Digital oscilloscope frequency domain triggering method based on direct digital integration method

Abstract

The invention discloses a digital oscilloscope frequency domain triggering method based on a direct digital integration method, which comprises the following steps of: generating a group of cosine waves with specific frequency through self-defined analysis frequency band and frequency resolution, and then multiplying a measured signal by the cosine waves with the specific frequency and integrating to directly obtain the energy of the signal on the frequency component; and finally, applying an analysis result to a frequency domain triggering function in the oscilloscope.

Description

Technical Field

[0001] The invention belongs to the technical field of digital oscilloscopes, and more specifically, relates to a digital oscilloscope frequency domain triggering method based on a direct digital integration method. Background Art

[0002] The trigger function is an essential part of oscilloscope design. Currently, common trigger methods are designed for the time domain characteristics of the measured signal, which may not be able to capture the signal that the user is interested in in more complex scenarios.

[0003] The trigger function is also the key to the oscilloscope's ability to capture the target signal. Common trigger methods such as edge triggering and level triggering are all based on the time domain characteristics of the measured signal. By comparing the characteristics of the measured signal with the size of the preset value, the read and write enable of the storage module is controlled to achieve the trigger function.

[0004] However, with the increasing complexity of signals in engineering applications, a single time domain trigger method can no longer meet the needs of users to capture target signals. Therefore, it is necessary to start from other information domains and study the frequency domain trigger module that is independent of the time domain trigger module.

[0005] Spectrum analysis is a key technology in signal processing, which is used to reveal the energy distribution of a signal at different frequency components. It is widely used in communication, radar, speech processing, medical signal analysis and other fields. Usually, spectrum analysis converts the time domain signal into the frequency domain signal through Fourier transform, thereby showing the strength of the signal at each frequency component.

[0006] FFT is an algorithm for efficiently calculating Fourier transforms. It makes spectrum analysis feasible and efficient by reducing computational complexity. FFT can quickly calculate the amplitude and phase information of the signal over the entire spectrum, providing detailed frequency distribution, and is a standard method for spectrum analysis. FFT is particularly suitable for obtaining a complete spectrum diagram and is widely used in broadband signal analysis. However, the frequency resolution of FFT depends on the sampling rate and signal length, and the frequency distribution is fixed and equally spaced. Although it is suitable for full-band analysis, the flexibility of FFT is particularly insufficient in application scenarios that require customized frequency resolution or only focus on certain specific frequency bands. Summary of the invention

[0007] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a frequency domain triggering method for a digital oscilloscope based on a direct digital integration method, by multiplying a measured signal with a cosine signal of a specific frequency and integrating the signal, the energy component of the signal at the frequency is directly obtained, which is then used for the triggering function in the digital oscilloscope.

[0008] To achieve the above-mentioned object of the invention, the present invention provides a digital oscilloscope frequency domain triggering method based on direct digital integration method, characterized in that it comprises the following steps:

[0009] (1) Set the analysis bandwidth and frequency resolution of the frequency domain trigger module on the software side of the digital oscilloscope;

[0010] (2) The software generates multiple cosine waves of corresponding frequencies according to the analysis bandwidth and resolution;

[0011] (3) Discretize each cosine wave to generate cosine wave coefficients of each frequency;

[0012] (4) The software side sends the cosine wave coefficients to the coefficient access module on the hardware side and stores them in a matrix form;

[0013] (5) The calculation module reads the sampled data and the cosine wave coefficients for direct digital integration;

[0014] (6) The trigger module generates a trigger signal according to the comparison result between the digital integration result and the preset trigger value;

[0015] The object of the invention of the present invention is achieved in this way:

[0016] The present invention is a digital oscilloscope frequency domain triggering method based on direct digital integration method. A set of cosine waves of specific frequencies are generated by customizing analysis frequency bands and frequency resolutions. Then, the measured signal is multiplied and integrated with the cosine wave of the specific frequency to directly obtain the energy of the signal on the frequency component. Finally, the analysis result is used for the frequency domain triggering function in the oscilloscope.

