4. Development of Telecommunication
From guttural sounds and facial
expressions to body moves and gestures.
In addition, there has always been a
need to communicate with others across
an arbitrary distance, for instructions and
orders while hunting etc.
5. There were three main means used:
Noise
(megaphones, church bells, cannons
etc.)
optical effects
(heliographs, watch towers and
smoke signals, flashlights
and semaphores)
physical delivery
(runners, horses, stage coaches,
carrier pigeons, later on trains and
other motor vehicles)
6. The First Big Breakthrough
Telegraph, invented in 1838, was
taken into wide use six years later, in
1844, when Samuel F.B.
Morse introduced his revolutionary new
language - the Morse code. During the
same year, the very first long-distance
telegraph message was sent
between Baltimore and Washington.
What made telegraph such breakthrough
was the incredible speed, at which data
could be transmitted; nearly at the speed
of light.
7. Distance
Bandwidth-
between distance
Method Data rate Msg speed "repeaters" product
------------------------------------------------------------------------
-----
Carrier pigeon ~10 kbit/pigeon 70 km/h 700 km 150 kbit-
m/sec
Megaphone 100 bits/sec 1000 km/h 2 km 30 bit-
km/sec
(but many
repeaters)
Train Very high/train 70 km/h Virtually very high
zero
Telegraph 100 bits/sec Very high 20 km 1 kbit-
km/sec
8. With short messages, telegraph was
far superior compared to any of the
earlier methods, due to its very
high transmission speed. The intrinsic
error rate of the telegraph was very low
and, in case of errors, re-transmission
was easy and quick. Also, telegraph was
relatively cheap, and it was not man-
power intensive.
9.
10. Megaphone was a very unreliable
transmission media, mainly due to its very
limited range of about a mile or two, if the
weather was good and there was little or no
wind. Thus, it was very man-power
intensive, if the distance between the
endpoints was high. Transmission speed of
the megaphone was relatively high -
the speed of sound or, 1000 km/h .
12. Telephone was a rather logical next step
after the telegraph.
Although the first telephone message ever was
sent as early as 1876 (7 words, from one room
to another) and, by 1890, many cities had
primitive telephone systems. The
first official trans-Atlantic message (90 words)
took 67 minutes to cross the ocean.
As of now, telephone is, by far, the most
popular transmission media used.
13.
14. The first trans-Atlantic wireless (radio)
transmission was made in 1901; radio was a
very expensive transmission media to use,
its quality was very poor and the availability
of radio links was very low. In short, radio
was a very poor transmission media for
critical data in its first years.
15.
16. In 1956 more phone cables were installed
across the Atlantic, Thus, the expensive and
unreliable radio links were closed. Only a few
months later, however, the radio links had to be
reopened due to high demand. This, in
part, triggered and encouraged the
development of a reliable wireless transmission
media. A demand, that was met in 1965, as the
first commercial geostationary communications
satellite Intelsat 1 (Early Bird), with 240 phone
circuits, was launched.
17.
18. The first trans-Atlantic fiber optic was
laid in 1988. It was called TAT-8, and it carried
40000 telephone circuits. Some subsequent
fiber optic cables include TAT-9 (1992, 80000
telephone circuits) and TAT-12 (1996, 300000
telephone circuits). Currently, there are 10
such cables in service and, another 10 under
construction or planned.
19. Data networking
1970's: limited long-distance (wide
area networking) networks
1980's: emergence of local area
networks, with standards
1990's: integration of the two - data
networks became ubiquitous.
20. The main differences between
Telecommunications and Data networking:
Telecommunications (referring mainly to
voice transmission) medias are mainly circuit
switched and the industry conservative.
Data networking (referring mainly to data
transmission) medias are mainly packet
switched and the industry dynamic.
21.
22. NETWORK
In information technology, a network
is a series of points or nodes
interconnected by communication paths.
Networks can interconnect with other
networks and contain sub networks
23. LAN
(Local Area Network)
A local area network (LAN) is
usually privately owned and links
the devices in asingle
office, building, or campus.
Depending on the needs of an
organization and the type of
technology used.
25. WAN
(Wide Area Network)
A wide area network (WAN)
provides long-distance
transmission of data, voice, image,
and video information over large
geographical areas that may
comprise a country, a continent, or
even the whole world.
26.
27. MAN
(Metropolitan Area Network)
A metropolitan area network
(MAN) is designed to extend over an
entire city. It may be a single network
such as a cable television
network, or it may be a means
of connecting a number of LANs into
a larger network so that resources
may be shared LAN-to-LAN as well
as device-to-device.
