JP2002243764A - Digital oscilloscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a digital oscilloscope with a mispulse counting function capable of counting even a mispulse without directly observing the waveforms of pulses. SOLUTION: This digital oscilloscope has the functions of measuring a pulse signal to be measured, storing waveform data thereof in a memory, thereafter reading out the waveform data, and displaying them on a display. The oscilloscope is equipped with a pulse counting means having the functions of detecting pulses from the waveform data read out from the memory, searching for mispulses whose amplitudes fall short of a prescribed size, and measuring the number and positions of the mispulses, and a display processing means having the function of displaying the results of the measurement by the counting means on the display.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital oscilloscope with a pulse counting function, and more particularly to an improvement in a pulse counting function.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for observing a binary signal such as a serial signal with a digital oscilloscope due to an increase in the speed of a processor (CPU or the like). Digital oscilloscopes with functions have emerged.

As this kind of digital oscilloscope, for example, there is a digital oscilloscope described in JP-A-2000-74948. The pulse counting function in this digital oscilloscope has three reference lines (three amplitude levels determined based on the maximum value and the minimum value of the input pulse) with respect to the pulse amplitude, and is referred to as distal, mesial, and proximal in descending order. ), A pulse is detected based on this reference line, and the number of pulses is obtained.

[0004]

However, in the conventional pulse counting function, a pulse whose amplitude does not reach the reference line (this pulse is called a mispulse) is not counted, so that the pulse has a size that does not reach a normal level. There was a problem that a mispulse was ignored.

That is, when a pulse having a normal level is inputted as shown in FIG. 12A, the pulse count becomes 5, but as shown in FIG. At some point, the pulse count becomes 4 because it is a miss pulse and is not counted.

If it is desired to count this miss pulse, it is impossible with the conventional function. Even if a method of calculating the pulse period and calculating the number of pulses based on the period is used, correct pulse counting cannot be performed. For example, taking pulse signals as shown in FIGS. 3C and 3D as examples, the pulse periods are all P1, P2, and P3, the number of pulses is 4, and the number of miss pulses is 4. I can't count.

As shown in FIGS. 3 (c) and 3 (d), the result is the same as the number of pulses 4 and whether the period value P2 is a mispulse is determined by not observing the corresponding portion of the display waveform. There was a problem that it could not be determined.

An object of the present invention is to solve the above-mentioned problems and to provide a digital oscilloscope with a mispulse counting function capable of counting mispulses without directly observing a pulse waveform.

[0009]

In order to achieve the above object, according to the present invention, a pulse signal to be measured is measured, its waveform data is stored in a memory, and then the waveform data is read out. In a digital oscilloscope having a function of displaying on a display, a pulse is detected from waveform data read from the memory, a miss pulse whose pulse amplitude does not reach a predetermined magnitude is detected, and the number and the position of the miss pulse are detected. And a display processing means having a function of displaying the measurement result of the pulse counting means on a display device.

According to such a configuration, a miss pulse can be easily measured when measuring the number of pulses, and the number of the miss pulses and the position where the miss pulse exists can be easily grasped.

[0011] In this case, the pulse counting means may be configured as follows.
The maximum value and the minimum value are obtained from the waveform data, and further, the distal, mesial, and proximal are determined based on the maximum value and the minimum value, and the mispulse is obtained based on this.
At the same time, the position of the miss pulse (the pulse position indicating the position of the miss pulse) is also obtained.

Further, the distal, the mesial, and the proximal are defined as follows: distal = (Max−Min) × a ÷ 100 + Min mesial = (Max−Min) × b ÷ 100 + Min Proximal = (Max−Min) × c ÷ 100 + Min Here, Max is the maximum value, Min is the minimum value a, b, c are each defined as an arbitrary value a ≧ b ≧ c in the range of 0 to 100, and the pulse count means is equal to or more than the mesial value and A rising pulse smaller than the value of the distal or a falling pulse smaller than the value of the mesial and larger than the value of the proximity is detected as a mispulse. In this way, the present invention can automatically measure a mispulse.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. FIG. 1 is a main part configuration diagram showing one embodiment of a digital oscilloscope according to the present invention. In the following embodiments, only the mispulse counting function will be described, and the description of the normal pulse counting function of the digital oscilloscope will be omitted. In the figure, 10 is a measuring circuit, 20 is a memory, 30 is a pulse counting means, 40 is a display processing means, and 50 is a display unit.