[0017] At the same time, the digital oscilloscope frequency domain triggering method based on the direct digital integration method of the present invention also has the following characteristics:

[0018] Beneficial effects:

[0019] (1) The present invention obtains the spectrum characteristics of the measured signal by customizing the analysis bandwidth and resolution, and then digitally integrating the measured signal and the corresponding frequency cosine signal, thereby achieving more targeted narrowband analysis, greatly improving the flexibility of spectrum analysis, and reducing resource consumption.

[0020] (2) The present invention realizes a custom trigger mechanism for special signals by combining spectrum analysis based on direct digital integration with frequency domain template triggering, which greatly improves the accuracy of the frequency domain trigger module and enriches the selection of triggering methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a principle diagram of a digital oscilloscope frequency domain triggering method based on a direct digital integration method of the present invention;

[0022] Figure 2 It is a schematic diagram of the storage matrix;

[0023] Figure 3 It is a schematic diagram of the operation of the parallel summation unit;

[0024] Figure 4 This is a schematic diagram of comparator processing in the trigger module. DETAILED DESCRIPTION

[0025] The specific implementation of the present invention is described below in conjunction with the accompanying drawings so that those skilled in the art can better understand the present invention. It should be noted that in the following description, when the detailed description of known functions and designs may dilute the main content of the present invention, these descriptions will be omitted here.

[0026] Example

[0027] In this embodiment, if Figure 1 As shown, the present invention provides a digital oscilloscope frequency domain triggering method based on direct digital integration method, comprising the following steps:

[0028] (1) Set the analysis bandwidth and frequency resolution of the frequency domain trigger module on the software side of the digital oscilloscope;

[0029] Set the analysis bandwidth B of the frequency domain trigger module. The analysis bandwidth B can completely cover the measured signal.

[0030] Set the frequency resolution f0 of the frequency domain trigger module, and the frequency resolution f0 is smaller than the minimum value of the difference between any two adjacent frequencies in the measured signal;

[0031] In this embodiment, the measured signal is assumed to be a multi-tone signal with multiple frequencies, and its frequency distribution is between 10MHz and 50MHz, wherein the minimum difference between two adjacent frequency components is 2MHz; therefore, the analysis bandwidth B of the frequency domain trigger module is set to 50MHz, the frequency resolution f0 is set to 1MHz, and the minimum analysis frequency f l The maximum analysis frequency is 5MHz. h 55MHz;

[0032] (2) The software generates n cosine waves of corresponding frequencies according to the analysis bandwidth B and resolution f0, where the frequencies of the n cosine waves are f l ,f l +f0,f l +2f0,…,f h , n=B / f0+1, B=f h -f l , f l is the minimum analysis frequency, f h is the maximum analysis frequency;

[0033] In this embodiment, based on the analysis bandwidth B=50 MHz and the frequency resolution f0=1 MHz of the frequency domain trigger module, the number of cosine waves n=51 can be calculated;

[0034] (3) Discretize the n cosine waves respectively to generate cosine wave coefficients of each frequency, where the jth cosine wave coefficient at the i-th frequency is denoted as coe i,j , i=1,2,…,n,j=1,2,…,kM, k is a positive integer, M is the number of parallel paths for sampling data in the digital oscilloscope, which is set to 80 here;

[0035] (4) The software end sends the cosine wave coefficients to the coefficient access module of the hardware end;

[0036] First, the software sends the first M cosine wave coefficients of the first frequency, i.e., coe 1,1 ~coe 1,M , and then send the first M cosine wave coefficients of the second frequency, i.e. coe 2,1 ~coe 2,M , and so on, after sending the first M cosine wave coefficients coe of the last frequency n,1 ~coe n,M After that, the cosine wave coefficients from the M+1th to the 2*Mth frequency of the first frequency are sent, i.e., coe 1,M+1 ~coe 1,2*M , and so on, until all the cosine wave coefficients of all frequencies are sent to the coefficient access module;

[0037] like Figure 2 As shown, the coefficient access module stores the cosine wave coefficients in a matrix form, stores the first M cosine wave coefficients at n frequencies in the first row of the storage matrix, stores the M+1th to 2*Mth cosine wave coefficients at n frequencies in the second row of the storage matrix, and so on, and finally obtains a storage matrix of X rows and Y columns, where Y=n*M, X=k;

[0038] (5) The calculation module reads the sampled data and cosine coefficients for direct digital integration;

