Signal receiving circuit, phase jitter suppression method, through-type detection system and security gate detection group

Abstract

The embodiment of the present application discloses a signal receiving circuit, a phase jitter suppression method, a through-type detection system and a security gate detection group. The signal receiving circuit comprises a receiving coil, an analog-to-digital conversion circuit connected with the receiving coil and a controller connected with the analog-to-digital conversion circuit. The receiving coil is used for receiving an induced signal of magnetic field change. The analog-to-digital conversion circuit is used for performing analog-to-digital conversion on the induced signal and a reference signal to obtain a digital induced signal and a digital reference signal. The controller corrects the phase of the digital induced signal according to the digital reference signal to obtain a calibrated signal. In the above manner, the embodiment of the present application can overcome the problem of phase jitter.

Description

Technical Field

[0001] This invention relates to the field of communication technology, specifically to a signal receiving circuit, a phase jitter suppression method, a walk-through detection system, and a security gate detection array. Background Technology

[0002] For security gates, if digital circuits (including analog-to-digital / digital-to-analog conversion and digital signal processing) are used for transmitting and receiving, the transmitting signal can be flexibly set according to different requirements, thus meeting the needs of more scenarios. Generally, a digital transmitting circuit outputs a sine wave to the transmitting coil, and the corresponding digital receiving circuit analyzes whether a target object has passed through based on the signal coupled back from the receiving coil. Summary of the Invention

[0003] In view of the above problems, embodiments of the present invention provide a signal receiving circuit for suppressing phase jitter, a phase jitter suppression method, a walk-through detection system, and a security gate detection group, which overcome the above problems or at least partially solve the above problems.

[0004] According to one aspect of the present invention, a signal receiving circuit is provided, comprising: a receiving coil, an analog-to-digital converter circuit connected to the receiving coil, and a controller connected to the analog-to-digital converter circuit; the receiving coil is used to receive an induced signal of magnetic field change, the analog-to-digital converter circuit is used to perform analog-to-digital conversion on the induced signal and a reference signal respectively to obtain a digital induced signal and a digital reference signal; the controller corrects the phase of the digital induced signal according to the digital reference signal to obtain a calibration signal.

[0005] Optionally, the number of receiving coils is multiple, and the analog-to-digital conversion circuit includes multiple acquisition channels and a reference channel. The reference channel is used to receive the reference signal, and each acquisition channel is connected to one of the receiving coils to receive the induced signal transmitted from the receiving coil.

[0006] Optionally, the controller includes a frequency domain conversion unit connected to the analog-to-digital conversion circuit and a main control unit connected to the frequency domain conversion unit. The frequency domain conversion unit performs frequency domain transformation on the digital sensing signal and the digital reference signal to obtain corresponding frequency domain signals. The main control unit derives the corresponding initial phase based on the frequency domain signal of the digital sensing signal and the corresponding reference phase based on the frequency domain signal of the digital reference signal. The main control unit subtracts the reference phase corresponding to the digital reference signal from the initial phase corresponding to the digital sensing signal to obtain the calibration signal.

[0007] Optionally, the reference signal is generated by a signal transmitting circuit located corresponding to the signal receiving circuit; the signal transmitting circuit is used to generate a magnetic field.

[0008] Optionally, the signal transmitting circuit includes a processor, a digital-to-analog converter circuit, and a transmitting coil connected in sequence; the analog-to-digital converter circuit is also connected to the digital-to-analog converter circuit; the processor is used to output a driving signal; the digital-to-analog converter circuit is used to perform digital-to-analog conversion on the driving signal; the signal output by the digital-to-analog converter circuit is used to drive the transmitting coil, and is also transmitted to the analog-to-digital converter circuit as a reference signal.

[0009] Based on the same inventive concept, a phase jitter suppression method is also provided, comprising: receiving a digital reference signal and a digital sensing signal output by an analog-to-digital conversion circuit; wherein the digital reference signal is a signal obtained by the analog-to-digital conversion circuit performing analog-to-digital conversion on a reference signal, and the digital sensing signal is a signal obtained by the analog-to-digital conversion circuit performing analog-to-digital conversion on a sensing signal output by a receiving coil; and correcting the phase of the digital sensing signal according to the digital reference signal to obtain a calibration signal.

