CN106918731A - A kind of digital oscilloscope and its signal frequency measuring method - Google Patents
A kind of digital oscilloscope and its signal frequency measuring method Download PDFInfo
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
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Abstract
A kind of digital oscilloscope is the embodiment of the invention provides, including：Direct frequency measurement module, judge module and period module；Direct frequency measurement module is used to determine to receive the first frequency of signal according to direct frequency measurement method；Judge module be used for judge first frequency whether less than treatment clock 1/10th, if it is, triggering period module, and using second frequency determined by period module as receive signal rate-adaptive pacemaker；If it is not, then using the first frequency as receive signal rate-adaptive pacemaker；Period module is used to determine to receive the second frequency of signal according to period method.Frequency measurement accuracy to high-frequency signal and low frequency signal can simultaneously be ensured based on digital oscilloscope provided in an embodiment of the present invention, in addition, due to substituted for analog comparator of the prior art using digital comparator, that is, hardware cost is reduced, also improve frequency measurement accuracy.The embodiment of the present invention additionally provides a kind of signal frequency measuring method of digital oscilloscope.
Description
Technical Field
The invention relates to the technical field of digital oscilloscopes, in particular to a digital oscilloscope and a signal frequency measuring method thereof.
Background
The digital oscilloscope is an instrument for vividly displaying the waveform of a signal changing along with time, and is a high-performance signal characteristic testing instrument integrating a series of technologies such as data acquisition, A/D conversion, software programming and the like.
In the digital oscillography technology, frequency is one of the most basic parameters, and has a close relationship with measurement schemes and measurement results of many electrical parameters, so that the measurement of frequency is very important. The frequency measurement method has various methods, and the hardware frequency meter has the advantages of high precision, convenient use, rapid measurement, convenient realization of automation of the measurement process and the like, and is one of important means of frequency measurement.
The current oscillograph has two schemes for realizing the function of a frequency meter, wherein the first scheme is a direct frequency measurement method; the second is a periodic frequency measurement method, the direct frequency measurement method is more suitable for frequency measurement of high-frequency signals, the periodic frequency measurement method is more suitable for frequency measurement of low-frequency signals, and any one of the two schemes cannot guarantee the frequency measurement accuracy of received signals.
In addition, in the two frequency measurement methods, signals input by an analog channel are sent to an analog comparator, and then comparison results are sent to a digital chip for frequency measurement, however, the analog comparator effectively counts the frequency of input signals and is limited by the processing clock frequency of the digital chip, moreover, because the output signals of the analog comparator are asynchronous with the processing clock frequency of the digital chip, the statistical precision is reduced, on the other hand, the cost of the analog comparator is high, and the hardware cost is increased.
Disclosure of Invention
In order to solve the problems in the prior art, embodiments of the present invention are expected to provide a digital oscilloscope and a signal frequency measurement method thereof.
The embodiment of the invention provides a digital oscilloscope, which comprises: the device comprises a direct frequency measurement module, a judgment module and a periodic frequency measurement module; wherein,
the direct frequency measurement module is used for determining a first frequency of a received signal according to a direct frequency measurement method;
the judging module is used for judging whether the first frequency is less than one tenth of a processing clock, if so, triggering a periodic frequency measurement module, taking a second frequency determined by the periodic frequency measurement module as the frequency of a received signal, and outputting the second frequency; if not, taking the first frequency as the frequency of the received signal, and outputting the first frequency;
and the periodic frequency measurement module is used for determining the second frequency of the received signal according to a periodic frequency measurement method when the periodic frequency measurement module is triggered by the judgment module.
In the above solution, the direct frequency measurement module includes:
the statistical unit is used for counting the number N of rising edges of the received signals in the gate time T1;
a first determining unit, configured to determine a ratio N/T1 of the number N of rising edges and the gate time T1 as a first frequency.
In the above solution, the direct frequency measurement module further includes: and the setting unit is used for setting the value of the gate time T1.
In the above solution, the periodic frequency measurement module includes:
a detection unit for detecting a time T2 when M cycles of an input signal occur;
a second determining unit for determining a ratio M/T2 of the number M of cycles and the time T2 as a second frequency.
In the above scheme, the time T2 is determined by:
t2 ═ total time of duration of the first rising edge of the input signal + (M-2) × T3+ total time of duration of the last rising edge of the input signal;
wherein, T3 is the period of the input signal.
