JPH05126857A - oscilloscope - Google Patents

Abstract

PURPOSE:To obtain an oscilloscope which releases an observer from the trouble of a synchronizing operation, operates at a high speed, makes few errors and needs only a small memory capacity. CONSTITUTION:A filter and level comparator 13 for a sync signal which extracts main cycle components contained in a signal to be observed, and CPU 16, a memory 17 and a display circuit 18 which display waveforms of relevant cycle components of N kinds out of them and the information on the cycle components with which these waveforms are synchronous, on the same screen of CRT 19 at once, while executing automatically a changeover of synchronization and a sweep time to other cycle components of N kinds according to an input from an operating part 20, etc., are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oscilloscope for observing unspecified electric signals.

[0002]

2. Description of the Related Art Generally, in a measuring instrument for observing an unspecified electric signal, a user himself / herself analyzes characteristics of a waveform he / she wants to observe, and selects a synchronizing signal, component separation, waveform shaping conditions,
It was necessary to manually perform all operations such as timing adjustment.

[0003]

However, this synchronization operation requires a great deal of knowledge and has some contradictions. In other words, when it is necessary to observe electrical signals, the signals that are expected to be observed may be unpredictable. Therefore, it is inconsistent to infer and determine the synchronization conditions in advance for this, and beginners are contradictory. Not only becomes a seriously difficult problem for the user, but also it may lead to lack of validity in the judgment by measuring by an incorrect operation. For this reason, among recent measuring instruments, there are also those that read the completed operation setting from the operation panel and save it as data in the storage device.If the same operation can be set next time, Some are designed so that the data can be retrieved from a storage device and electronically set automatically. However, originally, as a measuring instrument for observing various unspecified electrical phenomena, there is a problem that it is practically useless with a limited number of condition memories.

The present invention solves such a conventional problem, and provides an excellent oscilloscope which relieves the observer from the trouble of synchronizing operation, is high-speed, has few errors, and has a small memory capacity. The purpose is to

[0005]

In order to achieve the above object, the present invention provides a means for extracting a main periodic component contained in an observed signal, and N types of periodic components among the extracted periodic components. For displaying the waveforms and information on which periodic components these waveforms are synchronized with on the same screen, and switching the synchronization time and sweep time to another N types of periodic components by input from the operation unit. And means for automatically performing.

[0006]

According to the present invention, since various periodic components in the signal to be observed can be automatically extracted and displayed for each of the related N types by the above configuration, the synchronization setting for an unspecified electric signal and Observation can be done easily. Further, since the processing can be basically performed by hardware, it has an excellent effect that it is fast and has few errors, the CPU and program software are simple, and the memory capacity is small.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of an embodiment of the present invention. In FIG. 1, 1 is CH1 input, 2 is CH1A
TT, 3 is CH1 channel amplifier, 4 is CH2 input, 5
Is CH2ATT, 6 is CH2 channel amplifier, 7 is external synchronization signal input, 8 is external synchronization signal ATT, 9 is external synchronization signal amplifier, 10 is CH1 and CH2 selection / addition circuit / signal amplifier / A / D converter, 11 CH1 and CH2 sync signal amplifier / sync signal selection circuit, 12 sync level voltage generation DAC, 13 sync signal filter / level comparator, 14 sync signal selection / sync pulse generation circuit / sync timing data extraction circuit, 15 is a bus, 16 is a CPU,
Reference numeral 17 is a memory, 18 is a display circuit, 19 is a CRT, 20 is an operation unit, and 21 is a sampling clock generation circuit.