[0010] Optionally, the phase of the digital sensing signal is corrected according to the digital reference signal to obtain a calibration signal with phase jitter removed, including: performing frequency domain transformation on the digital sensing signal and the digital reference signal respectively to obtain corresponding frequency domain signals; deriving the corresponding initial phase according to the frequency domain signal of the digital sensing signal, and deriving the corresponding reference phase according to the frequency domain signal of the digital reference signal; subtracting the reference phase of the digital reference signal from the initial phase of the digital sensing signal to obtain the calibration signal.

[0011] Optionally, the reference signal is generated by a signal transmitting circuit corresponding to the signal receiving circuit; the signal transmitting circuit is used to generate a magnetic field.

[0012] Based on the same inventive concept, embodiments of the present invention also propose a through-type detection system, including the aforementioned signal receiving circuit.

[0013] Optionally, the through-type detection system further includes a processor, a digital-to-analog converter circuit, and a transmitting coil connected in sequence, wherein the analog-to-digital converter circuit is also connected to the digital-to-analog converter circuit; the processor is used to output a drive signal; the digital-to-analog converter circuit is used to perform digital-to-analog conversion on the drive signal; the signal output by the digital-to-analog converter circuit is used to drive the transmitting coil, and is also transmitted to the analog-to-digital converter circuit as a reference signal.

[0014] Based on the same inventive concept, embodiments of the present invention also propose a security gate detection group, including multiple of the aforementioned walk-through detection systems.

[0015] The signal receiving circuit of this invention includes: a receiving coil, an analog-to-digital converter circuit connected to the receiving coil, and a controller connected to the analog-to-digital converter circuit. The receiving coil receives an induced signal from a changing magnetic field. The analog-to-digital converter circuit performs analog-to-digital conversion on the induced signal and a reference signal respectively to obtain a digital induced signal and a digital reference signal. The controller corrects the phase of the digital induced signal based on the digital reference signal to obtain a calibration signal, which overcomes phase jitter and can be used to identify whether a target object is passing by.

[0016] The above description is merely an overview of the technical solutions of the embodiments of the present invention. In order to better understand the technical means of the embodiments of the present invention and to implement them in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the embodiments of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0017] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0018] Figure 1 A schematic diagram of a phase accumulator is shown;

[0019] Figure 2 A schematic diagram of a signal receiving circuit provided in an embodiment of the present invention is shown;

[0020] Figure 3 A schematic diagram of a signal receiving circuit and a signal transmitting circuit according to another embodiment of the present invention is shown;

[0021] Figure 4 A detailed circuit diagram of the signal receiving circuit according to an embodiment of the present invention is shown;

[0022] Figure 5 A schematic diagram of phase subtraction according to an embodiment of the present invention is shown;

[0023] Figure 6 A schematic diagram of the phase jitter suppression method according to an embodiment of the present invention is shown;

[0024] Figure 7 It shows Figure 6 A schematic diagram of step S12. Detailed Implementation

[0025] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0026] For walk-through detection systems (such as security gates), if digital circuits are used for both transmission and reception, the transmitted signal can be flexibly set according to different requirements to meet the needs of more scenarios. In the signal transmission circuit, a processor can control a DAC (digital-to-analog converter) to output a sine wave to drive the transmitting coil and generate a magnetic field. In the signal receiving circuit, an analog-to-digital converter (ADC) with a sampling rate of, for example, 192kHz, needs to receive the sine wave coupled to the receiving coil, perform analog-to-digital conversion, and then send the converted signal to a processor (such as an FPGA) for Fast Fourier Transform (FFT). Finally, the FFT-transformed signal can be used to analyze whether a target object has passed through.

