Electronics Notes: Analog

Tuesday, 13 August 2019

Analog August 13, 2019

Features of the analog voice

Features of the analog voice
The analog is defined as a signal that has amplitude or frequency continuously and smoothly diverse. What a person says, and everything else you hear, that is in the analog form, and the early telephone systems were analog too. Analog signals are often represented as smooth sine waves, but they express and other signals are more complex than that, since they contain many frequencies. The figure in the analog voice measurement section shows the typical distribution of energy in the voice signals.

The vertical axis is relative energy and the horizontal not horizontal axis is frequency. The figure in the analog voice measurement section shows that speech frequencies that contribute to speech can range from below 100 hertz to over 6000. However, most of the energy required for intelligible language is contained in a frequency band between 200 and 4000.

To eliminate unwanted signals (noise) that may disturb conversations or cause errors in control signals, the circuits that carry the telephone signals are designed to pass only certain frequencies. The frequency ranges are passed that are reputed in the pass band. Zero to 4000 hertz are the pass band of a channel of the VF channel-one of the Voice of the telephone system. (Sometimes this band is called a message channel.) Bandwidth is the difference between the upper limit and the lower limit of the pass band. Therefore, the bandwidth of the VF channel is 4k hertz. However, voice transmission does not require the entire VF channel. They restrict the band of passage of the Voice to 300 to 3300 hertz. Therefore, any signal continued the telephone circuit that is within the range of 300 to 3300 Hz is called an in-band signal. Any signal that is not within the 300 to 3300 Hz bands, but is within the VF channel, is called an out of band signal. All vocal signals are in-band signals. Some some signaling trans-missions are in -band and some are out of band.

Ravi Rana 0

Analog August 13, 2019

Electronics

Electronics

Electronics is, without a doubt, the fastest growing science of recent decades. This is because it has penetrated virtually all fields of human activity. Thanks to electronics, we enjoy digital clocks, cell phones, computers, televisions, video games, sound equipment and an endless list of products that have forever changed the way we live, work and interact with others.

Electronics and electronic systems are practical applications of the general principles of electricity. Electricity is a form of energy caused by the movement of tiny particles called free electrons. These particles, when circulating massively through certain materials, constitute electrical currents and produce important physical effects such as light, heat, movement, sound, magnetism, etc. Electronics deals primarily with the control of electric currents and, therefore, the effects produced by them. In other words, electronics is the science of domestication of electrons. Modern electronics have been driven primarily by the development of components to manipulate electric current in many different ways. Some of these components have been key in this process. The first one, which represented the passage from the electric age to the electronic era, was the vacuum tube or bulb, invented in 1906. Subsequently, the transistor (1948), the integrated circuit (1962), the microprocessor (1974) and the microcontroller (1982).

It is common that when a person wants to enter the fascinating world of electronics, they do not know what they should learn, what topics to master and, in what general order to cover those topics. A good starting point to get an idea of what is important to learn and in what order, is shown in Figure 2. This diagram provides an overview of the basic elements involved in the design of electronic devices.

At the top of the image comes the theory. This involves learning about voltage, current, resistance, capacitance, inductance, and various laws and theorems that can help you predict the size and direction of voltages and currents within circuits. As you learn the basic theory, you will know passive components such as resistors, capacitors, inductors, and transformers.

Next on the line come discrete passive circuits. These include current limiting networks, voltage dividers, filters, dimmers and so on. These simple circuits, by themselves, are not very interesting, but they are vital ingredients in much more complex circuits.

Having learned about passive components and circuits, he goes on to discrete active devices, which are constructed from semiconductor materials. These devices consist primarily of diodes (one-way current flow gates), transistors (electrically controlled switches / amplifiers), and thyristors (electrically controlled switches only).

Once you have covered the discrete active devices, continue with the discrete active / passive circuits. Some of these include rectifier circuits (ac-dc converters), amplifiers, oscillators, modulators, mixers, and voltage regulators.

To make things easier for the circuit designer, manufacturers have created integrated circuits (ICs) that contain discrete circuits - such as those mentioned in the last paragraph - which are placed inside a small silicone chip. The chip is usually inside a plastic package, where tiny internal wires connect the chip to the external metal terminals.

Ravi Rana 0