In the above scheme, the digital oscilloscope further comprises:
the digital chip ADC interface is used for receiving the digital waveform signal from the analog-to-digital converter and dividing the received digital waveform signal into two parts, wherein one part is sent to the down-sampling and model storage module and is used for subsequent display and test processing, and the other part is used as an input signal of the digital comparator;
the digital comparator is used for processing the signal sent by the ADC interface and outputting the processed signal to the rising edge detection module;
and the rising edge detection module is used for detecting the rising edge of the received signal and sending the detection result of the rising edge to the direct frequency measurement module or the periodic frequency measurement module.
The embodiment of the invention also provides a signal frequency statistical method in the digital oscilloscope, and the method comprises the following steps:
determining a first frequency of a received signal according to a direct frequency measurement method;
judging whether the first frequency is less than one tenth of a processing clock, if so, determining a second frequency of the received signal according to a periodic frequency measurement method, taking the determined second frequency as the frequency of the received signal, and outputting the second frequency; and if not, taking the first frequency as the frequency of the received signal, and outputting the first frequency.
In the foregoing solution, the determining a first frequency of a received signal according to a direct frequency measurement method includes:
counting the number N of rising edges of the received signal in the gate time T1;
and determining the ratio N/T1 of the rising edge number N and the gate time T1 as a first frequency.
In the foregoing solution, before determining the first frequency of the received signal according to the direct frequency measurement method, the method further includes: the value of the gate time T1 is set.
In the foregoing solution, the determining the second frequency of the received signal according to the periodic frequency measurement method includes:
detecting the time T2 when the input signal appears for M periods;
and determining the ratio M/T2 of the number M of the periods and the time T2 as a second frequency.
Compared with the prior art, the embodiment of the invention at least has the following advantages:
the digital oscilloscope provided by the embodiment of the invention comprises a direct frequency measurement module, a judgment module and a periodic frequency measurement module; after the direct frequency measurement module determines the first frequency of the received signal according to a direct frequency measurement method, the judgment module judges whether the first frequency is less than one tenth of a processing clock, if so, the periodic frequency measurement module is triggered to measure the frequency of the received signal, the second frequency determined by the periodic frequency measurement module is used as the frequency of the received signal to be output, and if not, the first frequency is used as the frequency of the received signal to be output. The oscilloscope provided by the embodiment of the invention can combine the respective advantages of a direct measurement method and a high-frequency measurement method, thereby simultaneously ensuring the frequency measurement precision of a high-frequency receiving signal and a low-frequency receiving signal;
in addition, the digital oscilloscope provided by the embodiment of the invention adopts the digital comparator to replace the analog comparator in the prior art, so that the hardware cost is reduced, the defects of the analog comparator are overcome, and the frequency measurement precision is improved.
Drawings
FIG. 1 is a basic block diagram of a digital oscilloscope according to one embodiment of the present invention;
FIG. 2 is a diagram showing a basic structure of a digital oscilloscope according to a second embodiment of the present invention;
FIG. 3 is a basic configuration diagram of a digital oscilloscope according to a third embodiment of the present invention;
FIG. 4 is a process flow diagram of a signal frequency measurement method of a digital oscilloscope according to an embodiment of the present invention;
FIG. 5 is a process flow diagram of a signal frequency measurement method of a digital oscilloscope according to another embodiment of the present invention;
fig. 6 is a basic configuration diagram of a digital oscilloscope according to a fourth 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.
Example one
Referring to fig. 1, there is shown a block diagram of a digital oscilloscope according to the present invention, including: a direct frequency measurement module 11, a judgment module 12 and a periodic frequency measurement module 13; wherein,
the direct frequency measurement module 11 is configured to determine a first frequency of a received signal according to a direct frequency measurement method;
the judging module 12 is configured to judge whether the first frequency is less than one tenth of a processing clock, and if so, trigger the periodic frequency measurement module 13, use a second frequency determined by the periodic frequency measurement module as a frequency of the received signal, and output the second frequency; if not, taking the first frequency as the frequency of the received signal, and outputting the first frequency;
and the periodic frequency measurement module 13 is configured to determine the second frequency of the received signal according to a periodic frequency measurement method when triggered by the determination module.
In the above solution, when the determining module 12 determines that the first rate is less than one tenth of the processing clock, it may be determined that the received signal is a low-frequency signal, at this time, the determining module 12 calls the period frequency measuring module 13 to perform frequency measurement on the received signal, and outputs a second frequency obtained by the measurement as the frequency of the received signal; when the determining module 12 determines that the first rate is greater than or equal to one tenth of the processing clock, it may be determined that the received signal is a high frequency signal, and at this time, the determining module 12 directly outputs the first frequency measured by the direct measuring module 11 as the frequency of the received signal.
