The document discusses the history and development of the internet and modems. It explains that the internet was first developed by the US military in 1979 and later opened to the public in the early 1990s. It then describes how modems allow users to connect to the internet by converting digital signals to analog signals that can be transmitted over phone lines. Finally, it outlines different types of modems including cable modems, wireless modems, and differences between DSL and broadband connections.

1. BY

2. THE BIRTH OF INTERNET
 Seeds of internet were planted way back in
1979 ,when U.S military forces used it to
communicate in better, organized and safer way
at ARPA (Advanced research project agency).
 President of U.S was the first citizen to share
this sophiciticated network to manage and
share all important information.
 Gates of internet were open to general public
by early 90’s.

3. INTRODUCTION
 With the introduction of
internet, world changed
quickly.
 We can experience world
coming closer day by day
by use of internet.
 ISP (internet service
provider ) provides us with this internet facility.
 MODEM is a most important hardware that
connects us and ISP and helps us to access
this valuable gift ‘INTERNET’.

4. WHAT IS MODEM ???
 A Modem (made of Modulator &
Demodulator) is a device that
converts data from digital
computer signals to analogue signals that are
generally ,sent over a phone line.

5. CONNECTING WORLD
 The sending modem modulates the data into a
signal that is compatible with the phone line,
and the receiving modem demodulates the
signal back into digital data. Wireless modems
convert digital data into radio signals and back.

6. WORKING OF MODEM
•Modem is a full duplex device having
modulator and demodulator.
•Modulator converts digital to analogue signals
and sends info via LAN whereas demodulator
receives info and converts analogue signals to
digital signals.

7. INTERNAL VIEW OF MODEM

8. TYPES OF MODEMS
MODEM
CABLE MODEM WIRELESS MODEM

9. 1. Cable Modem
 A cable modem is basically used for the one-one
basis or to connect multiple computers inside a
building as the signals degrade as more users come
online.
 Cable modem uses broadband Internet connection
that is designed to operate over cable TV lines

10. FREQUENCY

11. STREAM
 Downstream data -- data sent from the Internet to
an individual computer -- into a 6-MHz channel.
 Upstream data -- information sent from an
individual back to the Internet

12. WIRELESS MODEMS
 Wireless modem is a modem which
connects to a wireless network
instead of to the telephone system.
 Wireless modems operate at speeds
comparable to dialup modems,
not anywhere near the speed of
broadband Internet connections.
 Some wireless modems attach
directly to your notebook computer or PDA.

13. DIFFERENT TYPES OF WIRELESS
MODEMS

14. Types of connections
 DSL connection
 Dialup connection
 Broadband connection

15. DIAL-UP
 Data is transmitted through an analog phone
connection. An analog connection is the slowest type
of connection available, and will not permit you to
use your telephone for a voice connection at the same
time that you are connected to the Internet. Dial-up
connections allow only one computer at a time, per
line, to be connected.

16. FEATURES
 Slow and Economical
 Connection to network is established by dialing a
number provided by ISP
 Quality not so good because of telephone lines
 Phone modems only travel at speeds of 28.8k and 56k
and less.

17. DSL
 DSL means Digital Subscribers Line
 This is a method of transmitting data over telephone
lines prevalent in many countries.
 DSL connection uses existing 2-wire copper
telephone line connected to the premise and will not
tie up your phone as a dial-up connection does.
 DSL uses a sophisticated modulation scheme to pack
data onto copper wires.

18. TYPES OF DSL
 All types of DSL technologies are collectively
referred to as xDSL.
 xDSL connection speeds range from 128 Kbps to 8
Mbps.
 Two other types of DSL technologies are High-
data-rate DSL (HDSL),Very high DSL
(VDSL),Asymmetric Digital Subscriber
Line(ADSL) and Symmetric Digital Subscriber
Line (SDSL)

19. Advantages of DSL
 The speed is much higher than a regular modem (1.5
Mps vs. 56 kps)
 DSL doesn't necessarily require new wiring; it can
use the phone line you already have.
 Modem generally comes with company.

20. Disadvantages of DSL :
 Service is better ,when you are near service provider.
 Sending data slower compared to receiving.
 The service is not available everywhere.

21. BROADBAND
 Cable Internet works by using TV channel space for
data transmission, with certain channels used for
downstream transmission, and other channels for
upstream transmission.
 Coaxial cables are used by Broadband connection
provides much greater bandwidth than telephone
lines
 Broadband connection can be used to achieve
extremely fast access.
 Its speed ranges from 512 Kbps to 20 Mbps.

22. Broadband connection

23. FEATURES
 Broadband connection use complex waveforms to
carry digital data.
 They are more advanced devices than traditional
dial-up modems as they are capable of
modulating/demodulating hundreds of channels
simultaneously.
 New types of broadband modems are beginning to
appear, such as doubleway satellite and powerline
modems.

24.  Transfer rates are affected by the number of
subscribers online simultaneously.
Broadband connections can be used by
individual subscribers to connect one
computer to one line, or can be used to
connect multiple computers in a building to
the Internet.

25. DSL vs CABLE
 Cable modem speeds are upto two times faster
compared to DSL modem.
 Speeds in cable modem fluctuates depending on the
number of subscribers on the network.but this is not
the case in DSL.
 DSL boasts a bit better security compared to cable
modem.

26. Thank you
Prepared by:-jigar.p.patel
Roll no:-20
Class:-sybba(itm)sem-4
Collage:-cppatel&fhshah
commerce collage