User Guide

PAMS
Technical Documentation
NHD–4
System Overview
Page 3–6
Original 11/97
AMPS Cellular Theory
BS
R. F. Communication
MTX
Phone
Land Line Comms
AMPS_1
Figure 1. AMPS: BS/MS/MTX
The main objective of a cellular system is to provide communications to many
mobile users. Communication between the Base Station and Mobile Phone is via a
Radio Frequency (RF) link. A Mobile Telephone Exchange (MTX) is the interface
between usually several base stations and Land line communications. The MTX
has a number of functions that include, controlling mobile phone transfers between
base stations, regulating mobile phone power output, establishing mobile phone
identity and billing for the air time.
MIC
300Hz–3000Hz
Audio signals
INFO
AMPS_2
Figure 2. AMPS: Audio
Cellular phones are designed to transmit audio signals in a frequency range of 300
Hz to 3000 Hz. This range of frequencies contains most of the intelligibility
necessary for one person to understand what another is saying. As the figure
above shows one person wants to talk to another who is some distance away.
Cellular phones allow communication between two or more people almost without
geographical restrictions.