Specifically, the direct frequency measurement module 11 includes:
the statistical unit is used for counting the number N of rising edges of the received signals in the gate time T1;
a first determining unit, configured to determine a ratio N/T1 of the number N of rising edges and the gate time T1 as a first frequency.
In an optional embodiment of the present invention, the direct frequency measurement module 11 further includes: and the setting unit is used for setting the value of the gate time T1. Therefore, in practical applications, the gate time T1 can be adjusted or adjusted as needed.
Specifically, the periodic frequency measurement module 13 includes:
a detection unit for detecting a time T2 when M cycles of an input signal occur;
a second determining unit for determining a ratio M/T2 of the number M of cycles and the time T2 as a second frequency. Here, T2 refers to the time taken for the input signal to travel M cycles.
Specifically, the time T2 is determined by:
t2 ═ total time of duration of the first rising edge of the input signal + (M-2) × T3+ total time of duration of the last rising edge of the input signal; wherein, T3 is the period of the input signal.
The above-described method of determining T2 enables a more accurate determination of the time taken for the transmission of the input signal for M periods, because the first rising edge and the last rising edge cannot be guaranteed to be detected completely during the transmission of the signal, i.e., the statistics of the time duration of the first rising edge and the last rising edge cannot be guaranteed to be accurate, while the statistical time of the middle M-2 signal periods is determined. Thus, the total time during which the first rising edge and the last rising edge are determined separately is added to the time during which M-2 signal periods last, i.e., added to (M-2). times.T 3.
In another alternative embodiment of the present invention, referring to fig. 2, the digital oscilloscope further comprises:
an ADC interface 14, configured to receive the digital waveform signal from the analog-to-digital converter, and divide the received digital waveform signal into two parts, one part is used for subsequent display and test processing, and the other part is used as an input signal of the digital comparator 15;
the digital comparator 15 is configured to process a signal sent by the ADC interface and output the signal to the rising edge detection module 16;
and the rising edge detection module 16 is configured to perform rising edge detection on the received signal, and send a rising edge detection result to the direct frequency measurement module or the periodic frequency measurement module 13.
Therefore, in the above scheme, the received signal for which the direct frequency measurement module 11 or the periodic frequency measurement module 13 determines the frequency is a rising edge detection result output from the rising edge detection module.
In an alternative embodiment of the present invention, referring to fig. 3, the digital oscilloscope further comprises: and the down-sampling and model storage module 17 is configured to receive the digital waveform signal sent by the ADC interface 14, and use the digital waveform signal for display and test processing.
In a specific implementation process, the direct frequency measurement module 11, the judgment module 12, the period frequency measurement module 13, the ADC interface 14, the Digital comparator 15, the rising edge detection module 16, and the down-sampling and model storage module 17 may be implemented by a Central Processing Unit (CPU), a microprocessor Unit (MPU), a Digital Signal Processor (DSP), or a Programmable logic Array (FPGA).
In summary, the digital oscilloscope provided by the embodiment of the invention comprises a direct frequency measurement module, a judgment module and a periodic frequency measurement module; after the direct frequency measurement module determines the first frequency of the received signal according to a direct frequency measurement method, the judgment module judges whether the first frequency is less than one tenth of a processing clock, if so, the periodic frequency measurement module is triggered to measure the frequency of the received signal, the second frequency determined by the periodic frequency measurement module is used as the frequency of the received signal to be output, and if not, the first frequency is used as the frequency of the received signal to be output. The oscilloscope provided by the embodiment of the invention can combine the respective advantages of the direct measurement method and the high-frequency measurement method, thereby simultaneously ensuring the frequency measurement precision of the high-frequency receiving signal and the low-frequency receiving signal.
In addition, the digital oscilloscope provided by the embodiment of the invention adopts the digital comparator to replace the analog comparator in the prior art, so that the hardware cost is reduced, the defects of the analog comparator are overcome, and the frequency measurement precision is improved.
Example two
Referring to fig. 4, a second embodiment of the present invention provides a signal frequency measurement method of a digital oscilloscope, where the method includes:
step 401, determining a first frequency of a received signal according to a direct frequency measurement method;
specifically, the determining the first frequency of the received signal according to the direct frequency measurement method includes:
counting the number N of rising edges of the received signal in the gate time T1;
and determining the ratio N/T1 of the rising edge number N and the gate time T1 as a first frequency.
In an optional embodiment of the present invention, before determining the first frequency of the received signal according to the direct frequency measurement method, the method further comprises: the value of the gate time T1 is set.
Step 402, judging whether the first frequency is less than one tenth of a processing clock, if so, determining a second frequency of the received signal according to a periodic frequency measurement method, taking the determined second frequency as the frequency of the received signal, and outputting the second frequency; and if not, taking the first frequency as the frequency of the received signal, and outputting the first frequency.
