Method and apparatus for calibrating phase of analog channel of multi-channel oscilloscope

Abstract

This application belongs to the field of oscilloscope technology, and particularly relates to a method and apparatus for phase calibration of analog channels in a multi-channel oscilloscope. The method includes: dividing a standard signal into N synchronous signals and inputting them to N analog channels of the oscilloscope; defining one of them as a reference channel and acquiring the phase difference between the acquired signal of each channel and the reference channel; determining whether the phase difference meets a predetermined accuracy condition; if not, adjusting the input clock phase of the analog-to-digital converter of the corresponding analog channel to compensate for the phase difference; and cyclically performing detection and adjustment until the phase difference meets the condition. This application solves the problems of low calibration efficiency and poor accuracy caused by traditional manual adjustment through a closed-loop automated process; at the same time, by adjusting the clock phase instead of the signal path, it avoids introducing additional passive components in the analog front end, eliminates insertion loss and impedance matching problems, and ensures the purity of the signal path and measurement fidelity.

Description

Technical Field

[0001] This application relates to the field of oscilloscope technology, and in particular to a method and apparatus for calibrating the phase of analog channels of a multi-channel oscilloscope. Background Technology

[0002] Multichannel oscilloscopes, as key equipment in the field of electronic measurement, are widely used in multi-channel synchronous measurement scenarios of high-frequency signals. The phase consistency of its multiple analog channels directly determines the accuracy of the measurement results. In practical applications, each analog channel of a multichannel oscilloscope corresponds to an independent ADC (Analog-to-Digital Converter), and the input clock of all ADCs is provided by the same PLL (Phase-Locked Loop) module. Due to factors such as the differences in parasitic parameters of the analog signal transmission paths of each channel, the inherent discreteness of the ADC device characteristics, and the phase deviation of the PLL clock distribution link, when the same high-frequency signal is synchronously input to multiple analog channels through a power divider, the oscilloscope display will show a significant phase difference between the analog channels.

[0003] In related technologies, phase calibration for multi-channel oscilloscopes often employs either hardware circuit fine-tuning or software post-processing data compensation. Hardware circuit fine-tuning typically requires adding adjustable attenuators, delay lines, or other components to the signal path of each channel, manually adjusting component parameters to achieve phase calibration. This method is not only cumbersome and inefficient, but also limited by the precision of component adjustments, making it difficult to meet the high-precision calibration requirements of high-frequency scenarios. Software post-processing data compensation corrects the data acquired from each channel through algorithms. While it doesn't require changes to the hardware structure, the compensation effect depends on the accurate measurement of the phase difference and introduces data processing latency, making it unsuitable for real-time measurement scenarios.

[0004] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0005] In view of at least one of the above technical problems, this application provides a method and apparatus for calibrating the phase of analog channels of a multi-channel oscilloscope.

[0006] Firstly, a method for calibrating the phase of analog channels in a multi-channel oscilloscope is provided, which is applied to an oscilloscope and includes the following steps: S100 divides the standard signal into N synchronization signals, which are then input to the N analog channels of the oscilloscope, where N ≥ 2. S200, define one of the N analog channels as the reference channel, and obtain the phase difference between the signal acquired by each of the N analog channels and the reference channel; S300, determine whether the phase difference meets the predetermined accuracy condition; S400, if the phase difference does not meet the predetermined accuracy condition, the phase difference is compensated by adjusting the phase of the input clock of the analog-to-digital converter of the corresponding analog channel; S500, repeat steps S200 to S400 until the phase difference of all N analog channels meets the predetermined accuracy condition.

[0007] This method solves the technical problems of low calibration efficiency and poor accuracy caused by the need for manual adjustment of attenuators or delay lines in traditional calibration methods. It significantly reduces calibration time through a closed-loop automated process, greatly improving calibration efficiency. Furthermore, by adjusting the clock phase rather than the signal itself, it avoids introducing additional passive components in the analog front end, thereby eliminating insertion loss and impedance matching problems introduced by calibration components, ensuring the purity of the signal path after calibration, and ensuring the fidelity of the oscilloscope in subsequent actual measurements.

