JP4032277B2 - Digital oscilloscope - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a digital oscilloscope with a pulse count function, and more particularly to improvement of the pulse count function.
[0002]
[Prior art]
In recent years, the demand for observing binary signals such as serial signals with a digital oscilloscope has increased due to the increase in the speed of processors (CPU, etc.), and a digital having a function of counting pulses in order to meet such demands. An oscilloscope has appeared.
[0003]
As this type of digital oscilloscope, for example, there is a digital oscilloscope described in JP-A-2000-74948. The pulse count function in this digital oscilloscope has three reference lines (three amplitude levels determined based on the maximum value and minimum value of the input pulse) with respect to the amplitude of the pulse, which are called distal, mesial, and proximal in descending order. ), And detecting the number of pulses based on the reference line to obtain the number of pulses.
[0004]
[Problems to be solved by the invention]
However, with this conventional pulse count function, pulses that do not reach the reference line (referred to as mispulses) are not counted, so there is a problem that mispulses that do not reach the normal level are ignored. It was.
[0005]
That is, when a normal level pulse is input as shown in FIG. 12 (a), the pulse count is 5, but when there is a pulse whose level is not correctly output as shown in FIG. 12 (b). Since it is not counted as a miss pulse, the pulse count is 4.
[0006]
If it is desired to count this miss pulse, it is impossible with the conventional function. Even if a method of obtaining the pulse period and obtaining the number of pulses based on the period is used, correct pulse counting cannot be performed. For example, in the case of pulse signals as shown in FIG. 5C and FIG. 4D, the pulse periods are all determined as P1, P2, and P3, and both have a pulse number of 4 and the miss pulse is I can't count.
[0007]
As described above, both of the results shown in FIGS. 4C and 4D have the same result as the number of pulses 4, and it cannot be determined whether the portion of the cycle value P2 is a miss pulse by observing the corresponding portion of the display waveform. There was a problem.
[0008]
An object of the present invention is to solve the above-described problems, and to provide a digital oscilloscope with a miss pulse count function that can count miss pulses without directly observing a pulse waveform.
[0009]
[Means for Solving the Problems]
In order to achieve such an object, in the invention described in claim 1,
In a digital oscilloscope that has the function of measuring the pulse signal to be measured and storing the waveform data in the memory, then reading the waveform data and displaying it on the display,
A pulse count means having a function of detecting a pulse from the waveform data read from the memory, detecting a miss pulse in which the amplitude of the pulse does not reach a predetermined magnitude, and measuring the number and position of the miss pulse;
A display processing means having a function of displaying the measurement result of the pulse counting means on the display;
The pulse counting means includes
The maximum and minimum values are obtained from the waveform data in the memory, and the values of distal, mesial, and proximal are obtained based on the maximum and minimum values, and the presence of miss pulses and miss pulses based on the values of distal, mesial, and proxy Configured to be able to determine the position,
The pulse counting means includes
Distal, mesial, and proximal values
Distal = ( Max - Min ) x a ÷ 100 + Min
Mesial = ( Max - Min ) x b ÷ 100 + Min
Proximal = ( Max - Min ) x c ÷ 100 + Min
Where Max is the maximum value, Min is the minimum value
a , b , and c are arbitrary values within the range of 0 to 100
a ≧ b ≧ c
The rising pulse that is greater than the mesial value and smaller than the distal value or the falling pulse that is less than the mesial value and greater than the proxy value is searched for as a miss pulse.
In this way, the present invention can automatically measure miss pulses.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing the principal part of an embodiment of a digital oscilloscope according to the present invention. In the following embodiments, only the mispulse count function will be described, and the description of the normal pulse count function of the digital oscilloscope will be omitted.
In the figure, 10 is a measurement circuit, 20 is a memory, 30 is pulse counting means, 40 is display processing means, and 50 is a display rod.
[0014]
The measurement circuit 10 samples the input pulse signal at high speed and converts it into digital data. The memory 20 is a memory for storing the digital data (also referred to as measurement values or waveform data). The pulse count means 30 obtains the number of pulses of the input signal from the measurement value stored in the memory 20, searches for a miss pulse whose pulse amplitude does not reach a predetermined magnitude, and measures the number of miss pulses and their location. . The display processing means 40 reads the measured value from the memory 20 and displays the waveform on the display rod 50, and displays the number of pulses obtained by the pulse counting means 30 and the position of the miss pulse on the display rod 50.
[0015]
The pulse count means 30 will be described in more detail. As shown in FIG. 2, the pulse count means 30 includes a maximum / minimum value means 31, a determination value means 32, and a determination means 33.
The maximum / minimum value means 31 reads the measured value from the memory 20 and obtains the maximum value (Max) and the minimum value (Min) of the pulse signal as shown in FIG.
