Worldwide equipment sales
According to data collected by Gartnerand Ars Technical sales
of main consumer's telecommunication equipment worldwide in millions of units
was:
Equipment / year
|
1975
|
1980
|
1985
|
1990
|
1994
|
1996
|
1998
|
2000
|
2002
|
2004
|
2006
|
2008
|
Computers
|
0
|
1
|
8
|
20
|
40
|
75
|
100
|
135
|
130
|
175
|
230
|
280
|
Cell phones
|
N/A
|
N/A
|
N/A
|
N/A
|
N/A
|
N/A
|
180
|
400
|
420
|
660
|
830
|
1000
|
Telephone
Optical fiber provides
cheaper bandwidth for long distance communication.
In a telephone network,
the caller is connected to the person they want to talk to by switches at
various telephone
exchanges. The switches form an electrical connection between the
two users and the setting of these switches is determined electronically when
the caller dials the
number. Once the connection is made, the caller's voice is transformed to an
electrical signal using a small microphone in
the caller's handset.
This electrical signal is then sent through the network to the user at the
other end where it is transformed back into sound by a small speaker in that
person's handset.
The landline telephones in most residential homes are
analog—that is, the speaker's voice directly determines the signal's voltage. Although
short-distance calls may be handled from end-to-end as analog signals,
increasingly telephone service providers are transparently converting the
signals to digital signals for transmission. The advantage of this is that
digitized voice data can travel side-by-side with data from the Internet and
can be perfectly reproduced in long distance communication (as opposed to
analog signals that are inevitably impacted by noise).
Mobile phones have had a significant impact on telephone networks.
Mobile phone subscriptions now outnumber fixed-line subscriptions in many
markets. Sales of mobile phones in 2005 totalled 816.6 million with that
figure being almost equally shared amongst the markets of Asia/Pacific (204 m),
Western Europe (164 m), CEMEA (Central Europe, the Middle East and Africa)
(153.5 m), North America (148 m) and Latin America (102 m). In terms of new
subscriptions over the five years from 1999, Africa has outpaced other markets
with 58.2% growth[ Increasingly
these phones are being serviced by systems where the voice content is
transmitted digitally such as GSM or W-CDMA with
many markets choosing to deprecate analog systems such as AMPS.[
There have also been dramatic changes in telephone communication
behind the scenes. Starting with the operation of in 1988, the 1990s
saw the widespread adoption of systems based on optical fibers. The benefit of
communicating with optic fibers is that they offer a drastic increase in data
capacity. TAT-8 itself was able to carry 10 times as many telephone calls as
the last copper cable laid at that time and today's optic fibre cables are able
to carry 25 times as many telephone calls as TAT-8 This increase in data
capacity is due to several factors: First, optic fibres are physically much
smaller than competing technologies. Second, they do not suffer from crosstalk which means several hundred of them
can be easily bundled together in a single cable. Lastly, improvements in
multiplexing have led to an exponential growth in the data capacity of a single
fibre.
Assisting communication across many modern optic fibre networks
is a protocol known as Asynchronous Transfer Mode (ATM). The ATM
protocol allows for the side-by-side data transmission mentioned in the second
paragraph. It is suitable for public telephone networks because it establishes
a pathway for data through the network and associates a traffic contract with
that pathway. The traffic contract is essentially an agreement between the
client and the network about how the network is to handle the data; if the
network cannot meet the conditions of the traffic contract it does not accept
the connection. This is important because telephone calls can negotiate a
contract so as to guarantee themselves a constant bit rate, something that will
ensure a caller's voice is not delayed in parts or cut off completely. There
are competitors to ATM, such as Multiprotocol Label Switching(MPLS), that perform a
similar task and are expected to supplant ATM in the future.
Good///improve
ReplyDelete