The measuring circuit 10 samples the input pulse signal at high speed and converts it into digital data. Memory 2
Reference numeral 0 denotes a memory for storing the digital data (also referred to as measured values or waveform data). The pulse counting means 30 obtains the number of pulses of the input signal from the measured values stored in the memory 20, searches for a miss pulse whose pulse amplitude does not reach a predetermined magnitude, and measures the number of the miss pulses and their locations. . The display processing means 40 includes the memory 2
The measured value is read from 0 and displayed on the display unit 50 as a waveform, and the number of pulses and the position of the miss pulse obtained by the pulse counting unit 30 are displayed on the display unit 50.

The pulse counting means 30 will be described in more detail. As shown in FIG.
0 is composed of maximum / minimum value means 31, judgment value means 32, and judgment 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.

As shown in FIG. 4, the decision value means 32 has three values, Distal, Mesial, and Proximal, based on the maximum and minimum values obtained by the maximum and minimum value means 31. Find the level value. In addition, the distal, the mesial, and the proximity have the following relationships. Distal = (Max−Min) × a ÷ 100 + Min Mesial = (Max−Min) × b ÷ 100 + Min Proximal = (Max−Min) × c ÷ 100 + Min where a, b, and c are in the range of 0 to 100, respectively. , And in a relationship of a ≧ b ≧ c.

The judging means 33 judges the measured value of the memory 20 based on the values of the distance, mesial, and proximity, and obtains the number of pulses including a miss pulse and the location of the miss pulse.

The miss pulse in the present invention is defined as follows. The search for the rising edge of the pulse is as follows. In the normal rise, as shown in FIG. 5 (a), a point above the mesial is found once, and then a point above the distal is found. ). Such a pulse is referred to as a miss pulse.

In the search for the falling edge of the pulse, a pulse which once falls below the mesial like the third pulse in FIG. 5B but does not fall until the proximity but rises to the original level (Max) Is a mispulse.

Next, the principle of measuring the number of miss pulses according to the present invention will be described. The number of mispulses is measured as follows using reference lines of distal, mesial, and proximity. (1) A portion where a waveform crosses a line in the order of proximal → mesial → distal is defined as a rising edge. (2) Contrary to the above, a portion where the waveform crosses the line in the order of distal → mesial → proximal is defined as rising.

(3) Since rising and falling always exist alternately, it is determined that there is one pulse when rising and falling are detected one by one.
A portion which returns to the original level after the intersection of the mesial line as shown in FIG. Then, the number of the miss pulse and the count of the number of the miss pulse are obtained, the result is stored in the internal memory, and the result is displayed via the display processing means 40 after the completion of the entire search of the automatic measurement range. Is displayed on the monitor 50.

(4) Since the pulse is actually counted at the time of crossing the mesial line, FIG.
If there is a portion that intersects the mesial on the left side of the pulse train as shown in (a), it is determined that the signal rises, and if there is a portion that crosses the proximal or distal on the right side of the pulse train as shown in FIG. Judge as falling.

(5) Based on the above principle, 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. The position of the miss pulse is count 2.5 (meaning that it exists between the second and third pulses) in FIG. 7 and count 2 (meaning that it exists inside the second pulse) in FIG. ), And the counting result is displayed on the display unit 50.

The operation in such a configuration will be described next 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 end of the waveform acquisition, the pulse counting means 30 sets Max, Min, Distal,
The values of Mesial and Proximal are obtained, and then the measurement of miss pulse count is started by the following procedure.

First, it is determined whether or not the first data is between the proximity and the distal (step S2). If not, the process proceeds to step S4. In some cases, the data read from the memory is incremented until it becomes less than the proximity or more than the distal. In the case where there is an intersection with the mesial during that time, if the vehicle exits on the proximal side thereafter, it is counted that there is a fall, and if it exits on the distal side, it is counted that there is a rise (step S3).

In step 4, it is checked whether the head data is greater than the distal. If it is greater than the distal, the process proceeds to step S5, and if less than the distal, the process proceeds to step S9.

In step S5, the falling of the waveform is searched to count the number of mesial intersections. If the data is not completed, the rise is searched and the mesial intersection is counted (step S7). Steps S5 and S7 are repeated until the data ends, and when the intermediate data ends (steps S6 and S8), the process proceeds to step S13.

If it is determined in step S4 that the leading data is greater than the distal, the flow advances to step S9 to search for the rising edge of the waveform and count the number of mesial intersections.
If the data is not completed, the falling edge of the waveform is searched for and the mesial intersection is counted (step S1).
1). Steps S9 and S11 until the data ends
repeat. If the data has ended, the process proceeds to step S13.

In step S13, the rising and falling are regarded as one pair, and the number of pairs is counted.