[0008] In some possible implementations, the oscilloscope includes a phase-locked loop (PLL) used to adjust the phase of the input clock of the analog-to-digital converter for each analog channel.

[0009] In some possible implementations, the phase difference between the signal acquired by each of the N analog channels and the reference channel is obtained, including: Fourier transform is performed on the synchronization signals acquired from each analog channel to extract the fundamental phase of each signal; The phase difference is obtained by subtracting the fundamental phase of the remaining analog channels from the fundamental phase of the reference channel.

[0010] In some possible implementations, this is achieved by adjusting the phase of the input clock of the analog-to-digital converter for the corresponding analog channel, including: If one of the N analog channels is lagging in phase, adjust the phase of the input clock to be leading. If the phase of one of the N analog channels is ahead, adjust the phase of the input clock to be lagging. The adjustment amount is determined based on the phase difference between one of the N analog channels and the reference channel, where the adjustment amount is an integer multiple of the preset minimum phase adjustment step.

[0011] In some possible implementations, the adjustment amount is determined, including: Calculate the ratio of the phase difference between one of the N simulation channels and the reference channel to the minimum phase adjustment step. Round the ratio to the nearest integer and multiply the rounded value by the minimum phase adjustment step to obtain the adjustment amount.

[0012] In some possible implementations, the minimum phase adjustment step is 25 ps.

[0013] In some possible implementations, determining whether the phase difference meets a predetermined precision condition includes: determining whether the phase difference is less than 100 ps.

[0014] Secondly, a multi-channel oscilloscope analog channel phase calibration device is provided, the device comprising: The signal distribution module is used to divide the standard signal into N synchronization signals, which are then input to the N analog channels of the oscilloscope, where N ≥ 2. The signal acquisition module includes N analog channels and analog-to-digital converters corresponding to each of the N analog channels, used to acquire synchronization signals; The processing module is used to obtain the phase difference between the signal acquired by each of the N analog channels and the reference channel; Determine whether the phase difference meets the predetermined accuracy condition; If the phase difference does not meet the predetermined accuracy adjustment, the phase of the input clock of the analog-to-digital converter of the corresponding analog channel is adjusted. Iteratively obtain the phase difference between the signal acquired by each of the N analog channels and the reference channel until the phase difference of all N analog channels meets the predetermined accuracy condition.

[0015] In some possible implementations, the device includes a phase-locked loop (PLL) for adjusting the phase of the input clock of the analog-to-digital converter for each analog channel.

[0016] In some possible implementations, the processing module includes a phase analysis unit, which performs Fourier transform on the synchronization signals acquired by each analog channel to extract the fundamental phase of each signal; and calculates the difference between the fundamental phase of the remaining analog channels in the N analog channels and the fundamental phase of the reference channel to obtain the phase difference.

[0017] The present application will be further described below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A flowchart illustrating the multi-channel oscilloscope analog channel phase calibration method provided in this application embodiment; Detailed Implementation

[0020] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0021] Figure 1 The multi-channel oscilloscope analog channel phase calibration method provided in the embodiments of this application, such as Figure 1 As shown, one embodiment provides a multi-channel oscilloscope analog channel phase calibration method, which is applied in an oscilloscope. The method includes the following steps S100 to S500.

[0022] S100 divides the standard signal into N synchronization signals, which are then input to the N analog channels of the oscilloscope, where N ≥ 2. In step S100, the oscilloscope receives the externally input standard signal through a power divider, divides the standard signal into N synchronous signals with the same amplitude and phase through the power divider, and feeds them into the N analog channel ports of the oscilloscope respectively.

[0023] In S200, one of the N analog channels is defined as the reference channel, and the phase difference between the signal acquired by each of the N analog channels and the reference channel is obtained. In step S200, one of the N analog channels is defined as the reference channel. The N analog channels of the oscilloscope are controlled to start signal acquisition at the same trigger time. Subsequently, the phase difference between the signal waveforms acquired by the remaining N-1 analog channels and the waveform of the reference channel is calculated.