[0016]
Based on the maximum value and the minimum value obtained by the maximum / minimum value means 31, the judgment value means 32 obtains three level values of Distal, Mesial, and Proximal as shown in FIG. Ask.
Distal, mesial, and proximal have the following relationship.
Distal = (Max−Min) × a ÷ 100 + Min
Mesial = (Max−Min) × b ÷ 100 + Min
Proximal = (Max−Min) × c ÷ 100 + Min
Here, a, b, and c are arbitrary values within the range of 0 to 100,
There is a relationship of a ≧ b ≧ c.
[0017]
The determination means 33 determines the measurement value in the memory 20 using the values of the distal, mesial, and proximal as determination criteria, and obtains the number of pulses including a miss pulse and the position where the miss pulse exists.
[0018]
The miss pulse in the present invention is defined as follows. The search for the rising edge of the pulse is as follows. As shown in Fig. 5 (a), the normal rise once found a point above the mesial, and then found a point above the distal, but the third pulse did not rise to the distal even if the mesial was exceeded. ). Such a pulse is referred to as a miss pulse.
[0019]
Also, in the pulse fall search, a pulse that falls to the original level (Max) without falling to the proxy level although it falls below the mesial once like the third pulse in FIG. To do.
[0020]
Next, the principle of measuring the number of miss pulses in the present invention will be described. The number of miss pulses is measured as follows using a reference line of distal, mesial, and proximal.
(1) A rising edge is a portion where the waveform crosses the line in the order of proximal → mesial → distal.
(2) Contrary to the above, the waveform is assumed to rise when it crosses the line in the order of Distal → Mesial → Proximal.
[0021]
(3) Since rising and falling always exist alternately, it is determined that there is one pulse when one rising and one falling are detected, but the mesial line crossing as shown in FIG. The part that returns to the original level later is defined as a miss pulse. Then, the number of miss pulses and the count at which the miss pulse existed are obtained, the result is stored in the internal memory, and the result is displayed via the display processing means 40 after the entire search of the automatic measurement range is completed. Displayed on 噐 50.
[0022]
(4) Since the pulse is actually counted when the mesial line is crossed, if there is a portion that crosses the mesial on the left side of the pulse train as shown in FIG. In addition, as shown in FIG. 5B, if there is a portion that intersects the proxy or the distal on the right side of the pulse train, it is determined that it falls.
[0023]
(5) Based on the principle described above, the number of miss pulse counts is 1 in the waveforms shown in FIGS. FIG. 7 shows a case where there is a miss pulse in the active direction of the pulse, and FIG. 8 shows a case where there is a miss pulse in the direction opposite to the active direction of the pulse.
In the case of FIG. 7, the position of the miss pulse is a count of 2.5 (meaning that it exists between the second and third pulses), and in the case of FIG. 8, it is a count of 2 (meaning that it exists inside the second pulse). ) And the count result is displayed on the display 50.
[0024]
Next, the operation in such a configuration will be described with reference to the flowcharts of FIGS.
The input pulse signal is measured by the measurement circuit 10 and the waveform data is stored in the memory 20 (step S1).
After the waveform acquisition is completed, the pulse count means 30 obtains Max, Min, Distal, Mesial, and Proximal values, and then starts mispulse count measurement according to the following procedure.
[0025]
First, it is determined whether or not the head data is between the proxy and the distal (step S2).
If not, the process proceeds to step S4. In some cases, the read data from the memory is incremented until it is below the proxymal or above the distal. If there is an intersection with the mesial in the meantime, if it falls to the proxy side thereafter, it counts as having fallen, and conversely if it falls to the distal side, it counts as having risen (step S3).
[0026]
In step 4, it is checked whether the head data is greater than or equal to the distal. If it is equal to or larger than the distal, the process proceeds to step S5, and if not, the process proceeds to step S9.
[0027]
In step S5, the falling edge of the waveform is searched and the mesial intersection is counted. If the data is not finished, the rising edge is searched and the mesial intersection is counted (step S7). Steps S5 and S7 are repeated until the data is completed, and when the intermediate data is completed (steps S6 and S8), the process proceeds to step S13.
[0028]
When it is determined in step S4 that the head data is greater than or equal to the distal, the process proceeds to step S9, where the rising edge of the waveform is searched and the mesial intersection is counted. If the data is not finished, the falling edge of the waveform is searched and the mesial intersection is counted (step S11). Thereafter, steps S9 and S11 are repeated until the data is completed. In the case of end of data, the process proceeds to step S13.
[0029]
In step S13, the rising edge and the falling edge are defined as one pair, and the number of pairs is counted.
