Detection module and detection device

Abstract

This application relates to the field of detection technology, and discloses a detection module and detection device. The detection module includes a transmitting module and a receiving module. The transmitting module is used to generate and transmit a fundamental wave signal, and the receiving module includes at least: a receiving antenna circuit for acquiring an inductive signal carrying an audio signal from the object being detected; and a processing circuit connected to the receiving antenna circuit for processing the inductive signal to extract the audio signal. The detection module and detection device provided in this application can extract the audio signal from the inductive signal carrying the audio signal, facilitating the identification of true nodes based on the audio signal.

Description

Technical Field

[0001] This application relates to the field of detection technology, and in particular to a detection module and detection device. Background Technology

[0002] Nonlinear node detectors are used to search for electronic devices containing nonlinear nodes, such as eavesdropping devices, mobile phones, voice recorders, and cameras, and can accurately locate the device regardless of whether it is powered on, in standby mode, or powered off.

[0003] However, in practical applications, it has been found that in addition to nonlinear nodes (defined as true nodes) in electronic devices that radiate corresponding second and third harmonics under the influence of the fundamental wave, there is another type of pure metal object that also exhibits this phenomenon, such as keychains and irregular metal parts with extremely small gaps (defined as false nodes). As long as metals are connected together, because the metals will be oxidized, the contact surfaces of the two metals will form a structure similar to a semiconductor PN junction, and thus will also radiate second and third harmonics under the influence of the fundamental wave.

[0004] Therefore, there is an urgent need to provide a detection device that can easily identify true nodes. Summary of the Invention

[0005] This application provides a detection module and detection device to solve the above-mentioned problems.

[0006] In a first aspect, embodiments of this application provide a detection module, including a transmitting module and a receiving module. The transmitting module is used to generate and transmit a fundamental wave signal, and the receiving module includes at least: A receiving antenna circuit is used to collect inductive signals carrying audio signals from the probe. The processing circuit, connected to the receiving antenna circuit, is used to process the sensed signal to extract the audio signal.

[0007] Secondly, this application also provides a detection module, including a transmitting module and a receiving module. The transmitting module is used to generate a fundamental wave signal and transmit the fundamental wave signal. The receiving module includes: A receiving antenna circuit is used to collect harmonic signals generated by the probe based on the fundamental wave signal and induced signals carrying audio signals from the probe. The processing circuit, connected to the receiving antenna circuit, is used to process the sensed signal to extract the audio signal; the processing circuit is also used to process the harmonic signal to identify whether the probe has nonlinear nodes.

[0008] Thirdly, this application also provides a detection device, which includes the detection module provided in any of the above embodiments.

[0009] In summary, the embodiments of this application provide a detection module and a detection device. The detection module detects the object and can directly extract and play the audio signal from the sensing signal carrying the audio signal. Since the audio signals of true nodes and false nodes have different characteristics, it is easier to identify true nodes by using the audio signal.

[0010] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit the disclosure of the embodiments of this application. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 A block diagram of a first embodiment of the detection module provided in this application; Figure 2 This is a schematic diagram of a working scenario for one embodiment of the detection module provided in this application; Figure 3 A module block diagram of a second embodiment of the detection module provided in this application; Figure 4 A block diagram illustrating a third embodiment of the detection module provided in this application; Figure 5 The circuit diagram of the transmitting module of the detection module provided in the embodiments of this application; Figure 6 A circuit diagram of the receiving module of the detection module provided in this application, representing a first embodiment. Figure 7 A circuit diagram of a second embodiment of the receiving module of the detection module provided in this application; Figure 8 A circuit diagram of one embodiment of the clock signal generation unit of the detection module provided in this application; Figure 9 This is a schematic diagram illustrating the principle of a single frequency conversion of an inductive signal. Figure 10 (A) is a schematic diagram of the ideal frequency conversion effect of a single frequency conversion of the induced signal; Figure 10 (B) is a schematic diagram of the actual frequency conversion effect of a single frequency conversion of the induced signal; Figure 11(A) A spectrum diagram of the first frequency conversion signal before filtering by the filtering circuit of the detection module provided in the embodiment of this application; Figure 11 (B) A spectrum diagram of the first frequency conversion signal after being filtered by the filtering circuit of the detection module provided in the embodiment of this application; Figure 11 (C) is for Figure 11 (B) is a schematic diagram of the spectrum of the first frequency-converted signal after the second frequency-conversion process; Figure 12 A block diagram of one embodiment of the harmonic audio detection device provided in this application; Figure 13 A block diagram of one embodiment of the nonlinear node detection device provided in this application; Figure 14 A block diagram of one embodiment of the detection device provided in this application; Figure 15 A circuit diagram of the receiving module of the detection module provided in this application in a third embodiment; Figure 16 The waveform of the continuous wave emitted by the detection module provided in the embodiment of this application when using the second detection mode.

[0013] Figure label: 1. Detection module; 2. Harmonic audio circuit; 3. Detection equipment; 10. Transmitting module; 101. Transmitting local oscillator; 102. Attenuator; 103. First switching switch; 104. Power amplifier; 105. Second switching switch; 106. Low-noise amplifier unit; 107. First filter; 108. Transmitting antenna; 20. Receiving module; 30. Receiving antenna circuit; 31. First receiving antenna; 32. Second receiving antenna; 33. Third switching switch; 40. First frequency converter circuit; 41. Local oscillator unit; 411. Receiver local oscillator; 412. Fourth switching switch; 413. Frequency multiplier; 42. First mixer; 50. Second frequency converter circuit; 51. Second bandpass filter; 52. Second mixer; 60. Acquisition circuit; 61. Signal processing unit; 611. Second filter; 612. First operational amplifier; 613. Third filter; 62. Acquisition unit; 63. Switching unit; 64. Audio playback unit; 70. Filtering circuit; 71. First bandpass filter; 72. First lowpass filter; 80. Clock signal generation unit; 90. Processing circuit; 91. Frequency conversion circuit. Detailed Implementation

[0014] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the embodiments of this application.

[0015] First, it should be noted that during the detection process of nonlinear node detection equipment, pure metal objects may be falsely reported as nonlinear nodes. Pure metal objects, such as keychains or irregular metal parts with small gaps, can form structures resembling nonlinear nodes (defined as false nodes). Since false nodes also radiate harmonic signals under the influence of the fundamental frequency, the nonlinear node detection equipment receives harmonic signals from both genuine nonlinear nodes (defined as true nodes) and false nodes during operation, resulting in a high false alarm rate. Therefore, a solution is needed to more easily identify genuine nodes.

[0016] To solve the above problems, the inventors discovered through research that true and false nodes can be distinguished by the characteristics of audio signals.

[0017] In this regard, such as Figure 1 As shown in the figure, this application embodiment provides a detection module 1 that can use audio signals to identify real nodes and false nodes. The specific principle is as follows.

[0018] True nodes are typically found in electronic devices such as mice, keyboards, and mobile phones. Regardless of whether the electronic device is operational, nonlinear nodes will generate second and third harmonics under the influence of the fundamental signal. Simultaneously, when the electronic device is operational, it generates audio signals such as power supply noise and communication signals (e.g., SPI communication signals). Audio signals themselves have low frequencies and cannot radiate into the air. However, audio signals can be mixed with harmonic signals. Because the harmonic signals have higher frequencies, the mixed signal can radiate into the air. The specific principle is as follows... Figure 2 As shown. Furthermore, the amplitude of the audio signal generated by electronic devices is relatively stable, and the timbre is more regular, such as a continuous, sharp, and regular "da da da" sound. Moreover, the second harmonic energy of a true node is relatively strong, so a true node can be identified by judging whether the second harmonic carries the aforementioned regular audio signal (note: false nodes do not involve electronic devices, so they will not generate the aforementioned audio signal).

[0019] For dummy nodes, the state of the dummy node itself is not stable enough, and the amplitudes of the corresponding second and third harmonics are also not stable enough, while the energy of the third harmonic is relatively strong. Through extensive experiments, the inventors discovered that if a dummy node or its area is struck, the audio signal of the striking sound is more easily modulated onto the third harmonic generated by the dummy node (the harmonic signals generated by real nodes are relatively stable and are basically unaffected by striking, so the striking sound will not modulate the harmonic signals generated by real nodes). Furthermore, the frequency of the audio signal of the striking sound is similar to the frequency of the striking sound. Therefore, dummy nodes can be identified by judging whether the audio signal demodulated from the third harmonic is similar to the frequency of the striking sound during striking.

