CN110208588B - Digital oscilloscope, method for measuring baud chart and readable storage medium - Google Patents
Digital oscilloscope, method for measuring baud chart and readable storage medium Download PDFInfo
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- CN110208588B CN110208588B CN201910304757.2A CN201910304757A CN110208588B CN 110208588 B CN110208588 B CN 110208588B CN 201910304757 A CN201910304757 A CN 201910304757A CN 110208588 B CN110208588 B CN 110208588B
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Abstract
A digital oscilloscope, a method for measuring a baud chart and a readable storage medium are provided. The first front-end module and the second front-end module respectively collect input signals and output signals of a tested piece and preprocess the respectively collected signals; the processor searches effective signals of the preprocessed signals to obtain respective actual signal frequencies, improves measurement errors caused by component precision problems, filters the acquired signals according to search results to filter noise interference, improves signal to noise ratio of the signals, performs phase discrimination processing and effective value detection processing on the filtered signals to obtain phase differences between input signals and output signals and corresponding detection data, and finally draws a baud chart according to the phase differences and the detection data. The measured data is not easily interfered by various noises, the signal-to-noise ratio of the measured result is improved, and the drawn baud graph has higher precision.
Description
Technical Field
The invention relates to the technical field of test and measurement, in particular to a digital oscilloscope, a method for measuring a baud chart and a readable storage medium.
Background
The bode diagram, that is, the amplitude-frequency response and phase-frequency response graphs, is a diagram commonly used in electronic engineering to describe the frequency response of a system, and can reflect the relationship between the gain and phase change of the output signal of the system relative to the input signal and the frequency, respectively. The drawing method of the bode graph is various, and for example, the drawing can be completed by an oscilloscope and a signal source. When the traditional analog oscilloscope is used for drawing a baud chart, the baud chart can be read and drawn point by point only manually, time and labor are wasted, and the measurement precision is not high. The appearance of the digital oscilloscope provides more automatic functions for measuring the waveform, and makes automatic measurement of the baud chart possible.
At present, when a digital oscilloscope is used for drawing a baud chart, a processor of the oscilloscope controls a signal source to generate a required excitation signal and input the excitation signal into a tested piece, an analog front end of the oscilloscope collects an input signal and an output signal of the tested piece, then the input signal and the output signal are sent into the processor for waveform measurement, the amplitude and the phase of the input signal and the phase of the output signal are respectively obtained, and finally the baud chart is drawn according to the amplitude and the phase. However, the digital oscilloscope belongs to a broadband measuring instrument, and when the baud chart is drawn by adopting the existing method, the effect of the baud chart drawn by the digital oscilloscope is poor due to the influence of hardware of the oscilloscope, so that the dynamic range of the baud chart drawing is limited.
Disclosure of Invention
The application provides a digital oscilloscope, a method for measuring a baud chart and a readable storage medium, which are used for improving the performance of the digital oscilloscope for measuring the baud chart.
According to a first aspect, an embodiment provides a digital oscilloscope, including a first front end module, at least one second front end module, a signal source, and a processor, where the processor includes a main control module, a phase demodulation module corresponding to the second front end module, and a frequency selection module and an effective value detection module corresponding to the first front end module and the second front end module, respectively;
the signal source is connected with the main control module and used for generating an excitation signal for detecting the tested piece under the control of the main control module;
the first front-end module and the second front-end module are respectively used for acquiring input signals and output signals of a tested piece, conditioning the signals acquired respectively and outputting the conditioned signals to the frequency selection modules corresponding to the first front-end module and the second front-end module;
the frequency selection module is used for searching effective signals in received signals, filtering the received signals according to search results, and respectively outputting the filtered signals to the corresponding phase demodulation module and the corresponding effective value detection module;
the phase demodulation module is used for performing phase demodulation processing on the filtered signal corresponding to the second front-end module and the filtered signal corresponding to the first front-end module to obtain a corresponding phase difference, and outputting the phase difference to the main control module;
the effective value detection module is used for carrying out effective value detection on the received signals and outputting the obtained detection data to the main control module;
the main control module is used for drawing a Baud chart according to the phase difference output by the phase demodulation module and the demodulation data output by the effective value demodulation module.
