5 Recent trends in Communication Technology

P.G. Padma Gowri

epgp books

 

 

Introduction:

 

Communication is the act of conveying intended meanings from one entity or group to another  through  the  use  of  mutually  understood signs and  rules.  In  the  modern  times, Communication  and  Technology are  very closely related.  It  has  become  impossible  for institutions to run without the modern technology like Telephone, Television and Internet have become an integral part of day to day life. Wireless Technology and Free Space Optical (FSO) networks are capable of providing low cost fibre-like quality, reliability, and capacity, without requiring buried optical fibre cabling.

 

Objectives:

  • Understand the evolution of communication and its current place in the communications mix.
  • Implement various Communication Technology considerations

  Communication Technology:

 

Telecommunications involves the use of electrical devices such as the telegraph, telephone, and tele printer, as well as the use of radio and microwave communications, as well as fibre optics and their associated electronics, plus the use of the orbiting satellites and the Internet The Milestones of Technology in Communication

  • Telecommunication
  • Invention of Radio
  • Invention of Television
  • Invention of Computer
  • Internet
  • Wireless technologies

RADIO:

 

It started with the discovery of “radio waves” – electromagnetic waves that have the capacity to transmit music, speech, pictures and other data invisibly through the air .A radio transmitter, transmits information by means of radio waves. The information signal is first modulated with a high frequency carrier wave by the modulation process, then it is amplified and transmitted.

Classification of Transmitters:

 

The transmitter can be classified based on the following

 

Type of modulation

 

Type of carrier frequency Type of service provided

Amplitude Modulation radio broadcast transmitters:

 

AM radio broadcast transmitters are used for transmission of speech music, light entertainment programme. The block diagram is shown below,

 

Fig 1 AM Radio Broadcast transmitter block diagram

 

The microphone converts the speech or sound to be transmitted into an electrical voltage signal. The signal processing unit limits the band of the modulating signal to 5KHz.this signal is sent to audio pre and power amplifiers to amplify the voltages and power levels respectively and then to the modulator amplifier.

 

The desired carrier frequency is generated by a RF oscillator. The buffer amplifier isolates the RF oscillator from the other blocks to maintain the output frequency of RF oscillator constant. The power amplifier boosts the power level of the carrier finally the carrier is fed as another input to the modulator amplifier which performs amplitude modulation of the carrier by the modulating signal and then transmits the AM waves to antenna for radiation.

 

RADIO RECEIVER

 

A radio receiver picks up the desired signal from the various signals propagated through the atmosphere, amplifies the required signal to the desired level, recovers from it the original modulating signal and displays it in the desired manner.

 

AM Radio Broadcast Receiver:

                                             Fig 2 AM Radio Broadcast Receiver block diagram

 

The AM waves from different stations are received by the antenna present in the receiver. Required station is selected by tuning. The desired signal is amplified by the tuned amplifier and fed to the mixer. The output of the mixer will always be at a frequency called intermediate frequency that is the difference between the two input frequencies of the mixer. This is amplified by the IF amplifier. The modulating signal is recovered by demodulation. The audio signal output of the demodulator is amplified by voltage and power amplifiers and then fed to loud speakers for reproducing the sound/speech.

 

TELEVISION:

 

Unlike radio, television has both video and audio signals. The picture signal is generated by a TV camera and a sound signal by a microphone .the two signals are suitably modulated and radiated through a common antenna. The tuner in the TV receiver selects the desired channel signal out of the many picked by the antenna. The selected RF band is converted to IF band. The amplified IF signals are detected to obtain video and audio signals. The video signal is amplified to drive the picture tube and the audio signal is amplified and fed to the loudspeaker.

 

The TV system has to reproduce the shape, colour, movement, brightness of the object along with the associated sound. The TV camera converts the shape and the brightness level of the object into electrical signal by means of scanning. The picture of the scene is divided into many small elements called pixels. Each element is scanned to generate voltage corresponding to brightness of the pixel at a high rate and repeated many a times to create an illusion of continuity. Thus the eyes see continuous motion. To avoid the flicker, a technique called interlaced scanning is used at the transmitter and receiver.

 

Facsimile (FAX)

 

Facsimile is a method of transmitting still images over an electrical communication System.