Specifically, the determining the second frequency of the received signal according to the periodic frequency measurement method includes:
detecting the time T2 when the input signal appears for M periods;
and determining the ratio M/T2 of the number M of the periods and the time T2 as a second frequency.
Specifically, the time T2 is determined by:
t2 ═ total time of duration of the first rising edge of the input signal + (M-2) × T3+ total time of duration of the last rising edge of the input signal;
wherein, T3 is the period of the input signal.
Specifically, before determining the first frequency of the received signal according to the direct frequency measurement method, the method further includes:
receiving a digital waveform signal, dividing the received digital waveform signal into two parts, wherein one part is used for subsequent display and test processing, and the other part is subjected to digital comparison; and after the digital comparison result is subjected to rising edge detection, generating a rising edge detection result, and using the rising edge detection result as a receiving signal of a direct frequency measurement method or a periodic frequency measurement method.
In the foregoing scheme, the method may further include: and adjusting the value of M according to the first frequency in a specific adjustment mode that the time of one statistic is as close as possible to the set statistic interval.
In summary, the method for measuring the frequency of the signal in the digital oscilloscope provided by the embodiment of the present invention combines the respective advantages of the direct measurement method and the high-frequency measurement method, and can simultaneously ensure the frequency measurement accuracy of the high-frequency received signal and the low-frequency received signal.
Application example 1
Fig. 5 shows an exemplary flowchart of a signal frequency measuring method of a digital oscilloscope provided by the present invention, and as shown in fig. 5, the method comprises:
step 501, determining a first frequency of a received signal according to a direct frequency measurement method;
specifically, the determining the first frequency of the received signal according to the direct frequency measurement method includes:
counting the number N of rising edges of the received signal in the gate time T1;
and determining the ratio N/T1 of the rising edge number N and the gate time T1 as a first frequency.
Step 502, judging whether the first frequency is less than one tenth of a processing clock, if so, turning to step 503, and if not, turning to step 505;
step 503, determining a second frequency of the received signal according to a periodic frequency measurement method;
specifically, the determining the second frequency of the received signal according to the periodic frequency measurement method includes:
detecting the time T2 when the input signal appears for M periods;
and determining the ratio M/T2 of the number M of the periods and the time T2 as a second frequency.
Specifically, the time T2 is determined by:
t2 ═ total time of duration of the first rising edge of the input signal + (M-2) × T3+ total time of duration of the last rising edge of the input signal;
wherein, T3 is the period of the input signal.
Step 504, taking the determined second frequency as the frequency of the received signal, and outputting the second frequency;
and 505, taking the determined first frequency as the frequency of the received signal, and outputting the first frequency.
Application example two
Fig. 6 is a schematic view of an application structure of a digital oscilloscope according to an embodiment of the present invention, and as shown in fig. 6, an ADC interface, a down-sampling and storage module, a digital comparator, a rising edge detection module, a direct frequency measurement module, a judgment module, and a periodic frequency measurement module according to the present invention may be implemented in a digital chip (FPGA/CPLD/ASIC). Referring to fig. 6, the digital waveform signal received by the ADC interface from the analog-to-digital converter is divided into two parts, and one part is sent to the down-sampling and model storage module for subsequent display and test processing; the second part is used as the input signal for the digital comparator. The parallel result output by the digital comparator is firstly sent to a rising edge detection module (the position of the rising edge in the parallel result is recorded at the same time), and then the rising edge detection result of the parallel data is sent to a direct frequency measurement module and a periodic frequency measurement module for frequency detection. The judging module judges which statistical method should be adopted by the input signal and the number M of input signal periods needing to be detected in the period frequency measuring module according to the output of the direct frequency measuring module and the period frequency measuring module.
The embodiments in the present specification are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.
As will be appreciated by one skilled in the art, embodiments of the present invention may be provided as a method, apparatus, or computer program product. Accordingly, embodiments of the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, embodiments of the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
Embodiments of the present invention are described with reference to flowchart illustrations and/or block diagrams of methods, terminal devices (systems), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing terminal to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing terminal, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing terminal to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing terminal to cause a series of operational steps to be performed on the computer or other programmable terminal to produce a computer implemented process such that the instructions which execute on the computer or other programmable terminal provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
While preferred embodiments of the present invention have been described, additional variations and modifications of these embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the embodiments of the invention.
Finally, it should also be noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or terminal that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or terminal. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in a process, method, article, or terminal that comprises the element.
