Want to use the oscilloscope well, get these basic knowledge

Waves exist in nature in all forms, such as ocean waves, earthquakes, sound waves, explosions, sounds traveling through the air, or the natural rhythms of the body. Energy, vibrating particles, and invisible forces are everywhere in the physical world. Even light (a wave-particle duality) has its own frequency and appears in different colors depending on the frequency.

Oscilloscope

An oscilloscope is a must-have for anyone who designs, manufactures, or repairs electronic equipment. In today's fast-paced world, engineers need the best tools to solve measurement problems quickly and accurately.

The use of oscilloscopes is not limited to electronics. Oscilloscopes use signal converters and are applicable to a wide variety of physical phenomena. Signal converters can respond to various physical excitation sources and convert them into electrical signals, including sound, mechanical stress, pressure, light, and heat. Microphones are signal converters that convert sound into electrical signals. An example of scientific data collected by an oscilloscope is shown in Figure 1.

What is an oscilloscope and how does it work?

An oscilloscope is a waveform display instrument that can visually display the change of signal amplitude over time. It is a comprehensive signal characteristic tester and a basic electronic measuring instrument that depicts the graphical curve of electrical signals. In most applications, the displayed graph can show the change process of the signal over time: the vertical (Y) axis represents voltage, and the horizontal (X) axis represents time. Sometimes brightness is called the Z axis. (See Figure 2)

Types of Oscilloscopes

Electronic devices can be divided into two categories: analog devices and digital devices. Analog devices process voltage changes continuously, while digital devices process discrete binary codes that represent voltage samples. A traditional record player is an analog device, while a CD player is a digital device.

Similarly, oscilloscopes can be divided into analog and digital types. Both analog and digital oscilloscopes are capable of handling most applications. However, for some specific applications, each type has its own advantages and disadvantages due to their different characteristics. For further classification, digital oscilloscopes can be divided into digital storage oscilloscopes (DSO), digital phosphor oscilloscopes (DPO) and sampling oscilloscopes.

Analog Oscilloscope

Essentially, an analog oscilloscope works by measuring the voltage of a signal directly and plotting it vertically by moving an electron beam across the oscilloscope screen from left to right. The oscilloscope screen is usually a cathode ray tube (CRT). The electron beam is projected onto a certain part of the screen, and there is always a bright fluorescent substance behind the screen. As the electron beam sweeps horizontally across the display, the voltage of the signal is reflected directly onto the screen by the electron beam deflecting up and down, tracing the waveform. The more often the electron beam is projected onto the same part of the screen, the brighter the display will be.

The CRT limits the frequency range of the analog oscilloscope display. At very low frequencies, the signal appears as a bright, slow-moving dot, and it is difficult to distinguish the waveform. At high frequencies, the limiting factor is the CRT's write speed. When the signal frequency exceeds the CRT's write speed, the display is too dim to observe. The limit frequency of an analog oscilloscope is about 1CHz.

When the oscilloscope probe is connected to the circuit, the voltage signal passes through the probe to the vertical system of the oscilloscope. Figure 13 describes how an analog oscilloscope displays the measured signal. After setting the vertical scale (the volts/division control), the attenuator can reduce the voltage of the small signal, while the amplifier can increase the signal voltage. The signal is then directly sent to the vertical deflection plates of the CRT. The voltage applied to these vertical deflection plates causes the dot to move across the screen. The dot is produced by an electron beam hitting the phosphor inside the CRT. A positive voltage causes the dot to move upward, while a negative voltage causes the dot to move downward.

Digital Oscilloscope

与模拟示波器不同，数字示波器通过模数转换器（ ADC）把被测电压转换为数字信息。它捕获的是波形的一系列样值，并对样值进行存储，存儲限度是判断累计的样值是否能描绘出波形为止。随后，数字示波器重构波形。

Digital oscilloscopes are classified into digital storage oscilloscopes (DSO), digital phosphor oscilloscopes (DPO) and sampling oscilloscopes. The digital means that within the display range of the oscilloscope, waveforms of any frequency can be displayed stably, brightly and clearly. For repetitive signals, the bandwidth of a digital oscilloscope refers to the analog bandwidth of the front-end components of the oscilloscope, generally referred to as the 3dB point. For single pulses and transient events, such as pulses and step waves, the bandwidth is limited to the flesh of the oscilloscope sampling rate.