[0027] like Figure 1 As shown in the diagram, the sine wave generated by the DAC in the signal transmitting circuit is filtered as shown in TX. If the target object passes through the through-type detection system, the receiving coil in the signal receiving circuit generates an induced signal RX. The induced signal RX is first sampled by the ADC, with sampling points such as A1, A2, and A3. Then, the processor starts acquiring signals for FFT processing based on the sampling trigger signal Trig. Assuming the rising edge of the sampling trigger signal Trig is used as the trigger signal, i.e., the rising edge corresponds to sampling trigger signal points such as P1 (P1'), P2 (P2'), and P3 (P3'), the processor will start sampling at sampling trigger point P1 (P1'). After the next cycle's sampling trigger signal Trig arrives, data acquisition will start again from sampling trigger point P2 (P2'). The duration between sampling trigger points P1 (P1') and P2 (P2') is 1 / operating frequency. This process repeats for multiple cycles. The phases of sampling trigger points P1 (P1'), P2 (P2'), P3 (P3'), ... correspond to the phase of the target object.

[0028] If the through-feed detection system operates at 6kHz, and both the ADC and DAC have a sampling rate of 192kHz, since 192kHz is divisible by 6kHz, the sampling trigger points P1, P2, P3… can all correspond to the ADC's sampling points, resulting in phase consistency and no phase jitter. However, if the operating frequency is a value not divisible by 192kHz, such as 5.9kHz, if… Figure 1 As shown, the sampling trigger signal points (such as P1', P2', P3') cannot be aligned with the sampling points and are usually located between two adjacent sampling points, which makes the phase of each sampling trigger point inconsistent, that is, the phase jitter occurs. Therefore, it is impossible to accurately identify the target object based on the phase.

[0029] Therefore, for the reasons mentioned above, if the sampling rates of the DAC and ADC are fixed, the operating frequency of the walk-through detection system can only be one frequency (i.e., 6kHz). Switching to other operating frequencies will cause phase jitter. Since the received signal is used to identify the target object, phase jitter will prevent accurate identification. Furthermore, if multiple walk-through detection systems need to operate simultaneously, each must operate at the same frequency (e.g., 6kHz). If all walk-through detection systems operate at the same frequency, mutual interference will occur, causing false alarms and rendering them unusable.

[0030] In order to overcome the aforementioned phase jitter problem, this embodiment proposes a signal receiving circuit. Figure 2 A schematic diagram of the signal receiving circuit provided in an embodiment of the present invention is shown. Figure 2 As shown, the signal receiving circuit includes: a receiving coil 1, an analog-to-digital converter (ADC) 2 connected to the receiving coil 1, and a controller 3 connected to the ADC 2. The receiving coil 1 receives induced signals from changes in the magnetic field. The ADC 2 performs analog-to-digital conversion on the induced signal and a reference signal to obtain a digital induced signal and a digital reference signal, respectively. The controller 3 corrects the phase of the digital induced signal based on the digital reference signal to obtain a calibration signal.

[0031] When a target object passes through the detection channel of the walk-through detection system, if the target object is metallic, eddy currents will be generated, thus affecting the magnetic field distribution of the walk-through detection system. Receiving coil 1 can sense this change and therefore receive the induced signal corresponding to the change in magnetic field. The method of acquiring this induced signal can refer to the technical principles of existing security gates, and will not be elaborated here.

[0032] The analog-to-digital converter (ADC) 2 receives both the inductive signal transmitted from the receiving coil 1 and a reference signal. It then performs analog-to-digital conversion on both the inductive signal and the reference signal, obtaining corresponding digital inductive signals and digital reference signals. The controller 3 can then correct the phase of the digital inductive signal based on the digital reference signal to obtain a calibration signal. The reference signal corrects the phase of the inductive signal so that the final calibration signal is free from phase jitter. For example, the reference signal may have the same phase jitter as the inductive signal. The controller 3 acquires the initial phase of the digital inductive signal and the reference phase of the digital reference signal, subtracts the reference phase from the initial phase of the digital inductive signal to obtain the calibration signal, thus eliminating phase jitter. The reference signal can be provided directly by the signal transmitting circuit or by a signal source that generates phase jitter similar to that of the inductive signal.

[0033] In this embodiment, the controller 3 corrects the phase of the digital sensing signal based on the digital reference signal to obtain a calibration signal, thereby overcoming the phase jitter problem. Furthermore, if this calibration signal is used to identify whether a metallic target object is passing by, the accuracy of target object identification can be improved.

