4. • KEY CONCEPT
· Telephones convert the sound of voice (analogue) into an
electrical signal (digital).
· That electrical signal can travel:
a) through wires Fixed phones
b) as electromagnetic radio waves Mobile phones
· A mobile phone is a wireless portable device that allows
the user to make and receive calls. A mobile phone can be
used wherever its signals can be received.
Mobile phones are also called “cell phones”. We Will son learn why!
6. 1. MOBILE PHONES
• SMARTPHONES AND OPERATING SYSTEMS
· A smartphone is a device that combines a cell
phone and a handheld computer, normally
offering:
• an operating system
• data storage
• internet access
• the capability to run software
• multimedia functionalities (music, video,
camera and gaming)
• a touching screen for interaction.
7. · A smartphone can not run without a mobile operating
system (OS).
· The mobile operating system is the piece of software that
manages applications, processes, memory and hardware
(wifi antenna, touching screen, earphones, speakers,
microphone…) in a smartphone.
· The operating system is the interface between the
applications you want to use and the hardware that those
apps need.
For example, if you run Spotify in your phone, your OS is in
charge of giving instructions to the wifi antenna and to the
speakers.
If you are interested in different OS, you can read an interesting article
comparing them here.
8. • DATA AND VOICE TRANSMISSION: CELLULAR NETWORKS
· Cell towers interconnect to handle packets of
signals (data, voice and text messaging) through
radio waves in different frequencies. The
frequencies are constantly changing in order to
reduce interference.
· Finally, the mobile device (phone or tablet) acts as
a receiver of those signals.
· A cellular network is made out of cells. A cell is a portion
of land (typically hexagonal) that has at least one
transceiver cell tower (or base station) within its area.
9. · Rural areas’ cells are bigger and
normally don’t need more that
one tower.
· Urban areas are divided in
smaller microcells and have
more than one tower to
guarantee connection to the
network.
· Phone companies share their
structures in order to make sure
their clients have a good service.
The first commercial cellular network was created in Tokio in 1979, but it worked with analogue voice signals (it was
called 1G). The first digital voice cellular network (2G) was launched in 1991.
10. · The mobile phone signal is the voice or data signal strength (or coverage)
received by a mobile phone from a cellular network. The signal strength depends
mostly on the company you hire, but also varies depending on the proximity to a
tower, the presence of obstacles (trees, hills, buildings, being inside a tunnel,
clouds, rain…).
· We call dead zones to the areas where mobile phones cannot transmit to a
nearby base station or tower, normally due to obstacles.
· We can also use this concept when connecting to wifi local networks.
• SIGNAL OR COVERAGE
11.
12. · SIM is an acronym for Subscriber Identification Module.
· It’s a physical card with an integrated circuit made of PVC with embedded
contacts and conducting materials.
· It is necessary for all devices using GSM standards (Global System for Mobile
Communications), which is the 90% of the devices sold in the world.
• SIM CARD
Full size SIM Mini SIM Micro SIM Nano SIM
· The SIM card stores:
- the card’s serial number
- the subscriber’s international
identification number
- a list of the services the subscriber is
paying for and has access to
- two passwords (PIN -Personal
Identification Number- and PUK –personal
unblocking key-)
