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In
the United States, there are a number of different standards
and technologies for wireless phones. This combination of
standards and technologies can become very confusing for
you. This training guide will give you a brief overview
of the different technologies which will help you understand
the differences.
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Which technology is best?
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Wireless system operators (Carriers) have selected one or
two of these technologies which best serve their target
customers. All of these technologies can serve individual
subscribers well.
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Cellular
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is the term used to refer to the wireless phone systems
that originated in the United States and originally operated
in the 800 MHz frequency range. There are a maximum of two
cellular operators in each market. They are usually referred
to as the "Wireline" (landline phone company in
that particular market), and the "Non-Wireline"
carrier.
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800 Megahertz (800 MHz)
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is the radio frequency range originally allocated by the
FCC for cellular in 1983. Typically, the wireless phones
have been referred to as "cellular" operating
at these frequencies. AMPS, NAMPS, TDMA, and CDMA technologies
are all currently available in this frequency range.
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AMPS, (Advanced Mobile Phone Service)
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has been the original standard for cellular products in
the United States. All customers should be able to use their
AMPS phone in any 800 MHz cellular market across the United
States and Pan America.
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NAMPS, (Narrowband Advanced Mobile
Phone Service)
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is the "next generation" analog version of the
AMPS system which uses some digital technology to allow
the network to carry three times the number of conversations
as well as offering some enhanced user features such as
Short Message Service (SMS) and Voice Mail notification.
NAMPS phones automatically switch to the AMPS mode when
the user is in an area where NAMPS systems are not used.
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TDMA, (Time Division Multiple
Access)
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is a digital technology that allows multiple users to share
the same voice channel by having each conversation transmitted
alternately over short lengths of time.
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CDMA, (Code Division Multiple
Access)
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is a digital technology that separates communications by
code. This way, the system can mix a number of calls into
the same channel. When the tower receives the information,
it looks at the coding and reassembles each individual call,
completing the transmission.
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GSM, (Global System for
Mobil communication)
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is the name of a TDMA type of Digital system originally
developed in Europe, and common throughout Asia. This system
is being used by some of the PCS operators here in the US.
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PCS, (Personal Communications
Service)
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is the name adopted by the new, wireless service providers
who have been awarded licenses to operate new phone systems
in the 1900 MHz frequency range. There are up to three PCS
operators on the air in most major markets of the United
States.
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1900 Megahertz, (1900 MHz)
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is the radio frequency range allocated by the FCC in order
to create additional competition in wireless telephony services.
The wireless phones referred to as "PCS" typically
operate at these frequencies. GSM, TDMA, and CDMA technologies
are currently available in this frequency range.
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| ANALOG
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DIGITAL
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| In
analog communications, voice messages are transmitted
as sound waves. When someone speaks into an analog
wireless phone, the voice wave is linked to a radio
wave and transmitted. |
Digital
converts the sound wave created by the voice into
a stream of 1s and 0s. Once digitized, this information
is then compressed and manipulated in such a way that
the security of the conversation is enhanced and background
noise is reduced. The digital network has the ability
to carry more conversations at one time and additional
features are now available to the user. |
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AMPS
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NAMPS
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TDMA
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CDMA
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GSM
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| 800
Mhz |
X |
X
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X |
X
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| 1900
Mhz |
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X
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X |
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Q&A:
What is the difference between a "cellular"
CDMA phone that operates at 800 MHz and a "PCS"
CDMA phone that operates at 1900 MHz?
The primary difference is that one phone operates in the
800 MHz range on the "FM dial" while the other
phone operates in the 1900 MHz range on the "FM dial."
The user features (on the CDMA network) could be identical.
The other difference may be the ability to "roam"
or use the phone in other cities. Remember, for a phone
to work in an area other than the "home" area,
it must be in a system that supports the technology used
by that phone‚ in the frequency which the phone is
designed to work.
If
I have a TDMA phone, will that phone work in a city that
does not use a TDMA system?
A TDMA phone will only work in the TDMA mode in a system
that supports the TDMA technology. However, some phones
are designed to operate on more than one frequency band.
For instance, all Motorola's 800 MHz TDMA cellular phones
are also designed to work on the 800 MHz AMPS system. So,
if an 800 MHz TDMA system is not available, you could still
use your phone in the AMPS mode.
What
is a Dual Band phone?
A Dual Band phone can operate at two different frequencies.
This means the phone could operate on either an 800 MHz
system or on a 1900 MHz system. So, if a phone were single
mode (e.g. CDMA) and dual band (e.g. 800 MHz and 1900 MHz)
that phone could operate in the CDMA mode on either an 800
MHz system or a 1900 MHz system.
What
is a Dual Mode phone?
A Dual Mode phone can operate in two different technologies.
For instance, the phone could operate in either the AMPS
mode or the TDMA mode. So, if a phone was a single band,
but dual mode phone, it could operate on an 800 MHz system
in either the AMPS mode or the TDMA mode.
What
is a Dual Band, Dual Mode phone?
A Dual Band, Dual Mode phone can operate in some combination
of two different frequencies and two different technologies.
For instance, a Dual Band, Dual Mode phone could operate
at either 800 MHz or 1900 MHz and support both AMPS technology
and CDMA technology. Remember, in order for a wireless phone
to work, it must be within the boundaries of a wireless
phone system that supports both the same technology and
frequency with which that phone was designed to work. At
the same time, wireless operators are implementing new digital
systems with different technologies and at different frequencies
that are not compatible with each other. So, the implications
to these Dual Band, Dual Mode combinations is simply to
help the user take their phone outside of their home service
area and increase the probability that their phone will
continue to have wireless service available.
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