Next, the operation of the above embodiment will be described.
The signal to be observed is applied to CH1 input 1 or CH2 input 4, and CH1ATT2 or CH is adjusted to the desired amplitude.
Adjusted with attenuator in 2ATT5. The outputs are applied to CH1 channel amplifier 3 or CH2 channel amplifier 6 respectively, and after the necessary amplification is performed, CH
1, CH2 selection / addition circuit, signal amplifier, A / D converter 10, and the selected or combined result becomes a digital signal in the A / D converter 10a, and a C signal is passed through the bus 15.
It is sent to the PU 16 and stored in the memory 17. On the other hand, the synchronization signal obtained from each of the channels CH1, CH2 inputs 1 and 4 or the external synchronization signal input 7 is selected by the CH1 and CH2 synchronization signal amplifier / synchronization signal selection circuit 11, and then the synchronization signal filter / level comparator. 13 is supplied. The comparison signal input terminal of the level comparator 13b is supplied with the comparison voltage from the synchronization level voltage generating DAC 12, and all the synchronous features included in the synchronization signal are passed through the synchronization signal filter 13a, It is extracted by varying the comparison voltage over the entire signal amplitude. Level comparator 1
The output of 3b has the synchronization timing information grasped by the high-speed synchronization signal selection / synchronization pulse generation circuit / synchronization timing data extraction circuit 14, sent to the CPU 16 as data through the bus 15, and stored in the memory 17. The waveform data stored in the memory 17 is supplied to the display circuit 18 according to the instruction of the CPU 16, and the extracted waveforms of four related periodic components are simultaneously displayed on the same screen of the CRT (CRT) 19. , Displayed 4
Information on the synchronization condition and the sweep time indicating which period component the type of waveform is synchronized with is also displayed. Also, if the displayed waveform is not what the observer wants, CP
U16 displays the waveform of four different types of periodic components managed as one set of data in the memory 17, the synchronization condition and the sweep time by key input regarding the synchronization condition and the sweep time from the operation unit 20 of the observer. Switch to display circuit 1
It is displayed on the screen of the CRT 19 through 8.

Next, the sync signal filter 13a and the level comparator 13b, which are means for extracting the main periodic components contained in the observed signal, which is one of the essential parts of the present invention, will be described. First, the extraction of the periodic component by the level comparator 13b will be described. In the synchronous operation of the oscilloscope, it is the most necessary work to extract the periodic features contained in the synchronous signal. FIG. 2 shows that the periodicity of a signal differs by changing the comparison voltage of the level comparator, using a television signal as an example. It is considered that the magnitude of the sync signal is now between the voltage levels Vu and _VL as shown in FIG. This synchronizing signal is applied to one input terminal A of a voltage comparator (level comparator) consisting of a pair of transistors as shown in FIG. 3, and a synchronizing level voltage for comparison is applied to the other input terminal B. If the output at this time is taken out from the output terminal C connected to the collector of the transistor Q2, the voltage level for comparison is shown in FIG.
As shown in the lower part of FIG. 2, the values of a, Vb, Vc, Vd, Ve, Vf, and Vg are changed as shown in FIG.
A signal having a waveform as shown at the positions of t, bt, ct, dt, et, ft, gt is obtained. The comparison voltage level is Va,
It can be seen that the outputs of Vb and Vg have clearly the same period but different pulse widths. Vc, V
The output corresponding to d, Ve, Vf contains the response to the color burst signal and is more complex. Therefore, in the range shown in FIG. 2, it can be seen that if the comparison voltage level is set to any of Va, Vb, and Vg, the periodic component suitable for synchronization can be extracted from the output of the comparator shown in FIG.

By the way, FIG. 2 does not include one screen of the television signal. Therefore, this figure alone cannot grasp the whole picture of the periodic signal of the television signal. FIG. 4 shows two screens of a television signal, and it can be seen that one screen has a width of about 33 milliseconds. That is, the repetition frequency of the screen is about 30 hertz. Since this one screen uses the interlaced scanning method, it is composed of two fields.
Therefore, the repetition frequency as a field is about 6
It becomes 0 hertz. Since this one screen consists of 525 lines, the line repetition frequency is about 1
It becomes 5750 hertz, and its period becomes about 63.5 microseconds. FIG. 2 shows this line signal in the range of five lines. Since the color burst signal for controlling the color signal is added in this one line, the partial highest frequency component is about 3.58 MHz which is the frequency of the color burst signal. That is, its period is about 280 nanoseconds.

