Method and device for differentially suppressing low-frequency common-mode noise in channels based on time-division multiplexing

Abstract

The present application belongs to the field of common-mode noise suppression, and specifically discloses a method and device for differentially suppressing low-frequency common-mode noise in a channel based on time-division multiplexing. The method includes: time-division multiplexing the test signal and the reference signal to the same channel to obtain a multiplexed signal; time-division multiplexing is a periodic time-sharing alternating output of the test signal and the reference signal; sampling the multiplexed signal and averaging the sampled data within each half cycle to obtain a set of first superimposed signal average values ​​and a set of second superimposed signal average values; interpolating the set of first superimposed signal average values ​​and the set of second superimposed signal average values ​​respectively to obtain a set of interpolated first superimposed signal average values ​​and a set of interpolated second superimposed signal average values; performing differential subtraction on the interpolated set of first superimposed signal average values ​​and the interpolated set of second superimposed signal average values ​​to obtain measurement data. Through the present application, low-frequency common-mode noise can be effectively suppressed.

Description

Technical Field

[0001] The present application relates to the field of common-mode noise suppression, and more specifically, to a method and device for suppressing low-frequency common-mode noise in a channel based on time-division multiplexing differential suppression. Background Art

[0002] In precision optical measurement, electronic instrumentation, and other systems, noise is a key factor affecting system performance. Low-frequency drift noise is particularly significant in applications requiring long-term, high-precision measurements, severely impacting system stability and reliability. Low-frequency drift noise refers to signal deviations caused by factors such as temperature, vibration, and device aging over long periods of operation. Its frequency is typically below 1 Hz.

[0003] Traditional methods for suppressing low-frequency noise primarily rely on common-mode rejection. This method uses differential inputs to suppress common-mode noise, typically requiring balancing the signal under test and the reference signal. The common-mode rejection ratio is limited by component matching accuracy, resulting in complex circuit design and inconsistent test channel consistency, which limits the effectiveness of noise suppression. In scenarios where low-frequency signal measurements are particularly important, these methods are ineffective in combating the effects of low-frequency noise. Therefore, finding a more effective way to suppress low-frequency noise is an important issue worthy of discussion. Summary of the Invention

[0004] In response to the defects of the existing technology, the purpose of this application is to provide a method and device for differentially suppressing low-frequency common-mode noise in channels based on time-division multiplexing, aiming to solve the problems of complex and poor effects of traditional circuits for suppressing low-frequency noise in channels.

[0005] To achieve the above objectives, in a first aspect, the present application provides a method for differentially suppressing low-frequency common-mode noise in a channel based on time division multiplexing, comprising:

[0006] The test signal and the reference signal are time-division multiplexed and output to the same channel to obtain a multiplexed signal; the time-division multiplexing is a periodic time-division alternate output of the test signal and the reference signal; within one cycle of the multiplexed signal, half of the cycle is a first superimposed signal obtained by mixing the test signal and the channel noise at that time, and the other half of the cycle is a second superimposed signal obtained by mixing the reference signal and the channel noise at that time;

[0007] Sampling the multiplexed signal and averaging the sampled data in each half cycle to obtain a group of first superimposed signal average values ​​and a group of second superimposed signal average values; the sampling times of two adjacent superimposed signal average values ​​in the same group differ by one cycle, and the sampling times of superimposed signal average values ​​with the same sequence number in two groups differ by half a cycle;

[0008] interpolating the group of first superimposed signal average values ​​and the group of second superimposed signal average values ​​to obtain an interpolated group of first superimposed signal average values ​​and an interpolated group of second superimposed signal average values; the interpolation is used to calculate the superimposed signal average value at an intermediate sampling time based on two adjacent superimposed signal average values, so that the sampling times of the superimposed signal average values ​​with the same sequence number in the two groups are aligned after interpolation;

[0009] A set of interpolated first superimposed signal average values ​​and a set of interpolated second superimposed signal average values ​​are differentially subtracted to obtain measurement data; the measurement data is the difference between the signal to be measured and the reference signal measured in each half cycle.