According to a second aspect, an embodiment provides a digital oscilloscope, including a first front end module, at least one second front end module, and a processor, where the processor includes a main control module, a phase demodulation module corresponding to the second front end module, and a frequency selection module and an effective value detection module corresponding to the first front end module and the second front end module, respectively;
the first front-end module and the second front-end module are respectively used for acquiring input signals and output signals of a tested piece, conditioning the signals acquired respectively and outputting the conditioned signals to the frequency selection modules corresponding to the first front-end module and the second front-end module;
the frequency selection module is used for searching effective signals in received signals, filtering the received signals according to search results, and respectively outputting the filtered signals to the corresponding phase demodulation module and the corresponding effective value detection module;
the phase demodulation module is used for performing phase demodulation processing on the filtered signal corresponding to the second front-end module and the filtered signal corresponding to the first front-end module to obtain a corresponding phase difference, and outputting the phase difference to the main control module;
the effective value detection module is used for carrying out effective value detection on the received signals and outputting the obtained detection data to the main control module;
the main control module is used for being connected with a signal source, controlling the signal source to generate an excitation signal for detecting a detected piece, and drawing a baud chart according to the phase difference output by the phase demodulation module and the demodulation data output by the effective value demodulation module.
According to a third aspect, an embodiment provides a method for measuring a baud chart, applied to a digital oscilloscope, the method comprising:
collecting an input signal and an output signal of a tested piece;
searching effective signals in the input signals, determining first filtering parameters according to the effective signals, and filtering the input signals according to the first filtering parameters to obtain first filtering data;
searching an effective signal in the output signal, determining a second filtering parameter according to the effective signal, and filtering the input signal according to the second filtering parameter to obtain second filtering data;
performing phase discrimination processing on the first filtering data and the second filtering data to obtain a phase difference between an input signal and an output signal;
respectively carrying out effective value detection on the first filtering data and the second filtering data to obtain corresponding detection data;
and drawing a baud chart according to the phase difference and the detection data.
According to a fourth aspect, an embodiment provides a computer readable storage medium comprising a program executable by a processor to implement the method as described above.
According to the digital oscilloscope, the method for measuring the Baud chart and the readable storage medium in the embodiment, after the digital oscilloscope collects the input signal and the output signal of the tested piece, the digital oscilloscope respectively searches for the effective signals in the two current signals so as to obtain the respective actual signal frequency, and the measurement error caused by the component precision problem is improved; then, filtering the acquired signals according to the search result, so that the interference of noise signals is filtered, and the signal-to-noise ratio of the signals is improved; meanwhile, effective value detection is carried out on the filtered signals, so that the detection precision of the signal amplitude is improved; the measured data is not easily interfered by various noises, the signal-to-noise ratio of the measurement result is improved, and the accuracy of the drawn Baud chart is higher.
Drawings
FIG. 1 is a schematic diagram of the working principle of drawing a Baud chart using an oscilloscope in the prior art;
FIG. 2 is a schematic structural diagram of a digital oscilloscope according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of another digital oscilloscope according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of a digital oscilloscope according to an embodiment of the present invention;
fig. 5 is a flowchart of a method for measuring a bode plot according to an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the following detailed description and accompanying drawings. Wherein like elements in different embodiments are numbered with like associated elements. In the following description, numerous details are set forth in order to provide a better understanding of the present application. However, those skilled in the art will readily recognize that some of the features may be omitted or replaced with other elements, materials, methods in different instances. In some instances, certain operations related to the present application have not been shown or described in detail in order to avoid obscuring the core of the present application from excessive description, and it is not necessary for those skilled in the art to describe these operations in detail, so that they may be fully understood from the description in the specification and the general knowledge in the art.
Furthermore, the features, operations, or characteristics described in the specification may be combined in any suitable manner to form various embodiments. Also, the various steps or actions in the method descriptions may be transposed or transposed in order, as will be apparent to one of ordinary skill in the art. Thus, the various sequences in the specification and drawings are for the purpose of describing certain embodiments only and are not intended to imply a required sequence unless otherwise indicated where such sequence must be followed.
The numbering of the components as such, e.g., "first", "second", etc., is used herein only to distinguish the objects as described, and does not have any sequential or technical meaning. The term "connected" and "coupled" when used in this application, unless otherwise indicated, includes both direct and indirect connections (couplings).