[0020] Therefore, based on the above principles, if the received signal is a second harmonic and carries a relatively regular audio signal (or the amplitude of the audio signal is relatively stable), it can be considered a true node; if the received signal is a third harmonic and carries an audio signal with a frequency similar to the frequency of an externally applied knocking sound or the amplitude of the audio signal is unstable, it can be determined as a false node.

[0021] The detection module 1 provided in this embodiment includes a transmitting module 10 and a receiving module 20. The transmitting module 10 is used to transmit a fundamental wave signal, and the receiving module 20 is used to receive and process the induced signal. This detection module 1 can be used directly or integrated into other products. The specific structure and working mode of the detection module 1 are described below with reference to the figures. Specifically, such as Figure 1 As shown, the receiving module 20 includes at least a receiving antenna circuit 30 and a processing circuit 90. The receiving antenna circuit 30 is used to acquire an inductive signal carrying an audio signal from the probe. The processing circuit 90 is connected to the receiving antenna circuit 30 and is used to process the inductive signal to extract the audio signal.

[0022] The transmitting module 10 is used to generate and transmit a fundamental wave signal. After the fundamental wave signal is directed at the detector, the detector will generate a corresponding induced signal under the influence of the fundamental wave signal. Specifically, for example... Figure 2 As shown, the fundamental signal frequency can be f0, and the induced signal can include, for example, the second harmonic with a frequency of 2f0 and the third harmonic with a frequency of 3f0. As mentioned above, the second harmonic may carry an audio signal with a frequency of Δf, meaning the frequency of the corresponding induced signal received by the receiving antenna circuit 30 is 2f0 + Δf. Similarly, the third harmonic may carry an audio signal with a frequency of Δf, meaning the frequency of the corresponding induced signal received by the receiving antenna circuit 30 is 3f0 + Δf. Since true nodes and false nodes differ in the audio signals carried by the harmonic signals, the processing circuit 90 can distinguish between true nodes and false nodes based on the characteristics of the audio signal after extracting it.

[0023] For example, for a true node, the response of the second harmonic carrying the audio signal is relatively strong. Therefore, the processing circuit 90 can process the second harmonic. Specifically, it can down-convert the induced signal with a frequency of 2f0 + Δf to obtain an audio signal of Δf, thereby determining whether the probe is a true node based on the audio signal. For example, if the extracted audio signal is relatively regular, the probe can be determined to be a true node. The audio signal consists of low-frequency signals such as power supply noise and communication signals generated inside the probe when it is powered on.

[0024] For spurious nodes, the response of the third harmonic carrying the audio signal is relatively strong. Therefore, the processing circuit 90 can process the third harmonic, for example, by processing a signal with a frequency of 3f0 + Δf to extract an audio signal with a frequency of Δf. This audio signal is then used to determine whether the object being detected is a spurious node. For example, if the extracted audio signal is similar to the frequency of a knock, the object is determined to be a spurious node. The audio signal can be a knocking sound or other mechanical vibration.

[0025] For example, the frequency of the fundamental wave signal transmitted by the transmitting module 10 can be 2400MHz-2500MHz. The frequency of the audio signal is, for example, 20Hz-10kHz.

[0026] In this embodiment, the detection module 1 can identify true and false nodes based on audio signals. For example, it can identify true and false nodes by the different characteristics of the audio signals generated by them. Therefore, in this embodiment, identifying true nodes based on audio signals is more convenient. Furthermore, this judgment method is more intuitive and faster. Operators only need to determine whether they can hear the sound and listen to the timbre of the audio signal to distinguish between true and false nodes. This requires less expertise from the operator and thus improves the efficiency of identifying true nodes.

[0027] Furthermore, based on audio signals, in some application scenarios, it can also be used to determine whether illegal electronic products (such as illegal eavesdropping and recording devices) are embedded in electronic devices.

[0028] In one example, if the electronic device is powered off, the detection module 1 transmits a fundamental frequency signal towards the electronic device using the transmitting module 10. Since the electronic device is powered off, it will not generate an audio signal itself. However, the nonlinear node can still generate harmonics after receiving the fundamental frequency. Therefore, if no illegal electronic product is embedded inside the electronic device, the processing circuit 90 will not extract the audio signal. However, if an illegal electronic product is embedded inside the electronic device, although the electronic device is powered off, the illegal electronic product still works normally and can still generate an audio signal. If this audio signal is modulated onto the second harmonic, the receiving antenna circuit 30 will still receive the second harmonic carrying the audio signal, and the processing circuit 90 can extract the audio signal. If the audio signal is played and a sound can be heard with a relatively regular timbre, it can be determined that an illegal electronic product is embedded inside the electronic device.

[0029] like Figure 3 As shown, in some embodiments, the processing circuit 90 may include a frequency conversion circuit 91 and a data acquisition circuit 60. The frequency conversion circuit 91 is connected to the receiving antenna circuit 30 and is used to perform a preset frequency conversion operation on the sensed signal to obtain the audio signal carried in the sensed signal. The data acquisition circuit 60 is connected to the frequency conversion circuit 91 and is used to convert the audio signal into sound information and output the sound information.

[0030] For example, the fundamental frequency of the signal can be f0, and the induced signal can include, for example, the second harmonic modulated with an audio signal, i.e., the frequency of the induced signal is 2f0 + Δf. The frequency conversion circuit 91 can perform a down-conversion operation on the induced signal with a frequency of 2f0 + Δf, for example, by mixing it with a signal with a frequency of 2f0, to obtain an audio signal with a frequency of Δf. After obtaining the audio signal, it is input to the acquisition circuit 60 at the back end, which can convert the audio signal into sound information and output it. At this point, the true node can be identified relatively easily and quickly based on the sound information.

[0031] It should be noted that the frequency conversion circuit 91 can be any circuit capable of down-conversion, such as a mixer, other nonlinear second-order devices or other devices or circuits.

[0032] like Figure 3 As shown, in some embodiments, the acquisition circuit 60 may include a signal processing unit 61 and an audio playback unit 64. The input terminal of the signal processing unit 61 is connected to the output terminal of the frequency conversion circuit 91, and is used to perform preset processing on the audio signal to obtain the processed audio signal. The input terminal of the audio playback unit 64 is connected to the output terminal of the signal processing unit 61, and is used to convert the processed audio signal into sound information and play the sound information.

[0033] The signal processing unit 61 can perform preset processing (such as filtering, amplification, etc.) on the audio signal to obtain a processed audio signal. The signal processing unit 61 can block interference and noise, and improve the signal strength while introducing as little noise as possible, providing a high-quality input signal for the audio playback unit 64. In particular, the sound information obtained by converting the processed audio signal is of higher quality than the sound information obtained directly from the audio signal, thereby improving the accuracy of detection.

[0034] Specifically, such as Figure 6 As shown, the signal processing unit 61 may include a second filter 611, a first operational amplifier 612, and a third filter 613 connected in sequence. The second filter 611 and the third filter 613 can filter out noise signals (e.g., signals whose frequencies differ significantly from Δf) to avoid interference. The first operational amplifier 612 can enhance signal strength. As one embodiment, the audio playback unit 64 may include, for example, a speaker or headphones for playing sound information.

[0035] Since the audio signal needs to be listened to continuously in order to identify the characteristics of the timbre and the true node, the fundamental wave signal generated by the transmitting module 10 can be a continuous wave signal so that the sound information corresponding to the audio signal is a continuous audio segment.

[0036] like Figure 3 As shown, in some embodiments, the frequency conversion circuit 91 may include a first frequency conversion circuit 40 and a second frequency conversion circuit 50. The first frequency conversion circuit 40 is connected to the receiving antenna circuit 30 and is used to perform a first frequency conversion operation on the induced signal to obtain a first frequency-converted signal, wherein the frequency of the first frequency-converted signal is less than that of the induced signal. The second frequency conversion circuit 50 is connected to the first frequency conversion circuit 40 and the acquisition circuit 60 and is used to perform a second frequency conversion operation on the first frequency-converted signal to obtain an audio signal, wherein the frequency of the audio signal is less than that of the first frequency-converted signal. Both the first and second frequency conversion operations can reduce the frequency of the signal. The first frequency conversion circuit 40 and the second frequency conversion circuit 50 can be any circuit capable of down-conversion, such as a mixer, other nonlinear second-order devices, or other devices or circuits. The detection module 1 provided in this embodiment adopts a two-stage frequency conversion scheme, which can improve the detection sensitivity. The specific reasons are as follows.