[0010] It should be noted that the present application controls the measured signal and the reference signal to pass through the same sensing channel and sampling channel through time division multiplexing, so that the same channel noise is introduced into the measured signal and the reference signal. After that, the subsequent interpolation and differential processing can better suppress the influence of the channel low-frequency common-mode noise, thereby ensuring the measurement accuracy of the measured signal.

[0011] In a possible implementation, the interpolation is linear interpolation, and the linear interpolation is: averaging two adjacent superimposed signal average values ​​and then inserting a corresponding value between the two superimposed signal average values.

[0012] In one possible implementation, the signal to be tested and the reference signal are time-division multiplexed and output to the same channel, including:

[0013] The output of the signal to be tested and the reference signal is controlled by a periodic square wave timing signal, so that the signal to be tested and the reference signal are time-division multiplexed and output to the same channel; when the square wave timing signal is at a high level, the signal to be tested is output to the channel, and when the square wave timing signal is at a low level, the reference signal is output to the channel, or when the square wave timing signal is at a high level, the reference signal is output to the channel, and when the square wave timing signal is at a low level, the signal to be tested is output to the channel.

[0014] In one possible implementation, the clock used for sampling the multiplexed signal is co-origin with the clock of the square wave timing signal; and / or the time interval for sampling the multiplexed signal is less than or equal to half a period of the square wave timing signal.

[0015] In a possible implementation, when performing the differential subtraction, the transfer function H(f) of the channel noise in the frequency domain is:

[0016] H(f) =1–e -j2πfτ

[0017] Where f is the frequency of the channel noise and τ is half a period.

[0018] In a second aspect, the present application provides a signal measurement method. When the signal to be measured is a low-frequency signal, the signal to be measured is measured using the method described in the first aspect or any possible implementation of the first aspect.

[0019] In a third aspect, the present application provides a device for differentially suppressing low-frequency common-mode noise in a channel based on time-division multiplexing, comprising: a time-division multiplexing module, a signal sampling module, and a data processing module;

[0020] The time division multiplexing module is used to time-division multiplex the test signal and the reference signal and output them to the same channel to obtain a multiplexed signal; within one cycle of the multiplexed signal, half of the cycle is a first superimposed signal obtained by mixing the test signal with the channel noise at that time, and the other half of the cycle is a second superimposed signal obtained by mixing the reference signal with the channel noise at that time;

[0021] The signal sampling module is used to sample the multiplexed signal and average the sampled data in each half cycle to obtain a group of first superimposed signal average values ​​and a group of second superimposed signal average values; the sampling times of two adjacent superimposed signal average values ​​in the same group differ by one cycle, and the sampling times of superimposed signal average values ​​with the same sequence number in two groups differ by half a cycle;

[0022] The data processing module is used to interpolate the group of first superimposed signal average values ​​and the group of second superimposed signal average values ​​respectively to obtain an interpolated group of first superimposed signal average values ​​and an interpolated group of second superimposed signal average values; the interpolation is used to calculate the superimposed signal average value at the intermediate sampling time based on the two adjacent superimposed signal average values, so that the sampling times of the superimposed signal average values ​​with the same sequence number in the two groups are aligned after interpolation; and to perform differential subtraction on the interpolated group of first superimposed signal average values ​​and the interpolated group of second superimposed signal average values ​​to obtain measurement data; the measurement data is the difference between the signal to be measured and the reference signal measured in each half cycle.

[0023] In one possible implementation, the data processing module is used to perform linear interpolation on the group of first superimposed signal average values ​​and the group of second superimposed signal average values ​​respectively; the linear interpolation is: averaging two adjacent superimposed signal average values ​​and then inserting a corresponding value between the two superimposed signal average values.