The digital oscilloscope and the signal frequency measurement method thereof provided by the invention are introduced in detail, the principle and the implementation mode of the invention are explained by applying specific examples, and the description of the examples is only used for helping to understand the method and the core idea of the invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.
Claims (10)
1. A digital oscilloscope, the digital oscilloscope comprising: the device comprises a direct frequency measurement module, a judgment module and a periodic frequency measurement module; wherein,
the direct frequency measurement module is used for determining a first frequency of a received signal according to a direct frequency measurement method;
the judging module is used for judging whether the first frequency is less than one tenth of a processing clock, if so, triggering a periodic frequency measurement module, taking a second frequency determined by the periodic frequency measurement module as the frequency of a received signal, and outputting the second frequency; if not, taking the first frequency as the frequency of the received signal, and outputting the first frequency;
and the periodic frequency measurement module is used for determining the second frequency of the received signal according to a periodic frequency measurement method when the periodic frequency measurement module is triggered by the judgment module.
2. The digital oscilloscope of claim 1, wherein the direct frequency measurement module comprises:
the statistical unit is used for counting the number N of rising edges of the received signals in the gate time T1;
a first determining unit, configured to determine a ratio N/T1 of the number N of rising edges and the gate time T1 as a first frequency.
3. The digital oscilloscope of claim 2, wherein the direct frequency measurement module further comprises: and the setting unit is used for setting the value of the gate time T1.
4. The digital oscilloscope according to any one of claims 1 to 3, wherein the periodic frequency measurement module comprises:
a detection unit for detecting a time T2 when M cycles of an input signal occur;
a second determining unit for determining a ratio M/T2 of the number M of cycles and the time T2 as a second frequency.
5. The digital oscilloscope of claim 4, wherein the time T2 is determined by:
t2 ═ total time of duration of the first rising edge of the input signal + (M-2) × T3+ total time of duration of the last rising edge of the input signal;
wherein, T3 is the period of the input signal.
6. The digital oscilloscope of any of claims 1 to 3, further comprising:
the digital chip ADC interface is used for receiving the digital waveform signal from the analog-to-digital converter and dividing the received digital waveform signal into two parts, wherein one part is sent to the down-sampling and model storage module and is used for subsequent display and test processing, and the other part is used as an input signal of the digital comparator;
the digital comparator is used for processing the signal sent by the ADC interface and outputting the processed signal to the rising edge detection module;
and the rising edge detection module is used for detecting the rising edge of the received signal and sending the detection result of the rising edge to the direct frequency measurement module or the periodic frequency measurement module.
7. A method for counting signal frequencies in a digital oscilloscope, the method comprising:
determining a first frequency of a received signal according to a direct frequency measurement method;
judging whether the first frequency is less than one tenth of a processing clock, if so, determining a second frequency of the received signal according to a periodic frequency measurement method, taking the determined second frequency as the frequency of the received signal, and outputting the second frequency; and if not, taking the first frequency as the frequency of the received signal, and outputting the first frequency.
8. The method of claim 7, wherein determining the first frequency of the received signal according to direct frequency measurement comprises:
counting the number N of rising edges of the received signal in the gate time T1;
and determining the ratio N/T1 of the rising edge number N and the gate time T1 as a first frequency.
9. The method of claim 8, wherein prior to determining the first frequency of the received signal in accordance with direct frequency measurement, the method further comprises: the value of the gate time T1 is set.
10. The method of any of claims 7 to 9, wherein determining the second frequency of the received signal according to a periodic frequency measurement method comprises:
detecting the time T2 when the input signal appears for M periods;
and determining the ratio M/T2 of the number M of the periods and the time T2 as a second frequency.
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| CN108776264A (en) * | 2018-07-26 | 2018-11-09 | 电子科技大学 | The fft analysis device of digital oscilloscope |
| CN109541553A (en) * | 2018-11-28 | 2019-03-29 | 四川九洲电器集团有限责任公司 | A kind of synchronised clock feed circuit |
| CN110954745A (en) * | 2019-11-14 | 2020-04-03 | 中国航空工业集团公司西安航空计算技术研究所 | High-precision frequency acquisition method and device based on FPGA |
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| CN108776264B (en) * | 2018-07-26 | 2020-04-14 | 电子科技大学 | FFT analysis device of digital oscilloscope |
| CN109541553A (en) * | 2018-11-28 | 2019-03-29 | 四川九洲电器集团有限责任公司 | A kind of synchronised clock feed circuit |
| CN110954745A (en) * | 2019-11-14 | 2020-04-03 | 中国航空工业集团公司西安航空计算技术研究所 | High-precision frequency acquisition method and device based on FPGA |
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