13-04-2012, 03:52 PM
CELL-PHONE TECHNOLOGY
[attachment=20099]
Wireless phones which receive their signals from towers. A cell is typically the area (several
miles) around a tower in which a signal can be received.
Cell phones provide an incredible array of functions. Depending on the cell-phone model, you
can:
• Store contact information
• Make task or to-do lists
• Keep track of appointments and set reminders
• Use the built-in calculator for simple math
• Send or receive e-mail
• Get information (news, entertainment, stock quotes) from the internet
• Play games
• Watch TV
• Send text messages
• Integrate other devices such as PDAs, MP3 players and GPS receivers
ANALOG CELL-PHONES (FIRST GENERATION)
In 1983, the analog cell-phone standard called AMPS (Advanced Mobile Phone System) was
approved by the FCC and first used in Chicago. AMPS uses a range of frequencies between 824
megahertz (MHz) and 894 MHz for analog cell phones. In order to encourage competition and
keep prices low, the U. S. government required the presence of two carriers in every market,
known as A and B carriers. One of the carriers was normally the local-exchange carrier (LEC),
a fancy way of saying the local phone company.
DIGITAL CELL-PHONES (SECOND GENERATION)
They use the same radio technology as analog phones, but they use it in a different way. Analog
systems do not fully utilize the signal between the phone and the cellular network -- analog
signals cannot be compressed and manipulated as easily as a true digital signal. Digital phones
convert your voice into binary information (1s and 0s) and then compress it. This compression
allows between three and 10 digital cell-phone calls to occupy the space of a single analog call.
CELL-PHONE TOWER
A cell-phone tower is typically a steel pole or lattice structure that rises hundreds of feet into the
air. The box houses the radio transmitters and receivers that let the tower communicate with
the phones. The radios transmitters and receivers connect with the antennae on the tower through
a set of thick cables. The tower and all of the cables and equipment at the base of the tower are
heavily grounded.
HOW VIBRATOR WORKS IN CELLPHONE
If you have a cell phone or a pager, then you know that having it ring in the middle of a movie or
performance is enough to get you killed in some cities. Vibrating devices that quietly replace the
ringer are therefore life-saving devices that are an important part of urban survival
MULTI-BAND VS. MULTI-MODE CELL-PHONES
1. Multiple band - A phone that has multiple-band capability can switch frequencies. For
example, a dual-band TDMA phone could use TDMA services in either an 800-MHz or
a 1900-MHz system. A quad-band GSM phone could use GSM service in the 850-MHz,
900-MHz, 1800-MHz or 1900-MHz band.
2. Multiple mode - In cell phones, "mode" refers to the type of transmission technology
used. So, a phone that supported AMPS and TDMA could switch back and forth as
needed. It's important that one of the modes is AMPS -- this gives you analog service if
you are in an area that doesn't have digital support.
3. Multiple band/Multiple mode - It allows you to switch between frequency bands and
transmission modes as needed.
CELL PHONE JAMMERS
It's great to be able to call anyone at anytime. Unfortunately, restaurants, movie theaters,
concerts, shopping malls and churches all suffer from the spread of cell phones because not all
cell-phone users know when to stop talking. Who hasn't seethed through one side of a
conversation about an incredibly personal situation as the talker shares intimate details with his
friend as well as everyone else in the area?
CELL-PHONE VIRUSES
The first known cell-phone virus appeared in 2004 and didn't get very far. Cabir.A infected only
a small number of Bluetooth-enabled phones and carried out no malicious action -- a group of
malware developers created Cabir to prove it could be done. Their next step was to send it to
anti-virus researchers, who began the process of developing a solution to a problem that
promises to get a lot worse.
[attachment=20099]
Wireless phones which receive their signals from towers. A cell is typically the area (several
miles) around a tower in which a signal can be received.
Cell phones provide an incredible array of functions. Depending on the cell-phone model, you
can:
• Store contact information
• Make task or to-do lists
• Keep track of appointments and set reminders
• Use the built-in calculator for simple math
• Send or receive e-mail
• Get information (news, entertainment, stock quotes) from the internet
• Play games
• Watch TV
• Send text messages
• Integrate other devices such as PDAs, MP3 players and GPS receivers
ANALOG CELL-PHONES (FIRST GENERATION)
In 1983, the analog cell-phone standard called AMPS (Advanced Mobile Phone System) was
approved by the FCC and first used in Chicago. AMPS uses a range of frequencies between 824
megahertz (MHz) and 894 MHz for analog cell phones. In order to encourage competition and
keep prices low, the U. S. government required the presence of two carriers in every market,
known as A and B carriers. One of the carriers was normally the local-exchange carrier (LEC),
a fancy way of saying the local phone company.
DIGITAL CELL-PHONES (SECOND GENERATION)
They use the same radio technology as analog phones, but they use it in a different way. Analog
systems do not fully utilize the signal between the phone and the cellular network -- analog
signals cannot be compressed and manipulated as easily as a true digital signal. Digital phones
convert your voice into binary information (1s and 0s) and then compress it. This compression
allows between three and 10 digital cell-phone calls to occupy the space of a single analog call.
CELL-PHONE TOWER
A cell-phone tower is typically a steel pole or lattice structure that rises hundreds of feet into the
air. The box houses the radio transmitters and receivers that let the tower communicate with
the phones. The radios transmitters and receivers connect with the antennae on the tower through
a set of thick cables. The tower and all of the cables and equipment at the base of the tower are
heavily grounded.
HOW VIBRATOR WORKS IN CELLPHONE
If you have a cell phone or a pager, then you know that having it ring in the middle of a movie or
performance is enough to get you killed in some cities. Vibrating devices that quietly replace the
ringer are therefore life-saving devices that are an important part of urban survival
MULTI-BAND VS. MULTI-MODE CELL-PHONES
1. Multiple band - A phone that has multiple-band capability can switch frequencies. For
example, a dual-band TDMA phone could use TDMA services in either an 800-MHz or
a 1900-MHz system. A quad-band GSM phone could use GSM service in the 850-MHz,
900-MHz, 1800-MHz or 1900-MHz band.
2. Multiple mode - In cell phones, "mode" refers to the type of transmission technology
used. So, a phone that supported AMPS and TDMA could switch back and forth as
needed. It's important that one of the modes is AMPS -- this gives you analog service if
you are in an area that doesn't have digital support.
3. Multiple band/Multiple mode - It allows you to switch between frequency bands and
transmission modes as needed.
CELL PHONE JAMMERS
It's great to be able to call anyone at anytime. Unfortunately, restaurants, movie theaters,
concerts, shopping malls and churches all suffer from the spread of cell phones because not all
cell-phone users know when to stop talking. Who hasn't seethed through one side of a
conversation about an incredibly personal situation as the talker shares intimate details with his
friend as well as everyone else in the area?
CELL-PHONE VIRUSES
The first known cell-phone virus appeared in 2004 and didn't get very far. Cabir.A infected only
a small number of Bluetooth-enabled phones and carried out no malicious action -- a group of
malware developers created Cabir to prove it could be done. Their next step was to send it to
anti-virus researchers, who began the process of developing a solution to a problem that
promises to get a lot worse.