[0034] In one embodiment, see Figure 3 The controller 3 includes a frequency domain conversion unit 31 connected to the analog-to-digital conversion circuit 2 and a main control unit 32 connected to the frequency domain conversion unit 31. The frequency domain conversion unit 31 performs frequency domain transformation on the digital sensing signal and the digital reference signal to obtain corresponding frequency domain signals. For example, the frequency domain conversion unit 31 performs a Fast Fourier Transform (FFT) on the digital sensing signal and the digital reference signal to obtain the corresponding frequency domain signals. The frequency domain conversion unit 31 is, for example, an FPGA (Field-Programmable Gate Array). The main control unit 32 derives the corresponding initial phase based on the frequency domain signal of the digital sensing signal and derives the corresponding reference phase based on the frequency domain signal of the digital reference signal. The main control unit 32 subtracts the reference phase of the digital reference signal from the initial phase of the digital sensing signal to obtain a calibration signal with phase jitter removed. The main control unit 32 is, for example, an MCU (Microcontroller Unit) or a SoC (System on Chip).

[0035] In this embodiment, it is combined with Figure 4Because the phase of the sensed signal exhibits jitter, the main control unit 32 calibrates the phase by subtracting the reference phase (Phase_REF) of the digital reference signal from the initial phase (Phase_RXn) of the digital sensed signal. This subtraction yields the phase difference (Phase_RXn-REF) between the digital sensed signal and the digital reference signal, which is the phase of the calibration signal. Since the phase jitter of the digital sensed signal and the digital reference signal is the same, subtracting their phases yields a stable phase. Furthermore, the amplitude data of the calibration signal can still be the amplitude of the digital sensed signal. Thus, the through-type detection system can identify whether a metallic target object is passing by based on this calibration signal.

[0036] The specific scheme for the controller to identify metallic targets using calibration signals is not limited in this application and can be implemented with reference to the schemes used in security gates in the prior art (for example, comparing the amplitude and phase of the calibration signal with the characteristic data of various targets that have been stored to determine whether it is a metallic target). The controller 3 is not limited to the implementation by the frequency domain conversion unit 31 and the main control unit 32. In other embodiments, the controller 3 can be implemented by a single chip or by two or more chips working together; all of these are within the scope of protection of this application.

[0037] In one embodiment, the reference signal is generated by a signal transmitting circuit corresponding to the signal receiving circuit. The signal transmitting circuit generates a magnetic field. When the through-type detection system starts operating, the signal transmitting circuit generates the magnetic field first. When no metal target passes through, the magnetic field generated by the signal transmitting circuit remains unchanged, and the signal receiving circuit receives no induced signal. When a metal target passes through, the magnetic field generated by the signal transmitting circuit changes, and the signal receiving circuit receives the induced signal corresponding to the change in magnetic field. Since the induced signal received by the signal receiving circuit of the through-type detection system is generated based on the magnetic field generated by the signal transmitting circuit, the reference signal is provided by the signal transmitting circuit. This ensures that the reference signal and the induced signal have the same phase jitter, thereby improving the effectiveness of phase calibration of the induced signal.

[0038] In one embodiment, such as Figure 3 As shown, the signal transmitting circuit includes a processor 4, a digital-to-analog converter (DAC) circuit 5, and a transmitting coil 6 connected in sequence. The DAC circuit 2 is also connected to the DAC circuit 5. The processor 4 is used to output a drive signal. The DAC circuit 5 is used to perform digital-to-analog conversion on the drive signal. The signal output by the DAC circuit 5 is used to drive the transmitting coil 6, and is also transmitted to the DAC circuit 2 as a reference signal.

[0039] In this system, processor 4, for example, is an FPGA, which outputs a drive signal. The sampling rate of the digital-to-analog converter (DAC) 5 is the same as that of the analog-to-digital converter (ADC) 2. The DAC 5 converts the drive signal from digital to analog and then transmits it to the transmitting coil 6 to generate a constant magnetic field. When a metallic object passes through the through-type detection system, it causes a change in the magnetic field. The receiving coil 1 receives the induced signal of the magnetic field change for relevant detection. In this embodiment, both the induced signal and the reference signal originate from the DAC 5 of the signal transmitting circuit (the induced signal is essentially a signal coupled to the transmitting coil 6, which in turn originates from the DAC 5; the reference signal is directly output from the DAC 5 to the ADC 2). Therefore, the reference signal can be used to calibrate the phase of the induced signal to overcome the phase jitter problem.