[0024] S300, determine whether the phase difference meets the predetermined accuracy condition; In step S300, the oscilloscope calculates in real time whether the absolute value of the phase difference of each analog channel meets the accuracy requirements.

[0025] S400, if the phase difference does not meet the predetermined accuracy condition, the phase difference is compensated by adjusting the phase of the input clock of the analog-to-digital converter of the corresponding analog channel; In step S400, when the phase difference does not meet the predetermined accuracy condition, the phase of the input clock of the ADC corresponding to the analog channel is directly adjusted to compensate for the phase deviation at the sampling time.

[0026] S500, repeat steps S200 to S400 until the phase difference of all N analog channels meets the predetermined accuracy condition.

[0027] In step S500, the oscilloscope repeatedly performs the acquisition, calculation, judgment and adjustment steps until the phase consistency of all analog channels converges to the predetermined accuracy condition.

[0028] The multi-channel oscilloscope analog channel phase calibration method provided in this embodiment solves the technical problems of low calibration efficiency and poor accuracy caused by the need for manual adjustment of attenuators or delay lines in traditional calibration methods. It significantly reduces calibration time through a closed-loop automated process, greatly improving calibration efficiency. Furthermore, by adjusting the clock phase rather than the signal itself, it avoids introducing additional passive components at the analog front end, thereby eliminating insertion loss and impedance matching problems introduced by calibration components, ensuring the purity of the signal path after calibration, and ensuring the fidelity of the oscilloscope in subsequent actual measurements.

[0029] In some embodiments, the oscilloscope includes a phase-locked loop (PLL) for adjusting the phase of the input clock of the analog-to-digital converter for each analog channel.

[0030] A phase-locked loop (PLL) can independently adjust the input clock of the ADC corresponding to each analog channel, enabling fine-tuning of the phase difference of each analog channel to ensure that the phase difference of each channel meets the predetermined accuracy conditions and satisfies the high-precision requirements of high-frequency signal measurement.

[0031] In some embodiments, obtaining the phase difference between the signal acquired by each of the N analog channels and the reference channel includes: Fourier transform is performed on the synchronization signals acquired from each analog channel to extract the fundamental phase of each signal; The phase difference is obtained by subtracting the fundamental phase of the remaining analog channels from the fundamental phase of the reference channel.

[0032] It is understandable that FFT operations are performed on the synchronization signals acquired by the ADCs of each analog channel to transform the time-domain signals into the frequency domain. In this way, the spectral line corresponding to the specific calibration signal frequency can be accurately located, and the phase value corresponding to that frequency point can be directly read, which is the fundamental phase. This phase value is the absolute phase relative to the starting point of the FFT analysis window.

[0033] It is understandable that the remaining analog channels among the N analog channels refer to the analog channels other than the reference channel. For example, if analog channel CH1 is defined as the reference channel, then the phase difference between analog channels CH2, CH3, ..., CHn and the reference channel is calculated.

[0034] In some embodiments, adjusting the phase of the input clock of the analog-to-digital converter for the corresponding analog channel includes: If one of the N analog channels is lagging in phase, adjust the phase of the input clock to be leading. If the phase of one of the N analog channels is ahead, adjust the phase of the input clock to be lagging. The adjustment amount is determined based on the phase difference between one of the N analog channels and the reference channel, where the adjustment amount is an integer multiple of the preset minimum phase adjustment step.

[0035] Understandably, if one of the N analog channels is detected to be lagging behind the reference channel in phase, and the phase difference does not meet the predetermined accuracy condition, the oscilloscope will adjust the phase of the input clock of the ADC of that analog channel to shift forward. If one of the N analog channels is detected to be leading the reference channel in phase, and the phase difference does not meet the predetermined accuracy condition, the oscilloscope will adjust the phase of the input clock of the ADC of that analog channel to shift backward.

