JPS63300968A - Digital oscilloscope - Google Patents

Abstract

PURPOSE:To display the envelope of an input signal even by slow sweeping by sampling an observation signal at time corresponding to a random phase. CONSTITUTION:The observation signal from an input terminal IN is sampled and held 2 through an amplifier 1 and its amplitude is converted by an A/D converter 3 into a digital value, which is stored in a memory 7. When the sampling time from a clock generator 4 is reported to a sampling clock generator 6, the generator 6 generates a sampling clock delayed by time based upon a random signal from a random signal generator 5 and supplies it to a circuit 2. Further, the generator 4 supplies the sampling time as an address of the memory 7 and a waveform display part 8 displays a waveform by setting the amplitude digital value of data stored in the memory 7 on a vertical axis V and the address on a horizontal axis H. Therefore, when the input signal period is smaller than the sampling period, the input signal can be sampled at time corresponding to a random phase, so the envelope of the input signal can be displayed even by slow sweeping.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an oscilloscope that can directly visually observe changes in voltage, current, etc. as static waveforms, and in particular samples input signals to be observed and converts them into digital values. This invention relates to a digital oscilloscope that stores input signals as a waveform and displays them on a display screen as an input signal waveform based on the digital values.

[Conventional technology]

Digital oscilloscopes are now widely used, and have advantages over traditional analog (storage) oscilloscopes, such as the memorized screen that does not fade and the ability to trigger at a point before an event occurs. It has excellent points.

Conventional digital oscilloscopes sample the input signal to be observed based on a clock signal with a precise period, convert the amplitude from an alog to a digital value, and store the digital value in a digital format. The digital value of amplitude is plotted on the vertical axis of the waveform display section, and the sampling time is plotted on the horizontal axis.

[Problem that the invention seeks to solve]

In the conventional digital oscilloscope described above, the frequency at which the input signal is sampled is accurately determined based on a lock signal, and the number of points on the time axis that can be displayed on one display screen is finite. , when a signal with a sufficiently short period relative to the displayed time length is input, as shown in Figure 3, from the sampling theorem,
It has the disadvantage that it is displayed as signals with different frequencies (periods). In FIG. 3, A is an input signal, B is a sampling clock, and C is a display waveform.

In addition, even if you try to observe the amplitude fluctuation in 1 second of 1l (NZ sine wave), the number of sampling times per second is 1.
000 times, that is, if the sampling period is 1 ms, only the points of the same phase of the sine wave are sampled, so a waveform similar to that of a direct current is displayed on the display screen, and there is a drawback that fluctuations in amplitude cannot be observed.

An object of the present invention is to provide a digital oscilloscope that can display the envelope of an input signal even when the sweep speed on the time axis is low relative to the frequency of the input signal.

[Means for solving problems]

The digital oscilloscope of the present invention inputs and samples a signal to be observed, converts the sampled value into a digital value and stores it, and displays the waveform of the observed signal based on the stored digital value. - The oscilloscope is characterized in that it includes means for sampling the observation signal at random period shifts.

[Effect]

Therefore, according to the present invention, since the clock signal is sampled and held using a sampling clock signal in which the clock signal is perturbed by a random signal, it is possible to sample at a time corresponding to a random phase with respect to the observation input signal. Even when the time axis sweep speed is low, the envelope of the input signal can be displayed.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment according to the present invention.

As shown in FIG. 1, the input signal to be observed is input to the input terminal I.
A sample signal is input to the vertical component amplifier 1 via N.
Hold circuit 2 and analog/digital converter 3
are connected in series, and the data of the digital value of the amplitude which is the output of the analog-to-digital converter 3 is stored in the memory 7.

On the other hand, the clock generator 4 is replaced with a random signal generator 5. which is a dither (perturbation) signal. It is connected to the sampling clock generator 6 and the analog/digital converter 3, and also to the memory 7, and the sampling time by the clock is inputted as an address of the memory 7.

The random signal generator 5 is connected to a sampling clock generator 6, which outputs its sampling clock to the sample and hold circuit 2.

The memory 7 is connected to a waveform display section 8, and displays the waveform with the amplitude digital value of the data stored in the memory 7 as the vertical axis ■ and the address as the horizontal @H.

Next, the operation shown in FIG. 1 will be explained. observed input signal a
is amplified to an appropriate level by an amplifier 1, amplified by a sample-and-hold circuit 2, and the amplitude is converted into a digital value by an analog-to-digital converter 3, which becomes data in the memory 7.

On the other hand, the sampling clock generator 6 is informed of the sampling time by the clock generator 4, and also outputs a sampling clock which is delayed from the sampling time by a time corresponding to the random signal output from the random signal generator 5. b is generated and supplied to the sample and hold circuit 2.

Note that the clock generator 4 also supplies the main clock to the analog-to-digital converter 3, and also supplies the sampling time as an address to the memory 7.

The waveform display unit 8 displays the waveform with the address of the memory 7 as time @ (horizontal axis H) and data as the amplitude axis (vertical axis ■).

According to the embodiment, as shown in FIG. 2, since the sampling clock b can sample at a random phase with respect to the period of the input signal a, the displayed waveform C is almost the same as that of an analog type (storage) oscilloscope. become.

To summarize the above-mentioned embodiments, if the period of the input signal is shorter than the sampling period, it is possible to perform sampling at a time corresponding to a random phase with respect to the input signal. It can also display the envelope of the input signal.

〔Effect of the invention〕

As explained above, the present invention can sample the input signal to be observed at times corresponding to random phases, so even when the sweep speed on the time axis is low relative to the input frequency, the envelope of the input signal can be It has the effect of displaying.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG.
The figure is a waveform diagram explaining the same as the above, and FIG. 3 is a waveform diagram showing a conventional example. DESCRIPTION OF SYMBOLS 1...Amplifier, 2...Number hold circuit, 3...Analog-digital converter, 4...Clock generator, 5...Random signal generator, 6...Sampling clock generator , 7... Memory, 8... Waveform display section. 2nd cause diagram 3

Claims (1)

[Claims] 1) inputting and sampling a signal to be observed, converting the sampling value into a digital value and storing it;
A digital oscilloscope that displays the waveform of the observed signal based on the stored digital value, characterized in that the digital oscilloscope is equipped with means for sampling the observed signal at random period shifts. oscilloscope. 2) The observation signal random sampling means includes a clock generator, a random signal generator controlled by the clock generator, and a sampling clock generator controlled by the clock generator and the random signal generator. A digital oscilloscope according to claim 1, each comprising: