Communication device
A communication device is a hardware device capable of
transmitting an analog or digital signal over the telephone, other
communication wire, or wirelessly. The best example of a
communication device is a computer Modem, which is capable of
sending and receiving a signal to allow computers to talk to other
computers over the telephone. Other examples of communication
devices include a network interface card (NIC), Wi-Fi devices, and
an access point. Below is a picture of some of the different types of
Wi-Fi devices that are all examples of a communication device.
Communication device examples
Below is a full listing of all the different types of communications devices you
may encounter when dealing with a computer.
 Bluetooth devices
 Infrared devices
 Modem (over phone line)
 Network card (using Ethernet)
 Smartphone
 Wi-Fi devices (using a router)
The telephone has been a fact of life for more than a hundred years. A magnetic sensor
in the mouthpiece of the telephone moves in response to pressure waves — the sound
of your voice. That moving magnetic sensor creates an electrical signal. In a traditional
landline, the signal travels down wires to another telephone where the changing
electrical signal creates a magnetic field which moves a diaphragm up and down. The
diaphragm creates pressure waves — sound — and long-distance communication is
possible.
Cellphones also use magnets to convert sound to an electrical signal, but instead of
sending that signal along a wire, cellphones turn that sound into a radio signal. The
radio signal is picked up by a radio transceiver on a cell tower. Each tower has its own
coverage area — its "cell." As long as the phone is within range of a cell tower the
signal can be picked up and sent to any other phone in the world.
My Phone is a Radio?
Basically, the mobile phone is a radio. It relies on a radio signal in order to transmit and
receive voice and data information. Previously, the radio device can only receive a
signal from a commercial station making it a one way communication apparatus.
However, by integrating the principles behind Bell’s telephone, the simple radio became
a communication device which can also serve as a small transmitter thus giving it the
capability to become a mobile phone.
Mobile phones are small radios imbedded with mini transmitters. This means that it
actually transmits radio signals when powered on. This is a very important component
because it readily gives up your electronic radio location so that calls can be diverted to
you or make them.
Satellite Telephone
To function, your cellphone needs to be in the vicinity of a transceiver. But there's
another type of mobile phone that doesn't need to be near any towers, because it
communicates directly with satellites in orbit above the Earth. There is more than one
provider of satellite telephone service, but the industry leader is Iridium. The Iridium
system consists of an interconnected network of 66 satellites that provide global
service. That is, from the South Pole to the Amazon River basin, your Iridium phone will
let you communicate with anyone around the world.
The Hidden Network
Each of the telephone types described above has its own particular method of
transmitting and receiving signals, but behind each of them is an interconnected global
network. Signals from cellphones, landlines, possibly even satellite phones, all end up
travelling through the same network: a complex and sophisticated combination of wires,
fiber optics, and microwave and radio transmitters. The network is just full of
communication devices that you'll never see: routers, optical-to-electronic converters,
add/drop multiplexers and many more. The key to global interconnectivity is that each
different style of telephone can tap into the network, which allows billions of people to
reach each other.
Using the Hidden Network
Computer communications — email,
Twitter, Facebook, web searching —
use the same kind of network. In fact,
the networks are converging and
merging into an interconnected
monolith. That's one reason why the
phone company now offers television
service, the cable company offers
telephone service, and your Internet
provider wants you to buy television and
telephone from them. Any device that
can tap into that network — your
cellphone, your tablet, your laptop —
can conceivably offer all the services
available through that network.
Augmentative and Alternative
Communication Devices
The previous sections outlined various
options for telecommunications,
reaching people well beyond your
vicinity. There is an entire class of
devices designed to help people
communicate with others right next to
them. These devices are called
augmentative and alternative
communication, or AAC, devices, and
they're intended to help people with
communication disabilities interact with
the people around them. Some AAC
devices simulate speech and some
display messages, and different input
styles fit different people's needs.
http://www.brighthubengineering.com/diy-electronics-devices/3885-how-cell-phoneswork/
http://itstillworks.com/different-kinds-communication-devices-1479.html