[0036] Understandably, the phase adjustment resources of an oscilloscope are deployed in a hierarchical structure. An oscilloscope may include an external clock chip, an analog-to-digital converter, an aperture delay adjustment unit, and an FPGA digital phase delay unit. The external clock chip offers the largest phase adjustment range and relatively coarse adjustment steps, typically 200 ps. The aperture delay adjustment unit provides a medium adjustment range and finer adjustment steps, typically 25 ps. The FPGA digital phase delay unit offers the smallest adjustment range, such as within ±50 ps, ​​and fine compensation capabilities with arbitrary steps.

[0037] To fully utilize phase modulation resources at all levels, a hierarchical allocation strategy is adopted for the decomposition and execution of adjustment quantities. Specifically, based on the phase difference between one of the N analog channels and the reference channel, the phase modulation resource with the largest adjustment range and coarsest step is prioritized for large-step approximation adjustment. Then, resources with finer steps are used at each level to precisely compensate for the remaining residual. The principle of hierarchical allocation is as follows: the adjustment quantity at each level is quantified in units of the adjustment step of that level of resource, and the calculation results are rounded to the nearest integer. Rounding errors from each level are automatically included in the residual and compensated by the next level of resource.

[0038] Specifically, the steps of determining the adjustment amount and performing graded adjustment include steps A1 to A3.

[0039] Step A1: Determine if the phase difference of the simulated channel to be compensated is greater than the adjustment step of the first-level resource. If it is greater, calculate the first ratio of the phase difference to the adjustment step of the first-level resource, round the first ratio to the nearest integer, and multiply the rounded value by the adjustment step of the first-level resource to obtain the first-level adjustment amount, which drives the resource to perform adjustment. After execution, calculate the remaining residual, which is equal to the original phase difference minus the first-level adjustment amount.

[0040] Step A2: Compare the residual of the previous level with the adjustment step of the second-level resource. If the residual of the previous level is greater than the adjustment step of the second level, calculate the second ratio of the residual of the previous level to the adjustment step of the second level, round the second ratio to the nearest integer, multiply it by the adjustment step of the second level to obtain the adjustment amount of the second level, and drive the second-level resource to perform adjustment. In addition, update the residual value.

[0041] Step A3: The current residual is handed over to the final-level fine compensation resource for full compensation in arbitrary steps, such as an FPGA digital phase delayer, so that the final remaining residual converges to the minimum adjustable accuracy range of the resource at this level.

[0042] For example, suppose the phase difference is 231ps. The first-level resource is an external clock chip, with an adjustment step of 200ps; the second-level resource is an ADC aperture delay, with an adjustment step of 25ps; the third-level resource is an FPGA digital phase delay unit, which can be compensated in arbitrary steps. The adjustment process is as follows: 231 ÷ 200 = 1.155, rounded to the nearest integer, the first-level adjustment is 200ps, leaving a residual difference of 31ps; 31 ÷ 25 = 1.24, rounded to the nearest integer, the second-level adjustment is 25ps, leaving a residual difference of 6ps; the remaining 6ps are fully compensated by the FPGA, resulting in a final residual difference of 0ps.

[0043] In scenarios where the phase difference is small, if the initial phase difference is already less than the first-stage phase modulation step, the first-stage adjustment amount is directly set to 0, and the residual is fully transferred to the second stage and subsequent fine-tuning stages for processing.

[0044] It is worth noting that by quantizing the adjustment amount step by step using multi-level resource adjustment increments and rounding the comparison value, a balance is struck between adjustment speed and compensation accuracy. Large step resources achieve rapid convergence, while the rounded residual is propagated downwards, ensuring that the final residual is completely absorbed by the fine compensation stage. This hierarchical allocation and multi-level compensation method maximizes the utilization of existing phase adjustment resources in the system, achieving a balance between wide-range phase deviation and high-precision calibration requirements, thereby ensuring phase consistency of the multi-channel oscilloscope in complex application scenarios.

[0045] In some embodiments, the minimum phase adjustment step is 25 ps, corresponding to the step capability of the ADC aperture delay adjustment unit.