FIG. 1 illustrates the operation of using an oscilloscope to plot a Baud chart, wherein, as shown in FIG. 1, a processor of the oscilloscope controls a signal source to generate an excitation signal, and the excitation signal is input to a tested piece; the first analog front end and the second analog front end of the oscilloscope respectively acquire an input signal and an output signal of a tested piece, the signals of the two channels are converted by the converter and then sent to the processor for waveform measurement, namely, the amplitude and the phase of the signals are measured, and finally, data obtained by measurement are sent to the main control unit for drawing and displaying a Bode plot. The method for controlling the signal source by the processor and the method for drawing the baud chart by the main control unit according to the data measured by the waveform refer to the patent with application publication number CN109030899A and invention name "a method for drawing the baud chart and an oscilloscope".
Unlike special frequency response analyzers and baud charts, general-purpose digital oscilloscopes belong to broadband measuring instruments, and compromise is made on the hardware performance of the oscilloscopes for the universality of the instruments. Therefore, when the bode graph is drawn by adopting the waveform measuring method, the hardware performance of the oscilloscope is limited, and when signals are submerged in the background noise of the oscilloscope, effective results cannot be obtained in waveform measurement, so that the dynamic range of the oscilloscope for drawing the bode graph is limited. On the other hand, for signals with small amplitude, the waveform measurement process is easily interfered by noise, so that an erroneous measurement result is caused, and even the situation that the signal cannot be used at all under an extreme environment can occur. Moreover, the waveform measurement process is easily interfered by noise, and simultaneously is also influenced by the quantization noise of the oscilloscope data converter, and the measurement result usually has fixed fluctuation, so that the curve has obvious saw-tooth feeling and is not smooth enough. Therefore, compared with a special frequency response analyzer or a baud chart instrument, the effect of drawing the baud chart by using the digital oscilloscope is poor, and the digital oscilloscope cannot be used even in a test environment with large interference.
The invention provides a proposal for improving the performance of a digital oscilloscope for drawing a baud chart as much as possible under the condition of not changing the hardware architecture of the existing digital oscilloscope.
In the embodiment of the invention, effective signal searching is firstly carried out on the collected input signals and the collected output signals to obtain the current actual frequency of the signals, then the collected signals are filtered according to the searching result, irrelevant noise signals are filtered, phase discrimination processing is carried out on the two filtered signals to obtain the phase difference of the two signals, meanwhile, effective value detection is carried out on the two filtered signals to obtain detection data, and finally, a baud chart is drawn according to the phase difference and the detection data.
The embodiment of the invention provides a digital oscilloscope, which comprises a first front-end module, at least one second front-end module, a signal source and a processor, wherein the processor comprises a main control module, a phase demodulation module corresponding to the second front-end module, a frequency selection module and an effective value detection module, wherein the frequency selection module and the effective value detection module respectively correspond to the first front-end module and the second front-end module. That is, for each second front-end module, a phase discrimination module, a frequency selection module and an effective value detection module corresponding to the second front-end module are arranged in the processor; for the first front-end module, a frequency selection module and an effective value detection module corresponding to the first front-end module are arranged in the processor.
In order to facilitate the description of the operation principle of the digital oscilloscope, the digital oscilloscope includes a second front-end module as an example for explanation.