[0030]
As described above, the pulse count means 30 measures a miss pulse. The measurement result is displayed on the display 50 through the display processing means 40. Details of the waveform falling search in steps S5 and S11 and the waveform rising search in steps S7 and S9 will be described below with reference to FIGS.
[0031]
(1) Operation when searching for falling edges and counting mesial intersections (see FIG. 10)
After detecting the distal intersection and the mesial intersection (steps S21 and S22), it is checked again whether or not the distal intersection or less is reached (step S23).
[0032]
If it is not less than the distal in step S23, the process waits until a proxy intersection is detected (step S28).
If it is below the distal, it is counted as a miss pulse (step S24). In this case, it is checked whether or not the first waveform is falling (S25). If the first waveform is falling, the miss pulse position is made the same as the current miss pulse count value (step S26). If it is a rise, the miss pulse position is set to the current pulse count value +0.5 (step S27).
Then, the process ends after the proxy intersection is detected (step S28).
[0033]
(2) Operation when searching for rising edges and counting mesial intersections (see FIG. 11)
After detecting the proximal intersection and the mesial intersection (steps S31 and S32), it is checked again whether or not the proximal intersection is reached (step S33).
[0034]
If it is not less than or equal to the proxy circle in step S33, the process ends after waiting for the detection of a distant intersection (step S34).
If it is less than the proxymal, it is counted as a miss pulse (step S35). In this case, it is checked whether or not the first waveform is rising (S36). If the first waveform is rising, the mispulse position is made the same as the current mispulse count value (step S37), and the falling edge is reversed. If it is, the miss pulse position is set to the current pulse count value +0.5 (step S36).
Then, the process ends after waiting for the detection of the distant intersection (step S38).
[0035]
The above description merely shows a specific preferred embodiment for the purpose of explanation and illustration of the present invention. Therefore, the present invention is not limited to the above-described embodiments, and includes many changes and modifications without departing from the essence thereof.
[0036]
For example, the pulse count means 30 is composed of three means, that is, a maximum / minimum value means 31, a determination value means 32, and a determination means 33. However, the present invention is not limited to such a structure, and may have these functions. Any configuration is acceptable.
[0037]
【The invention's effect】
As described above, according to the present invention, it is possible to easily obtain a miss pulse in response to a request for checking the pulse count, and when the number of pulses assumed for the measurement waveform is insufficient, And where it exists can be determined automatically and accurately.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a main part of an embodiment of a digital oscilloscope according to the present invention.
FIG. 2 is a block diagram showing an embodiment of pulse counting means.
FIG. 3 is an explanatory diagram of a maximum value and a minimum value.
FIG. 4 is an explanatory diagram of distal, mesial, and proximal.
FIG. 5 is an explanatory diagram of a miss pulse.
FIG. 6 is an explanatory diagram regarding determination of the rise and fall of a pulse.
FIG. 7 is an explanatory diagram of a miss pulse and a position where a miss pulse exists.
FIG. 8 is an explanatory diagram of a miss pulse and a position where a miss pulse exists.
FIG. 9 is a flowchart for explaining the operation.
FIG. 10 is a flowchart relating to a waveform falling search;
FIG. 11 is a flowchart according to a waveform rising search.
FIG. 12 is a waveform diagram for explaining a conventional pulse count function.
[Explanation of symbols]
10 measuring circuit 20 memory 30 pulse counting means 31 maximum / minimum value means 32 judgment value means 33 judgment means 40 display processing means 50 display lamp

Claims (1)

In a digital oscilloscope that has the function of measuring the pulse signal to be measured and storing the waveform data in the memory, then reading the waveform data and displaying it on the display,
A pulse count means having a function of detecting a pulse from the waveform data read from the memory, detecting a miss pulse in which the amplitude of the pulse does not reach a predetermined magnitude, and measuring the number and position of the miss pulse;
A display processing means having a function of displaying the measurement result of the pulse counting means on the display;
The pulse counting means includes
The maximum and minimum values are obtained from the waveform data in the memory, and the values of distal, mesial, and proximal are obtained based on the maximum and minimum values, and the presence of miss pulses and miss pulses based on the values of distal, mesial, and proxy Configured to be able to determine the position,
The pulse counting means includes
Distal, mesial, and proximal values
Distal = ( Max - Min ) x a ÷ 100 + Min
Mesial = ( Max - Min ) x b ÷ 100 + Min
Proximal = ( Max - Min ) x c ÷ 100 + Min
Where Max is the maximum value, Min is the minimum value
a , b , and c are arbitrary values within the range of 0 to 100
a ≧ b ≧ c
A digital pulse characterized in that a rising pulse greater than the mesial value and smaller than the distal value or a falling pulse less than the mesial value and larger than the proximal value is searched for as a miss pulse. oscilloscope.

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