[0040] It is understood that in other embodiments, if a filter is provided between the digital-to-analog converter circuit 5 and the transmitting coil 6 in the signal transmitting circuit, the reference signal can also be sent to the analog-to-digital converter circuit 2 by the filter. That is, the output of the filter is connected to the transmitting coil 6 and the analog-to-digital converter circuit 2 respectively. In this way, the effect of the reference signal and the induced signal being from the same source can also be guaranteed, that is, they have the same phase jitter.

[0041] In one embodiment, the number of receiving coils 1 is multiple, and the analog-to-digital converter circuit 2 includes multiple acquisition channels and a reference channel. The reference channel is used to receive a reference signal, and each acquisition channel is connected to one of the receiving coils 1 to receive the induced signal transmitted from the receiving coil 1. The acquisition channels and reference channel are, for example, internal channels of the analog-to-digital converter circuit 2. For example, if there are 12 receiving coils, a total of 3 analog-to-digital converter circuits 2 are used. One analog-to-digital converter circuit 2 includes one reference channel and 3 acquisition channels, while the other two each include 4 acquisition channels. Each acquisition channel is connected to one receiving coil 1, and the reference channel is connected to the analog-to-digital converter circuit 2. For ease of explanation, this embodiment uses two analog-to-digital converter circuits 2 as examples. Figure 4As shown, ADC1 and ADC2 represent two analog-to-digital converter circuits 2. RX1 to RX7 are seven channels of sensing signals, REF represents the reference signal, and CH1-CH7 are the internal channels of the digital-to-analog converter circuit 2, i.e., the aforementioned acquisition channels. The reference channel CH8 receives the reference signal (REF signal) introduced from the digital-to-analog converter circuit 5 (DAC), which is, for example, a reference sine wave signal. The frequency domain conversion unit 31 (FPGA_FFT) performs frequency domain transformation on the digital sensing signal and the digital reference signal respectively to obtain the corresponding frequency domain signals. The main control unit 32 derives the corresponding initial phase based on the frequency domain signal of the digital sensing signal and the corresponding reference phase based on the frequency domain signal of the digital reference signal. The main control unit 32 also subtracts the reference phase corresponding to the digital reference signal from the initial phase corresponding to the digital sensing signal to obtain a calibration signal to remove phase jitter. The main control unit 32 can be any microcontroller or processor capable of performing the corresponding function, such as... Figure 4 The processor 14 is model RK3568.

[0042] The working principle of a traditional receiving circuit is as follows: first, the sensed signal enters the ADC, and then it is fed to the FPGA_FFT to perform an FFT. If a frequency other than 6kHz is used, the amplitude of the frequency domain signal after the FFT is stable, but the phase keeps fluctuating. In this embodiment of the invention, reference... Figure 4 , Figure 5 Multiple sensing signals (e.g., RX1-RX7) are sent to ADC1 and ADC2 for analog-to-digital conversion via acquisition channels (e.g., CH1-CH7). Reference channel CH8 receives the reference signal REF from the digital-to-analog converter circuit 5 (DAC). ADC1 and ADC2 perform analog-to-digital conversion on each sensing signal and reference signal, respectively, to obtain signals as shown in S1-S7 and S8. The signals output from ADC1 and ADC2 are then input to FPGA_FFT for Fourier transform, yielding the frequency domain signals [I1,Q1]...[I7,Q7] corresponding to the seven sensing signals and the frequency domain signal [I8,Q8] corresponding to the reference signal, thus obtaining the digital sensing signal and the digital reference signal. The main control unit 32 calculates the phase and amplitude based on the frequency domain signals of the digital sensing signal and the digital reference signal. Specifically, the main control unit 32 derives the corresponding initial phase based on the frequency domain signal of the digital sensing signal and the corresponding reference phase based on the frequency domain signal of the digital reference signal. The main control unit 32 subtracts the reference phase corresponding to the digital reference signal from the initial phase corresponding to the digital sensing signal to obtain a phase-stable calibration signal. The initial phase of the digital sensing signal is... Where RXn represents the induced signal, and n is a natural number, such as Figure 5 The result shows jitter. The reference phase of the digital reference signal is... Where REF represents the reference signal, such as Figure 5 The result shows jitter. Subtracting the two values ​​yields a stable phase, i.e. Figure 5 The Phase_(RXn-REF) shown remains unchanged, indicating no jitter. Here, Phase_(RXn-REF) represents the phase of the calibration signal.