The first embodiment is as follows:
fig. 2 shows a schematic structural diagram of a digital oscilloscope in an embodiment of the present invention, and as shown in fig. 2, the digital oscilloscope includes a first front end module 1, a second front end module 2, a signal source 3, and a processor 4, where the processor 4 includes: the main control module 40, the frequency selection module 41 and the effective value detection module 42 corresponding to the first front end module 1, the frequency selection module 43 and the effective value detection module 44 corresponding to the second front end module 2, and the phase discrimination module 45. The main control module 40 is connected to the signal source 3 and configured to control parameters of the signal source 3, such as controlling the frequency of the signal source 3 and the amplitude of the output signal; when the main control module 40 works, the signal source 3 is controlled by the main control module 40 to generate an excitation signal of the current frequency to be detected, and the signal source 3 inputs the excitation signal to the input port of the piece to be detected to detect the piece to be detected. The first front-end module 1 is configured to collect an input signal of an input port of a tested device, perform signal conditioning on the input signal, for example, perform processing such as amplification and conversion, and output the conditioned signal to the frequency selection module 41 of the processor 4; the frequency selection module 41 searches the received signal, searches an effective signal therein, that is, a signal at the current frequency, to obtain the frequency of the current actual signal, then filters the received signal according to the search result, and then outputs the filtered signal to the effective value detection module 42 and the phase detection module 45, respectively. The second front-end module 2 is configured to collect an output signal of the output port of the tested component, perform the same processing as the input signal on the output signal, and output the processed signal to the frequency selection module 43 of the processor 4. The frequency selection module 43 performs the same processing procedure as the frequency selection module 41 on the received signal, and then outputs the obtained signal to the effective value detection module 44 and the phase detection module 45, respectively. The effective value detection module 42 is configured to perform effective value detection on the signal output by the frequency selection module 41 to obtain first detection data, and output the first detection data to the main control module 40; similarly, the effective value detection module 44 is configured to perform effective value detection on the signal output by the frequency selection module 43 to obtain second detection data, and output the second detection data to the main control module 40. The phase discrimination module 45 is configured to perform phase discrimination processing on the filtered signal (i.e., the signal output by the frequency selection module 43) corresponding to the second front-end module 2 and the filtered signal (i.e., the signal output by the frequency selection module 41) corresponding to the first front-end module 1 to obtain a corresponding phase difference, and then output the phase difference to the main control module 40. The main control module 40 draws a bode plot according to the phase difference output by the phase discrimination module 45, the first detection data output by the effective value detection module 42, and the second detection data output by the effective value detection module 44.
Specifically, the main control module 40 draws a corresponding phase-frequency response curve according to the phase difference output by the phase detection module 45, calculates a ratio of first detection data (i.e., detection data corresponding to the first front-end module 1) output by the effective value detection module 42 to second detection data (i.e., detection data corresponding to the second front-end module 2) output by the effective value detection module 44, obtains a gain between the input signal and the output signal, and draws a corresponding amplitude-frequency response curve according to the gain.
According to the digital oscilloscope provided by the embodiment, after the input signal and the output signal of the tested piece are collected, the effective signals in the two current signals are respectively searched, so that the current actual signal frequency is obtained, and the measurement error caused by the component precision problem is improved; then, filtering and frequency selecting are carried out on the acquired signals according to the search results, so that the interference of noise signals is filtered, and the signal-to-noise ratio of the signals is improved; meanwhile, effective value detection is carried out on the filtered signals, so that the detection precision of the signal amplitude is improved; the measured data is not easily interfered by various noises, the signal-to-noise ratio of the measurement result when the digital oscilloscope measures the baud chart is improved, and the accuracy of the drawn baud chart is higher.
Example two:
in the first embodiment, a signal source is integrated in a digital oscilloscope as an example, and an external signal source may also be used to provide an excitation signal in practical application, based on which, the digital oscilloscope may include only a first front end module, at least one second front end module, and a processor, where the processor includes a main control module, a phase detection module corresponding to the second front end module, and a frequency selection module and an effective value detection module corresponding to the first front end module and the second front end module, respectively.
Similarly, taking an example that the digital oscilloscope includes a second front end module as an example, the digital oscilloscope has a structural schematic diagram as shown in fig. 3, and includes a first front end module 1, a second front end module 2, and a processor 4, where the processor 4 includes: the main control module 40, the frequency selection module 41 and the effective value detection module 42 corresponding to the first front end module 1, the frequency selection module 43 and the effective value detection module 44 corresponding to the second front end module 2, and the phase discrimination module 45. The functions of the first front-end module 1, the second front-end module 2, the main control module 40, the frequency selection module 41, the effective value detection module 42, the frequency selection module 43, the effective value detection module 44, and the phase detection module 45 are the same as those in the first embodiment, and are not described herein again. In contrast, in the present embodiment, the digital oscilloscope provides a port S, so that the main control module 40 can be connected to an external signal source through the port S to control the signal source to generate an excitation signal for detecting the tested piece.
