Wednesday, 30 May 2012

8th entry

today is the last week of our class, so that's mean that no more post after this :( it is true??
I'am not sure actually hehe....
so today we learn about


*hierarchy of network
  • from a single computer to LAN
  • from LAN to ISP
  • from ISP to WWW
*in order to connect yourself, you need
  • computer
  • web browser
  • internet acces
--however the policy is quite complicated

  • internet standard protocol that provide a common layer over dissimilar network
  • to move packet among 'host' computer through gateways
  • every computer assign unique IP address
  • IP address consist of 32 bits (shows as 4 octets of number from 0-225 represented in decimal form instead of binary)
        1 octet = 8 bits
        4 octet = 32 bits
        1 IP     = 32 bits
  • IP address consist of 2 parts:
  1.  identify the networks
  2. identify the node/host
  • class of address determines which parts belongs to the networks address and which part belongs to node.
  • all node on a given network share the same network prefixes but must have a unique host number
  • binary address start with 0
  • decimal no. are from 2 to 126
  • the first 8 bits (the first octets) identify the networks and the remaining 24 bits indicate the host within the network
  • exp:
  • binary address starts with 10
  • decimal no. are from 128 to 191
  • the no. 127 is reserved for loopback and is used for internal testing for local machine
  • the first 16 bits (first 2 octets) identify the networks and the remaining 16 bits indicate the host
  • exp: 168.212. 226.204
  • binary address starts with 110
  • decimal no. are from 192 to 223
  • the first 24 bits (first 3 octets)  identify the networks
  • binary address starts with 1110
  • decimal no. are from 224 to 239
  • used to support multicasting
  • binary address starts 1111
  • decimal no. are from240 to 254
  • used for experimentation
  • internet service that translate domain names likes into numerical IP address likes
  • it more easy to remember
  • is a company that offer its customer access to the internet
  • connects to its customer using a data transmission technology 
  • may provide Internet e-mail accounts to user which allow them to communicate with one another by sending and receiving electronic messages through their ISPs' server.
  • HTTP stand for Hypertext Transfer Protocol
  • set of rule for transferring files such as text, graphic images, sound, video and other multimedia files on the World Wide Web (WWW)
  •  HTTP is an aplication protocol that runs on top of the TCP/IP suite of protocols (the foundation protocols for the internet)
bye2 that's all for today
see yaa (^-^)

Sunday, 13 May 2012

7th entry

I am so busy this week :( however this blob need to go on. In this week we continue our lesson about bluetooth and another wireless technology. So here they are.....

  • concept: focus on point to point and point to multiple with small network called piconets
  • when multiple network exist within the same room they become known as scatternet
  • each piconet hold up 8 active unit
Piconets with a single slave operation (a), a multi-slave operation (b),
and a scatternet operation (c).

Bluetooth is a wireless technology that is composed of hardware, software and interoperability requirement. Bluetooth is specification for short-,range radio link between mobile computers, mobile phones, digital camera and other portable devices.

Many think that Bluetooth is a technology that is going to be here to stay, however, just as many disagree. It is believed by ,many that there is a huge future for bluetooth. Many believed that bluetooth will be able to compete with other wireless technologies such as WiFi and it could possibly eliminates technologies such as IrDA(Infrafed Data Association)
Figure shows  where Bluetooth stands among some of the
competing wireless technologies:

Device synchronization data transfer
Low frequency
Cable Replacement Ad Hoc
PCs to Consumer Goods
High speed LAN

  • eliminates wires and cables between both stationary and mobile phone
  • facilitates both data and voice communication
  • offers the possibility of ad hoc networks and delivers the ultimate synchronicity between all your personal devices
  • it's inexpensive
  • compability between Bluetooth product
  • security
  • relatively short range
  • interference with other devices that may use the same frequency such as baby monitors, garage door openers, cordless phones, microwave ovens and other wireless technologies which use the same frequency
  • mediocre data transfer rate
bluetooth allow three types of data links between any two holes:
  • an asynchronous data channel
  • simultaneous voice channel
  • asynchronous data chanel 

