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Electromagnetic Interference Testing | Troubleshooting Techniques

Troubleshooting Techniques Electromagnetic : Some of the main duties of a communication expert are to troubleshoot, service, and maintain communication equipment. Most communication equipment is relatively reliable and requires little maintenance. However, equipment does fail. Most electronic communication equipment fails because of on-the-job wear and tear. Of course, it is still possible for…

Communication Test Equipment | RF Voltmeters | Power Meters

Communication Test Equipment This section gives a broad overview of the many different types of test instruments available for use with communication equipment. It is assumed that you already know basic test and measurement techniques used with conventional low-frequency test equipment, such as multimeters, signal generators, and oscilloscopes. In your communication work, you will continue to…

Communication Tests | Fiber-Optic | Antenna and Transmission Line Tests

Common Communication Tests Hundreds, even thousands, of different tests are made on communication equipment. However, some common tests are widely used on all types of communication equipment. This section summarizes the most common tests and measurements made in the servicing of communication equipment. Most of the tests described here focus on standard radio communication equipment. Tests for…

Electronic Emission Quiz | Mcqs Of basic Electronics

Electronic Emission Test is started What is Electron Emission ? Electron Emission:- As we know the valence electrons of the conductor atoms are loosely attached to the atomic nuclei. At room temperature, the thermal energy in the conductor is enough to break the bonds of the last valence electrons and leave them free to any one nucleus. These unbound electrons move at random within the…

Infrared Wireless | Ultra wideband Wireless | Multiband OFDM UWB

Infrared Wireless Perhaps the most widespread wireless system uses infrared light for short-distance data communication. The most ubiquitous example is the wireless remote control on virtually all TV sets, DVD players, and most audio CD stereo systems. This standard feature on most consumer electronic products is so common that it is taken for granted. Infrared has also been used for wireless…

Wireless LAN | IEEE 802.11b | PANs | Bluetooth | ZigBee | WiMAX

Wireless LAN Wireless LANs are more commonly referred to by their trade name Wi-Fi. The terms Wi-Fi, WLAN, and 802.11 are used interchangeably in this text. Local-area networks (LANs) within a company, government agency, hospital or other organization typically use CAT5 or CAT6 unshielded twisted pair as the transport medium. However, more and more, wireless extensions to these LANs are becoming…

LTE Cellular Systems | 4G | 5G | Data Rate | TD-LTE | Voice over LTE

Long Term Evolution ( LTE ) and 4G Cellular Systems Long Term Evolution (LTE) is the wireless cellular technology that is being adopted around the world as the primary cell phone communications service. Multiple 2G and 3G cellular radio methods are heading toward phase-out as carriers build their new LTE networks. It will be years before this expansion is complete, and the older radio…

Cellular Telephone | Duplexing | 2G & 3G | EDGE | GPRS | WCDMA

Cellular Telephone Systems A cellular radio system provides standard telephone service by two-way radio at remote locations. Cellular radios or telephones were originally installed in cars or trucks, but today most are handheld models. Cellular telephones permit users to link up with the standard telephone system, which permits calls to any part of the world. The Bell Telephone Company division…

Transistor complete info | Common Base | Common Emitter | Collector

What is Transistor ? When a third doped element is added to a crystal diode in such a way that two pn junctions are formed, the resulting device is known as a transistor. The transistor—an entirely new type of electronic device—is capable of achieving amplification of weak signals in a fashion comparable and often superior to that realised by vacuum tubes. Transistors are far smaller than vacuum…

WDM ( Wavelength-Division Multiplexing ) | Passive Optical | Transport

Wavelength-Division Multiplexing WDM : Data is most easily multiplexed on fiber-optic cable by using time-division multiplexing (TDM), as in the T1 system or in the SONET system described later in this chapter. However, developments in optical components make it possible to use frequency- division multiplexing (FDM) on fiber-optic cable (called wavelength-division multiplexing, or WDM), which…

Optical Transmitters & Receivers | Regeneration & Amplification

Optical Transmitters and Receivers In an optical communication system, transmission begins with the transmitter, which consists of a carrier generator and a modulator. The carrier is a light beam that is usually modulated by turning it on and off with digital pulses. The basic transmitter is essentially a light source. The receiver is a light or photodetector that converts the received light…

Optical Communication | Reflection | Connectors | Types of Fiber-Optics

Optical Principles Optical : Optics is a major field of study in itself and far beyond the scope of this book. Most courses in physics introduce the basic principles of light and optics. We review briefly those principles that relate directly to optical communication systems and components. Light Light, radio waves, and microwaves are all forms of electromagnetic radiation. Light frequencies…

Facsimile | Fax | Image Processing | Modems | VoIP | Internet Telephony

Facsimile Facsimile, or fax, is an electronic system for transmitting graphic information by wire or radio. Facsimile is used to send printed material by scanning it and converting it to electronic signals that modulate a carrier to be transmitted over telephone lines. Since modulation is involved, fax transmission can also take place by radio. With facsimile, documents such as letters,…

Telephones | Types | Cordless Telephones | Telephone System | Dialing

Telephones The original telephones system was designed for full-duplex analog communication of voice signals. Today, the telephone system is still primarily used for voice, but it employs mostly digital techniques, not only in signal transmission but also in control operations. The telephone system permits any telephone to connect with any other telephone in the world. This means that each…

Microwave Antennas | Horn | Parabolic | Helical | Bicone | Patch | Radar

Microwave Antennas All the antennas we discussed can also be used at microwave frequencies. However, these antennas will be extremely small. At 5 GHz a half-wave dipole is slightly less than 1 in long and a one-quarter wavelength vertical is slightly less than 0.5 in long. These antennas can, of course, radiate microwave signals, but inefficiently. Because of the line-of-sight transmission of…

Diode | Semiconductor | Special Diode | LED | Varactor | Schottky | Tunnel

INTRODUCTION TO SEMICONDUCTOR Diode :- Materials such as germanium, silicon, carbon, etc. are not good conductors like copper nor insulators like glass. In other words, the resistivity of these substances lies in between conductors and insulators. Such materials are known as semiconductors. Semiconductors have some useful characteristics and are being extensively used in electronics devices. For…

Gas Tube | Cold Cathode Gas Diode | Hot Cathode Gas Diode | Thyratron

INTRODUCTION OF GAS-FILLED TUBE Gas Tube : In the vacuum tubes, the electrons pass from the cathode to anode in a vacuum. In that type of tubes, extreme care is taken to generate as perfect a vacuum as possible to prevent ionization of gases and the resulting large uncontrolled currents. It may be mentioned here that the logic of the triode is the fine control of free electrons within the valve…