[0039] (5.1) The measured signal enters the digital oscilloscope for sampling, and obtains M channels of parallel sampling data; at the same time, the digital oscilloscope generates a valid signal with a duration aligned with the M channels of parallel sampling data, and the valid signal is transmitted to the coefficient access module as a read enable;

[0040] (5.2), the M-channel parallel sampling data is copied into n copies through the splitter and then sent to n computing units respectively;

[0041] (5.3) In the first clock cycle of the valid signal, read the first row of elements in the storage matrix, and then use the cosine wave coefficient coe 1,1 ~coe 1,M Distribute to the first calculation unit and convert the cosine wave coefficient coe 2,1 ~coe 2,M Distribute to the second computing unit, and then and so on, the cosine wave coefficient coe n,1 ~coe n,M Distribute to the nth computing unit;

[0042] When each computing unit receives the M sample values ​​collected in the first clock cycle, it multiplies them with the corresponding M cosine wave coefficients one by one and then sums them up to obtain the sum value S 1,i ;

[0043] In this embodiment, let A i,j is the jth sampling value under the i-th clock during the duration of the valid signal; taking the first parallel summing unit as an example, Figure 3 As shown, the M sample values ​​collected in the first clock cycle are expressed as: A 1,1 ,A 1,2 ,…,A 2,M , the corresponding M cosine wave coefficients are: coe 1,1 ~coe 1,M , then A 1,1 With coe 1,1 Multiply, A 1,2 With coe 1,2 Multiply, and then repeat this process, and finally sum these M products to get the sum value S 1,i ;

[0044] (5.4) In the second clock cycle of the valid signal, read the second row elements in the storage matrix, and then distribute the cosine wave coefficients according to step (5.3) and calculate the sum value S of each calculation unit 2,i Then the sum value S 1,i , S 2,i Accumulate and get the accumulated value S i ;

[0045] (5.5) In the third clock cycle of the valid signal, read the third row of elements in the storage matrix, and then distribute the cosine wave coefficients according to step (5.3) and calculate the sum of each calculation unit S 3,i Then the sum value S 3,i With the accumulated value S i Sum and update the accumulated value S i ;

[0046] (5.6) When the k+1th clock cycle of the valid signal comes, read again from the first row of elements in the storage matrix and repeat the above operation until the accumulation ends when the valid signal fails. Then the updated accumulated value {S1, S2, …, S i ,…,S n} Input to trigger module;

[0047] (6) generating a trigger signal through a trigger module;

[0048] (6.1), such as Figure 4 As shown, in the comparator of the trigger module, by comparing each accumulated value S i Compare with the preset threshold Q i For comparison, if S i Greater than Q i , it is considered that the energy of the frequency component of the measured signal meets the trigger requirement, and the comparison result is set to 1; otherwise, it is considered that the energy of the frequency component of the measured signal has not yet reached the requirement, and the comparison result is set to 0, thereby obtaining a set of 0 and 1 sequences with a length of n;

[0049] (6.2) The user extracts one or several values ​​from the 0 and 1 sequences according to actual needs, and then ANDs the extracted values. The AND result is used as the trigger signal. If the AND result is 1, it means that the energy of several frequency components of interest in the measured signal meets the trigger requirements, the target signal has arrived, and a trigger signal is generated, and the trigger signal is valid at a high level; if the AND result is 0, it means that the target signal has not arrived yet, and the trigger signal is invalid at a low level, and the waiting continues.

[0050] Although the above describes the illustrative specific embodiments of the present invention to facilitate those skilled in the art to understand the present invention, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations using the concept of the present invention are protected.

