JP3731441B2 - Digital oscilloscope - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a digital oscilloscope, and more particularly to a function for automatically measuring waveform parameters for measured waveform data.
[0002]
[Prior art]
The digital oscilloscope is configured to convert analog measurement waveforms into digital signals and load them into the memory as waveform data, and to display the waveform data on the display unit via the display processing unit. It is widely used as a waveform measurement display means in quality control and maintenance work.
[0003]
FIG. 6 is a block diagram showing an example of a conventional digital oscilloscope.
The analog measurement waveform input to the input terminal 1 is converted into a digital signal by the AD converter 1 and is taken into the RAM 3 as waveform data. The waveform data captured in the RAM 3 is stored as a waveform data file in a storage medium 5 such as an HD, FD, or ATA flash under the control of the CPU 4 or input to the display control unit 6 or the waveform parameter measurement unit 7. The
[0004]
The display control unit 6 displays the waveform data on the display unit 8 in accordance with display conditions set by setting means (not shown).
[0005]
The waveform parameter measurement unit 7 performs the following automatic measurement of waveform parameters for the two systems of the voltage axis system and the time axis system. For the voltage axis system, a PP (maximum-minimum) value, maximum voltage value, minimum voltage value, effective value, average voltage, standard deviation, undershoot amount, overshoot amount, and the like are measured. For the time axis system, the rise time, fall time, frequency, period, average frequency in the measurement range, average period in the measurement range, and the like are measured.
[0006]
Here, in the waveform parameter measurement unit 7, the voltage axis parameter is for the entire waveform data fetched in the RAM 3, and the time axis parameter is for only one period selected from the waveform data fetched in the RAM 3.
[0007]
[Problems to be solved by the invention]
By the way, with the recent increase in the capacity (long memory) of the RAM 3 in a digital oscilloscope, various waveform analyzes have been performed after a large amount of data is taken into the RAM 3 at once.
[0008]
For example, when evaluating a switching power supply, it is important to measure the current, voltage, power, etc. of the device at each switching cycle. In particular, check the transient phenomena of each parameter when the power is turned on or when the power load changes. This is very important, but the current situation is that simply analyzing the waveform parameters as in the case of a conventional digital oscilloscope cannot answer the user's request.
[0009]
In addition, for example, when analyzing a PWM (pulse width modulation) signal in an inverter circuit, when the frequency is constant and the duty ratio is changed, when the duty ratio is constant and the frequency is changed, both the frequency and the duty ratio are changed every cycle. Various measurement patterns are conceivable, such as when doing so, but current digital oscilloscopes are not sufficient.
[0010]
That is, in analyzing waveform data stored in the RAM 3 of the digital oscilloscope having a long memory, the voltage axis parameters are obtained across the entire waveform data, but the time axis parameters Can only determine parameters for a certain period of the waveform, and the operator must set a range for each period in order to capture changes in parameter values in multiple periods. There is also a problem that the value of the parameter to be obtained differs depending on which periodic position the automatic measurement range is applied to.
[0011]
Furthermore, when performing statistical processing on the time axis parameters of these multiple cycles, the procedure of setting each automatic value within each cycle position of the waveform data and recording each parameter value each time is set for a predetermined cycle. After repeating, the statistical value must be calculated manually, which requires considerable work man-hours.
[0012]
The present invention focuses on these problems, and an object of the present invention is to realize a digital oscilloscope that can automatically execute statistical processing on waveform parameters of a plurality of cycles stored in a long memory.
[0013]
[Means for Solving the Problems]
The invention of claim 1 which achieves such an object,
[Claim 5]
In a digital oscilloscope configured to convert an analog measurement waveform into a digital signal and load it into memory as waveform data.
A period dividing unit for dividing the waveform data captured in the memory into a plurality of periods;
A waveform parameter measuring unit for measuring a waveform parameter for each divided period;
A waveform parameter statistical calculation unit for performing statistical calculation processing based on the measured waveform parameter;
A display unit for displaying the statistical calculation processing results,
A digital oscilloscope characterized by
[0014]
According to a second aspect of the present invention, in the digital oscilloscope according to the first aspect, the division period is equal to the period of the measurement waveform.
[0015]
According to a third aspect of the present invention, in the digital oscilloscope according to the first aspect, the division period is different from the period of the measurement waveform.
[0016]
According to a fourth aspect of the present invention, in the digital oscilloscope according to the first aspect of the present invention, the waveform parameters corresponding to the number of cycles are used for the statistical calculation processing.
[0017]
Accordingly, it is possible to realize a digital oscilloscope that can automatically perform statistical processing on waveform parameters of a plurality of cycles stored in a memory based on measurement data of waveform parameters for each cycle.
[0018]
Since the division period can be made equal to or different from the period of the measurement waveform, an appropriate division period can be set according to the measurement application. For example, when statistically processing the waveform parameters for each light emission period of a continuous strobe light emission circuit, the division period should be synchronized with the measurement waveform period, and the reference period and the measurement waveform period are constant. If it is desired to measure also the relationship with the above, it is sufficient to divide by a reference period asynchronous to the measurement period.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an example of an embodiment of the present invention, and parts common to FIG. The period dividing unit 9 divides the waveform data fetched into the RAM 3 into a plurality of periods along the time axis direction at a period equal to the waveform data as shown in FIG. 2, or as shown in FIG. Is divided into a plurality of periods with a predetermined reference period waveform different from the period of the first period.
