Sunday, 13 May 2012

Bluetooth + Broadband + Infrared >>> Unbounded Media

Wednesday, 9th May 2012

Bluetooth >>> this is a very familiar word among youngster. We use it whenever we want to transfer media like songs and pictures between mobile phones. 
So, the function of Bluetooth is to connect and exchange information between devices such as mobile phones, laptops, PCs, printers, digital cameras and video game consoles over a secure, globally unlicensed short-range radio frequency. Similarly, we need to know how the data transfer through Bluetooth and what are the devices used in the transfer.

Transfer of Data using Bluetooth

Basically, Bluetooth technology use radio wave to transmit data and it follows the IEEE 802.15 standard. The technology that enables it to transmit data with lesser problems caused by interference is Spread-spectrum Frequency Hopping technology. This technology enables the data transfer occurs on unlicensed 2.4 GHz (Industrial, Scientific and Medical) frequency band that is shared among other devices (microwave ovens, cordless phones, garage door openers, etc. ) and hence, avoiding the interference with other devices.
On the other hand, the speed of the data transmission is the same when there are more than one user using Bluetooth technology to transfer data at the same time. Unlike Wi-Fi, when there are many users using Wi-Fi at the same time, the speed of data transmission is definitely slower. 

Before the client (the sender) transfers a media (data) to the server (other bluetooth enabled devices), the client has to send a request to the server. Then, the server has to receive the data transfer from the client in order to initiate the transfer of data. 

The data transfer through Bluetooth consume only a little amount of energy as compared to cellphone. Bluetooth transfer emit only 1 miliwatt of signal whereas cellphone emit 3 milliwatt. However, one of the advantages of bluetooth transfer is that it can tranmit data although there is barrier like walls.

The Devices Used
In order to connect with other Bluetooth enabled devices, every device no matter the client or the server has to associate with a transceiver microchips, either build in (eg. Bluetooth card) or connect externally (eg. Bluetooth USB Dongle). 
     Devices build-in with transceiver microchips which function as transferring and receiving devices.


-    External Bluetooth device called Bluetooth dongle for those devices that do not have build-in transceiver.

^^ Bluetooth Microchip
^^ Bluetooth Dongle

Drawbacks of Using Bluetooth to Transfer Data
-     Distance covered is limited within 10m
-    Speed of transferring data is slowest (1Mbps) when it compared to Infrared (4Mbps) and Wi-Fi (11Mbps – 54Mbps)

The Future of Bluetooth
Bluetooth technology is expected to stay strong in the future because Windows and Mac OS continue their native support for it. Besides, there are also many emerging features such as Bluetooth in cars; automatic configuration of Piconets; and Quality of Service (QoS) improvements which shows its potential to be used widely in the future.

Broadband is a technology that transmits data faster than Bluetooth. Band refers to the bandwidth which means the amount of data that can be sent from one computer to another through a particular connection in a certain amount of time; thus, broadband means that this technology is able to transmit more data and at a higher speed than narrowed frequencies (eg. Bluetooth).
Data transmission using broadband is more effective than Bluetooth because it can carry multiple media such as voice, video or other data at once with different channels. These channels are taking different frequencies or specific time slot to avoid interference occur. Examples of broadband technologies are broadcast television, cable television, microwave, satellite, wireless phones and others. To make it clear, let’s take cable television as an example. Cable television is able to carry 30 or more TV channels just like broadband.     

Infrared technology transmits data slower than broadband but faster than Bluetooth. The maximum amount of data that can be carried through infrared is 4Mb. 

To understand the data transfer through infrared, let’s use remote control as an example.
Basically, remote control use a particular wavelength to communicate with the device that it command. When there is an instruction from the remote control, its transmitter sends out infrared light in the form of pulses to the device that is commanded by it. Then, the pulses are translated into binary codes which represent its command. At this moment, the remote control must be placed in front of the commanded device in order to transmit data in the line of sight.  Later on, the commanded device receives these pulses of light and decodes them into binary data, which is understood by the microprocessor inside it. 

That's all from me. Thanks!

Saturday, 5 May 2012

Unbounded Media....(haizzz....abstract....==")

Wednesday, 2nd May 2012

We learned about Unbounded Media today. As I mentioned last week, Unbounded Media is also known as Unguided Media. This means that transmission of data is done without any physical conductor or in other words, wireless. When I learned the introduction of Unbounded Media, the first thing came into my mind was Wi-Fi. I can imagine that the data is all over the air and some devices are used to receive the data so that Internet users can online. However, this was only my own perception and I not sure whether it was correct or not before I learned it in advance.

Basically, there are several examples of Wireless Technology such as Terrestrial Microwave, Satellite Communication, Cellular Telephony, Wi-Fi and Radio Frequency.

Chart 1 below shows the differences between these technologies.

The aspects that I am going to compare are based on these questions : -

A.) What are the equipments used?

B.) How does it work?

C.) How is the distance covered for the transmission of data?

Chart 1

Figure 1.1 : Two pairs of parabolic dish antenna, 60 feet in diameter supported on seven lattice steel girder legs

Figure 1.2 : The transmitters, receivers and power supplies were located in a single storey brick building between the pairs

Figure 1.3 : Horn Antenna

Figure 2 : Geostationary Satellite
Figure 3.1 : Mechanism of Calling from a Phone

Figure 3.2 : Mechanism of Calling from a Land Phone to a Mobile Phone

  So, here is the video clip that shows how Wi-Fi works.

Then, here is the classification of Radio Frequency based on different types of radio waves' propagation.

Table 1 : Different types of Radio Waves Propagation

 That's all, thanks!!