 

Fax Transmitter

 

In fax transmitter, the scanning mechanism is done by light beam which incident on a pixel of the document and photocell converts the light into electrical beam.

 

The scanning can be done in following methods,

1.  Flying spot scanning

2.  Flying sensor scanning

3.  Electronic scanning

 

Fax Receiver

 

The receiver receives the modulated signal and pixel information by demodulation process. Then it allows recording the signal on paper through another scanning process.

 

The methods of recordings are’

1.  Direct method

2.  Photographic method

 

Digital Fax

 

In digital fax, information stored is digitized. The digital fax provides the following advantages.

1.  Checking and correcting errors.

2.  Restructuring binary pulse to make them free of noise.

3.  Computer storage, processing and retrieval.

4.  Secured fax at reduced cost

5.  It allows transmission over public switched telephone network (PSTV) with the help of modem.

 

Microwave Communication:

 

Microwave transmission extents from 2GHz to about 40GHz. microwaves travel more or less in straight lines. Long distance transmission can be achieved by using number of microwave repeaters or relay station between the transmitter and receiver. However, microwave link requires fewer number of repeaters than coaxial cable systems.

 

A microwave repeater receives the modulated microwave signal from the previous repeater. The received signal is converted into IF signal of frequency 70MHz and then amplified. For retransmission, these amplified signals are further converted into higher frequency signals. To avoid interference, the frequency of the received and transmitted signal differs by a few MHz.

 

The Height of the tower used for the microwave link depends on the terrain tower location etc. Usually the Height of the tower is around 25 meters. The repeater makes use of 300W dc power supply by a battery. The antenna is mounted at the top of the tower.

  • Microwave Communication is used for
  • Transmitting TV signals
  • Transmitting voice signals
  • Establishing closed circuit TV
  • Establishing LAN network
  • Short distance point to point connections between different buildings in a campus.

Satellite communication:

 

Satellite communication system made the feasibility of long distance high quality communication. If a satellite placed height of 35880 Km from the equator (geo-synchronous orbit), would rotate at exactly the same speed as the earth and therefore appear to e stationary over a fixed point over the equator. The orbit of satellite determines the area witch the satellite can serve. For communication via satellite, frequencies the microwave band ranging from 3 to 30 Hz is used to avoid ay obstruction, absorption or deflection. The basic blocks of satellite communication system was shown in fig3

Fig 3 Satellite Communication System

 

Optical Communication:

 

In optical communication system the information is transmitted in the form of light energy (frequency range 10 10 hz ). The medium used for carrying this light energy may be either free space or optical fibre. The optical fibre is a dielectric medium with centre part called core and which surrounded by cladding. The information signal (modulating signal ) which is to be transmitted, will modulate the light waveform (carrier signal) and the modulated light is transmitted through the medium. The device used for generating this light carrier is LED (Light Emitting Diode) or LASER (light amplification by simulated emission of radiation) diode. Since, the carrier signal is a light signal with the frequency range 10 10 Hz, the bandwidth of the optical communication system is very large.

 

Application of fibre optical communication system:

  • Telephone system
  • Defence applications( like laser radar, thermal imaging, night vision)
  • Aeroplanes and ships
  • Inter city communications
  • Computer networks
  • Data links and industrial control systems

Advantages of fibre optics:

  • Advantages of fibre optics over co- axial cables (for communication systems) are listed below,
  • Fibre cables, being flexible and lighter, can be easily pulled through the conduit pipes and channels.
  • Fibre -optic terminal equipment is not as heavy as wire or coaxial equipment
  • Fibre -optics the interference is less.
  • It is difficult to tap optical signals out of fibres and hence the information is highly secured.
  • They have large band width
  • They are less expensive
  • They are less affected by moisture, temperature variations and noise.
  • No shielding of fibres is required

There is no electric hazards

  1.  Light source
  2. Light wave modulator
  3. The photo detector

Internet

 

The Internet is a giant network consisting of millions of computers interconnected in a global network. The Internet service provider is accessed through telephone network with the help of modem and the computer. Internet is used to send messages through electronic mail(e-mail) to an user across the globe in a more quick, efficient and also economical way Internet is also used to download/upload programs, login to other computers and also to browse various websites.