[0043] Therefore, please refer to this again. Figure 4 The frequency domain signals [I1,Q1]...[I8,Q8] undergo phase and amplitude conversion in the main control unit 32 to obtain the phase signal. n and amplitude Amp n If the frequency is not 6kHz, the amplitudes Amp1, ... Amp7 are stable, but the phases Phase1, ... Phase7 are constantly fluctuating. Here, Amp1, ... Amp7 represent the amplitudes of each digital sensing signal. Phase1, ... Phase7 are equivalent to Phase_RX1, ... Phase_RX7 mentioned above. Phase8 is equivalent to Phase_REF mentioned above. Simultaneously, Amp8 also has a stable amplitude, while Phase8 exhibits phase fluctuations. In this embodiment, the main control unit 32 further subtracts the phase of the digital sensing signal from the phase of the digital reference signal for each acquisition channel to obtain Phase1-Phase8, ... Phase7-Phase8. Since the jitter magnitude of any one of Phase1, ... Phase7 is consistent with that of Phase8, the phase difference between any one of Phase1, ... Phase7 and Phase8 remains unchanged. Therefore, subtracting any one of Phase1-Phase7 from Phase8 yields a phase-stable signal, without needing to subtract the amplitude. The main control unit 32 can then use this stable calibration signal to identify whether a target object has passed through the security gate. Regarding the calibration signal, taking RX1 as an example, the amplitude of the calibration signal corresponding to RX1 is Amp1, and the phase is Phase1-Phase8.

[0044] Therefore, in this embodiment of the invention, a reference channel CH8 is introduced to receive the reference signal. Although the amplitude of the reference signal is stable and the phase fluctuates, since the phase fluctuation of the reference signal and the induced signal is the same (because the source of the reference signal and the induced signal is the digital-to-analog converter circuit 5), the phase difference between the two is stable. Therefore, the main control unit 32 subtracts the phases of the two to obtain a fixed phase value, thereby achieving the effect that the phase of non-6kHz frequency points is also stable. That is, the signal received can be applied to various frequencies.

[0045] Furthermore, since the signal receiving circuit of this embodiment introduces a reference channel, regardless of the frequency band in which the transmitting coil 6 and the receiving coil 1 operate, the final calibration signal will not have phase jitter. Therefore, if applied to a pass-through detection system, different pass-through detection systems can operate in different frequency bands, thus preventing mutual interference between different pass-through detection systems and enabling multiple pass-through detection systems to operate simultaneously.

[0046] For ease of description, the above devices are described in terms of function, divided into various modules. Of course, in implementing the embodiments of the present invention, the functions of each module can be implemented in one or more software and / or hardware.

[0047] Based on the same inventive concept, embodiments of the present invention also provide a pass-through detection system, which includes the aforementioned signal receiving circuit.

[0048] Based on the same inventive concept, embodiments of the present invention also provide a security gate detection group, including multiple of the aforementioned walk-through detection systems.

[0049] For traditional pass-through detection systems, if digital circuits are used for transmission and reception, the aforementioned drawback exists: the system can only operate at one frequency without phase jitter and cannot operate at other frequencies. Therefore, when multiple pass-through detection systems exist, they all operate at the same frequency, leading to interference between them.