As described above, communication signals in recent years have become very complicated, and when observing such a signal, it is impossible to set the synchronization condition in advance without sufficient knowledge. For example, the comparison output of this television signal with respect to the level voltages Va and Vb of the comparator shown in FIG. 3 is not limited to the characteristics shown by at and bt in FIG. 2, but the first field and the second field shown in FIG. A long pulse is generated during the blanking period of the television scanning signal existing between the field and the field. The state is shown in FIG.
Is.

In FIG. 5, Va, Vb, Vc, Vd,
Ve, Vf, and Vg are exactly the same as the voltages for voltage comparator comparison used in FIG. 2, and at, bt, and
ct, dt, et, ft, and gt also indicate outputs under exactly the same conditions. As can be seen from this figure, the comparison voltage level is V
If either a or Vb is set, the output becomes a simple pulse train, and no pulse change occurs during the field switching period. Therefore, if this output is passed through a low-pass filter, a signal component indicating the field repetition period can be obtained. On the contrary, if the sync signal is passed through a high pass filter before being applied to the comparator, the component of the color burst signal can be taken out, and if this signal is shaped by the comparator, its period can be measured. Therefore, in the present embodiment, in the level comparator 13b having the same configuration as the voltage comparator shown in FIG. 3, by changing the sync level voltage from the sync level voltage generating DAC 12 over the entire signal width, the observed The main periodic component is extracted from the signal.

Next, the details of the sync signal filter 13a for extracting the periodic components thus extracted by the level comparator 13b from different bands of the observed signal will be described. FIG. 6 shows the structure of the sync signal filter 13a. The sync signal filter 13a shown in FIG. 1 which receives the output of the CH1 and CH2 sync signal amplifier / sync signal selection circuit 11 as an input is usually realized as a kind of amplifier capable of selecting four types of frequency characteristics. The synchronizing signal inputs are added to the differential type filter circuit as TRIG IN + and TRIG IN- in the form of a differential signal while ensuring noise resistance. Transistors Q1 and Q2 are emitter followers as buffer amplifiers and drive the input impedance reduction of the filter circuit. Transistor Q3
Q4 is a grounded-emitter amplifier in which the feedback circuit between the emitters is formed only by resistors, and transistors Q5 and Q6 are grounded-emitter amplifier in which the feedback circuit between the emitters is formed by a large-capacity capacitor and resistance. Transistors Q7 and Q8 are A grounded-emitter amplifier, in which a feedback circuit between the emitters is formed of a small-capacity capacitor and a resistor, transistors Q9 and Q1
Reference numeral 0 is a grounded-emitter amplifier in which a feedback circuit between the emitters is formed of an inductance and a resistance. Each of the differential grounded-emitter amplifiers includes transistors Q15 and Q1.
6, Q17, Q18, Q19, Q20, or Q21 is registered in the register U1 according to an instruction from the control system such as the CPU 16.
The amplification function is provided by making only one set conductive at the output port.

When the transistors Q3 and Q4 are turned on by the conduction of the transistor Q15, the feedback circuit between the emitters is a grounded-emitter amplifier formed only of resistors, so that the amplifying action is performed over a wide band from the DC band. Will have. When the transistors Q5 and Q6 are activated by the conduction of the transistors Q16 and Q17, the direct current signal is cut off because the feedback circuit between the emitters is a grounded-emitter amplifier formed of a large-capacity capacitor and a resistor. Has an amplifying effect over a wide range from a very low frequency. Transistor Q1
When the transistors Q7 and Q8 are activated by the conduction of Q8 and Q19, the direct current signal is cut because the feedback circuit between the emitters is a grounded-emitter amplifier formed of a small capacity capacitor and a resistor. It has an amplifying effect only at a considerably higher frequency. Due to conduction of the transistors Q20 and Q21, the transistor Q9,
When Q10 is in an operating state, the feedback circuit between the emitters is a grounded-emitter amplifier formed of an inductance and a resistance, and therefore has an amplifying function from the DC band to a certain frequency.