[0046] In some embodiments, determining whether the phase difference meets a predetermined accuracy condition includes: determining whether the phase difference is less than 100 ps. If the phase difference of a certain analog channel is 150 ps, ​​which is greater than the predetermined accuracy condition of 100 ps, ​​it is determined that the condition is not met, and the above-mentioned graded adjustment process is triggered; if the phase difference of a certain analog channel is 10 ps, ​​which is less than 100 ps, ​​it is determined that the condition is met. The calibration process terminates only when the phase differences of all N analog channels are less than the predetermined accuracy threshold.

[0047] Secondly, a multi-channel oscilloscope analog channel phase calibration device is provided, the device comprising: The signal distribution module is used to divide the standard signal into N synchronization signals, which are then input to the N analog channels of the oscilloscope, where N ≥ 2. Understandably, the signal distribution module is a power divider, which operates at a frequency of 10MHz-1GHz and is responsible for the synchronous distribution of signals at the physical layer.

[0048] The signal acquisition module includes N analog channels and analog-to-digital converters corresponding to each of the N analog channels, used to acquire synchronization signals; The processing module is used to obtain the phase difference between the signal acquired by each of the N analog channels and the reference channel; Determine whether the phase difference meets the predetermined accuracy condition; If the phase difference does not meet the predetermined accuracy adjustment, the phase of the input clock of the analog-to-digital converter of the corresponding analog channel is adjusted. Iteratively obtain the phase difference between the signal acquired by each of the N analog channels and the reference channel until the phase difference of all N analog channels meets the predetermined accuracy condition.

[0049] In some embodiments, the apparatus includes a phase-locked loop (PLL) for adjusting the phase of the input clock of the analog-to-digital converter for each analog channel.

[0050] In some embodiments, the processing module includes a phase analysis unit, which performs Fourier transform on the synchronization signals acquired by each analog channel to extract the fundamental phase of each signal; and calculates the difference between the fundamental phase of the remaining analog channels in the N analog channels and the fundamental phase of the reference channel to obtain the phase difference.

[0051] In the description of the embodiments of this application, unless otherwise stated, " / " means "or", for example, A / B can mean A or B; "and / or" in this document is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. In addition, in the description of the embodiments of this application, "multiple" means two or more.

[0052] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0053] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0054] The terms "coupled," "connected," or "connected" in the instruction manual include both direct and indirect connections. An indirect connection is a connection made through an intermediate medium, such as a connection made through an electrically conductive medium, which may have parasitic inductance or capacitance. An indirect connection may also include connections made through other active or passive devices to achieve the same or similar functional purpose, such as connections made through circuits or components such as switches or follower circuits.

[0055] In the detailed description of this specification, reference is made to the accompanying drawings, which form a part thereof, wherein like reference numerals always denote like parts, and wherein exemplary embodiments are shown by way of example that may be implemented. It should be understood that other embodiments may be utilized, and structural or logical changes may be made, without departing from the scope of this application. Therefore, the following detailed description should not be considered limiting.

[0056] The various operations in the specification may be described sequentially as multiple discrete actions or operations in a manner most conducive to understanding the claimed subject matter. However, the order of description should not be construed as implying that these operations must be sequentially related. Specifically, these operations may not be performed in the order presented. The described operations may be performed in a different order than in the described embodiments. Various additional operations may be performed in additional embodiments and / or the described operations may be omitted.

[0057] Various components and devices may be referred to or shown in the singular (e.g., “MOS transistor”, “transistor”, “switch”, etc.) in this document, but only for the convenience of discussion, and any element referred to in the singular may include multiple such elements as taught herein.

[0058] The above are merely preferred embodiments of this application and do not constitute any limitation on this application. Any person skilled in the art can make many possible variations and modifications to the technical solution of this application, or modify it into equivalent embodiments, without departing from the scope of the technical solution of this application. Therefore, all equivalent changes made based on the shape, structure, and principle of this application without departing from the content of the technical solution of this application should be covered within the protection scope of this application.