[0024] In a possible implementation, the device further includes: a timing generation module and a time-sharing output module;

[0025] The timing generation module is used to provide a periodic square wave timing signal to the time division multiplexing module and the time division output module;

[0026] The time division multiplexing module is used to output the signal to be tested and the reference signal to the same channel in a time division multiplexing manner under the drive of the square wave timing signal; when the square wave timing signal is at a high level, the signal to be tested is output to the channel, and when the square wave timing signal is at a low level, the reference signal is output to the channel; or when the square wave timing signal is at a high level, the reference signal is output to the channel, and when the square wave timing signal is at a low level, the signal to be tested is output to the channel;

[0027] The time-sharing output module is used to output a group of first superimposed signal average values ​​and a group of second superimposed signal average values ​​obtained by the signal sampling module in a time-sharing manner under the triggering of the square wave timing signal; the timing of the time-sharing output is the same as the timing of the time-division multiplexing output.

[0028] In one possible implementation, the clock used for sampling the multiplexed signal is co-origin with the clock of the square wave timing signal; and / or the time interval for sampling the multiplexed signal is less than or equal to half a period of the square wave timing signal.

[0029] In a possible implementation, when the data processing module performs the differential subtraction, the transfer function H(f) of the channel noise in the frequency domain is:

[0030] H(f) =1–e -j2πfτ

[0031] Where f is the frequency of the channel noise and τ is half a period.

[0032] In general, the above technical solutions conceived by this application have the following beneficial effects compared with the existing technologies:

[0033] The present application provides a method and device for differentially suppressing low-frequency common-mode noise in a channel based on time-division multiplexing. The method controls the measured signal and the reference signal to pass through the same sensing channel and sampling channel through time-division multiplexing, so that the measured signal and the reference signal are introduced with the same channel noise. The channel noise is then effectively subtracted through subsequent interpolation and differential processing. After studying the frequency domain transfer function of the above-mentioned channel noise, it is found that the above-mentioned scheme can have a better suppression effect on low-frequency channel noise, thereby ensuring the measurement accuracy of the measured signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a flow chart of a method for differentially suppressing low-frequency common-mode noise in a channel based on time-division multiplexing provided in an embodiment of the present application.

[0035] Figure 2 This is a structural diagram of a device for suppressing low-frequency common-mode noise of a channel based on time-division multiplexing differential provided in an embodiment of the present application.

[0036] Figure 3Schematic diagram of signal waveforms and timing provided in an embodiment of the present application.

[0037] Figure 4 This is a data waveform diagram of signal sampling, time-sharing output, interpolation and differential processing provided in an embodiment of the present application.

[0038] Figure 5 It is a schematic diagram of the signal and data processing process provided in the embodiment of the present application.

[0039] In all the drawings, the same figure marks are used to represent the same elements or structures, where: 10 is the object mechanism to be measured, 11 is the signal module to be measured, and 12 is the reference signal module; 20 is the time division multiplexing and time sharing output mechanism, 21 is the timing generation module, 22 is the time division multiplexing module, 23 is the signal sampling module, 24 is the time sharing output module, 25 is the channel noise module, and 26 is the addition module; 30 is the data processing mechanism, 31 is the first interpolation module, 32 is the second interpolation module, 33 is the differential module, and 34 is the measurement data module. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0041] First, the technical terms involved in the embodiments of this application are introduced.

[0042] (1) Signal to be tested

[0043] In electronics testing, a signal under test is a signal that needs to be measured or analyzed. It may be the output of an electronic device or system to evaluate whether its performance meets the expected standards or specifications.

[0044] (2) Reference signal

[0045] A reference signal is a signal used as a basis for comparison. In measurement and testing, a reference signal is typically a known, stable signal used to calibrate measurement equipment or as a comparison standard to ensure the accuracy of measurement results.

