 in the opposite side panel will also affect the primary magnetic field generated by the magnetic field generating module 22. Second, environmental noise will also affect the detection accuracy of the eddy current detection unit 2.

[0094] Furthermore, referring to Figure 10, to avoid the background noise generated by the metal nodes and / or environmental noise in the nonlinear node detection unit 1 affecting the detection of the eddy current detection unit 2, the following step S11 is performed in the detection method disclosed in some embodiments: calibrating the eddy current features using background noise data before the step of target identification of the object 4 to be detected based on the nonlinear features and eddy current features.

[0095] In some embodiments, the background noise data may be background noise data measured in real time by other devices, or it may be background noise data pre-stored in the target recognition unit 3.

[0096] Furthermore, in some of the detection methods disclosed in the embodiments, the method for acquiring the noise floor data includes:

[0097] Step A: When the detection range of the detection device does not contain the object to be detected 4, receive the initial data detected by the eddy current detection unit 2.

[0098] Step B: Obtain the noise floor data based on the initial data.

[0099] When there is no object 4 to be detected within the detection range of the detection device, the metal nodes of the nonlinear node detection unit 1 within the detection range and the ambient noise generate induced currents under the influence of the original magnetic field generated by the magnetic field generation module 22. The induced currents generate secondary magnetic fields, which in turn affect the original magnetic field. The receiving coil generates an unbalanced induced electromotive force, and the voltage signal formed by this induced electromotive force is the initial data. This initial data is converted into a digital signal, for example, via an analog-to-digital conversion circuit (such as an analog-to-digital converter ADC 27), and sent to the control chip 21 for data processing to obtain the noise floor data.

[0100] In some embodiments, the digital signal is sent to the field-programmable gate array (FPGA) module for Fourier transform processing and amplitude and phase analysis to obtain noise floor data. For example, when no object 4 to be detected passes by, the detection device receives the electromagnetic signal A(t) (the initial data mentioned above) through the sensing module 23 and performs analog-to-digital conversion on the electromagnetic signal A(t) to obtain the discrete-time domain signal An(t). The FPGA module performs a discrete Fourier transform on the discrete-time domain signal An(t) to obtain the noise floor. in, This represents the complete frequency domain signal of the noise floor, where RE1n(f) represents the real part of the frequency domain signal of the noise floor, and jI1mn(f) represents the imaginary part of the frequency domain signal of the noise floor. It is generated by environmental noise and nonlinear node detection unit 1.

[0101] Furthermore, in some embodiments of the detection method, the step of calibrating the eddy current features using noise floor data includes: subtracting the eddy current features from the noise floor data and obtaining the difference result. The difference result is the calibrated data. In actual detection, when the object to be detected 4 passes through the detection device, the sensing module 23 receives the electromagnetic signal X(t), and performs analog-to-digital conversion on the electromagnetic signal X(t) to obtain a discrete-time domain signal Xn(t). The programmable gate array performs a discrete Fourier transform on the discrete-time domain signal Xn(t) to obtain a discrete-frequency domain signal. in, The signal is a discrete frequency domain signal, REn(f) is the real part of the discrete frequency domain signal, and jImn(f) is the imaginary part of the discrete frequency domain signal. Next, the received signal is calibrated using the noise floor, i.e. in It is a calibrated discrete frequency domain signal, and REn(f)' is the real part of the calibrated discrete frequency domain signal, and jImn(f)' is the imaginary part of the calibrated discrete frequency domain signal. The calibrated discrete frequency domain signal is calculated using the arctangent operation. The phase is given by Phasen(f) = arctan(Imn(f)' / REn(f)'), where Phasen(f) is the phase and arctan(Imn(f)' / REn(f)') is the inverse tangent function of the imaginary part of the discrete frequency domain signal. The calibrated discrete frequency domain signal is then calculated using square root operations. The amplitude Ampn(f), phase Phasen(f), and amplitude Ampn(f) are the data after calibrating the eddy current characteristics.

[0102] Furthermore, in some embodiments of the detection method, target identification is performed on the object to be detected 4 based on nonlinear features and eddy current features, i.e., the above-mentioned step S20, which includes: target identification on the object to be detected 4 based on nonlinear features and data calibrated for eddy current features.

[0103] By combining the nonlinear characteristics of the object to be detected 4 with the data after calibrating the eddy current characteristics, the product category of the object to be detected 4 is analyzed, thereby achieving target recognition. In this embodiment, since the eddy current characteristics are calibrated using the noise floor data, interference from the nonlinear node detection unit 1 to the eddy current detection unit 2 can be avoided, thereby improving the accuracy of target recognition.

[0104] Embodiments of the present invention also disclose a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the above-described detection method.

[0105] This invention also discloses a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the above-described detection method.

[0106] Embodiments of the present invention also disclose a computer program product, including a computer program that, when executed by a processor, implements the steps of the above-described detection method.