[0037] First, we introduce the formula for calculating the sensitivity of the receiving circuit: S = -174dBm + NF + SNR + 10log(BW). Where S represents sensitivity, NF represents system noise, SNR represents minimum demodulation signal-to-noise ratio, and BW represents bandwidth. SNR generally has a relatively small impact on sensitivity. As for BW, it can be kept very low as long as a digital demodulation scheme is used. Therefore, to improve the sensitivity of the receiving circuit, the value of NF needs to be reduced. It should be noted that the smaller NF is, the smaller the value of S. For signal receiving circuits, a lower sensitivity value S is better. For example, a receiving circuit with S = -140 dBm has better sensitivity than a receiving circuit with S = -125 dBm.

[0038] In the receiving module 20, the radio frequency signal needs to be down-converted to mid- and low-frequency signals using a local oscillator. The phase noise of the local oscillator is the main source of system noise. For a single-conversion scheme (i.e., directly down-converting the radio frequency signal to mid- and low-frequency signals using the local oscillator), to facilitate backend processing (e.g., considering cost and performance, the frequency range that the acquisition circuit can handle is usually low), the frequency of the down-converted mid- and low-frequency signals needs to be low, for example, 1kHz. However, the lower the frequency of the mid- and low-frequency signals, the more susceptible they are to phase noise. Therefore, the signal after single-conversion is significantly affected by phase noise, resulting in a higher frequency response (NF) and decreased sensitivity of the receiving circuit. When phase noise is high, it will superimpose on the audio signal, affecting the timbre of the audio signal and potentially leading to misjudgment by the operator. In other words, the presence of phase noise may affect the detection efficiency and accuracy of the detection module 1.

[0039] In the detection module 1 provided in this embodiment, to overcome the aforementioned phase noise problem, a first frequency conversion circuit 40 and a second frequency conversion circuit 50 are provided. That is, the first frequency conversion circuit 40 and the second frequency conversion circuit 50 perform two frequency conversion operations on the received induced signal, converting it to a lower frequency so that the acquisition circuit 60 can convert the audio signal into sound information. For this embodiment, it is not necessary to convert the induced signal to a lower frequency all at once. Instead, the induced signal can be first converted to a first frequency conversion signal (with a lower frequency than the induced signal, and which can be higher than the frequency of the medium and low frequency signals in a traditional single-conversion scheme), and then a second frequency conversion operation is performed to finally extract the audio signal. Even if the first frequency conversion operation uses a local oscillator, the frequency of the first frequency conversion signal is relatively high, so it is less affected by phase noise. For the second frequency conversion operation, since the frequency difference before and after the conversion is small, a local oscillator is not required; instead, a crystal oscillator or other components with good phase noise performance can be used to achieve the down-conversion. Therefore, in the detection module provided in this embodiment, the first frequency conversion operation is less affected by phase noise, and the second frequency conversion operation can be performed without a local oscillator for down-conversion. Overall, it is less affected by the phase noise of the local oscillator, resulting in a smaller NF (Frequency Not Found). According to the above formula, the sensitivity of the receiving module 20 will also be smaller, meaning the sensitivity is better than that of a single-frequency conversion scheme. Simultaneously, the impact of phase noise on the audio signal will also be lower.

[0040] As can be seen from the foregoing, both single-conversion and double-conversion schemes (the schemes provided in this embodiment of the invention) will be affected by phase noise to varying degrees. In order to further improve the sensitivity of the receiving module 20, it is necessary to process the phase noise.

[0041] like Figure 4 As shown, in some embodiments, the receiving module 20 further includes a filter circuit 70 connected between the first frequency conversion circuit 40 and the second frequency conversion circuit 50. The filter circuit 70 is used at least to filter out low-frequency noise in the first frequency conversion signal, wherein the maximum value of the frequency band in which the low-frequency noise is located is less than the frequency of the first frequency conversion signal. It should be noted that the maximum value of the frequency band in which the low-frequency noise is located refers to the highest frequency value within the frequency range in which the low-frequency noise is located, while the frequency of the first frequency conversion signal is, for example, the center position of the signal energy distribution of the first frequency conversion signal in the frequency domain.

[0042] like Figure 9 and Figure 10 As shown, if a single-conversion scheme is used to mix the RF signal (inductive signal) and the LO signal (local oscillator signal) to obtain a signal of the desired frequency (e.g., 52kHz), it should be noted that, ideally, the spectrum obtained after the single-conversion scheme completes the conversion operation should look like this. Figure 10As shown in (A), only the frequency points of the frequency-converted signal (taking 52kHz as an example) have a higher amplitude compared to the noise floor, while the amplitudes of other frequency points remain near the noise floor (which can be understood as environmental noise, which is acceptable because it is relatively stable). However, in reality, due to the influence of various other noises, the frequency spectrum obtained after frequency conversion will be as shown in (A). Figure 10 As shown in (B), it can be seen that in actual conditions, the amplitude-frequency curve in the spectrum will show a raised noise floor at lower frequencies. This is equivalent to indirectly increasing the overall noise floor of the frequency-converted signal, and a higher overall noise floor will lead to a decrease in detection sensitivity and signal-to-noise ratio.

[0043] This phenomenon occurs because the frequency-converted signal carries phase noise. Phase noise, measured in dBc, is the ratio of noise power density to local oscillator carrier power. Specifically, it's the ratio of the noise signal power at a certain frequency offset to the useful signal power; dividing this ratio by the measurement bandwidth gives the phase noise. Phase noise is relatively high in the low-frequency band, and since the audio signal obtained by the detection module 1 in this embodiment has a low frequency, any existing phase noise will be high, significantly impacting the audio signal's noise floor.

[0044] Therefore, in the detection module 1 provided in this application embodiment, although the first frequency-converted signal generated after frequency conversion by the first frequency conversion circuit 40 is relatively less affected by phase noise, the influence of phase noise cannot be completely eliminated. The first frequency-converted signal generated by the first frequency conversion circuit 40 may still contain low-frequency noise (i.e., the aforementioned phase noise), which will affect the second frequency conversion operation and the audio signal obtained from the second frequency conversion operation. To overcome this problem, this embodiment sets up a filter circuit 70 to filter out low-frequency noise, enabling the first frequency conversion operation to achieve an effect close to the ideal frequency conversion effect. Furthermore, it can avoid affecting subsequent frequency conversion operations (such as the second frequency conversion operation), improving the quality of the audio signal, thereby avoiding a decrease in detection sensitivity and signal-to-noise ratio due to increased background noise. For example, the frequency range of the first frequency-converted signal is approximately 189MHz + 1kHz (1kHz is, for example, the frequency of the audio signal), while the frequency range of low-frequency noise is much smaller than 189MHz + 1kHz.

[0045] It should be noted that, by Figure 11 (A) It can be seen that the signal frequency of low-frequency noise is lower than that of the first frequency conversion signal. It is easier and more effective to filter out low-frequency noise before the second frequency conversion operation. Therefore, the above-mentioned filter circuit 70 is set between the first frequency conversion circuit 40 and the second frequency conversion circuit 50. Figure 11 (B) is the spectrum of the first frequency-converted signal after filtering out low-frequency noise. Figure 11 (C) is the spectrum of the audio signal obtained after the second frequency conversion. It can be seen that the first frequency conversion signal and the audio signal are relatively stable after filtering out low-frequency noise, which can improve the detection sensitivity.

[0046] It should also be noted that for traditional single-stage frequency conversion schemes, phase noise cannot be eliminated by setting filters. The reason is: according to Figure 10 (B) It can be seen that the frequency of the phase noise is close to the center frequency of the mid- and low-frequency signals after frequency conversion (e.g., 1kHz), only a few kHz. That is, only a filter with a low bandwidth can filter out the phase noise. However, due to the limitations of the filter hardware, its bandwidth usually cannot be so narrow, generally only at the MHz level. Therefore, the phase noise cannot be directly filtered out by the filter in a single-conversion scheme.

[0047] For the detection module 1 provided in this embodiment of the invention, a secondary frequency conversion scheme is adopted, such as... Figure 11 As shown in (A), the frequency of the first frequency-converted signal obtained after the first frequency conversion operation is relatively high, and the center frequency point is far from the frequency band of the phase noise, for example, tens to hundreds of MHz. This is equivalent to significantly increasing the frequency interval between the effective signal and the phase noise. Thus, the performance requirements of the filter are reduced, meaning that a conventional filter can meet the requirements. At this time, the aforementioned filter circuit 70 can easily filter out the phase noise.