 

The Internet has brought the entire world under one umbrella in the communication point of view and has made the world look like a global village.

 

Some of the specific applications of Internet are presented below:

  1. Internet is used as an important tool to enhance the learning process. Educators and students can access electronic libraries through Internet. The virtual universities offer online distances leaning facility.
  2. News papers, magazines, shopping details can be browsed through Internet.
  3. Radio broadcasting can be carried out using Internet.
  4. Spots news and other topics can be broadcaster over the Internet in audio and video forms of communication
  5. Video phone/video conferencing can be carried out using Internet
  6. They are many more uses of Internet likes virtual hospitals, matrimonial alliances using Internet, marketing the products, job opportunity details etc.

Wireless technology:

 

There are is a broad spectrum of applications that have stemmed from progress in wireless tech. There are several billion dollar satellites that orbit the Earth today which beam signals on to your receiver which you operate with an infrared remote. Both of these are wireless applications but at varying scopes, tied together in the same communication chain.

 

Wireless internet

 

There has been a huge global influx of people on the internet in the past few years and this is only projected to rise to an even more extreme number. Compared it will grow to about 4.5 billion in 2020. This is more than the current population numbers of the top 10 countries in the world.

 

MODEM

 

In the modern Internet world, every one of us might have come across the device named as MODEM. It is a device used to connect the computer terminal to the communication network such as telephone network. MODEM is an acronym for Modulation De Modulation .

 

At the source or transmitting end, a modem takes the digital signal or binary signal from the computer terminal and converts them into a continuous analog signal that is needed for transmission over the telephone channels. at the destination on receiving end, the modem converts the analog signal coming through the telephone channel into binary signal that is feed into the computer terminals shown in fig

 

Modem use amplitude modulation (AM), frequency modulation (FM), phase modulation (PM)or combination of these, to achieve the desired data rates and low error performance over different types of telephone channels.

 

Integrated service digital network (ISDN)

 

Till the recent past, telephone and telegraph service provided the major telecommunication service. With the development of digital computers, there is a need of data for data communication. Since, establishing a separate network requires very big investment, the telephone networks were used for data communication. But telephone system is an analog voice transmission system. Thus to use the telephone network for data communication, the data has to be converted in voice frequency band used in telephony with the help of modems. These signals are to be converted back to digital from at the receiver, as the speed of data transmission increases, the cost, complexity and inefficiency of modem increases. The integration of digital switching and digital transmission resulted in integrated service digital network (ISDN).

 

Mobile Phone:

 

The mobile phone works on the principle of wireless mobile communication. Mobile phones can be used not only for voice communication, but also for transferring messages, files, pictures, videos, etc. The standards used for wireless communications are Global System for Mobile communications (GSM), code division multiple access(CDMA), time division multiple access (TDMA) and wireless in local loop(WLL). Among these standards the GSM is very popular and is widely used in cellular mobile communication .The name cellular is used due to the fact that the geographic region is divided into cells of radius ranging from few kilometres to tens of kilometres. The radius is decided depending on the transmission range of the base stations within the cell.

Evolution of Mobile Networks

 

The main achievements in the evolution of mobile networks, moving from second generation (2G) systems towards third generation (3G) and 4th generation (4G)through The passage from generation to generation is not only characterized by an increase in the data rate, but also by the transition from pure circuit-switched (CS) systems to CS-voice/packed data and IP-core-based systems

 

A smart phone is a great choice for those professionals who spend a significant amount of their time travelling round the globe.

 

The information access features that we can expect in smart phones are:

  • wireless e-mail
  • Internet/Web browsing
  • fax
  • intercom
  • Personal Information Management (PIM)
  • online banking
  • LAN connectivity
  • local as well as remote data transfer between phone and computer

Conclusion:

 

These latest technology trends of 2017 are going to rule the information technology sector and will play crucial role in development of communication, education and business growth. Adoption of these latest technology trends will surely make difference to Information technology planning. Mobile devices have been slowly adding technology into our daily lives. It’s rare to see anyone without a smart phone at any given time, giving us access to practically infinite information in the real-world. As the next step in the continuous innovation and evolution of the mobile industry, 5G will not only be about a new air interface with faster speeds, but it will also address network congestion, energy efficiency, cost, reliability, and connection to billions of people and devices.

 

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