Example three:
based on the digital oscilloscope described in the first embodiment, fig. 4 shows a structural schematic diagram of a specific digital oscilloscope, as shown in fig. 4, different from fig. 2, a first front end module 1 of the digital oscilloscope includes an analog front end 11 and an analog-to-digital converter 12, a second front end module 2 includes an analog front end 21 and an analog-to-digital converter 22, a frequency selection module 41 includes a signal search unit 411 and a filtering unit 412, and a frequency selection module 43 includes a signal search unit 431 and a filtering unit 432; the effective value detection module 42 is further configured to control a gain parameter of the corresponding first front-end module 1 according to the detection result, and the first front-end module 1 performs signal conditioning on the acquired input signal according to the gain parameter; the effective value detection module 44 is further configured to control a gain parameter of the corresponding second front-end module 2 according to the detection result, and the second front-end module 2 performs signal conditioning on the acquired output signal according to the gain parameter.
Specifically, the analog front end 11 is configured to collect an input signal of an input port of a tested device, condition the input signal according to data fed back by the effective value detection module 42, and input the conditioned signal to the analog-to-digital converter 12; the analog-to-digital converter 12 performs analog-to-digital conversion on the signal processed by the analog front end 11 to obtain a corresponding digital signal, and then inputs the digital signal to the frequency selection module 41 of the processor 4. The signal search unit 411 acquires the signal output by the first front-end module 1 (i.e., the digital signal output by the analog-to-digital converter 12), and searches for a current effective signal therefrom, and then controls the filter parameters of the filter unit 412 according to the searched effective signal. The filtering unit 412 filters the signal output by the first front-end module 1 under the control of the signal searching unit 411, and then outputs the filtered signal to the corresponding phase detection module 45 and the corresponding effective value detection module 42, respectively. The filtering unit 412 may be a band-pass filter, so that in the signal searching and filtering process, the signal searching unit 411 and the filtering unit 412 form a parameter-controlled tunable band-pass filter, the signal searching unit 411 controls the center frequency of the filtering unit 412 according to the searched effective signal, and the filtering unit 412 removes the uncorrelated noise signals according to the center frequency to keep the useful signal. After the input signal is processed by the process, the signal-to-noise ratio is greatly improved.
Similarly, the analog front end 21 is configured to collect an output signal of an output port of the tested component, condition the output signal according to data fed back by the effective value detection module 44, input the conditioned signal to the analog-to-digital converter 22, convert the conditioned signal into a corresponding digital signal, and input the digital signal to the frequency selection module 43 of the processor 4. The functions of the signal searching unit 431 and the filtering unit 432 in the frequency selecting module 43 are similar to those of the signal searching unit 411 and the filtering unit 412, respectively, and are not described herein again.
After receiving the signal output by the filtering unit 412, the effective value detection module 42 performs effective value detection on the signal to obtain first detection data, that is, an effective value of the input signal waveform, and then outputs the first detection data to the main control module 40; meanwhile, the effective value detection module 42 compares the current detection result with the preset amplitude range, and controls the gain parameter of the analog front end 11 corresponding thereto according to the comparison result, specifically, if the effective value detection module 42 compares that the amplitude obtained by the current measurement is not within the preset amplitude range, the measured value is compared with the standard value to obtain an appropriate gain parameter, and the gain parameter is sent to the analog front end 11 to adjust the gain of the analog front end 11, so that the measured effective value falls within the preset amplitude range. In the prior art, a method for acquiring signal amplitude by waveform measurement is similar to peak detection and is easily interfered by glitches to cause inaccurate measurement results, while an effective value detection method is an integration process and obtains energy of corresponding signals, so that glitches can be effectively avoided, and the precision of measurement data is improved.
Similarly, after receiving the signal output by the filtering unit 432, the effective value detection module 44 performs effective value detection on the signal to obtain second detection data and outputs the second detection data to the main control module 40; meanwhile, the effective value detection module 44 also controls the gain parameter of the corresponding analog front end 21 in the same way as the effective value detection module 42, so that the measured effective value falls within the preset amplitude range.
In practical application, if the gain of the analog front end is too small, the signal acquired by the processor will be small, and thus the signal-to-noise ratio of the system will be poor, thereby affecting the accuracy of the bode diagram measurement. If the gain of the analog front end is too large, the signal will saturate before it is sent to the processor, and the signal waveform collected by the processor will be distorted, and such measurement data will be meaningless. The detection data of the effective value detection module is used for controlling the gain of the analog front end, so that the digital oscilloscope can acquire data meeting conditions, namely signals with the amplitude within a preset amplitude range, the influence on measurement caused by too large or too small gain is avoided, and the accuracy of the baud chart measurement is improved.