Claims

1. A method for calibrating the phase of analog channels in a multi-channel oscilloscope, applied in an oscilloscope, characterized in that, The method includes the following steps: S100, the standard signal is divided into N synchronization signals, which are then input to the N analog channels of the oscilloscope, where N≥2; S200, define one of the N analog channels as a reference channel, and obtain the phase difference between the signal acquired by each of the N analog channels and the reference channel; S300, determine whether the phase difference meets the predetermined accuracy condition; S400, if the phase difference does not meet the predetermined accuracy condition, the phase difference is compensated by adjusting the phase of the input clock of the analog-to-digital converter of the corresponding analog channel; S500, repeat steps S200 to S400 until the phase difference of all N analog channels meets the predetermined accuracy condition.

2. The multi-channel oscilloscope analog channel phase calibration method according to claim 1, characterized in that, The oscilloscope includes a phase-locked loop (PLL) for adjusting the phase of the input clock of the analog-to-digital converter in the analog channel.

3. The multi-channel oscilloscope analog channel phase calibration method according to claim 1, characterized in that, The step of acquiring the phase difference between the signal acquired by each of the N analog channels and the reference channel includes: Fourier transform is performed on the synchronization signals acquired from each analog channel to extract the fundamental phase of each signal; The phase difference is obtained by subtracting the fundamental phase of the remaining analog channels from the fundamental phase of the reference channel.

4. The multi-channel oscilloscope analog channel phase calibration method according to claim 1, characterized in that, The step of adjusting the phase of the input clock of the analog-to-digital converter for the corresponding analog channel includes: If one of the N analog channels is phase-lagging, adjust the phase of the input clock to be leading; If the phase of one of the N analog channels is ahead, adjust the phase lag of the input clock. The adjustment amount is determined based on the phase difference between one of the N analog channels and the reference channel, wherein the adjustment amount is an integer multiple of the preset minimum phase adjustment step.

5. The multi-channel oscilloscope analog channel phase calibration method according to claim 4, characterized in that, The determination of the adjustment amount includes: Calculate the ratio of the phase difference between one of the N analog channels and the reference channel to the minimum phase adjustment step; The ratio is rounded down, and the rounded value is multiplied by the minimum phase adjustment step to obtain the adjustment amount.

6. The multi-channel oscilloscope analog channel phase calibration method according to claim 5, characterized in that, The minimum phase adjustment step is 25 ps.

7. The multi-channel oscilloscope analog channel phase calibration method according to claim 5, characterized in that, The step of determining whether the phase difference meets the predetermined accuracy condition includes: Determine whether the phase difference is less than 100 ps.

8. A phase calibration device for analog channels of a multi-channel oscilloscope, characterized in that, The device includes: The signal distribution module is used to divide the standard signal into N synchronization signals, which are then input to the N analog channels of the oscilloscope, where N ≥ 2. The signal acquisition module includes N analog channels and analog-to-digital converters corresponding to the N analog channels, used to acquire the synchronization signal; The processing module is used to obtain the phase difference between the signal acquired by each of the N analog channels and the reference channel; Determine whether the phase difference meets the predetermined accuracy condition; If the phase difference does not meet the predetermined accuracy adjustment, the phase of the input clock of the analog-to-digital converter of the corresponding analog channel is adjusted. The phase difference between the signal acquired by each of the N analog channels and the reference channel is obtained iteratively until the phase differences of the N analog channels all meet the predetermined accuracy condition.

9. The multi-channel oscilloscope analog channel phase calibration device according to claim 8, characterized in that, The device includes a phase-locked loop (PLL) for adjusting the phase of the input clock of the analog-to-digital converter in the analog channel, respectively.

10. The multi-channel oscilloscope analog channel phase calibration device according to claim 8, characterized in that, The processing module includes a phase analysis unit, which performs Fourier transform on the synchronization signals acquired by each analog channel to extract the fundamental phase of each signal; and calculates the difference between the fundamental phase of the remaining analog channels in the N analog channels and the fundamental phase of the reference channel to obtain the phase difference.

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