[0046] (3) Common mode noise

[0047] Common-mode noise refers to noise signals that appear simultaneously on two or more conductors in a circuit. It is usually caused by external environmental interference, power supply spurious noise, ground-introduced noise, etc.

[0048] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application.

[0049] Figure 1 This is a flow chart of a method for suppressing low-frequency common-mode noise of a channel based on time-division multiplexing differential provided in an embodiment of the present application. Figure 1 As shown, the following steps are included:

[0050] Step S101: Time-division multiplexing a test signal and a reference signal to the same channel to obtain a multiplexed signal; the time-division multiplexing is to periodically and alternately output the test signal and the reference signal; within a cycle of the multiplexed signal, half a cycle is a first superimposed signal obtained by mixing the test signal with the channel noise at that time, and the other half a cycle is a second superimposed signal obtained by mixing the reference signal with the channel noise at that time;

[0051] In one example, the output of the signal to be tested and the reference signal is controlled by a periodic square wave timing signal, so that the signal to be tested and the reference signal are time-division multiplexed and output to the same channel; when the square wave timing signal is at a high level, the signal to be tested is output to the channel, and when the square wave timing signal is at a low level, the reference signal is output to the channel, or when the square wave timing signal is at a high level, the reference signal is output to the channel, and when the square wave timing signal is at a low level, the signal to be tested is output to the channel.

[0052] Step S102: Sampling the multiplexed signal and averaging the sampled data within each half cycle to obtain a group of first superimposed signal average values ​​and a group of second superimposed signal average values; the sampling times of two adjacent superimposed signal average values ​​within the same group differ by one cycle, and the sampling times of superimposed signal average values ​​with the same sequence number within two groups differ by half a cycle;

[0053] In one example, the clock used for sampling the multiplexed signal is the same as the clock of the square wave timing signal; further, the time interval for sampling the multiplexed signal is less than or equal to half a period of the square wave timing signal.

[0054] Step S103: interpolating a group of first superimposed signal average values ​​and a group of second superimposed signal average values ​​to obtain an interpolated group of first superimposed signal average values ​​and an interpolated group of second superimposed signal average values; the interpolation is used to calculate the superimposed signal average value at an intermediate sampling time based on two adjacent superimposed signal average values, so that the sampling times of the superimposed signal average values ​​with the same sequence number in the two groups are aligned after interpolation;

[0055] In an example, the above interpolation is linear interpolation, which is: averaging two adjacent superimposed signal average values ​​and then inserting a corresponding value between the two superimposed signal average values.

[0056] Step S104 , performing differential subtraction on a set of interpolated first superimposed signal average values ​​and a set of interpolated second superimposed signal average values ​​to obtain measurement data; the measurement data is the difference between the signal to be measured and the reference signal measured in each half cycle.

[0057] In a more specific embodiment, Figure 2 : is a structural diagram of a device for suppressing low-frequency common-mode noise of a channel based on time-division multiplexing differential provided in an embodiment of the present application, such as Figure 2 As shown, the device includes a time division multiplexing and time division output mechanism 20 and a data processing mechanism 30; the corresponding test object is: the object mechanism to be tested 10.

[0058] The test object 10 includes a test signal 11 and a reference signal 12. The test signal can be denoted as s1(t), and the reference signal can be denoted as s2(t). The embodiment of the present application aims to precisely measure the difference between the test signal 11 and the reference signal 12, s1(t)-s2(t).

[0059] The time-division multiplexing and time-sharing output mechanism 20 includes a timing generation module 21, a time-division multiplexing module 22, a signal sampling module 23, and a time-sharing output module 24. To illustrate the introduction of channel noise, the channel noise caused by multiplexing the test signal and the reference signal into a single channel is represented by a channel noise module 25 and an addition module 26. The process of measuring the test signal 11 and the reference signal 12 inevitably results in interference from the channel noise 25. By way of further example, this channel noise may be introduced by the timing generation module 21, the time-division multiplexing module 22, the signal sampling module 23, the time-sharing output module 24, and the transmission lines between these modules.