The phase discrimination module 45 performs phase discrimination processing on the signal output by the filtering unit 412 and the signal output by the filtering unit 432 to obtain a corresponding phase difference, and then outputs the phase difference to the main control module 40. The main control module 40 draws a corresponding phase-frequency response curve according to the phase difference. Meanwhile, after the main control module 40 receives the first detection data transmitted by the effective value detection module 42 and the second detection data transmitted by the effective value detection module 44, the effective values of the input signal and the output signal waveform of the detected piece are obtained, the main control module 40 calculates the ratio of the first detection data to the second detection data to obtain the gain of the input signal and the output signal, and then draws a corresponding amplitude-frequency response curve according to the gain, thereby realizing the drawing of the wave characteristic diagram.
The digital oscilloscope provided by the embodiment collects the input signal of the input port and the output signal of the output port of the tested piece through the analog front end, and the two paths of signals are sent to the processor for processing after analog-to-digital conversion, so that the measurement of the baud chart is realized. Firstly, a signal searching unit searches a current effective signal to obtain the frequency of the current actual signal, then the central frequency of a filtering unit is controlled through the frequency, so that the filtering unit filters the signal received by a processor according to the central frequency, wherein the signal searching unit and the filtering unit form an adjustable band-pass filter with controlled parameters, and the signal-to-noise ratio is greatly improved after the signal received by the processor is processed by the two units. Then, the signals processed by the filtering unit are respectively sent to a phase demodulation module and an effective value demodulation module for phase demodulation and effective value demodulation, and compared with the existing waveform measurement scheme, the accuracy of effective value demodulation is higher, and the interference of accidental noise is less prone to occurring; moreover, the result of the effective value detection controls the gain of the analog front end at the same time, so that the effective value detection module can work in the optimal state, and the dynamic range of measurement is improved. Compared with the waveform measuring method in the prior art, the phase difference between the input signal and the output signal is measured by using the phase discrimination module, so that the problem that the phase measurement precision is poor due to the fact that the edge position cannot be accurately judged when the signal-to-noise ratio of the signal is poor, and the problem that the phase measurement precision is poor can be solved, the phase measurement precision is improved, and the interference of noise is less prone to being caused. By processing the signals acquired by the digital oscilloscope in such a way, the accuracy and the dynamic range of the baud chart measured by the digital oscilloscope are effectively improved.
According to the digital oscilloscope in each of the above embodiments, an embodiment of the present invention further provides a method for measuring a bode plot, and a flowchart thereof refers to fig. 5, where the method may include the following steps:
step 101: and acquiring an input signal and an output signal of the tested piece.
The digital oscilloscope collects input signals of an input port of a tested piece through the first front end module 1, collects output signals of an output port of the tested piece through the second front end module 2, conditions the two paths of signals, and inputs the conditioned signals to the processor 4 respectively.
Step 102: the effective signal is searched and filtered.
After receiving the conditioned input signal and output signal, the processor 4 searches for an effective signal in the conditioned input signal through the signal search unit 411, determines a first filtering parameter according to the effective signal, and filters the conditioned input signal according to the first filtering parameter to obtain first filtering data. Meanwhile, the processor 4 searches for an effective signal in the conditioned output signal through the signal search unit 431, determines a second filter parameter according to the effective signal, and filters the conditioned input signal according to the second filter parameter to obtain second filter data.
Specifically, the processor 4 controls the center frequency of the filtering unit 412 thereof through the effective signal searched by the signal searching unit 411, so that the filtering unit 412 filters the signal output by the first front-end module 1 according to the center frequency. Similarly, the processor 4 controls the center frequency of its filter unit 432 according to the effective signal searched by the signal search unit 431, so that the filter unit 432 filters the signal output by the second front-end module 2 according to the center frequency. The process realizes the parameter-controlled band-pass filtering function, and the signal-to-noise ratio of the signal is greatly improved after the processing of the process. The process of measuring the bode diagram is a process of obtaining gain and phase relation frequency by frequency, the limit of oscilloscope components is adopted, the frequency of an actual signal has certain deviation from a theoretical value, the signal searching unit searches the signal in a limited frequency range to obtain the frequency of the actual signal, and the influence of the deviation on the measurement of the bode diagram can be avoided.