[0048] As one example, such as Figure 6 As shown, the filter circuit 70 may include a first bandpass filter 71 connected between the first frequency conversion circuit 40 and the second frequency conversion circuit 50. The first bandpass filter 71 is used to filter out low-frequency noise in the first frequency conversion signal.

[0049] Specifically, the input terminal of the first bandpass filter 71 is connected to the output terminal of the first frequency converter circuit 40 to receive the first frequency-converted signal output by the first frequency converter circuit 40, and the output terminal of the first bandpass filter 71 is connected to the input terminal of the second frequency converter circuit 50. The first bandpass filter 71 is an electronic component that allows signals of a specific frequency band to pass through while blocking signals of other frequency bands, thus filtering out low-frequency noise in the first frequency-converted signal. The first frequency-converted signal after low-frequency noise filtering is then input to the second frequency converter circuit 50 for further processing.

[0050] As one embodiment, the center frequency of the first frequency conversion signal is 189MHz+Δf, and the first bandpass filter 71 only allows signals in the frequency band near 189MHz+Δf to pass through, thereby further filtering out signals in the frequency band near 189MHz+Δf, and at the same time filtering out low-frequency noise (such as phase noise).

[0051] It should be noted that the first frequency-converted signal in the above embodiments does not necessarily contain phase noise. In other words, if the local oscillator has superior performance, the phase noise in the first frequency-converted signal is very weak, or even non-existent. In this case, the first frequency-converted signal is a purely valid signal, such as a signal with a frequency of 189MHz + Δf. If the local oscillator has relatively inferior performance, the first frequency-converted signal will contain phase noise in addition to the valid signal (such as a signal with a frequency of 189MHz + Δf). After the first frequency-converted signal passes through the first bandpass filter 71, only the valid signal will be output, thus filtering out the phase noise.

[0052] As one example, such as Figure 6 As shown, the filter circuit 70 may further include a first low-pass filter 72 connected between the first frequency conversion circuit 40 and the first bandpass filter 71. The first low-pass filter 72 is used to filter out high-frequency noise, where the minimum value of the frequency band in which the high-frequency noise is located is greater than the frequency of the first frequency conversion signal. It should be noted that the minimum value of the frequency band in which the high-frequency noise is located refers to the lowest frequency value within the frequency range of the high-frequency noise. The frequency of the first frequency conversion signal, for example, is the center position of the signal energy distribution of the first frequency conversion signal in the frequency domain.

[0053] The first low-pass filter 72 is an electronic component that allows signals with frequencies below a preset specific frequency to pass through while shielding signals with frequencies above a specific frequency, thus filtering out high-frequency noise in the first frequency conversion signal.

[0054] It should be noted that, ideally, a mixer can perform a mixing operation on 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 signal at the input terminal of the first mixer 42 may be directly coupled to the first converted signal output by the first mixer 42. For example... Figure 6As shown, the induced signal (including second and third harmonics) transmitted from the receiving antenna circuit 30 to the first mixer 42, and the local oscillator signal (including second-order and third-order local oscillator signals) transmitted from the local oscillator unit 41 to the first mixer 42, may both be directly coupled to the first frequency-converted signal output by the first mixer 42. That is, the first frequency-converted signal may contain not only the effective signal but also the induced signal and the local oscillator signal. In this case, the aforementioned induced signal and local oscillator signal, due to their high frequency, belong to the aforementioned high-frequency noise. High-frequency noise may propagate backward along the signal transmission direction in the receiving module 20, thereby interfering with the clarity and stability of the signal, leading to signal distortion or errors.

[0055] Therefore, filtering out high-frequency noise in the first frequency conversion signal can significantly improve signal quality, ensure accurate signal transmission and reception, and prevent high-frequency noise from interfering with the normal operation of detection module 1, thereby improving detection accuracy.

[0056] Specifically, as one embodiment, the filter circuit 70 may also include a first low-pass filter 72 and a first band-pass filter 71. The input terminal of the first low-pass filter 72 is connected to the output terminal of the first frequency conversion circuit 40, the output terminal of the first low-pass filter 72 is connected to the input terminal of the first band-pass filter 71, and the output terminal of the first band-pass filter 71 is connected to the input terminal of the second frequency conversion circuit 50. Therefore, in this embodiment, high-frequency noise is first filtered out by the first low-pass filter 72, and then low-frequency noise (such as phase noise) is filtered out by the first band-pass filter 71. It should be understood that in some other embodiments (not shown in the figure), the filter circuit 70 may also be configured such that the input terminal of the first band-pass filter 71 is connected to the output terminal of the first frequency conversion circuit 40, the output terminal of the first band-pass filter 71 is connected to the input terminal of the first low-pass filter 72, and the output terminal of the first low-pass filter 72 is connected to the input terminal of the second frequency conversion circuit 50, that is, low-frequency noise is filtered out first and then high-frequency noise is filtered out.

[0057] By cooperating with the first low-pass filter 72 and the first band-pass filter 71, the filter circuit 70 allows only signals in the frequency band near the center frequency (e.g., 189MHz + Δf) of the first frequency-converted signal to pass through, while simultaneously filtering out phase noise and high-frequency noise. This allows the filtered first frequency-converted signal to, for example, exhibit... Figure 11 The effect shown in (B).

[0058] It should be noted that if the first bandpass filter 71 is effective in filtering out phase noise and high-frequency noise, the first low-pass filter 72 may not be necessary. Only the first bandpass filter 71 is needed to achieve the filtering purpose, thus saving on the cost of electronic components.

[0059] like Figure 4As shown, in some embodiments, the detection module 1 may further include a clock signal generation unit 80, which generates a clock signal and outputs it to at least the transmitting module 10 and the first frequency conversion circuit 40. The transmitting module 10 generates a fundamental frequency signal using the clock signal. The first frequency conversion circuit 40 generates a local oscillator signal using the clock signal and performs a first frequency conversion operation on the sensed signal using the local oscillator signal to obtain a first frequency-converted signal.

[0060] Specifically, the transmitting module 10 uses the clock signal as a reference clock and generates a fundamental wave signal with a frequency that is a certain multiple of the clock signal frequency, and then transmits the fundamental wave signal externally. The probe generates an induced signal under the influence of the fundamental wave signal. The first frequency conversion circuit 40 also uses the clock signal as a reference clock and multiplies the clock signal to generate a local oscillator signal with a frequency related to the induced signal. It should be noted that if the fundamental signal and the local oscillator signal use different clock signals as reference clocks, for example, if the fundamental signal and the local oscillator signal are generated based on different crystal oscillators, and the frequencies of the crystal oscillators, even if they are from the same batch, will have slight differences, the difference between the fundamental signal and the local oscillator signal obtained after the frequency multiplication operation will be amplified by a factor of two, resulting in a deviation from the expected signal, which will affect the sensitivity of the detection module 1.

[0061] In this embodiment, both the fundamental signal and the local oscillator signal use the same clock signal as the reference clock, meaning they originate from the same source (have the same clock reference). Therefore, the local oscillator signal and the fundamental signal have consistent timing. Since the frequency of the sensed signal is related to the frequency of the fundamental signal, if the timing of the local oscillator signal is consistent with that of the fundamental signal, it can be guaranteed that the timing of the local oscillator signal and the sensed signal is also consistent. This allows the first frequency-converted signal obtained by down-converting based on the local oscillator signal to accurately reflect the properties of the probe, avoiding the problem of decreased sensitivity of the detection module 1 due to inconsistent clock signal timing.

[0062] For example, the frequency of the clock signal is approximately 27 MHz.

[0063] In some implementation methods, please refer to Figure 6 The first frequency conversion circuit 40 includes at least a local oscillator unit 41 and a first mixer 42. The local oscillator unit 41 is connected to the clock signal generation unit 80 and is used to generate a local oscillator signal using a clock signal. The first mixer 42 is connected to the receiving antenna circuit 30, the local oscillator unit 41, and the second frequency conversion circuit 50, respectively, and is used to mix the local oscillator signal with the induced signal to obtain the first frequency conversion signal.

[0064] The local oscillator unit 41 uses the clock signal as a reference clock and multiplies the clock signal to obtain the local oscillator signal. The specific value of the local oscillator signal depends on the induced signal to ensure that the induced signal can be converted into a first frequency-converted signal that reflects the characteristics of the detected object without distortion. The first mixer 42 has a first input terminal, a second input terminal, and an output terminal. Its first input terminal is connected to the receiving antenna circuit 30 to receive the induced signal, its second input terminal is connected to the local oscillator unit 41 to receive the local oscillator signal, and its output terminal is connected to the second frequency conversion circuit 50 to output the first frequency-converted signal obtained by mixing. The frequency of the first frequency-converted signal output by the first mixer 42 is the frequency difference between the induced signal and the local oscillator signal.