[0050] In this embodiment, different walk-through detection systems can acquire a phase-jitter-free calibration signal through the internal signal receiving circuit provided in the aforementioned embodiments. This stable signal is used to identify whether a metallic target is passing through. That is, regardless of the frequency band in which the walk-through detection system operates, it can output a calibration signal without phase jitter. In this way, different walk-through detection systems can operate in different frequency bands, thus preventing interference between them.

[0051] Based on the same concept, this invention also provides a flowchart illustrating a phase jitter suppression method. This phase jitter suppression method is applied to the signal receiving circuits of the foregoing embodiments, and can be specifically executed by a controller within the signal receiving circuit. Figure 6 As shown, the phase jitter suppression method includes the following steps.

[0052] Step S11: Receive the digital reference signal and digital sensing signal output by the analog-to-digital converter circuit; the digital reference signal is the signal obtained by the analog-to-digital converter circuit after performing analog-to-digital conversion on the reference signal, and the digital sensing signal is the signal obtained by the analog-to-digital converter circuit after performing analog-to-digital conversion on the sensing signal output by the receiving coil.

[0053] In this embodiment of the invention, when a target object passes through the through-type detection system, the magnetic field of the receiving coil in the signal receiving circuit changes, and the receiving coil receives the induced signal of the magnetic field change. The analog-to-digital conversion circuit includes multiple acquisition channels and a reference channel. The reference channel is used to receive the reference signal transmitted from the digital-to-analog conversion circuit in the signal transmitting circuit. Each acquisition channel is connected to a receiving coil to receive the induced signal transmitted from the receiving coil. The analog-to-digital conversion circuit performs analog-to-digital conversion on the acquired induced signal and the reference signal to obtain a digital induced signal and a digital reference signal, respectively, and outputs the digital induced signal and the digital reference signal to the controller.

[0054] Step S12: Correct the phase of the digital sensing signal according to the digital reference signal to obtain a calibration signal.

[0055] The controller subtracts the phase of the digital sensing signal from the phase of the digital reference signal to perform phase correction, obtaining a calibration signal after phase jitter removal. This step is detailed as follows: Figure 7 As shown, it includes the following steps.

[0056] Step 121: Perform frequency domain transformation on the digital sensing signal and the digital reference signal respectively to obtain the corresponding frequency domain signal.

[0057] Specifically, the frequency domain transformation unit in the controller can be used to perform frequency domain transformation on the digital sensing signal and the digital reference signal to obtain the corresponding frequency domain signal. For example, a Fast Fourier Transform (FFT) can be performed on the digital sensing signal and the digital reference signal to obtain the corresponding frequency domain signal.

[0058] Step 122: Obtain the corresponding initial phase based on the frequency domain signal of the digital sensing signal, and obtain the corresponding reference phase based on the frequency domain signal of the digital reference signal.

[0059] Specifically, the main control unit in the controller can derive the corresponding initial phase from the frequency domain signal of the digital sensing signal and the corresponding reference phase from the frequency domain signal of the digital reference signal.

[0060] Step 123: Subtract the reference phase corresponding to the digital reference signal from the initial phase corresponding to the digital sensing signal to obtain the calibration signal.

[0061] In this embodiment of the invention, the initial phase corresponding to the digital sensing signal is subtracted from the reference phase corresponding to the digital reference signal to obtain a phase-stable calibration signal.

[0062] The specific scheme of the phase jitter suppression method provided in this embodiment can be referred to the signal receiving circuit of the above embodiment, and will not be repeated here.

[0063] The foregoing has described specific embodiments of the present invention. In some cases, the actions or steps described in the embodiments of the present invention may be performed in a different order than that shown in the embodiments and the desired results may still be achieved. Furthermore, the processes depicted in the drawings do not necessarily require a specific or sequential order to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0064] The methods described above are applied to the corresponding apparatuses in the foregoing embodiments and have the beneficial effects of the corresponding apparatus embodiments, which will not be repeated here.

[0065] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of this disclosure is limited to these examples; within the framework of this disclosure, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the embodiments of the present invention as described above, which are not provided in detail for the sake of brevity.

[0066] This application is intended to cover all such substitutions, modifications, and variations that fall within the broad scope of all embodiments. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the embodiments of this invention should be included within the protection scope of this disclosure.