Step 103: and (5) phase discrimination processing.
After the processor 4 performs filtering processing on the acquired signals through the filtering unit 412 and the filtering unit 432, the phase discrimination module 45 performs phase discrimination processing on the obtained first filtering data and second filtering data to obtain a phase difference between the input signal and the output signal. The phase detection module 45 preferably employs multiplicative phase detection.
Step 104: and detecting the effective value.
The processor 4 performs filtering processing on the acquired signal through the filtering unit 412 and the filtering unit 432, performs effective value detection on the obtained first filtered data through the effective value detection module 42, and performs effective value detection on the obtained second filtered data through the effective value detection module 44 to obtain corresponding detection data.
The processor 4 may also control the gains of the corresponding first front-end module 1 and the second front-end module 2 by using the detection data after obtaining the corresponding detection data, so that the processor 4 can acquire data meeting the condition, that is, signals with amplitudes within a preset amplitude range, thereby avoiding the influence on the measurement caused by too large or too small gain, and improving the accuracy of the bode plot measurement.
Step 105: and drawing a baud chart.
The processor 4 obtains the phase difference and the detection data, and then draws a bode diagram based on the phase difference and the detection data. Specifically, the processor 4 draws a corresponding phase-frequency response curve according to the phase difference, calculates a ratio of the first detection data to the second detection data to obtain a corresponding gain, and then draws a corresponding amplitude-frequency response curve according to the gain.
In practical applications, the digital oscilloscope may also be a multi-channel oscilloscope, that is, the digital oscilloscope may measure one input signal and multiple output signals, so that the above processing process may be performed on the output signal of each channel to obtain the gain and phase relationship between the output signal and the input signal of each channel.
Those skilled in the art will appreciate that all or part of the functions of the various methods in the above embodiments may be implemented by hardware, or may be implemented by computer programs. When all or part of the functions of the above embodiments are implemented by a computer program, the program may be stored in a computer-readable storage medium, and the storage medium may include: a read only memory, a random access memory, a magnetic disk, an optical disk, a hard disk, etc., and the program is executed by a computer to realize the above functions. For example, the program may be stored in a memory of the device, and when the program in the memory is executed by the processor, all or part of the functions described above may be implemented. In addition, when all or part of the functions in the above embodiments are implemented by a computer program, the program may be stored in a storage medium such as a server, another computer, a magnetic disk, an optical disk, a flash disk, or a removable hard disk, and may be downloaded or copied to a memory of a local device, or may be version-updated in a system of the local device, and when the program in the memory is executed by a processor, all or part of the functions in the above embodiments may be implemented.
The present invention has been described in terms of specific examples, which are provided to aid understanding of the invention and are not intended to be limiting. For a person skilled in the art to which the invention pertains, several simple deductions, modifications or substitutions may be made according to the idea of the invention.
Claims (10)
1. A digital oscilloscope is characterized by comprising a first front end module, at least one second front end module, a signal source and a processor, wherein the processor comprises a main control module, a phase demodulation module corresponding to the second front end module, a frequency selection module and an effective value demodulation module which respectively correspond to the first front end module and the second front end module;
the signal source is connected with the main control module and used for generating an excitation signal for detecting the tested piece under the control of the main control module;
the first front-end module and the second front-end module are respectively used for acquiring input signals and output signals of a tested piece, conditioning the signals acquired respectively and outputting the conditioned signals to the frequency selection modules corresponding to the first front-end module and the second front-end module;
the frequency selection module is used for searching effective signals in received signals, filtering the received signals according to search results, and respectively outputting the filtered signals to the corresponding phase demodulation module and the corresponding effective value detection module;
the phase demodulation module is used for performing phase demodulation processing on the filtered signal corresponding to the second front-end module and the filtered signal corresponding to the first front-end module to obtain a corresponding phase difference, and outputting the phase difference to the main control module;
the effective value detection module is used for carrying out effective value detection on the received signals and outputting the obtained detection data to the main control module;
the main control module is used for drawing a Baud chart according to the phase difference output by the phase demodulation module and the demodulation data output by the effective value demodulation module.