[0065] As previously explained, the induced signal includes, but is not limited to, the second and third harmonics of the fundamental signal. If the probe is powered on or is a dummy node and is struck, the induced signal also includes at least the second and third harmonics carrying audio signals generated based on the fundamental signal. In one embodiment, the receiving antenna circuit 30 is configured to output one of the second and third harmonics carrying audio signals to the first frequency conversion circuit 40. Specifically, when the receiving antenna circuit 30 outputs the second harmonic carrying audio signals to the first frequency conversion circuit 40, the frequency of the local oscillator signal output by the local oscillator unit 41 is twice the frequency of the fundamental signal and the difference between the frequencies of the higher harmonics. When the antenna receiving circuit 30 outputs the third harmonic carrying audio signals to the first frequency conversion circuit 40, the frequency of the local oscillator signal output by the local oscillator unit 41 is three times the frequency of the fundamental signal and the difference between the frequencies of the higher harmonics.

[0066] In the first frequency conversion operation, taking a high-order harmonic signal frequency of 189MHz as an example, the local oscillator unit 41 generates a local oscillator signal with a frequency of 2f0-189MHz or 3f0-189MHz. Thus, the first mixer 42 mixes the local oscillator signal with a frequency of 2f0-189MHz with a second harmonic carrying an audio signal at a frequency of 2f0+Δf to obtain a first frequency-converted signal with a frequency of 189MHz+Δf. Alternatively, the first mixer 42 mixes the local oscillator signal with a frequency of 3f0-189MHz with a third harmonic carrying an audio signal at a frequency of 3f0+Δf to obtain a first frequency-converted signal with a frequency of 189MHz+Δf. Furthermore, in this embodiment, since both the local oscillator unit 41 and the fundamental signal use the clock signal as a reference clock, it can be ensured that the f0 frequency of the local oscillator signal generated by the local oscillator unit 41 is the same as the fundamental signal frequency, thereby ensuring the accuracy of the detection.

[0067] In addition, the clock signal generation unit 80 is also used to output the clock signal to the second frequency conversion circuit 50. The second frequency conversion circuit 50 is used to extract the high-order harmonic signal from the clock signal and use the high-order harmonic signal to perform a second frequency conversion operation on the first frequency conversion signal to obtain an audio signal.

[0068] Therefore, the frequency of the audio signal is the frequency difference between the higher harmonic signal and the first frequency conversion signal. The fundamental signal, the local oscillator signal in the first frequency conversion circuit 40, and the higher harmonic signals in the second frequency conversion circuit 50 are generated based on the same clock signal. Therefore, the fundamental signal, local oscillator signal, and higher harmonic signals originate from the same source and have consistent timing, avoiding the problem of decreased sensitivity of the detection module 1 due to inconsistent clock signal timing. The specific principle is the same as in the aforementioned embodiments and will not be elaborated further here.

[0069] In some implementation methods, please refer to Figure 6 The second frequency conversion circuit 50 includes at least a second bandpass filter 51 and a second mixer 52.

[0070] Specifically, the second bandpass filter 51 is connected to the clock signal generation unit 80 and is used to extract higher harmonic signals from the clock signal. The frequency of the higher harmonic signal is equal to the frequency difference between the first frequency conversion signal and the second frequency conversion signal. The second mixer 52 is connected to the second bandpass filter 51, the first frequency conversion circuit 40, and the acquisition circuit 60, respectively, and is used to mix the higher harmonic signal with the first frequency conversion signal to obtain an audio signal. Furthermore, the frequency of the audio signal output by the second mixer 52 is the frequency difference between the higher harmonic signal and the first frequency conversion signal.

[0071] The second mixer 52 has a first input terminal, a second input terminal, and an output terminal. Its first input terminal is connected to the first frequency conversion circuit 40 to receive the first frequency conversion signal, its second input terminal is connected to the second bandpass filter 51 to receive the high-order harmonic signal, and its output terminal is connected to the acquisition circuit 60 to output the audio signal obtained by mixing to the acquisition circuit 60.

[0072] In addition, such as Figure 6 and Figure 8 As shown, the input terminal of the second bandpass filter 51 is connected to the clock signal generation unit 80, and the clock signal generation unit 80 transmits the generated clock signal to the second bandpass filter 51. Since the clock signal is usually a square wave, it carries harmonic signals (such as high-order harmonic signals), and the second bandpass filter 51 only allows specific frequency bands, namely the aforementioned high-order harmonic signals (for example, signals around 189MHz), to pass through. Therefore, the output terminal of the second bandpass filter 51 only outputs high-order harmonic signals to facilitate the second frequency conversion operation.

[0073] It should be noted that in the first frequency conversion operation performed by the first frequency conversion circuit 40, the frequency of the output first frequency conversion signal is the frequency difference between the induced signal and the local oscillator signal. In the second frequency conversion operation performed by the second frequency conversion circuit 50, the frequency of the output audio signal is the frequency difference between the first frequency conversion signal and the higher harmonic signal. That is, both frequency conversion operations are down-conversion operations, which can effectively adjust the high-frequency induced signal to the frequency range of the intermediate frequency signal or low-frequency signal (e.g., 1kHz). It should also be noted that the value of the higher harmonic signal should be greater than the maximum frequency value of the frequency band where the low-frequency noise (e.g., phase noise) is located, so that the low-frequency noise can be filtered out by the filter circuit 70 after the first frequency conversion operation.

[0074] It should be noted that the detection module 1 focuses on the attribute information represented by the frequency Δf of the audio signal. At this time, the frequency of the local oscillator signal generated by the local oscillator unit 41 is the difference between an integer multiple of the fundamental signal frequency and the frequency of the higher harmonic signal of the clock signal. Specifically, the frequency of the local oscillator signal is the difference between 2f0 (i.e., twice the fundamental signal frequency) and the higher harmonic signal frequency (for the second harmonic carrying the audio signal), or it is the difference between 3f0 (i.e., three times the fundamental signal frequency) and the higher harmonic signal frequency (for the third harmonic carrying the audio signal). The first frequency conversion signal frequency obtained from the first frequency conversion operation is the sum of the higher harmonic signal frequency and the audio signal frequency Δf.

[0075] Taking a high-order harmonic signal with a frequency of 189MHz as an example, in the first frequency conversion operation, the local oscillator unit 41 generates a local oscillator signal with a frequency of 2f0-189MHz, so that the first mixer 42 mixes the local oscillator signal with an induced signal with a frequency of 2f0+Δf to obtain a first frequency-converted signal with a frequency of 189MHz+Δf. Alternatively, the first mixer 42 mixes the local oscillator signal with a frequency of 3f0-189MHz with an induced signal with a frequency of 3f0+Δf to obtain a first frequency-converted signal with a frequency of 189MHz+Δf.

[0076] In the second frequency conversion operation, the second mixer 52 uses a higher harmonic signal to perform a second frequency conversion operation on the first frequency conversion signal. For example, it mixes the first frequency conversion signal with a frequency of 189MHz + Δf with a higher harmonic signal with a frequency of 189MHz to obtain an audio signal with a frequency of Δf. At this time, the frequency of the audio signal is the audio signal frequency Δf. The acquisition circuit 60 can convert the audio signal into sound information and output it. Based on the audio information, it can identify whether the probe contains nonlinear nodes, or distinguish between true and false nodes.

[0077] As one embodiment, the local oscillator signal generated by the local oscillator unit 41 may include a second-order local oscillator signal and a third-order local oscillator signal. Furthermore, different local oscillator units 41 can be used to output second-order and third-order local oscillator signals respectively, or the same local oscillator unit 41 can be reused to output both signals, thus saving on the cost of electronic components. Specifically, only one local oscillator unit 41 can be provided. This unit 41 is connected to the first frequency conversion circuit 40. When the receiving antenna circuit 10 inputs the received second harmonic carrying the audio signal to the first frequency conversion circuit 40, it outputs a second-order local oscillator signal. When the receiving antenna circuit 30 inputs the received third harmonic carrying the audio signal to the first frequency conversion circuit 40, it outputs a third-order local oscillator signal. The second-order local oscillator signal is the difference between twice the fundamental signal frequency and the higher harmonic signal frequency. The third-order local oscillator signal is the difference between three times the fundamental signal frequency and the higher harmonic signal frequency.

