Transmission Media Flashcards
what is broadband?
refers to any high-speed internet access that is always on and faster than traditional dial-up access
it has wide bandwidth data transmission which transports multiple signals and traffic types
what is the name of the method of connecting to the internet?
Digital Subscriber Line (DSL)
what is bandwidth?
its a measure of the capacity of a communication channel. it is the range of frequencies that a channel can handle
what is transmission rates referred to?
line speed
what are the types of twisted pair of wires called?
unshielded twisted pair (UTP)
shieled twisted pair (STP)
what is UTP?
Unshielded Twisted Pair
its similar to STP, but has no earthed shield- in some cases they can be used for data transmission
UTP is a type of cable that consists of two independently insulated wires twisted around one another
how is UTP connected?
one wire carries the signal while the other is only used to cancel out interference - e.g. electronic interference
why twist UTP this way?
twisting it this way reduces signal loss over any given length of cable. the media allows for very high speed data transmission
the quality of the cable may vary from telephone grade wire to extremely high speed cable
what are the advantages of UTP?
high transformation speeds
cheap costs of insulation
what are disadvantages of UTP?
the cable can only be used over a short distance
cable may be susceptible to radio and electrical frequency interference
there are security concerns regarding the intercepting of data along transmission lines
what is STP?
Shielded Twisted Pair
its similar but expect it has copper shielding around each pair of cables. this makes it suitable for environment where electric interference may be an issue
the shielding protects the data from corruption due to interference
what is a coaxial cable?
same kind of cable used for connecting a TV arial to a TV
what are the two of conductors in a coaxial cable?
one is wire down the centre of the cable, which is made of a single strand
the other is insulated by many strands braided around insulation for the inner wire
what is the advantage of having an outer shield?
it protects against interference
very fast transmission speeds
cheap to purchase
what is disadvantage of having outer shield?
it being the only capable for short distance communication
it is physically inflexible
what type of cable consists in fibre optic?
very fine glass strands that allow rapid transmission of data, using modulated beams
what does fibre optic do ?
it provides interference free, secure data transmission and unlike metal wires it not subject to corrosion
multiple strands are placed together in a single cable, each on capable of carrying one or more data signals
fiber optic used for very high speed, long distance data transmission and is not a subject to electrical interference
how is fibre optic wires protected?
the fine glass strands are surrounded by cladding layer and jacket. cladding is an insulated material and jacket with a protective covering
why is their two fibers in fiber optic?
one for sending and one recieving
fibers are undirectional
how does data travel in fiber optic?
it has the ability to transmit signals over much longer distances than coaxial and twisted pair
the data is transmitted as a series of pulses of light along thin fibers whereby each fiber can tansmit in one direction
advantages of fiber optic
greater bandwidth than metal cables, which means it has a bigger data capacity
less susceptible than metal cables to interference
data can be transmitted in digital form
data can travl in a secure way, impossible for hackersto intercept data
disadvantages of fiber optic
its expensive to install
what is wireless?
it cover a range of possible methods of data transmission, which can be used for linking computers
what is bluetooth?
its a short range wireless communications standard that uses low-power radio waves
it allows bluetooth equipped devices to communication with other bluetooth devices in a peer-to-peer relationship
what do bluetooth and wifil have in common?
standards continue to improve
speeds up transfer times
reducing power use
what is wifi?
wifi is a communication technology that makes use of radio waves in order to connect to a local area network
its a way of connecting computers to a network by wireless via radio waves
how does wifi transfer from computer to a mobile phone?
both must be connected to the same router. file sharing must be enabled on both the computer and device. the computer will display the devices on the network. the mobile device will be selected. then the data will be transferred via router
twisted pair bandwidth and security?
low bandwidth
low security
coaxial bandwidth and security?
moderately high bandwidth
fair security
fiber optic bandwidth and security?
very high bandwidth
high security
wifi bandwidth and security?
high bandwidth
low security
how does bluetooth transfer data from computer to device?
both bluetooth must be enabled. the computer will display the devices within range which are set to visible. the mobile device will be selected. the device may require pairing. a piconet is created
fibre optic and mental wire in relation to data security
fibre optic consists of many strands of glass fibres inside an insulated casing. data is transported using pulses of light. data security- its not prone to interception. its less susceptible to interception than metal cable
metal copper wire are used to transmit electrical signals. the wires are encased by an insulating layer- data security- it can be tapped into using listening devices wrapped round it which doesn’t interfere with the signal