[0107] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0108] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A detection device, the detection device comprising: At least one nonlinear node detection unit is provided, which is used to acquire the nonlinear features of the object to be detected and send the nonlinear features to the target recognition unit. At least one eddy current detection unit is provided, which is used to acquire the eddy current features of the object to be detected and send the eddy current features to the target recognition unit; the detection frequency of the eddy current detection unit is different from that of the nonlinear node detection unit, and the eddy current detection unit and the nonlinear node detection unit work simultaneously. The target recognition unit is used to identify the object to be detected based on the received nonlinear features and eddy current features.

2. The detection device according to claim 1, characterized in that, On the same side panel of the detection device, there are two or more nonlinear node detection units, and all the nonlinear node detection units are arranged sequentially along a set direction.

3. The detection device according to claim 2, characterized in that, The different nonlinear node detection units operate at different frequencies.

4. The detection device according to claim 2, characterized in that, The set direction is the direction of gravity.

5. The detection device according to claim 1, characterized in that, The nonlinear node detection unit includes: a signal transmitting module, a first signal receiving module, a second signal receiving module, and a third signal receiving module; the first signal receiving module, the second signal receiving module, and the third signal receiving module are all connected to the target identification unit. The signal transmitting module is used to transmit the fundamental wave signal; The first signal receiving module is used to receive the first harmonic signal generated by the object to be detected according to the fundamental wave signal, and send the first harmonic signal or the signal obtained after processing the first harmonic signal to the target recognition unit. The second signal receiving module is used to receive the second harmonic signal generated by the object to be detected according to the fundamental wave signal, and send the second harmonic signal or the signal obtained after processing the second harmonic signal to the target recognition unit. The third signal receiving module is used to receive the third harmonic signal generated by the object to be detected based on the fundamental wave signal, and send the third harmonic signal or the signal obtained after processing the third harmonic signal to the target recognition unit.

6. The detection device according to claim 5, characterized in that, The signal transmission module includes a fundamental wave signal source and a transmission processing circuit; the transmission processing circuit is used to generate a fundamental wave signal based on the fundamental wave signal source. The first signal receiving module is used to mix the first harmonic signal and the first reference signal to obtain a first identification signal, and send the first identification signal to the target identification unit; The first reference signal is generated based on the fundamental signal source.

7. The detection device according to claim 6, characterized in that, The second signal receiving module is used to mix the second harmonic signal and the second reference signal to obtain a second identification signal, and send the second identification signal to the target identification unit; The third signal receiving module is used to mix the third harmonic signal and the third reference signal to obtain a third identification signal, and send the third identification signal to the target identification unit; The fundamental signal source, the signal source of the second reference signal, and the signal source of the third reference signal all reference the same clock signal.

8. The detection device according to claim 5, characterized in that, The antenna of the second receiving module and / or the antenna of the third receiving module are disposed between the antenna of the signal transmitting module and the antenna of the first receiving module.

9. The detection device according to claim 6, characterized in that, The fundamental signal source includes a first signal generator and a power divider; the input terminal of the first signal generator is connected to the target identification unit, and the output terminal of the first signal generator is connected to the input terminal of the power divider; the first output terminal of the power divider is connected to the transmission processing circuit, and the second output terminal of the power divider is connected to the first signal receiving module.

10. The detection device according to claim 9, characterized in that, The first signal receiving module includes a first mixer; the first signal receiving module also includes a first receiving antenna, a first filter and a first receiving amplifier connected in sequence; the first receiving amplifier is electrically connected to the first mixer, and the first mixer is also connected to the second output terminal of the power divider.

11. A detection method applied to a detection device, the detection method comprising: The nonlinear characteristics of the object to be detected obtained by the nonlinear node detection unit and the eddy current characteristics obtained by the eddy current detection unit are obtained, wherein the detection frequency of the eddy current detection unit and the detection frequency of the nonlinear node detection unit are different, and the eddy current detection unit and the nonlinear node detection unit work simultaneously. The target object to be detected is identified based on the nonlinear characteristics and the eddy current characteristics.

12. The detection method according to claim 11, characterized in that, Prior to the step of identifying the object to be detected based on the nonlinear characteristics and the eddy current characteristics, the detection method further includes: The eddy current characteristics are calibrated using the noise floor data; The target identification of the object to be detected based on the nonlinear characteristics and the eddy current characteristics includes: The target object to be detected is identified based on the nonlinear characteristics and the data calibrated according to the eddy current characteristics.

13. The detection method according to claim 12, characterized in that, The method for obtaining the background noise data includes: When the object to be detected is not within the detection range of the detection device, the initial data detected by the eddy current detection unit is received; The noise floor data is obtained based on the initial data.

14. The detection method according to claim 13, characterized in that, The noise floor data is obtained based on the initial data, including: The initial data is subjected to Fourier transform to obtain the noise floor data.

15. The detection method according to claim 14, characterized in that, The eddy current characteristics are calibrated using noise floor data, including: The difference between the eddy current feature and the noise floor data is calculated, and the difference result is used as the calibrated data.

16. A computer device comprising a memory and a processor, the memory storing a computer program, the processor executing the computer program to implement the steps of the detection method according to any one of claims 11 to 15.

17. A computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the detection method according to any one of claims 11 to 15.

18. A computer program product comprising a computer program that, when executed by a processor, implements the steps of the detection method according to any one of claims 11 to 15.

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