4 Research of Waveformelectrical signal

Visual, or visual reproduction of the form of oscillations is an important task of radio measurements, since the form allows you to immediately evaluate many parameters of oscillations. One of the main instruments used for visual observation and study of the shape of electrical signals is an oscilloscope (from the Latin. "Oscillo" - oscillation and the Greek. "Grafo" - I am writing). Most modern oscilloscopes in use are equipped with a cathode ray tube (CRT) and are called cathode ray oscilloscopes. However, in the latest developments of oscilloscopes, matrix display panels are used as display devices - gas-discharge, plasma, liquid-crystal, solid-state, etc.

An electron beam oscilloscope is a measuring instrument for visual observation in a rectangular coordinate system of electrical signals and measuring their parameters. Using the oscilloscope, periodic continuous and pulsed signals, non-periodic and random signals, single pulses are observed and their parameters are estimated. Most often, an oscilloscope is used to observe the dependence of voltage on time, and, as a rule, the axis of time is the abscissa axis, and the ordinate axis reflects the signal level. On the images obtained on the oscilloscope screen, you can measure the amplitude, frequency and phase shift, the parameters of the modulated signals and a number of other indicators. On the basis of the oscilloscope created devices for the study of transition, frequency and amplitude characteristics of various radio devices.

For many purposes, developed and used various types of electron-beam oscilloscopes: universal, high-speed, strobe, storage, special, etc. Differing in technical characteristics, circuit and design solutions, these oscilloscopes use the general principle of obtaining oscillograms. The possibility of observing the form of the signal under study and the simultaneous measurement of its parameters and characteristics push the electron-beam oscilloscope into the category of universal instruments.

The most widely used universal oscilloscopes , allowing to investigate electrical signals with a duration of from nanoseconds to several seconds in the amplitude range from fractions of millivolts to hundreds of volts, as well as measure the parameters of such signals with acceptable for practice error (5 ... 7%). The bandwidth of the best universal oscilloscopes is 300 ... 500 MHz and more.

Repeated short-term processes are examined using stroboscopic oscilloscopes . According to the principle of operation, stroboscopic oscilloscopes are referred to devices with time scale conversion and are distinguished by high sensitivity and a wide (up to 10 GHz) working band.

Storage oscilloscopes with special CRTs have the ability to store and reproduce the signal image for a long time after it disappears at the input. The main purpose of storage oscilloscopes is the study of single and rarely repetitive processes. Storage oscilloscopes have almost the same characteristics as the universal ones, however, they are distinguished by enhanced functionality.

Special oscilloscopes are equipped with additional target units. These include television oscilloscopes, which make it possible to observe the video signal of a given image line, and digital ones, which make it possible not only to observe the signal, but also to transmit it in digital form to a computer for further processing. Special oscilloscopes supply with multimeters, allowing to measure voltages, current strength and resistance, as well as devices for studying the current-voltage characteristics of semiconductor devices.

By the number of signals simultaneously observed on a CRT screen, single-channel and multichannel oscilloscopes are distinguished . The combination of images of several input signals on the screen is realized either by using a special multi-beam felling, or by periodically switching signals to different inputs using an electronic switch.