[0078] As one embodiment (not shown in the figure), the local oscillator unit 41 may include a receiving local oscillator 411, the output terminal of the receiving local oscillator 411 is connected to the first mixer 42, and the receiving local oscillator 411 is used to switch the output of the second-order local oscillator signal and the third-order local oscillator signal to the first mixer 42.

[0079] As another embodiment, such as Figure 6 As shown, the local oscillator unit 41 may include a receiving local oscillator 411, a fourth switching switch 412, and a frequency multiplier 413. The first output terminal of the receiving local oscillator 411 is connected to the first input terminal of the fourth switching switch 412, the second output terminal of the receiving local oscillator 411 is connected to the second input terminal of the fourth switching switch 412 through the frequency multiplier 413, and the output terminal of the fourth switching switch 412 is connected to the first mixer 42.

[0080] Specifically, the receiving local oscillator 411 is used to output a second-order local oscillator signal through the first output terminal. The second-order local oscillator signal is, for example, a local oscillator signal with a frequency of 2f0-189MHz. Alternatively, the receiving local oscillator 411 outputs a half-frequency third-order local oscillator signal through the second output terminal. The half-frequency third-order local oscillator signal is, for example, a local oscillator signal with a frequency of (3f0-189MHz) / 2. Furthermore, the detection module 1 can control the on / off state of each input and output terminal in the fourth switching switch 412. When mixing the second harmonic carrying an audio signal is required, the receiving local oscillator 411 outputs a second-order local oscillator signal through the first output terminal, and this signal is input to the first mixer 42 via the fourth switching switch 412. When it is necessary to mix the third harmonic of the audio signal, the local oscillator 411 outputs a third-order local oscillator signal with a frequency of half the frequency through the second output terminal (i.e., the output signal frequency is half the frequency of the third-order local oscillator signal), and the output signal is multiplied by the frequency multiplier 413 to obtain the third-order local oscillator signal, which is then input to the first mixer 42 through the fourth switching switch 412.

[0081] It should be understood that, due to hardware and cost limitations, conventional local oscillator sources can only output local oscillator signals with relatively low frequencies, and therefore may not be able to directly output higher frequency local oscillator signals (such as third-order local oscillator signals). Therefore, to reduce the difficulty of selecting electronic components and control costs, a frequency multiplier 413 can be placed between the receiving local oscillator 411 and the first mixer 42. By setting the frequency multiplier 413 to multiply the half-frequency third-order local oscillator signal, for example, a local oscillator signal with a frequency of (3f0-189MHz) / 2, a third-order local oscillator signal with a frequency of 3f0-189MHz can be obtained.

[0082] Optionally, a local oscillator capable of outputting a higher frequency can be selected, in which case the frequency multiplier 413 may not be necessary. Those skilled in the art can choose whether or not to use the frequency multiplier 413 based on actual needs.

[0083] This application also provides Figure 1 Another implementation of the detection module 1 shown is as follows: Figure 5 , Figure 7 As shown, the system includes a transmitting module 10 and a receiving module 20. The transmitting module 10 generates and transmits a fundamental wave signal. The receiving module 20 includes a receiving antenna circuit 30 and a processing circuit 90. The receiving antenna circuit 30 is used to acquire harmonic signals generated by the probe based on the fundamental wave signal and an inductive signal carrying an audio signal from the probe. The processing circuit 90 is connected to the receiving antenna circuit 30 and is used to process the inductive signal to extract the audio signal. The processing circuit 90 is also used to process the harmonic signals to identify whether the probe has nonlinear nodes.

[0084] It should be noted that the detection module 1 in this embodiment can be applied to two different detection modes. In the first detection mode, the detection module 1 receives harmonic signals and can process these signals to detect whether the object being detected includes nonlinear nodes or is an item with nonlinear characteristics. In the second detection mode, the detection module 1 receives inductive signals carrying audio signals and can process these signals to obtain audio signals, thereby identifying whether the object being detected is a true node or a false node based on the audio signals.

[0085] The two detection modes described above can share the same transmitting module 10. In some implementations, such as... Figure 5As shown, the transmitting module 10 may include a transmitting local oscillator 101, an attenuator 102, a first switching switch 103, a power amplifier 104, a second switching switch 105, a low-noise amplifier unit 106, a first filter 107, and a transmitting antenna 108. The output of the transmitting local oscillator 101 is connected to the input of the attenuator 102; the output of the attenuator 102 is connected to the input of the first switching switch 103; the first output of the first switching switch 103 is connected to the input of the power amplifier 104; the second output of the first switching switch 103 is connected to the input of the low-noise amplifier unit 106; the first input of the second switching switch 105 is connected to the output of the power amplifier 104; the second input of the second switching switch 105 is connected to the output of the low-noise amplifier unit 106; the output of the second switching switch 105 is connected to the input of the first filter 107; and the output of the first filter 107 is connected to the transmitting antenna 108.

[0086] The low-noise amplification unit 106 includes, for example, one, two, or more low-noise amplifiers. For example, such as... Figure 5 As shown, the low-noise amplifier unit 106 includes two low-noise amplifiers.

[0087] In this embodiment, the transmitting local oscillator 101 can use the clock signal generated by the clock signal generation unit 80 as a reference clock to generate a fundamental wave source. The fundamental wave source is then processed by the attenuator 102 and subsequent amplifiers to form a fundamental wave signal. The transmitting antenna 108 is used to transmit the generated fundamental wave signal to the probe.

[0088] In this embodiment, the link for the fundamental wave signal output can be adjusted by controlling the first switching switch 103 and the second switching switch 105 (e.g., automatically controlled by a processor or manually controlled). In the first detection mode, transmitting a pulse wave signal is more effective, as the pulse wave signal has high instantaneous power and a low duty cycle. The power amplifier 104 can meet the instantaneous high power requirements of the pulse wave signal; therefore, the power amplifier 104 can be selected for transmitting the pulse wave signal. Furthermore, the power amplifier 104 can enter a low-power state during idle periods, thereby avoiding continuous high power loss. Therefore, in this embodiment, the processing circuit 90 controls the first switching switch 103 to connect the link between the input terminal and the first output terminal, and controls the second switching switch 105 to connect the link between the first input terminal and the output terminal, thus enabling the power amplifier 104 to participate in the operation.

[0089] In the second detection mode, the detection effect is better if the transmitted fundamental wave is a continuous wave signal. Continuous wave signals are characterized by their continuous existence and relatively stable but typically low power. Therefore, since the low-noise amplifier unit 106 can provide stable power and has low power consumption, meeting the requirements of continuous waves, it can be selected. Therefore, in this embodiment, the processing circuit 90 controls the first switching switch 103 to connect the link between the input terminal and the second output terminal, and controls the second switching switch 105 to connect the link between the second input terminal and the output terminal, thus enabling the low-noise amplifier unit 106 to operate.

[0090] In summary, by switching between the power amplifier 104 and the low-noise amplifier unit 106 under different detection modes, not only can their respective specific requirements for the fundamental wave signal be met, but energy consumption can also be saved.

[0091] For details regarding the specific implementation of the receiving module 20 in the second detection mode, please refer to the description of the detection module 1 in the foregoing embodiments; it will not be repeated here. The first detection mode will be described in detail below.

[0092] It should be noted that in the first detection mode, the processing circuit 90 processes the harmonic signal in order to down-convert the harmonic signal to the acquisition circuit 60 (for example, as described below). Figure 15 The acquisition unit 62) can process data within the frequency range, and then determine whether the probe includes nonlinear nodes based on the processed data.

[0093] In this regard, in the first detection mode, the specific composition of the receiving module 20 in the detection module 1 is as follows: Figure 15 As shown, it includes a receiving antenna circuit 30, a first frequency conversion circuit 40, a filter circuit 70, a second frequency conversion circuit 50, and a data acquisition circuit 60 connected in sequence. The specific composition and working principle of the receiving antenna circuit 30, the first frequency conversion circuit 40, the filter circuit 70, and the second frequency conversion circuit 50 are the same as in the aforementioned embodiment, and will not be described in detail here. Only the differences are described below.

[0094] In some implementations, such as Figure 15As shown, the acquisition circuit 60 may include a signal processing unit 61 and an acquisition unit 62. The second frequency conversion circuit 50 is connected to the input terminal of the signal processing unit 61, and the output terminal of the signal processing unit 61 is connected to the acquisition unit 62. The signal processing unit 61 is used to process the second frequency conversion signal and output the processed signal. The signal processing unit 61 is the same as in the above embodiments and will not be described again here. The acquisition unit 62 is used to obtain acquisition data based on the processed signal. The signal processing unit 61 can filter, amplify, and perform other processing on the received second frequency conversion signal and send it to the acquisition unit 62. The acquisition unit 62 processes the signal and obtains the acquisition data, thereby realizing the detection of nonlinear nodes. The acquisition unit 62 includes, for example, an ADC and a processor.

