## What is Capacitor (C)? - Definition

by Dinesh Thakur Category: DIGITAL CONCEPTS

Definition: Capacitor or Condenser is an insulating medium that can separate two conducting surfaces.The insulating medium is called dielectric constant or relative permittivity of the material. Most commonly used dielectric materials in the capacitor are air, mica, and paper, ceramic, plastic.

## What is Resistance? - Definition

by Dinesh Thakur Category: DIGITAL CONCEPTS

Definition: Resistance (Represented by R) offers hindrance to the flow of current in an electrical circuit. It is measured in ohms, which is named after its developer George Simon Ohm. He is a German physicist, who has studied the relationship between voltage, current and resistance and tells us that when one volt of voltage is applied across the component and one ampere of current is passed through it, then the resistance offered by that component is one ohm. The symbol used for resistance is the Greek letter omega (Ω).

## what is diode | diode definition

by Dinesh Thakur Category: DIGITAL CONCEPTS

Definition: A diode is an electronic component that allows the flow of current in only one direction and when the current flows in the other direction, then it blocks the current. The name diode is derived from the word “di-ode” which means that a device having two electrodes. Thus, a diode has two electrodes one electrode is known as the anode and the other electrodes are known as the cathode.

## Direct Sequence Spread Spectrum - DSSS

by Dinesh Thakur Category: DIGITAL CONCEPTS

The DSSS (Direct Sequence Spread Spectrum) is a technique spread spectrum, but unlike the FHSS, no frequency hopping is place: DSSS causes very rapid state transitions (chipping) which tend to spread the spectrum of the signal: in fact, we have seen that with the modulations FSK, PSK and QAM width of the spectrum was twice the rate of the source. Causing "artificially" very high throughput, spectrum is spread.

## Frequency Hopping Spread Spectrum (FHSS)

by Dinesh Thakur Category: DIGITAL CONCEPTS

The FHSS (Frequency Hopping Spread Spectrum) was invented and patented in 1942 by the actress Hedy Lamarr and pianist George Antheil, which were quite versatile! The principle of FHSS is quite simple: a wide frequency band is divided into multiple channels and communications are jumping (hopping) sequentially from one channel to another in a sequence and a rate agreed to advance between the transmitter and the receiver.

## Type of Radio Modulations

by Dinesh Thakur Category: DIGITAL CONCEPTS

## The basic modulations

### No modulation

Take the example of an opera broadcast on a radio station: how music, that is to say, an audio signal, it may be channeled through wave electromagnetic? Audible sound waves have frequencies between 20 Hz to 20 kHz for bass and treble. It would be tempting to simply convert the sound wave in radio waves of the same frequency. Unfortunately, there would be several problems: first, the low radio frequencies also are very difficult to produce and capture; then two simultaneous radios would overlap since they would be issued on the same frequency band (20 Hz to 20 kHz) and would cacophony.

## What is Boolean Logic?

by Dinesh Thakur Category: DIGITAL CONCEPTS

This was first created by an English mathematician named George Boole in 1847 and yet, in one of the strange quirks of the computer industry, is now used in everything from circuit design to searching the Internet. In essence Boole developed a system for reducing complex questions into simple yes or no answers by using what are known as truth tables, sometimes called gates.

## What is MOSFET (Metal Oxide Semiconductor Field- Effect Transistor)?

by Dinesh Thakur Category: DIGITAL CONCEPTS

(Metal Oxide Semiconductor Field- Effect Transistor) The fundamental building block of modern VLSI chips such as microprocessors and memory chips. A microscopically small FIELD-EFFECT TRANSISTOR formed on the surface of a prepared silicon wafer by exposing it to a succession of chemical treatments through a sequence of masks.

## What is Flip-flop?

by Dinesh Thakur Category: DIGITAL CONCEPTS

A digital logic circuit that can store a single BIT of information, and is therefore used as the basis for the construction of MEMORY chips, LATCHES and the REGISTERS within processors. A flip-flop can exist in two states, with either a high or low voltage at its output, and flips from one state to the other at each pulse of a CLOCK SIGNAL. Two different implementations of flip-flop are commonly used, called the D flip flop and the j-K flip flop.

