SINGLE TWO-WAY RADIO HAVING MULTIPLE SUBCHANNELS

摘要

A system for creating multiple subchannels in a single two-way radio channel is described. Each subschannel (12-20) in the system is capable of carrying voice or data. Each subchannel is split into an upper (12u-20u) and a lower (121-12u) band with the upper band placed in a particular frequency range above the center of the channel and the lower band below the center of the channel. Either one or two pilot tones (24) placed at or adjacent to the center of the channel are used to provide a reference for all the subchannels to allow for correction of distortions when the signal is received. The system includes a base station with a transmitter and receiver and a plurality of mobile units each with a transmitter and receiver. The base station transmits a signal which is the sum of all the subchannels. The mobile unit receives the signal, separates and processes the particular subchannel for that mobile unit. The mobile unit transmits only the desired subchannel or subchannels with a pilot tone located adjacent to one of the bands of the subchannel. Two or more subchannels can be used in conjunction to achieve faster data rates of higher quality voice transmissions.