[0060] For example, the signal to be measured 11 and the reference signal 12 are Figure 3 The output signals of the timing generation module for the signals A1 and A2 shown in (a) are Figure 3 In one example, when the square wave is high, B1 is connected to A1 and is superimposed with the channel noise 25 in the adding module 26; when the square wave is low, B1 is connected to A2 and is superimposed with the channel noise 25 in the adding module 26. Therefore, the data after B1 and the channel noise are superimposed is Figure 3 Signal C1 shown in (c).

[0061] In general, the measured signal and the reference signal contain time-varying common-mode noise. However, in this embodiment, for simplicity, a constant offset is used for the reference signal, and the measured signal also contains the same offset. Furthermore, based on the noise characteristics of actual circuit channel components, 1 / f noise is used as the channel noise in this embodiment. This type of noise has a power spectral density that is inversely proportional to frequency, and the noise data exhibits significant drift in the time domain.

[0062] After sampling, the signal C1 is obtained as a discrete digital signal D1, such as Figure 4 As shown in (a) of Figure 1, in this embodiment, the signal sampling interval is less than or equal to half the period of the square wave. Therefore, D1 has multiple data points at both high and low levels. The average of some data points at high levels is E1, while the average of some data points at low levels is E2.

[0063] Data processing mechanism 30 includes a first interpolation module 31, a second interpolation module 32, a difference module 33, and measurement data 34. First interpolation module 31 performs linear interpolation on the sampled data E1 of the test signal; second interpolation module 32 performs linear interpolation on the sampled data E2 of the reference signal. The sampling rate of the interpolated data F1 or F2 is twice the sampling rate of the pre-interpolated data E1 or E2, and the sampling time of the F1 and F2 data is the same.

[0064] Further preferably, the linear interpolation can be performed by inserting the average value at the intermediate moments of adjacent data. The high-level sampled data separated by one square wave cycle are averaged pairwise as the interpolated value at the intermediate moments, resulting in discrete data separated by half a square wave cycle. The same process is performed on the low-level data, thereby obtaining two sets of data with synchronized sampling times, which are then subtracted in the difference module.

[0065] Since there is a time delay of half a square wave period between the high-level sampled data E1 and the low-level sampled data E2, directly subtracting E1 and E2 will result in noise terms at different times being subtracted. Considering the randomness of the noise, direct subtraction is difficult to completely suppress the common-mode noise. Based on this, the interpolated data F1 and F2 are used for differentiation, and their sampling times are synchronized, such as Figure 4 As shown in (b). Output F1 and F2 to the difference module for subtraction processing, and obtain the difference data G1 as shown in Figure 4 As shown in (c). Figure 4 Middle (d) is the result of differential data for a long time. It can be seen that the method described in this application can significantly suppress the influence of channel common-mode low-frequency noise.

[0066] In traditional methods, the measured signal and reference signal must pass through different sensing channels and sampling channels, introducing different channel noise. Assuming the two channel noises are n1(t) and n2(t), differential processing cannot remove the n1(t)-n2(t) noise.

[0067] Therefore, we propose a method based on time division multiplexing to differentially suppress channel common mode low-frequency noise, and give the principle of noise suppression by this method, such as Figure 5As shown in the figure, this method can time-division multiplex the sensing and acquisition channels, avoiding the introduction of different channel noise by two or more channels. The specific process is as follows: After the measured signal s1(t) and the reference signal s2(t) pass through the two-way multiplexer, the output signal B1 is output. This signal undergoes the same sensing and acquisition channels. During this process, s1(t) and s2(t) are superimposed with the same noise n(t), but there is a fixed time delay between the superposition of the noise. The superposition of the noise with signal B1 is C1, which is then sampled to D1. The time-division output module outputs D1 as two discrete signals E1 and E2 according to a square wave timing sequence. The period of the square wave timing sequence is T, and the sampling interval of the signal sampling module is Ts. The relationship between the two is T / 2 ≥ Ts. Therefore, when the square wave is at a high or low level, there are a number of sampled data points greater than 1. When the time sequence is high, the average value of several sampled data is E1, which can be written as s1[k·T]+n[k·T] (where k is a positive integer); similarly, when the time sequence is low, the average value of several sampled data is E2, which can be written as s2[(k- )T]+n[(k- )T]. Here, the sampling times of E1 and E2 are inconsistent, with a difference of half a square wave period.