## What are DIP switches?

by Dinesh Thakur Category: DIGITAL CONCEPTS

DIP switches are those nasty, tiny plastic toggle switches that come mounted together in a row on a little box-like part attached to your computer's motherboard or on some of your add-in boards. Each individual switch in a DIP switch unit can be set either on or off, allowing you to control some aspect of your computer's function. For example, on the older IBM pcs and compatibles, you had to set the DIP switches to match the amount of memory installed in your computer, to tell it what kind of monitor you had, and so on. On the add-in modem board I just installed, I had to flip some of the DIP switches so the computer would know where to find the board electronically.

## What is DIP (dual inline package)?

by Dinesh Thakur Category: DIGITAL CONCEPTS

DIP is an acronym that stands for dual inline package and refers to the physical layout of most computer chips. The standard chip looks like a bug, or a little rectangular box with legs. Those two rows of metal legs are the "pins" that connect the chip to the computer's circuits. The whole chip is referred to as a "package," and it's a dual inline package because the pins are lined up in two rows.

## What is chip?

by Dinesh Thakur Category: DIGITAL CONCEPTS

A chip is that truly amazing and remarkably tiny piece of silicon that has an entire integrated electronic circuit embedded within it. Chips are what make the computer. Chips are the computer. A tiny chip is one of the biggest pieces of human-made magic on earth. There are different kinds of chips, the most common being the microprocessors which run the whole computer, and memory chips, in which the computer holds and works with your information until you send it to a disk.

## What is breadboard?

by Dinesh Thakur Category: DIGITAL CONCEPTS

A breadboard is a thin board, sometimes fiberglass and sometimes plastic, with lots of little holes arranged in a grid. Electronics engineers use breadboards to create prototypes of circuit boards by wiring chips, resistors, and other electronic parts onto the board by hand, with the connecting wires running underneath. The term sometimes refers to the finished prototype itself, but more often it's applied to the hole-filled board to which the electronic components are attached.

## What is Boolean expression or Boolean logic?

by Dinesh Thakur Category: DIGITAL CONCEPTS

Boolean logic A formal logic system derived from the BOOLEAN ALGEBRA by interpreting its two permissible values 0and 1 as the TRUTH VALUES True and False. It is used in electronics to define the behavior of all the kinds of LOGIC GATE from which computer processors are constructed, and in programming to define operators that work on truth-valued variables.

## What is analogue-to-digital converter?

by Dinesh Thakur Category: DIGITAL CONCEPTS

Analogue-to-digital converter (AID converter, ADC) An important type of electronic circuit that inputs an ANALOGUE signal and outputs a stream of bits that reproduces that input signal in the digital domain. Conversion involves sampling the strength of the input signal at very short intervals and expressing the sampled value as a binary number. ADCs are widely employed in electronic equipment of many kinds, including digital cameras and camcorders, telephones and MODEMS, and the SOUNDCARDS used in personal computers.

## What is analogue or analog?

by Dinesh Thakur Category: DIGITAL CONCEPTS

1. A physical object or quantity, for example a moving clock hand or an electrical voltage, that is used to measure or represent some other quantity, and is hence analogous to it.

2 A family of electronic devices that represent other physical quantities by continuously varying voltages rather than the two discrete voltage levels used in DIGITAL devices.

## What are Amplitude and Amplitude modulation?

by Dinesh Thakur Category: DIGITAL CONCEPTS

Amplitude Size, magnitude, extent. When used of a WAVEFORM it refers to the height of the wave, measured from top to bottom of the following trough.

## What is amplifier?

by Dinesh Thakur Category: DIGITAL CONCEPTS

An electronic circuit that increases the amplitude of its input signal and outputs the result. The most familiar type is the audio amplifier, as found in domestic hi fi or telephones, but amplifiers are to be found in every sort of device, including silicon chips:

## What is alternating current (AC)?

by Dinesh Thakur Category: DIGITAL CONCEPTS

An electrical current that periodically reverses its direction. The electrical mains supply is an alternating current that varies in a sinusoidal fashion, reversing itself 50 times per second in the UK and Europe, and 60 times per second in the USA.

## What is analog-to-digital conversion (ADC)?

by Dinesh Thakur Category: DIGITAL CONCEPTS

A-to-D conversion (analog-to-digital conversion) is the process of converting analog information from life into digital information that a computer can understand. Most information in nature is in analog form, covering a continuous range of values (such as the passing of time, as exemplified by the hands of a regular clock).

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