2. The digital oscilloscope of claim 1, wherein the frequency selection module comprises a signal search unit and a filtering unit;
the signal searching unit is used for acquiring the signal output by the first front-end module, searching an effective signal in the signal, and controlling a filtering parameter of the filtering unit according to the searched effective signal;
the filtering unit is used for filtering the signal output by the first front-end module under the control of the signal searching unit and respectively outputting the filtered signal to the corresponding phase discrimination module and the effective value detection module.
3. The digital oscilloscope of claim 2, wherein the filtering unit is a band-pass filter, and the signal searching unit is specifically configured to control the center frequency of the filtering unit according to the searched effective signal.
4. The digital oscilloscope of claim 1, wherein the effective value detection module is further configured to control a gain parameter of the corresponding first front-end module or second front-end module according to the detection result;
the first front-end module and the second front-end module are specifically configured to perform signal conditioning on the respective acquired signals according to the respective corresponding gain parameters.
5. The digital oscilloscope of claim 4, wherein the first front end module and the second front end module each comprise an analog front end and an analog-to-digital converter;
the analog front end of the first front end module is used for acquiring an input signal of a tested piece, conditioning the input signal according to data fed back by the corresponding effective value detection module, and inputting the conditioned signal to the corresponding analog-to-digital converter;
the analog front end of the second front end module is used for collecting an output signal of a tested piece, conditioning the output signal according to data fed back by the corresponding effective value detection module, and inputting the conditioned signal to the corresponding analog-to-digital converter;
the analog-to-digital converter is used for performing analog-to-digital conversion on the input signal to obtain a corresponding digital signal, and inputting the digital signal to the corresponding frequency selection module.
6. The digital oscilloscope of claim 5, wherein the effective value detection module is specifically configured to compare a current detection result with a preset amplitude range, and control a gain parameter of a corresponding analog front end according to the comparison result.
7. The digital oscilloscope of claim 1, wherein the main control module is specifically configured to draw a corresponding phase-frequency response curve according to the phase difference output by each phase detection module, calculate a ratio between the detection data corresponding to the first front-end module and the detection data corresponding to each second front-end module, obtain a gain corresponding to each second front-end module, and draw a corresponding amplitude-frequency response curve according to the gain.
8. A digital oscilloscope is characterized by comprising a first front end module, at least one second front end module and a processor, wherein the processor comprises a main control module, a phase demodulation module corresponding to the second front end module, a frequency selection module and an effective value demodulation module which respectively correspond to the first front end module and the second front end module;
the first front-end module and the second front-end module are respectively used for acquiring input signals and output signals of a tested piece, conditioning the signals acquired respectively and outputting the conditioned signals to the frequency selection modules corresponding to the first front-end module and the second front-end module;
the frequency selection module is used for searching effective signals in received signals, filtering the received signals according to search results, and respectively outputting the filtered signals to the corresponding phase demodulation module and the corresponding effective value detection module;
the phase demodulation module is used for performing phase demodulation processing on the filtered signal corresponding to the second front-end module and the filtered signal corresponding to the first front-end module to obtain a corresponding phase difference, and outputting the phase difference to the main control module;
the effective value detection module is used for carrying out effective value detection on the received signals and outputting the obtained detection data to the main control module;
the main control module is used for being connected with a signal source, controlling the signal source to generate an excitation signal for detecting a detected piece, and drawing a baud chart according to the phase difference output by the phase demodulation module and the demodulation data output by the effective value demodulation module.
9. A method of measuring a bode plot, applied to a digital oscilloscope, the method comprising:
collecting an input signal and an output signal of a tested piece;
searching effective signals in the input signals, determining first filtering parameters according to the effective signals, and filtering the input signals according to the first filtering parameters to obtain first filtering data;
searching an effective signal in the output signal, determining a second filtering parameter according to the effective signal, and filtering the input signal according to the second filtering parameter to obtain second filtering data;
performing phase discrimination processing on the first filtering data and the second filtering data to obtain a phase difference between an input signal and an output signal;
respectively carrying out effective value detection on the first filtering data and the second filtering data to obtain corresponding detection data;
and drawing a baud chart according to the phase difference and the detection data.
10. A computer-readable storage medium, characterized by comprising a program executable by a processor to implement the method of claim 9.
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