[0095] In this process, after the transmitting module 10 transmits the fundamental wave signal, the first receiving antenna 31 and the second receiving antenna 32 in the receiving module 20 receive the second harmonic and the third harmonic, respectively. The harmonic signals are subsequently filtered, amplified, and then sent to the first mixer 42. At this time, the local oscillator unit 41 outputs a local oscillator signal to the first mixer 42 (if the received signal is the second harmonic, the output signal is the second-order local oscillator signal; if the received signal is the third harmonic, the output signal is the third-order local oscillator signal). The first mixer 42 performs a first frequency conversion operation on the harmonic signal to initially reduce its frequency. The first frequency-converted signal is then transmitted to the second mixer 52. The second bandpass filter 51 filters out the higher-order harmonic signals in the clock signal. The second mixer 52 mixes the higher-order harmonic signals with the first frequency-converted signal, i.e., performs a second frequency conversion operation, ultimately obtaining the second frequency-converted signal, which further reduces the frequency of the harmonic signals. Finally, the second frequency conversion signal is transmitted to the acquisition circuit 60. The acquisition circuit 60 processes the second frequency conversion signal accordingly to obtain the detection result. The detection result is used to indicate whether the object in the detection target area has a nonlinear node. The specific principle for determining whether it is a nonlinear node can refer to existing technologies, such as analyzing whether the amplitude of the second frequency conversion signal is greater than a set threshold; if so, a nonlinear node is considered to exist.

[0096] Furthermore, in the first detection mode, the local oscillator signal used during down-conversion differs from that in the second detection mode. When the receiving antenna circuit 30 inputs the second harmonic to the first frequency conversion circuit 40, the local oscillator unit 41 outputs a second-order local oscillator signal. When the receiving antenna circuit 30 inputs the third harmonic to the first frequency conversion circuit 40, the local oscillator unit 41 outputs a third-order local oscillator signal. The frequency of the second-order local oscillator signal is the difference between twice the fundamental signal frequency and a first summation value. The first summation value is the sum of the frequencies of the higher harmonic signals of the clock signal and the desired frequency. The frequency of the third-order local oscillator signal is the difference between three times the fundamental signal frequency and a second summation value. The second summation value is the sum of the frequencies of the higher harmonic signals and the desired frequency. The desired frequency is a value within a specified frequency range to which the harmonic signal is expected to decrease after the first and second frequency conversion operations; that is, the frequency of the second frequency conversion signal is the desired frequency. For example, the desired frequency is 52kHz, and 52kHz is within the frequency range of signals that the acquisition circuit 60 can process. The desired frequency value depends on the characteristics of the acquisition circuit 60 itself. For example, if the acquisition circuit 60 can handle a frequency range of 40kHz-200kHz, then the desired frequency can be a value within that range, such as 52kHz. Furthermore, the desired frequency value can be selected and adjusted according to actual needs.

[0097] For example, assuming the clock signal frequency is approximately 27MHz, the higher harmonic frequency of the clock signal is approximately 189MHz (taking the seventh harmonic as an example), the desired frequency is approximately 52kHz, and the fundamental frequency is f0. The second-order local oscillator signal generated by the local oscillator unit 41 has a frequency of 2f0-189MHz-52kHz (where 189MHz+52kHz is the first summation value mentioned above), and the third-order local oscillator signal has a frequency of 3f0-189MHz-52kHz (where 189MHz+52kHz is the second summation value mentioned above). If the receiving antenna circuit 30 receives the second harmonic, the first mixer 42 mixes the second-order local oscillator signal with a frequency of 2f0-189MHz-52kHz with the second harmonic with a frequency of 2f0 to obtain a first frequency-converted signal with a frequency of 189MHz+52kHz. If the receiving antenna circuit 30 receives the third harmonic, the first mixer 42 mixes the frequency of 3f0-189MHz-52kHz with the third harmonic of 3f0 to obtain a first frequency-converted signal with a frequency of 189MHz+52kHz. Therefore, regardless of whether it is the second or third harmonic, the frequency of the first frequency-converted signal after the first frequency conversion operation is 189MHz+52kHz. In the second frequency conversion operation, the first frequency-converted signal with a frequency of 189MHz+52kHz is mixed with the higher harmonic signal with a frequency of 189MHz to obtain a second frequency-converted signal with a frequency of 52kHz. The frequency of this second frequency-converted signal is the desired frequency and is transmitted to the acquisition circuit 60. The acquisition circuit 60 processes the second frequency-converted signal accordingly to finally obtain the detection result.

[0098] In the first detection mode, the fundamental wave signal can be a pulse wave signal. As long as the receiving module 20 receives the harmonic signal, the acquisition circuit 60 can generate the corresponding detection data. Therefore, detection can be achieved without using a continuous wave signal, and using a pulse wave signal can reduce the power of the transmitting module 10 without affecting the detection effect. Therefore, in the first detection mode, the fundamental wave signal generated by the transmitting module 10 can be a pulse wave signal.

[0099] It should be noted that in the first detection mode, a pulse wave signal is usually transmitted. Although the harmonic signal will be superimposed on the audio signal Δf, it cannot demodulate a continuous audio signal. Furthermore, the frequency of the second frequency-converted signal (i.e., the desired frequency) is different from the frequency of the audio signal, and therefore will not affect the second frequency-converted signal obtained after demodulation in the first detection mode. Therefore, for ease of understanding, Δf has not been included in the above analysis.

[0100] In another embodiment, the detection module 1 can also switch between the two detection modes described above. For this embodiment, the transmitting module 10 in the detection module 1 can employ... Figure 5 The embodiment shown illustrates a scheme where the detection module 1 is configured to switch between a first detection mode and a second detection mode. In the first detection mode, the fundamental wave signal generated by the transmitting module 10 can be a pulse wave signal. The detection module 1 controls the input and output terminals of the first switching switch 103 to be connected, and controls the first input and output terminals of the second switching switch 105 to be connected, so that the power amplifier 104 amplifies the signal. In the second detection mode, the fundamental wave signal generated by the transmitting module 10 can be a continuous wave signal. The detection module 1 controls the input and output terminals of the first switching switch 103 to be connected, and controls the second input and output terminals of the second switching switch 105 to be connected, so that the low-noise amplification unit 106 amplifies the fundamental wave signal. The specific reasons are explained above and will not be elaborated further here.

[0101] The specific composition of the receiving module 20 is as follows: Figure 7 As shown. The two detection modes can share the receiving antenna circuit 30, the first frequency conversion circuit 40, the second frequency conversion circuit 50, and the signal processing unit 61. The local oscillator signal of the first frequency conversion circuit 40 is set according to the above embodiments in both detection modes. In addition to the signal processing unit 61, the acquisition circuit 60 in the detection module 1 may also include an acquisition unit 62 and an audio playback unit 64, and a switching unit 63 is provided between the signal processing unit 61 and the audio playback unit 64.

[0102] Specifically, such as Figure 7 As shown, the second frequency conversion circuit 50 is connected to the input terminal of the signal processing unit 61, and the first output terminal of the signal processing unit 61 is connected to the acquisition unit 62. The signal processing unit 61 processes the second frequency conversion signal and outputs the processed signal. The acquisition unit 62 obtains the acquired data based on the processed signal. The signal processing unit 61 can filter, amplify, and process the received frequency conversion signal, and send it to the acquisition unit 62. The acquisition unit 62 processes the signal and obtains the acquired data, thereby realizing the detection of nonlinear nodes. The acquisition circuit 60 may also include a switching unit 63 and an audio playback unit 64. The second output terminal of the signal processing unit 61 is connected to the input terminal of the switching unit 63, and the output terminal of the switching unit 63 is connected to the audio playback unit 64. The switching unit 63 is used to realize the switching on or off, for example, disconnected in the first detection mode and connected in the second detection mode.

[0103] Please see Figure 12 This application also provides a harmonic audio detection device 2, including the detection module 1 provided in at least one embodiment related to the second detection mode.

[0104] Specifically, the harmonic audio detection device 2 provided in this application embodiment can use the detection module 1 to identify true nodes based on audio signals.

[0105] It should be understood that the harmonic audio detection device 2 uses the aforementioned detection module 1 to detect the object, which can extract the audio signal from the induction signal carrying the audio signal and play it, making it easy to quickly and conveniently identify the true node.