Transistors Q11, Q12, Q13, Q
14 has a common emitter and has a base and a collector connected to each other, and has base control signals POL + and P
The polarity of the output can be reversed by applying opposite potentials to OL-. With this circuit, it is possible to select whether the position at which the sync pulse is generated is to be performed with the rising gradient or the falling gradient of the synchronizing signal. Capacitors C _F1 and C _F2 on the collector side of the transistors Q11, Q12, Q13, and Q14 and a diode CR _F1 ,
CR _F2 , CR _F3 , and CR _F4 are short-circuits in the high frequency region between the collectors of the transistors Q11, Q12, Q13, and Q14 by the capacitors C _F1 and C _F2 due to the conduction of the transistor Q22. Become. This filter is not only for the synchronous circuit system, but also for CH1,
CH2 selection / addition circuit, signal amplifier, A / D converter 10
It is often added to the inside of the, and is generally used when observing after removing noise in the high frequency region. The output thus obtained is the transistor Q23, Q
24, which supplies the output to the next stage while keeping the operating point constant by the feedback effect of the operational amplifier U2.

FIG. 7 shows a typical example of the frequency characteristic of this filter circuit. As an example of one having an amplifying action over a wide band from the DC band when the transistors Q3 and Q4 are in the operating state, 100 MHz is shown. The above shows a case where the amplifier is used, and is generally called DC coupling because it amplifies up to the DC band. Transistor Q
Although the DC signal when 5 and Q6 are in the operating state is cut, as an amplifier having an amplifying action from a very low frequency to a wide band, the low range is 10 Hz to the high range is 100.
This is an example of an amplifier up to MHz, and AC is meant to pass almost all AC components.
Called join. The DC signal when the transistors Q7 and Q8 are in the operating state is cut, and it has an amplifying function only at a considerably high frequency or higher. In the case where the low frequency band is an amplifier from 50 kHz to the high frequency band up to 100 MHz. In the sense that only high frequencies are passed, it is called HF coupling. As an amplifier having an amplifying function from the DC band to a certain frequency when the transistors Q9 and Q10 are in the operating state, an example in which the high band is up to 50 kHz is shown, which means that only the low band frequency is passed. It is called LF coupling.

FIG. 8 shows a difference in response when a signal having a constant amplitude but a different cycle (also called a pulse train) is passed through the above filter circuit. In the DC coupling, the signal is transmitted faithfully, but in the HF coupling, one of the change points exhibits the maximum value due to the differential action, while in the LF coupling, the integral action causes the maximum value near the end of the flat portion. It takes the form of a value. This allows the periodicity hidden in the signal to be extracted in all frequency bands by passing the input signal through this filter circuit.

FIG. 9 and FIG. 10 show means for specifically realizing the extraction of the spectrum by using these, and the output of the filter circuit is read by the sampling clock and a simple operation is performed on the read time series data. It is shown that the periodicity can be extracted by applying. In the DC coupling example, if the time-series sampling data of f (t) is delayed by one pulse and this is f (t−t _clk ), the polarity (gradient) of the change point can be known from the difference between these two data. The maximum and minimum positions can be found from the exclusive OR, and the points that represent the cycle can be found from the size comparison. As is clear from these figures, various periodic components can be grasped very clearly.

FIG. 11 shows an example of the spectrum thus obtained, showing the spectrum frequency of the television signal. Further, FIG. 12 is a schematic view of a signal waveform in the natural world represented by musical instruments and voices, and shows an example in which all high-frequency spectrums are formed by overtones of a basic repeating frequency. Therefore, it is very important to know the lowest repetition frequency.

In this embodiment, with respect to the main periodic components including the basic repetition frequency extracted by the sync signal filter 13a and the level comparator 13b in this way, the related periodic components of four types are described. The waveform, sweep time, and synchronization conditions are displayed on the same CRT screen at one time, and the observer can arbitrarily select the waveform of the group that the observer wants most from among them. is there. FIG. 13 shows a screen display example of a television signal in the present embodiment, and shows the sweep time (time axis) and the value of the repetition frequency (synchronization condition) for each waveform. It is managed in the memory 17 as data. Obviously, the observer understands that all of the waveforms in FIG. 13 are correct waveforms, but the most necessary thing is to be able to display the screen that the observer wants. Therefore, if the observed waveform automatically displayed by the machine does not fit the purpose, the observer moves the marker to a desired spectrum using a key on the panel surface of the operation unit 20 and the CPU 16 causes the memory 17 to move. The necessary waveform data is extracted from the inside, and the waveform of the group most desired by the observer is displayed on the screen of the CRT 19 through the display circuit 18.

