Networks and the effects of using them (4.1 Networks (4.1.1 Network…
Networks and the effects of using them
4.1.1 Network devices
Modem means 'modulator demodulator' and is a device that ransmission over an existing telephone line. It also does the reverse process and it converts analogue signals from a telephone line into digital signals,(demodulates), to enable the computer to process the data.Modems are essentially used to allow computers to connect to netnworks (for example, the internet) over long distances using the existing telephone networks.(i.e. modulates) a computer's digital signal into an analogue signal for Dial-up modems operate at transmission speeds of about 60 kilobits per second whit is very slow compared to today.
nodems also exist, u.hich allou c:...-e
internet sigrrirls so they dor-r't intcr':c:'c s-ith norrn:Ll telephone traffic). Clble
of tl-re u'idc bandwiclth sign;rl usc.t l:ttcr:ent ti'ecluencies arc used to transrnit
telephone conr,ers;rtions ancl ir-rtclnli tr;rfhc to occur at the same time Lrecause
llncllinc telephone can be Llser'1 .r: :l:c s.rmc tirne. Al)Sl, modems can allou,'
arln al\:alrs bc'on', so internet.raac\ is ar-ailable 24 hor.rrs ilnecessart,, and thc
Lliil-np moclems tl-Let, do not tic LlLr the lrne u'hile acccssir-rg the internet - thcr-
Nthough ADSL rnoclems stili Lr:c r1-rc eristing teiephone nefir.ork, unlike
1 byte = 8 bits; 100 megabits = 100 million bits .
uploading data (i.e. sending data).
that the modem is faster at downloading data (i.e. receiving data) than it is at
offer a maximum of 20 Mbits/second). The term 'asymmetric' actually means
fibre-optic cables ( although the old technology copper cables can usually only
operate at up to 100 Megabits* per second (12.5 Mbytes/second) when using
Modern broadband or ADSL (asymmetric digital subscriber line) modems
*60 kilobits= 60000 bits. 1 bit refers to a binary digit and has the value 1 or 0.