[0068] In order to ensure that the two sets of data are sampled at the same time, data interpolation can be used. The specific process is: insert the average value of the two points between the adjacent sampling data of E1 s1[k·T]+n[k·T] and s1[(k-1)T]+n[(k-1)T] to obtain the interpolated data s 1插 [(k- )T]+n 插 [(k- )T]; in E2 adjacent sampling data s2[(k- )T]+n[(k- )T] and s2[(k+ )T]+n[(k+ The interpolated data obtained by inserting the average value of the two points at the middle moment of )T] is s 2插 [k·T]+n 插 [k·T]. The sampling time interval obtained by combining the interpolation data with the measurement data is The integrated data, that is, the average value of a set of first superposition signals after interpolation can be expressed as: s1[(k-1)T]+n[(k-1)T], s 1插 [(k- )T]+n 插 [(k- )T], s1[k·T]+n[k·T]......(k is a positive integer); the average value of a set of second superimposed signals after interpolation can be expressed as: s2[(k- )T]+n[(k- )T]、s 2插 [k·T]+n 插 [k·T]、s2[(k+ )T]+n[(k+ )T]......(k is a positive integer).

[0069] Furthermore, to simplify the representation, the interpolated data can be expressed as The periodic integration is expressed as: The average value of the first superposition signal after interpolation is: s 1插 [ k·T]+n 插 [ k·T]...... (k is a positive integer); the average value of a set of second superposition signals after interpolation can be expressed as: s 2插 [ k·T]+n' 插 [ k·T]...... (k is a positive integer); half of the above interpolation data is the actual sampled data, and half is the interpolated data. The corresponding expression can be: high level data is s 1插 [ k·T]+n 插 [ k·T] (measured signal + channel noise), low-level data is s 2插 [ k·T]+n' 插 [ k·T] (reference signal + channel noise). At this point, two sets of time-synchronized data are obtained. The difference module is used to subtract the two sets of data to obtain the final measurement data.

[0070] The measurement data obtained in this application has a significant suppressive effect on the low-frequency components in the channel noise. The principle is that the subtraction of the same source noise before and after still has the effect of noise suppression. For ease of understanding, consider the process of continuous signal processing: the channel noise at a high level is recorded as n(t), and its frequency domain expression after Fourier transform is N(f). The channel noise at a low level is n(t-τ). Considering the time shift characteristics of the Fourier transform, its frequency domain expression after Fourier transform is N(f) · e -j2πfτ By performing differential processing on these two sets of data, the entire system processes the noise n(t) in the time domain as n(t) – n(t-τ), and its transfer function in the frequency domain can be written as H(f) = [ N(f)– N(f) ·e -j2πfτ ] / N(f) =1–e -j2πfτ, where f is the channel noise frequency. Analyzing this transfer function, it's clear that as the frequency f decreases, H(f) approaches 0, effectively acting as a high-pass filter. This system effectively suppresses the low-frequency components of common-mode noise. Therefore, the method described in this application can effectively suppress low-frequency common-mode noise in the channel.

[0071] It is further understood that the methods provided in the above embodiments of the present application are well-suited for measuring low-frequency test signals, effectively suppressing low-frequency common-mode noise and ensuring high measurement accuracy for such low-frequency test signals. This is particularly useful when the reference signal and the test signal pass through the same acquisition and sensing channels, and the high-frequency component of the channel noise is smaller than the low-frequency component, thereby improving the suppression of common-mode noise, especially low-frequency drift noise.