Claims

1. A digital oscilloscope frequency domain triggering method based on direct digital integration method, characterized in that: The following steps are involved: (1) Set the analysis bandwidth and frequency resolution of the frequency domain trigger module on the software side of the digital oscilloscope; Set the analysis bandwidth B of the frequency domain trigger module. The analysis bandwidth B can completely cover the measured signal. Set the frequency resolution f0 of the frequency domain trigger module, and the frequency resolution f0 is smaller than the minimum value of the difference between any two adjacent frequencies in the measured signal; (2) The software generates n cosine waves of corresponding frequencies according to the analysis bandwidth B and resolution f0, where the frequencies of the n cosine waves are f l ,f l +f0,f l +2f0,…,f h , n=B / f0+1, B=f h -f l , f l is the minimum analysis frequency, f h is the maximum analysis frequency; (3) Discretize the n cosine waves respectively to generate cosine wave coefficients of each frequency, where the jth cosine wave coefficient at the i-th frequency is denoted as coe i,j , i=1,2,…,n,j=1,2,…,kM,k is a positive integer, and M is the number of parallel paths for sampling data in the digital oscilloscope; (4) The software side sends the cosine wave coefficients to the coefficient access module on the hardware side and stores them in a matrix form; (5) The calculation module reads the sampled data and cosine coefficients for direct digital integration; (5.1) The measured signal enters the digital oscilloscope for sampling, and obtains M channels of parallel sampling data; at the same time, the digital oscilloscope generates a valid signal with a duration aligned with the M channels of parallel sampling data, and the valid signal is transmitted to the coefficient access module as a read enable; (5.2), the M-channel parallel sampling data is copied into n copies through the splitter and then sent to n computing units respectively; (5.3) In the first clock cycle of the valid signal, read the first row of elements in the storage matrix, and then use the cosine wave coefficient coe 1,1 ~coe 1,M Distribute to the first calculation unit and convert the cosine wave coefficient coe 2,1 ~coe 2,M Distribute to the second computing unit, and then and so on, the cosine wave coefficient coe n,1 ~coe n,M Distribute to the nth computing unit; When each computing unit receives the M sample values ​​collected in the first clock cycle, it multiplies them with the corresponding M cosine wave coefficients one by one and then sums them up to obtain the sum value S 1,i ; (5.4) In the second clock cycle of the valid signal, read the second row elements in the storage matrix, and then distribute the cosine wave coefficients according to step (5.3) and calculate the sum value S of each calculation unit 2,i Then the sum value S 1,i , S 2,i Accumulate and get the accumulated value S i ; (5.5) In the third clock cycle of the valid signal, read the third row of elements in the storage matrix, and then distribute the cosine wave coefficients according to step (5.3) and calculate the sum of each calculation unit S 3,i Then the sum value S 3,i With the accumulated value S i Sum and update the accumulated value S i ; (5.6) When the k+1th clock cycle of the valid signal comes, read again from the first row of elements in the storage matrix and repeat the above operation until the accumulation ends when the valid signal fails. Then the updated accumulated value {S1, S2, …, S i ,…,S n } Input to trigger module; (6) Generate a trigger signal through a trigger module; (6.1) In the comparator of the trigger module, by comparing each accumulated value S i Compare with the preset threshold Q i For comparison, if S i Greater than Q i , then the comparison result is set to 1, otherwise the comparison result is set to 0, thus obtaining a set of 0 and 1 sequences of length n; (6.2) The user extracts one or several values ​​from the 0 and 1 sequences according to actual needs, and then ANDs the extracted values. The AND result is used as the trigger signal. If the AND result is 1, it means that the trigger signal is valid at a high level. If the AND result is 0, it means that the trigger signal is invalid at a low level.

2. The digital oscilloscope frequency domain triggering method based on direct digital integration method according to claim 1, characterized in that: The method for the software end to send down the cosine wave coefficient is: First, the software sends the first M cosine wave coefficients of the first frequency, i.e., coe 1,1 ~coe 1,M , and then send the first M cosine wave coefficients of the second frequency, i.e. coe 2,1 ~coe 2,M , and so on, after sending the first M cosine wave coefficients coe of the last frequency n,1 ~coe n,M After that, the cosine wave coefficients from the M+1th to the 2*Mth frequency of the first frequency are sent, i.e., coe 1,M+1 ~coe 1,2*M , and so on, until all cosine wave coefficients of all frequencies are sent to the coefficient access module.

3. The digital oscilloscope frequency domain triggering method based on direct digital integration method according to claim 1, characterized in that: The method of storing the cosine wave coefficients in the matrix form in the coefficient access module is: The coefficient access module stores the cosine wave coefficients in matrix form. The first M cosine wave coefficients at n frequencies are stored in the first row of the storage matrix, and the M+1th to 2*Mth cosine wave coefficients at n frequencies are stored in the second row of the storage matrix, and so on, finally obtaining a storage matrix with X rows and Y columns, where Y=n*M, X=k.

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