Claims

1. A signal receiving circuit, characterized in that, The signal receiving circuit includes: a receiving coil, an analog-to-digital converter circuit connected to the receiving coil, and a controller connected to the analog-to-digital converter circuit; the receiving coil is used to receive an induced signal of magnetic field change, the analog-to-digital converter circuit is used to perform analog-to-digital conversion on the induced signal and the reference signal respectively to obtain a digital induced signal and a digital reference signal; the controller is used to subtract the phase of the digital induced signal from the phase of the digital reference signal to obtain a calibration signal; the amplitude of the calibration signal is the same as the amplitude of the digital induced signal. The reference signal is generated by a signal transmitting circuit corresponding to the signal receiving circuit, or the reference signal is generated by a signal source that can produce the same phase jitter as the induced signal. The signal transmitting circuit is used to generate a magnetic field.

2. The signal receiving circuit according to claim 1, characterized in that, The number of receiving coils is multiple, and the analog-to-digital conversion circuit includes multiple acquisition channels and a reference channel. The reference channel is used to receive the reference signal. Each acquisition channel is connected to one of the receiving coils and is used to receive the induced signal transmitted from the receiving coil.

3. The signal receiving circuit according to claim 1, characterized in that, The controller includes a frequency domain conversion unit connected to the analog-to-digital conversion circuit and a main control unit connected to the frequency domain conversion unit. The frequency domain conversion unit performs frequency domain transformation on the digital sensing signal and the digital reference signal to obtain corresponding frequency domain signals. The main control unit derives the corresponding initial phase based on the frequency domain signal of the digital sensing signal, and derives the corresponding reference phase based on the frequency domain signal of the digital reference signal. The main control unit subtracts the reference phase corresponding to the digital reference signal from the initial phase corresponding to the digital sensing signal to obtain the calibration signal.

4. The signal receiving circuit according to claim 1, characterized in that, The signal transmitting circuit includes a processor, a digital-to-analog converter circuit, and a transmitting coil connected in sequence. The analog-to-digital converter circuit is also connected to the digital-to-analog converter circuit; the processor is used to output a drive signal; the digital-to-analog converter circuit is used to perform digital-to-analog conversion on the drive signal; the signal output by the digital-to-analog converter circuit is used to drive the transmitting coil, and is also transmitted to the analog-to-digital converter circuit as the reference signal.

5. A phase jitter suppression method, characterized in that, The phase jitter suppression method, applied to the signal receiving circuit according to any one of claims 1-4, comprises: The receiver receives a digital reference signal and a digital sensing signal output from an analog-to-digital converter circuit; the digital reference signal is the signal obtained by the analog-to-digital converter circuit performing analog-to-digital conversion on the reference signal, and the digital sensing signal is the signal obtained by the analog-to-digital converter circuit performing analog-to-digital conversion on the sensing signal output from the receiving coil. The calibration signal is obtained by subtracting the phase of the digital sensing signal from the phase of the digital reference signal.

6. The method according to claim 5, characterized in that, The calibration signal is obtained by subtracting the phase of the digital sensing signal from the phase of the digital reference signal, including: The digital sensing signal and the digital reference signal are respectively subjected to frequency domain transformation to obtain the corresponding frequency domain signal; The initial phase is obtained from the frequency domain signal of the digital sensing signal, and the reference phase is obtained from the frequency domain signal of the digital reference signal. The calibration signal is obtained by subtracting the reference phase corresponding to the digital reference signal from the initial phase corresponding to the digital sensing signal.

7. A through-type detection system, characterized in that, Includes the signal receiving circuit as described in any one of claims 1-4.

8. The through-type detection system according to claim 7, characterized in that, The through-type detection system further includes a processor, a digital-to-analog converter (DAC), and a transmitting coil connected in sequence. The DAC is also connected to the digital-to-analog converter. The processor is used to output a drive signal. The DAC is used to perform digital-to-analog conversion on the drive signal. The signal output by the DAC is used to drive the transmitting coil and is also transmitted to the DAC as a reference signal.

9. A security gate detection array, characterized in that, Includes multiple through-type detection systems as described in any one of claims 7-8.

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