[0072] It should be understood that expressions such as "include" and "may include" used in this application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In this application, terms such as "include" and / or "have" may be interpreted as indicating specific characteristics, numbers, operations, constituent elements, components, or combinations thereof, but may not be interpreted as excluding the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0073] In addition, in this application, the expression "and / or" includes any and all combinations of the associated listed words. For example, the expression "A and / or B" may include A, may include B, or may include both A and B.

[0074] In the description of the embodiments of the present application, it should be noted that, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium. Among them, "fixed connection" means that the two are connected to each other and the relative position relationship after the connection remains unchanged. "Rotational connection" means that the two are connected to each other and can rotate relative to each other after the connection. "Sliding connection" means that the two are connected to each other and can slide relative to each other after the connection. The directional terms mentioned in the embodiments of the present application, such as "top", "bottom", "inside", "outside", "left", "right", etc., are only reference to the directions of the accompanying drawings. Therefore, the directional terms used are for better and clearer explanation and understanding of the embodiments of the present application, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0075] In addition, in the embodiments of the present application, the mathematical concepts mentioned include symmetry, equality, parallelism, and perpendicularity. These limitations are all for the current state of the art, rather than being absolutely strict definitions in a mathematical sense. A small amount of deviation is allowed, and it is possible to be approximately symmetric, approximately equal, approximately parallel, or approximately perpendicular. For example, A and B are parallel, which means that A and B are parallel or approximately parallel, and the angle between A and B can be between 0 and 10 degrees. A and B are perpendicular, which means that A and B are perpendicular or approximately perpendicular, and the angle between A and B can be between 80 and 100 degrees.

[0076] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A method for differentially suppressing low-frequency common-mode noise in a channel based on time division multiplexing, characterized in that: include: The test signal and the reference signal are time-division multiplexed and output to the same channel to obtain a multiplexed signal; the time-division multiplexing is a periodic time-division alternate output of the test signal and the reference signal; within one cycle of the multiplexed signal, half of the cycle is a first superimposed signal obtained by mixing the test signal and the channel noise at that time, and the other half of the cycle is a second superimposed signal obtained by mixing the reference signal and the channel noise at that time; Sampling the multiplexed signal and averaging the sampled data in each half cycle to obtain a group of first superimposed signal average values ​​and a group of second superimposed signal average values; the sampling times of two adjacent superimposed signal average values ​​in the same group differ by one cycle, and the sampling times of superimposed signal average values ​​with the same sequence number in two groups differ by half a cycle; interpolating the group of first superimposed signal average values ​​and the group of second superimposed signal average values ​​to obtain an interpolated group of first superimposed signal average values ​​and an interpolated group of second superimposed signal average values; the interpolation is used to calculate the superimposed signal average value at an intermediate sampling time based on two adjacent superimposed signal average values, so that the sampling times of the superimposed signal average values ​​with the same sequence number in the two groups are aligned after interpolation; performing differential subtraction on a set of interpolated average values ​​of the first superimposed signals and a set of interpolated average values ​​of the second superimposed signals to obtain measurement data; the measurement data is the difference between the measured signal and the reference signal measured in each half cycle; When performing the differential subtraction, the transfer function of the channel noise in the frequency domain is for: in, is the frequency of the channel noise, For half a cycle.

2. The method according to claim 1, characterized in that The interpolation is linear interpolation, and the linear interpolation is: averaging the average values ​​of two adjacent superimposed signals and then inserting the corresponding value between the two superimposed signal average values.

