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.
Carriers A and B are each assigned 832 frequencies: 790 for voice and 42 for data. A pair of
frequencies (one for transmit and one for receive) is used to create one channel. The frequencies
used in analog voice channels are typically 30 kHz wide -- 30 kHz was chosen as the standard
size because it gives you voice quality comparable to a wired telephone.


The transmit and receive frequencies of each voice channel are separated by 45 MHz to keep
them from interfering with each other. Each carrier has 395 voice channels, as well as 21 data
channels to use for housekeeping activities like registration and paging.
A version of AMPS known as Narrowband Advanced Mobile Phone Service (NAMPS)
incorporates some digital technology to allow the system to carry about three times as many
calls as the original version. Even though it uses digital technology, it is still considered analog.
AMPS and NAMPS only operate in the 800-MHz band and do not offer many of the features
common in digital cellular service, such as e-mail and Web browsing.