Infrared (IR) light is electromagnetic radiation with longer wavelengths than those of visible light, extending from the nominal red edge of the visible spectrum at 0.74 micrometers (µm) to 300 µm. This range of wavelengths corresponds to a frequency range of approximately 1 to 400 THz,[1] and includes most of the thermal radiation emitted by objects near room temperature. Infrared light is emitted or absorbed by molecules when they change their rotational-vibrational movements.

objects generally emit infrared radiation across a spectrum of wavelength, but somestimes only a limited region of the spectrum is of interest because sensors usually collect radiation only within a specific bandwith. Therefore, the infrared is often subdivided into smaller sections 
     commonly used sub-division scheme:
Division Name
Photon Energy
0.75-1.4 µm
0.9-1.7 eV
Defined by the water absorption, and commonly used in fiber optic telecommunication because of low attenuation losses in the SiO2 glass (silica) medium. Image intensifiers are sensitive to this area of the spectrum. Examples include night vision devices such as night vision goggles.
Short-wavelength infrared
1.4-3 µm
0.4-0.9 eV
Water absorption increases significantly at 1,450 nm. The 1,530 to 1,560 nm range is the dominant spectral region for long-distance telecommunications.
Mid-wavelength infrared
MWIR, IR-C DIN. Also called intermediate infrared (IIR)
3-8 µm
150-400 meV
In guided missile technology the 3-5 µm portion of this band is the atmospheric window in which the homing heads of passive IR 'heat seeking' missiles are designed to work, homing on to the Infrared signature of the target aircraft, typically the jet engine exhaust plume
Long-wavelength infrared
8–15 µm
80-150 meV
This is the "thermal imaging" region, in which sensors can obtain a completely passive picture of the outside world based on thermal emissions only and requiring no external light or thermal source such as the sun, moon or infrared illuminator.Forward-looking infrared (FLIR) systems use this area of the spectrum. This region is also called the "thermal infrared."
Far infrared
15 - 1,000 µm
1.2-80 meV
(see also far-infrared laser).

i think that's all see yaaa...

Friday, 4 May 2012

6th entry

waaa it has been six posting already. I can't believe that I am a blogger although it just for my task-proud of myself : p.
ok so for the topic for this week is 


---media transport electromagnetic wave without physical conductor 
---signal are broadcasting through air or water & therefore available to anyone who has a devices capable   of receiving them.

---require line of sight transmission & reception equipment
---taller the antenna the longer the distance
---towers=on hill
---signals transmit 1 way direction at a time.
---to increase the distance - a system (repeater) can be installed with antenna.
Parabolic dish
Horn dish
.          Based on geometry of parabola
      Looks like gigantic scoop
           Works like a funnel - catching a wide range of waves and directing to a common point call focus
           Outgoing transmission are broadcast up a stem & deflected outward in  a series of source parallel beams by the scoop shaped of the horn
parabolic dish

horn dish

---same principle as microwave
---satellite acting as a super fall antenna & repeater
---single bounce
---capability=any location on earth no matter how   
---high quality communication without requiring a          huge investment in ground-based infrastructure..
---same speed as earth
---geosynchronous satellite=orbit speed is based on     distance from the planet
---minimum 3 satellite to provide full global transmission.
---uplink = transmission from earth to satellite
---downlink = transmission from satellite to earth