2 and 3 is appropriately selected according to the purpose of measurement analysis.
[0020]
The waveform parameter measuring unit 10 measures the waveform parameter of the waveform data fetched into the RAM 3 for each period divided based on the divided output of the period dividing unit 9.
[0021]
The waveform parameter statistical calculation unit 11 performs various statistical calculation processes based on the waveform parameters measured by the waveform parameter measurement unit 9 and displays these statistical calculation processing results on the display unit 8.
[0022]
FIG. 4 is a flowchart for explaining the flow of the measurement process of FIG. In step S1, a histogram of the waveform data fetched into the RAM 3 is created, and Max, Min, High, and Low of the waveform data are calculated.
Subsequently, in step S2, on the basis of the waveform data histogram calculated in step S1 and the waveform data Max, Min, High, and Low, the waveform data stored in the RAM 3 is set to the start and end points of each cycle. In addition to detecting, the number of periods is detected. Note that the processing of these steps S1 and S2 is repeatedly executed for all waveforms as shown in step S3.
[0023]
When the period detection for all the waveforms is completed, in step S4, the waveform parameters within the range are calculated with each period as an automatic measurement range. Subsequently, in step S5, statistical calculation processing such as maximum value / minimum value / average value / standard deviation value based on the value of each waveform parameter in each period is executed. Note that the processing of step S4 and step S5 is also repeatedly executed for all waveforms as shown in step S6.
[0024]
When the statistical calculation processing for all waveforms is completed, as shown in step S7, the statistical calculation processing results such as the maximum value, the minimum value, the average value, and the standard deviation value of each waveform parameter are displayed.
[0025]
FIG. 5 is a flowchart for explaining the flow of the measurement process of FIG. In step S1, a histogram of the reference periodic waveform is created, and Max, Min, High, and Low of the reference periodic waveform are calculated.
Subsequently, in step S2, on the basis of the histogram of the reference periodic waveform calculated in step S1 and the Max, Min, High, Low of the reference periodic waveform, the waveform start point / end of each period is acquired for the waveform data stored in the RAM 3. A point is detected and the number of periods is detected.
[0026]
When the period detection for the reference period waveform is completed, in step S3, the waveform parameters within the range are calculated with each period as an automatic measurement range. Subsequently, in step S4, statistical calculation processing such as maximum value / minimum value / average value / standard deviation value based on the value of each waveform parameter in each cycle is executed. Note that the processing of step S3 and step S4 is repeatedly executed for all waveforms as shown in step S5.
[0027]
When the statistical calculation processing for all the waveforms is completed, as shown in step S6, the statistical calculation processing results such as the maximum value, the minimum value, the average value, and the standard deviation value of each waveform parameter are displayed.
[0028]
Thus, in the present invention, first, the number of periods of the waveform data fetched in the RAM 3 and the start / end points of each period are obtained, and thereafter, the waveform parameters are automatically calculated within the respective periods. A series of processing is automatically executed inside the digital oscilloscope until the maximum value, minimum value, average value, and standard deviation of each parameter are calculated and displayed for the number of cycles. By manually selecting each time, each parameter value is recorded and repeated for a predetermined period, and then the statistical value is calculated manually. Accuracy is significantly improved.
[0029]
【The invention's effect】
As described above, according to the present invention, it is possible to realize a digital oscilloscope that can automatically execute statistical processing on waveform parameters of a plurality of cycles stored in a long memory, and at the time of switching on power supply or power load It is suitable for confirming a transient phenomenon such as a current, voltage, and power of a device for each switching cycle at the time of fluctuation, and for analyzing and measuring a PWM (pulse width modulation) signal in an inverter circuit.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an example of an embodiment of the present invention.
FIG. 2 is an explanatory diagram of an example of period division of waveform data in the apparatus of FIG. 1;
FIG. 3 is an explanatory diagram of another example of waveform data periodic division in the apparatus of FIG. 1;
4 is a flowchart for explaining the flow of measurement processing in FIG. 2;
FIG. 5 is a flowchart for explaining the flow of the measurement process in FIG. 3;
FIG. 6 is a block diagram showing an example of a conventional digital oscilloscope.
[Explanation of symbols]
1 Input terminal 2 AD converter 3 RAM
4 CPU
5 Storage Media 6 Display Control Unit 7 Condition Determination Unit 8 Display Unit 9 Period Division Unit 10 Waveform Parameter Measurement Unit 11 Waveform Parameter Statistical Calculation Unit

Claims (4)

In a digital oscilloscope configured to convert an analog measurement waveform into a digital signal and load it into memory as waveform data.
A period dividing unit for dividing the waveform data captured in the memory into a plurality of periods;
A waveform parameter measurement unit for measuring a waveform parameter for each divided period;
A waveform parameter statistical calculation unit that performs statistical calculation processing based on the measured waveform parameters;
A display unit for displaying the statistical calculation processing results,
A digital oscilloscope characterized by 2. The digital oscilloscope according to claim 1, wherein the division period is equal to the period of the measurement waveform. The digital oscilloscope according to claim 1, wherein the division period is different from the period of the measurement waveform. 2. The digital oscilloscope according to claim 1, wherein the waveform parameters for the number of periods are used in the statistical calculation processing.

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