[0021]

As is apparent from the above-described embodiment, the present invention provides means for extracting main periodic components contained in the signal to be observed and N types of periodic components among the extracted periodic components. A means for displaying on the same screen information about waveforms and which periodic components these waveforms are synchronized with,
Since a means for automatically synchronizing with another N kinds of periodic components and switching the sweep time by means of an input from the operating section is provided, the observer can be relieved from the trouble of the synchronizing operation and the related operation can be performed. It is possible to observe N kinds of periodic components that are used at one time, and it is possible to realize an oscilloscope having high universality that is not restricted by a specific signal. Also,
Since the processing is basically performed by hardware, there are excellent effects that the processing speed is high, there are few errors, the CPU and program software are simple, and the memory capacity is small.

[Brief description of drawings]

FIG. 1 is a block diagram of an oscilloscope showing an embodiment of the present invention.

FIG. 2 is a signal waveform diagram showing a difference in generation of a sync pulse due to a difference in sync level voltage in one embodiment of the present invention.

FIG. 3 is a block diagram of a voltage comparator corresponding to a level comparator for extracting a periodic component according to an embodiment of the present invention.

FIG. 4 is a signal waveform diagram showing the complexity of periodic components seen in a television signal according to an embodiment of the present invention.

FIG. 5 is a signal waveform diagram showing a difference in generation of sync pulses corresponding to a difference in sync level when a television signal is viewed in a wide range in one embodiment of the present invention.

FIG. 6 is a block diagram of a sync signal filter according to an embodiment of the present invention.

FIG. 7 is a frequency characteristic diagram of a sync signal filter according to an embodiment of the present invention.

FIG. 8 is a signal waveform diagram showing the difference in response depending on the coupling type of the sync signal filter in the embodiment of the present invention.

FIG. 9 is a signal data diagram showing the difference between the sampled data and the calculation result from the difference in response due to the coupling type of the sync signal filter in the embodiment of the present invention.

FIG. 10 is a signal data diagram showing the difference in the sampled data and the difference in the operation result from the difference in the response depending on the coupling type of the sync signal filter in the embodiment of the present invention.

FIG. 11 is a frequency characteristic diagram showing an example of spectrum frequencies included in a synchronization signal obtained by the synchronization signal filter according to the embodiment of the present invention.

FIG. 12 is a frequency characteristic diagram showing an example of a waveform and a spectrum of a periodic signal in the natural world found in a musical instrument or the like in an embodiment of the present invention.

FIG. 13 is a display screen diagram showing an example of a CRT display screen in one embodiment of the present invention.

[Explanation of symbols]

1 CH1 input 2 CH1ATT 3 CH1 channel amplifier 4 CH2 input 5 CH2ATT 6 CH2 channel amplifier 7 external synchronization signal input 8 external synchronization signal ATT 9 external synchronization signal amplifier 10 CH1, CH2 selection / addition circuit / signal amplifier / A
/ D converter 11 CH1, CH2 sync signal amplifier / sync signal selection circuit 12 sync level voltage generation DAC 13 sync signal filter / level comparator 13a sync signal filter 13b level comparator 14 sync signal selection / sync pulse generation circuit・ Synchronization timing data extraction circuit 15 Bus 16 CPU 17 Memory 18 Display circuit 19 CRT 20 Operation unit 21 Sampling clock generation circuit

Claims (1)

[Claims] 1. A means for extracting main periodic components contained in an observed signal, and waveforms of N types of periodic components in the extracted periodic components and which waveforms these waveforms are synchronized with. An oscilloscope having means for displaying information on the same screen and means for automatically synchronizing with another N types of periodic components and switching the sweep time by input from the operation unit.