---rate of oscillation in the range of about  3kHz to 300 kHz.
---the mode of communication for wireless technology of all kinds such as-cordless phone,radar,ham radio        and many more
---These frequencies make up part of the electromagnetic radiation spectrum:
  • Ultra-low frequency (ULF) -- 0-3 Hz
  • Extremely low frequency (ELF) -- 3 Hz - 3 kHz
  • Very low frequency (VLF) -- 3kHz - 30 kHz
  • Low frequency (LF) -- 30 kHz - 300 kHz
  • Medium frequency (MF) -- 300 kHz - 3 MHz
  • High frequency (HF) -- 3MHz - 30 MHz
  • Very high frequency (VHF) -- 30 MHz - 300 MHz
  • Ultra-high frequency (UHF)-- 300MHz - 3 GHz
  • Super high frequency (SHF) -- 3GHz - 30 GHz
  • Extremely high frequency (EHF) -- 30GHz - 300 GHz
Radio frequency is also abbreviated as rf or r.f
 how it works??
========> A label -- basically a miniature, disposable electronic circuit and antenna -- attached to a product responds to a specific frequency emitted by a transmitter antenna (usually one pedestal of the entry/exit gate). The response from the label is then picked up by an adjacent receiver antenna (the other pedestal). This processes the label response signal and will trigger an alarm when it matches specific criteria. The distance between the two gates, or pedestals, can be up to 80 inches wide. Operating frequencies for RF systems generally range from 2 to 10 MHz (millions of cycles per second); this has become standard in many countries. Most of the time, RF systems use a frequency sweep technique in order to deal with different label frequencies.

---device that can make & receive telephone calls over a radio link whilst moving around a a wide geographic area
---it woks by connecting to a cellular network provided by a mobile phone operator, allowing access to the public telephone network.

---The common components found on all phones are:
  • A battery, providing the power source for the phone functions.
  • An input mechanism to allow the user to interact with the phone. The most common input mechanism is a keypad but touch screen are also found in some high-end smartphones.
  • Basic mobile phone services to allow users to make calls and send text messages.
  • All GSM phones use a SIM card to allow an account to be swapped among devices. Some CDMA devices also have a similar card called a R-UIM.
  • Individual GSM, WCDMA, iDEN and some satellite phone devices are uniquely identified by an International Mobile Equipment Identity (IMEI) number.
---stand for "Wireless Fidelity"
---refers to wireless networking technology
---allows computer & other devices to communicate over a wireless signal.
---transmit data using radio wave
wi-fi signal logo
---describe all network component that are based on one of the               802.11standards
---these standards were developed by IEEE (Institute of Electrical         and Electronic Engineers)
---have limited range
---the maximum amount of power that a Wi-Fi device can transmit is      limited by local regulations

3G & 4G
3rd generation
4th generation
The technologies are widespread used
The technologies are still in horizon
3G speeds can reach up to 3 Megabits per second (Mbps), with average speeds tending to be closer to 1Mbps or lower
4G average speeds are targeted to be in the 100Mbps to 1Gbps range, roughly 10 to 100 times (dependent on location) faster than 3G networks.
3G is a mix of circuit and packet switching network
4G is only a packet switching network

---short-distance wireless connections.
---It essentially is a cable-replacement technology. 
---allows two Bluetooth enabled devices to communicate with each other from a distance of 30 feet apart.
---Bluetooth takes small-area networking to the next level by removing the need for user intervention and          keeping transmission power extremely low to save battery power.
---Bluetooth is essentially a networking standard that works at two levels:

  •     It provides agreement at the physical level -- Bluetooth is a radio-frequency standard.
  •     It provides agreement at the protocol level, where products have to agree on when bits are sent,        how many will be sent at a time, and how the parties in a conversation can be sure that the message     received is the same as the message sent.

finish already fuhhh...
TQ  (^-^)

Wednesday, 25 April 2012

5th Entry

waaa.... i think its been quite long i have not posting anything :0..This is because the class keep being postponed so, i have nothing to write :(
oK lets proceed to our main topic. So the topic for this week is....


What is network cabling?
Cable is the medium through which information usually moves. In some cases, a network will utilize only one type of cable, other networks will use a variety of cable types. The type of cable chosen for a network is related to the network's topology, protocol, and size.