3. The method according to claim 1, characterized in that Time-division multiplexing of the test signal and the reference signal to the same channel, including: The output of the signal to be tested and the reference signal is controlled by a periodic square wave timing signal, so that the signal to be tested and the reference signal are time-division multiplexed and output to the same channel; when the square wave timing signal is at a high level, the signal to be tested is output to the channel, and when the square wave timing signal is at a low level, the reference signal is output to the channel, or when the square wave timing signal is at a high level, the reference signal is output to the channel, and when the square wave timing signal is at a low level, the signal to be tested is output to the channel.

4. The method according to claim 3, characterized in that The clock used for sampling the multiplexed signal is of the same origin as the clock of the square wave timing signal; and / or the time interval for sampling the multiplexed signal is less than or equal to half a period of the square wave timing signal.

5. A signal measurement method, characterized in that: When the signal to be measured is a low-frequency signal, the method according to any one of claims 1 to 4 is used to measure the signal to be measured.

6. A device for suppressing low-frequency common-mode noise of a channel based on time-division multiplexing differential, characterized in that: include: Time division multiplexing module, signal sampling module and data processing module; The time division multiplexing module is used to time-division multiplex the test signal and the reference signal and output them to the same channel to obtain a multiplexed signal; within one cycle of the multiplexed signal, half of the cycle is a first superimposed signal obtained by mixing the test signal with the channel noise at that time, and the other half of the cycle is a second superimposed signal obtained by mixing the reference signal with the channel noise at that time; The signal sampling module is used to sample the multiplexed signal and average the sampled data in each half cycle to obtain a group of first superimposed signal average values ​​and a group of second superimposed signal average values; the sampling times of two adjacent superimposed signal average values ​​in the same group differ by one cycle, and the sampling times of superimposed signal average values ​​with the same sequence number in two groups differ by half a cycle; The data processing module is configured to interpolate the group of first superimposed signal average values ​​and the group of second superimposed signal average values ​​respectively to obtain an interpolated group of first superimposed signal average values ​​and an interpolated group of second superimposed signal average values; the interpolation is configured to calculate the superimposed signal average value at an intermediate sampling time based on the two adjacent superimposed signal average values, so that the sampling times of the superimposed signal average values ​​with the same sequence number in the two groups are aligned after interpolation; and to perform differential subtraction on the interpolated group of first superimposed signal average values ​​and the interpolated group of second superimposed signal average values ​​to obtain measurement data; the measurement data is the difference between the measured signal and the reference signal measured in each half cycle; When performing the differential subtraction, the transfer function of the channel noise in the frequency domain is for: in, is the frequency of the channel noise, For half a cycle.

7. The device according to claim 6, characterized in that The data processing module is used to perform linear interpolation on the group of first superimposed signal average values ​​and the group of second superimposed signal average values ​​respectively; the linear interpolation is: averaging two adjacent superimposed signal average values ​​and then inserting the corresponding value between the two superimposed signal average values.

8. The device according to claim 6, characterized in that It also includes: a timing generation module and a time-sharing output module; The timing generation module is used to provide a periodic square wave timing signal to the time division multiplexing module and the time division output module; The time division multiplexing module is used to output the signal to be tested and the reference signal to the same channel in a time division multiplexing manner under the drive of the square wave timing signal; when the square wave timing signal is at a high level, the signal to be tested is output to the channel, and when the square wave timing signal is at a low level, the reference signal is output to the channel; or when the square wave timing signal is at a high level, the reference signal is output to the channel, and when the square wave timing signal is at a low level, the signal to be tested is output to the channel; The time-sharing output module is used to output a group of first superimposed signal average values ​​and a group of second superimposed signal average values ​​obtained by the signal sampling module in a time-sharing manner under the triggering of the square wave timing signal; the timing of the time-sharing output is the same as the timing of the time-division multiplexing output.

9. The device according to claim 8, characterized in that The clock used for sampling the multiplexed signal is of the same origin as the clock of the square wave timing signal; and / or the time interval for sampling the multiplexed signal is less than or equal to half a period of the square wave timing signal.

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