As described above, the pulse counting means 30
Measures the mispulse. The measurement result is displayed by the display processing means 40.
Is displayed on the display device 50 via the. Step S5
And S11 for the falling edge of the waveform, steps S7 and S9
The details of the waveform rising search will be described below with reference to FIG. 10 and FIG.

(1) Operation for Counting Mesial Intersections by Searching for Fall (see FIG. 10) After detecting the distal intersection and the mesial intersection (steps S21 and S22), it is checked again whether or not the distance falls below the distal. (Step S23).

If the distance does not fall below the distal in step S23, the process ends after a proximity intersection is detected (step S28). If it is less than the distal, it is counted as a miss pulse (step S2).
4). In this case, it is checked whether or not the waveform has a falling edge (S25). If the waveform has a falling edge, the mispulse position is set to be the same as the current mispulse count value (step S26). If it is the rising edge, the position of the mispulse is calculated as the current pulse count value +
0.5 (step S27). Then, the process ends after a proximity intersection is detected (step S).
28).

(2) Operation for Counting Mesial Intersections by Searching for Rising (See FIG. 11) After detecting the proximity intersection and the mesial intersection (steps S31 and S32), it is determined whether or not the intersection has fallen below the proximity again. Check (step S33).

If it does not become less than or equal to the proximity in step S33, the process ends after detecting a distal intersection (step S34). If it becomes less than the proximity, it is counted as a miss pulse (step S
35). In this case, it is checked whether or not the beginning of the waveform is the rising edge (S36). If the beginning is the rising edge, the mispulse position is set to be the same as the current mispulse count value (step S37), and conversely, the falling edge is set. If so, the mispulse position is set to the current pulse count value + 0.5 (step S36). Then, the process waits until a distal intersection is detected (step S).
38).

The foregoing description has been directed to specific preferred embodiments for the purpose of describing and illustrating the invention. Therefore, the present invention is not limited to the above-described embodiments, and includes many more modifications without departing from the spirit thereof.
This includes deformation.

For example, the pulse counting means 30 is composed of three means of maximum and minimum value means 31, judgment value means 32 and judgment means 33. However, the present invention is not limited to such a structure, and has these functions. Any configuration is acceptable as long as it is present.

[0037]

As described above, according to the present invention, it is possible to easily obtain a miss pulse in response to a request to check the pulse count, which is less than the pulse count assumed for the measured waveform. If not, there are several miss pulses, and it can be automatically and accurately determined where they are.

[Brief description of the drawings]

FIG. 1 is a main part configuration diagram showing an embodiment of a digital oscilloscope according to the present invention.

FIG. 2 is a configuration diagram showing one embodiment of a 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 proximity.

FIG. 5 is an explanatory diagram of a miss pulse.

FIG. 6 is an explanatory diagram of determination of a rise and a fall of a pulse.

FIG. 7 is an explanatory diagram of a mispulse and a position where the mispulse exists.

FIG. 8 is an explanatory diagram of a mispulse and a position where the mispulse exists.

FIG. 9 is a flowchart illustrating an operation.

FIG. 10 is a flowchart for searching for a falling edge of a waveform.

FIG. 11 is a flowchart illustrating a search for a rising edge of a waveform.

FIG. 12 is a waveform diagram for explaining a conventional pulse counting function.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Measurement circuit 20 Memory 30 Pulse count means 31 Maximum / minimum value means 32 Judgment value means 33 Judgment means 40 Display processing means 50 Display

Claims (3)

[Claims] 1. A digital oscilloscope having a function of measuring a pulse signal to be measured, storing the waveform data in a memory, reading the waveform data, and displaying the waveform data on a display, wherein the waveform data read from the memory is read. A pulse counting means having a function of detecting a pulse from which the amplitude of the pulse does not reach a predetermined magnitude, and measuring the number and the position of the miss pulse, and displaying a measurement result of the pulse counting means. A digital oscilloscope comprising display processing means having a function of displaying on a filter. 2. The pulse counting means calculates a maximum value and a minimum value from waveform data in the memory, and calculates values of a distal, a mesial, and a proxy based on the maximum and the minimum values. 2. The digital oscilloscope according to claim 1, wherein a mispulse and a position where the mispulse is present can be obtained based on the value of the circle. 3. The pulse counting means according to claim 1, wherein
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 any values within the range of 0 to 100, respectively, and are obtained from the relationship of a ≧ b ≧ c. 3. The digital oscilloscope according to claim 2, wherein a falling pulse that is less than or equal to the value of the proximity is searched for as a mispulse.