Type of cable
  •  Unshielded Twisted Pair (UTP) Cable
  •  Shielded Twisted Pair (STP) Cable
  •  Coaxial Cable
  •  Fiber Optic Cable
  •  Wireless LANs    
Unshielded Twisted Pair Cable (UTP)
>> has four pairs of wires inside the jacket.
>> Each pair is twisted with a different number of twists per  inch to help eliminate interference from adjacent   pairs and other electrical devices.
>>The tighter the twisting, the higher the supported transmission rate and the greater the cost per foot.
>>Disadvantage: may be susceptible to radio & electrical frequency interference.
Unshielded twisted pair

Types of UTP
1 Mbps
Voice Only (Telephone Wire)
4 Mbps
LocalTalk & Telephone (Rarely used)
16 Mbps
10BaseT Ethernet
20 Mbps
Token Ring (Rarely used)
100 Mbps (2 pair)
1000 Mbps (4 pair)
100BaseT Ethernet
Gigabit Ethernet
1,000 Mbps
Gigabit Ethernet
10,000 Mbps
Gigabit Ethernet
UTP Connector
>>The standard connector for UTP = RJ-45 connector.
>> plastic connector that looks like a large telephone-style connector.
>>A slot allows the RJ-45 to be inserted only one way.This standard designates which wire goes with each pin inside the connector.  
RJ-45 Connector
  Shielded Twisted Pair Cable (STP)
>>consist of 2 individual wires.

>>suitable in environments with lots of potential interference or in extremely sensitive environments that may be susceptible to the electrical current in the UTP.
>>Shielded cables can also help to extend the maximum distance of the cables.

>>Shielded twisted pair cable is available in three different configurations:
  1. Each pair of wires is individually shielded with foil.
  2. There is a foil or braid shield inside the jacket covering all wires (as a group).
  3. There is a shield around each individual pair, as well as around the entire group of wires (referred to as double shield twisted pair). 
Coaxial Cable  
>>has a single copper conductor at its center. 
>>A plastic layer provides insulation between the center conductor and a braided metal shield. 
>>The metal shield helps to block any outside interference from fluorescent lights, motors, and other computers.
coaxial cable
 Coaxial Cable Connector
>>most common type of connector= Bayone-Neill-Concelman (BNC) connector.
>>Different types of adapters are available for BNC connectors:
  • T-connector
  • barrel connector
  • terminator.
>>Connectors on the cable are the weakest points in any network. To help avoid problems, always use the BNC connectors that crimp, rather screw, onto the cable.
a BNC Connector

Fibre Optic Cable
>> consists of a center glass core surrounded by several layers of protective materials.
>>transmits light rather than electronic signals eliminating the problem of electrical interference.
>>ideal for certain environments that contain a large amount of electrical interference.
>>the standard for connecting networks between buildings, due to its immunity to the effects of moisture and lighting.
>>transmit signals over much longer distances than coaxial and twisted pair.
>>carry information at vastly greater speeds.
>>more difficult to install and modify.

two common types of fiber cables

                                            *single mode                        *Multimode
                                 provide more distance                   larger diameter
                                 more expensive                                     
                          #both cables provide high bandwidth at high speeds.

fibre optic cable
                                   summary of ethernet cabling


Cable Type
Unshielded Twisted Pair
Thin Coaxial
Thick Coaxial
Unshielded Twisted Pair
Fiber Optic
Single mode Fiber
Multimode Fiber
Unshielded Twisted Pair
Fiber Optic
Single mode Fiber
Multimode Fiber
Wireless LANs

>> use high frequency radio signals, infrared light beams, or lasers to communicate between the workstations, servers, or hubs.
>> Each workstation and file server has some sort of transceiver/antenna to send and receive the data.
>> For longer distance, wireless communications can also take place through cellular telephone technology, microwave transmission, or by satellite. 

fuhhh..tired already
I think that's all from me......TQ