[0106] Please see Figure 13 This application also provides a nonlinear node detection device 3, which includes the detection module 1 provided in at least one embodiment related to the first detection mode.

[0107] For details regarding the specific implementation of detection module 1, please refer to the description of detection module 1 in the foregoing embodiments (e.g., the embodiment of detection module 1 applicable to the first detection mode), which will not be repeated here. Please refer to... Figure 14 This application also provides a detection device 4, which includes the detection module 1 provided in at least one of the above embodiments.

[0108] As one embodiment, the detection device 4 provided in this application is compatible with both the first and second detection modes and can be selected by the user, so that the user can selectively use either of the two detection modes using the same module to perform nonlinear node detection or harmonic audio detection.

[0109] In summary, this application provides a detection module 1, including a transmitting module 10 and a receiving module 20. The transmitting module 10 generates and transmits a fundamental wave signal. The receiving module 20 includes a first receiving antenna 31, a second receiving antenna 32, and a third switching switch 33. The first receiving antenna 31 receives the induced signal (e.g., a second harmonic or a second harmonic carrying an audio signal) generated by the nonlinear node under the influence of the fundamental wave signal. The second receiving antenna 32 receives the induced signal (e.g., a third harmonic or a third harmonic carrying an audio signal). The first receiving antenna 31 is connected to the first input terminal of the third switching switch 33, and the second receiving antenna 32 is connected to the second input terminal of the third switching switch 33. The output terminal of the third switching switch 33 is connected to a first frequency conversion circuit 40, for example, to a first mixer 42. In this embodiment, the received induced signal can be selectively input to the first mixer 42 via the third switching switch 33. The first mixer 42 is connected to a local oscillator unit 41, which can output a second-order local oscillator signal or a third-order local oscillator signal. The first mixer 42 mixes the sensed signal with the local oscillator signal and outputs the result. A first low-pass filter 72 is connected to the rear end of the first mixer 42, which filters out high-frequency noise carried in the signal output by the first mixer 42 (i.e., the first frequency-converted signal). A first band-pass filter 71 is connected to the rear end of the first low-pass filter 72, which filters out phase noise in the first frequency-converted signal to improve the sensitivity of the detection module 1. A second frequency conversion circuit 50 is connected to the rear end of the first band-pass filter 71, for example, it can be connected to the second mixer 52. The second band-pass filter 51 is connected to both the clock signal generation unit 80 and the second mixer 52, and can extract high-order harmonic signals and send them to the second mixer 52. The second mixer 52 mixes the high-order harmonic signals with the first frequency-converted signal to obtain a second frequency-converted signal (such as an audio signal or a signal of the desired frequency).

[0110] The harmonic audio device 2, nonlinear node detection device 3, and detection device 4 provided in the foregoing embodiments can all adopt the detection module 1 provided in the embodiments of this application, thereby enabling the detection of nonlinear nodes while ensuring good detection sensitivity.

[0111] Among them, the harmonic audio detection device 2, the nonlinear node detection device 3, and the detection device 4 can all be any one of the following: handheld detection device, fixed detection device, backpack detection device, and box-type detection device.

[0112] For example, the aforementioned detection devices can be handheld detection devices, which include a housing and have the detection module 1 provided in this application embodiment disposed inside the housing. A portion of the housing forms a grip, allowing the user to hold the handheld detection device to detect walls, floors, gaps, human bodies, etc.

[0113] It should be understood that the modular structure diagrams shown in the accompanying drawings are merely illustrative and do not necessarily include all the connections between structures. In the description of this application, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linkage" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0114] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the application. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0115] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0116] It should also be understood that the term "and / or" as used in this specification and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations. It should be noted that, herein, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or system. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or system that includes that element.

[0117] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments. The above descriptions are merely specific implementations of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A detection module, characterized in that, The system includes a transmitting module and a receiving module. The transmitting module is used to generate and transmit a fundamental frequency signal, and the receiving module includes at least: A receiving antenna circuit is used to collect inductive signals carrying audio signals from the probe. A processing circuit, connected to the receiving antenna circuit, is used to process the sensed signal to extract the audio signal.

2. The detection module as described in claim 1, characterized in that, The processing circuit includes: A frequency conversion circuit, connected to the receiving antenna circuit, is used to perform a frequency conversion operation on the sensed signal to obtain the audio signal carried in the sensed signal; The acquisition circuit, connected to the frequency conversion circuit, is used to convert the audio signal into sound information and output the sound information.

3. The detection module as described in claim 2, characterized in that, The acquisition circuit includes: A signal processing unit, the input terminal of which is connected to the output terminal of the frequency conversion circuit, is used to perform preset processing on the audio signal to obtain the processed audio signal; An audio playback unit, the input of which is connected to the output of the signal processing unit, is used to convert the processed audio signal into sound information and play the sound information.

4. The detection module as described in claim 1, characterized in that, The fundamental wave signal is a continuous wave signal.

5. The detection module as described in claim 2, characterized in that, The frequency conversion circuit includes: A first frequency conversion circuit, connected to the receiving antenna circuit, is used to perform a first frequency conversion operation on the sensed signal to obtain a first frequency conversion signal, wherein the frequency of the first frequency conversion signal is less than that of the sensed signal. The second frequency conversion circuit is connected to the first frequency conversion circuit and the acquisition circuit, and is used to perform a second frequency conversion operation on the first frequency conversion signal to obtain the audio signal, wherein the frequency of the audio signal is less than that of the first frequency conversion signal.

6. The detection module as described in claim 5, characterized in that, The receiving module further includes a filtering circuit connected between the first frequency conversion circuit and the second frequency conversion circuit. The filtering circuit is at least used to filter out low-frequency noise in the first frequency conversion signal. The maximum value of the frequency band in which the low-frequency noise is located is less than the frequency of the first frequency conversion signal.

7. The detection module as described in claim 5, characterized in that, The detection module further includes a clock signal generation unit, which generates a clock signal and outputs it to at least the transmitting module and the first frequency conversion circuit. The transmitting module is used to generate the fundamental wave signal using the clock signal; The first frequency conversion circuit is used to generate a local oscillator signal using the clock signal, and to perform the first frequency conversion operation on the induced signal using the local oscillator signal to obtain the first frequency conversion signal.

8. The detection module as described in claim 7, characterized in that, The first frequency converter circuit includes at least: The local oscillator unit is connected to the clock signal generation unit and is used to generate the local oscillator signal using the clock signal. The first mixer is connected to the receiving antenna circuit, the local oscillator unit, and the second frequency conversion circuit, respectively, and is used to mix the local oscillator signal with the induced signal to obtain the first frequency conversion signal.

9. The detection module as described in claim 7, characterized in that, The second frequency converter circuit includes at least: The second bandpass filter is connected to the clock signal generation unit and is used to extract higher harmonic signals from the clock signal. The frequency of the higher harmonic signals is equal to the frequency difference between the first frequency conversion signal and the audio signal. The second mixer is connected to the second bandpass filter, the first frequency conversion circuit, and the acquisition circuit, respectively, and is used to mix the higher harmonic signal with the first frequency conversion signal to obtain the audio signal.

10. The detection module as described in claim 8, characterized in that, The sensing signal includes a second harmonic carrying an audio signal and a third harmonic carrying an audio signal generated based on the fundamental wave signal. The receiving antenna circuit is configured to output one of the second harmonic carrying an audio signal and the third harmonic carrying an audio signal to the first frequency conversion circuit. Wherein, when the receiving antenna circuit outputs the second harmonic carrying the audio signal to the first frequency conversion circuit, the frequency of the local oscillator signal output by the local oscillator unit is twice the frequency of the fundamental signal and the difference between the frequency of the higher harmonic signal. When the receiving antenna circuit outputs the third harmonic carrying the audio signal to the first frequency conversion circuit, the frequency of the local oscillator signal output by the local oscillator unit is three times the frequency of the fundamental signal and the difference between the frequency of the higher harmonic signal.

11. A detection module, characterized in that, The system includes a transmitting module and a receiving module. The transmitting module generates and transmits a fundamental frequency signal. The receiving module includes: A receiving antenna circuit is used to collect harmonic signals generated by the probe based on the fundamental wave signal and induced signals carrying audio signals from the probe. The processing circuit, connected to the receiving antenna circuit, is used to process the sensed signal to extract the audio signal; the processing circuit is also used to process the harmonic signal to identify whether the probe has nonlinear nodes.

12. A detection device, characterized in that, The detection device includes the detection module as described in any one of claims 1-11.

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