Friday, 4 May 2012

Wireless a.k.a Unbounded Media

Assalamualaikum and hello to all of you readers.

First and foremost, here's the definition of wireless a.k.a unbounded media.This term means it is a media that transport electromagnetic waves without the need of physical conductors. In this case, signals are broadcasted through air or water and thus, it's available to anyone and everyone to use. However, a device is needed to actually transmit the signals.

TERRESTRIAL MICROWAVE
  • Terrestrial microwave requires line of sight transmission and also reception equipment.
  • The taller the antennas, the longer the sight of distance. For instance, the antennas are put at a high position such as on the hills or mountains.
  • Signals from terrestrial microwave transmit signals in a one way direction, once at a time. 
  • As an extra option to increase the distance, a system such as the repeater can be installed with an antenna. 
ANTENNA

For your information, there are two types of antennas namely parabolic dish and horn

1) Parabolic Dish
  • It is based on the geometry of parabola where it works like a tunnel which catches a wide range of waves  and directing to a common point.
  • This common point is called FOCUS POINT. 
  • It has a line of symmetry between the two dish at both left and right hand side. 
  • The devices known to use this antenna are Celcom, Maxis, and others in order to catch data. 
  • The concept of this antenna is that it bounces back in one direction from one dish to another. 

The image of Parabolic Dish

2)Horn
Horn antenna from New Jersey, 1960
  •  It looks like a gigantic scoop and the outgoing transmission are broadcasted up a stem and deflected outwards in a series of narrow parallel beam by the scooped shape of the horn. 
SATELLITE
  • Satellite owns a similar principle as terrestrial microwave where it acts as a super tall antenna and repeater.
  • Furthermore, in parallel with terrestrial microwave, satellites applies the movement of data in a single bounce method from the transmitter to the receiver. 
  • Satellites have the capability of working in any location on Earth, no matter how remote it is placed. 
  • It is considered very clear compared to the others as it has high quality communication without the requirement of large investments in ground. 
  • This is based on its infrastructures.
  • Speed = same as the Earth.
  • GEOSYNCHRONOUS SATELLITE : The orbit speed is based on the distance from the planet.
  • DOWNLINK : Transmission from satellite to the Earth.
  • UPLINK : Transmission from the Earth to the satellites.
  • Minimum of 3 satellites are required to provide full global transmission.

Here's a satellite!

RADIO FREQUENCY
  • For radio frequency, the rate of oscillation is in the range of about 3 kHz to 300 GHz.
  • It corresponds to the frequency of radio waves, and the alternating currents which carry radio signals.
  • Antenna must be used to receive the signals.
  • Usually done via a resonator which is a circuit with a capacitor and an inductor forming a tuned circuit.
  • Resonator act as an amplifier to the oscillations within a particular frequency band.
CELLULAR PHONE
The examples of cellular phones these days.


The famous of all among the users ^^
  • Cellular phone has a variety of transmissions. For example, 3G and 4G is implied in cellular phones as data transmitters or networks that are available.
  • As for 3G, the technologies use for this network are usually WDM A, EVDO, HSP and others too.
  • Other than that, it has the speed of 600Kb per second where its downlink is 1.4Mb/sec and its uplink is 5.8Mb/sec.
  • In terms of data transmission, 3G networks applies the concept of circuit switching where it is done one at time.
  • As for 4G, it make use of the technologies known as LTE and also WiMax.
  • 4G networks has the speed which is ten times faster than 3G network where it owns a downlink of 3.6Mb/sec.
  • In terms of its data transmission, 4G undergoes packet switching where it transmits data in a whole (like a bag). 
 WIFI
  • WiFi is the original technology of wireless local area network or WLAN.
  • It is usually based on IEEE 802.11 specifications.
  • WiFi uses the same radio frequencies as Bluetooth, but with higher power consumption resulting in a stronger connection.
  • The devices that are able to access this type of transmission are mobile computing devices such as laptops.
  • With the frequency of 2.4 GHz, WiFi has the range 100-300 feet indoor and 300-900 feet outdoor.         
 
In a nutshell, we actually know that all of these technologies exist around us. However, to thoroughly know and gain knowledge about all these things, not everybody would have the initiative to do so. We should realize that all of these inventions has helped us in our daily lives so much, more than we could ever imagine. 
 
In terms of my lecturer's teaching, I could easily understand as she used drawings and brief explanations in order to elaborate on a particular matter. 
 
Well, enjoy reading readers! Till next time ^^

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