Patent ID: 6084905
Filing Date: 2000-07-04
Classification: H04B,H04L

Abstract:
A radio communication system in which a communication frame including a preamble field and an information transfer field is transmitted from transmitter site communication equipment, and receiver site communication equipment receives the information transmitted in the information transfer field of the communication frame synchronously with a timing signal recovered from the preamble field,wherein the preamble field of the communication frame includes a first portion and a second portion succeeding the first portion, andwherein said receiver site communication equipment includes:automatic gain control means for adjusting automatically the gain of a receiver amplifier in accordance with an electric power of the received signal in the first portion of the preamble field;carrier recovering means for detecting both a frequency and a phase of a carrier of the received signal in the first portion of the preamble field, and recovering the carrier of the received signal using a local frequency synchronized with a frequency of the carrier;clock producing means for recovering a timing signal from the received signal in the second portion of the preamble field and generating a clock signal having a symbol frequency with the timing signal thus recovered; andmeans for receiving the information which has been transmitted in the information transfer field of the communication frame synchronously with the clock signal having the symbol frequency,wherein said transmitter site communication equipment includes means for sending a transmission carrier with no modulation in the first portion of the preamble field of the communication frame and sending a carrier, a phase of which is changed every symbol, in the second portion, andwherein said receiver side communication equipment carries out an operation of controlling automatically the gain and an operation of synchronizing the local oscillation frequency with the carrier on a basis of results of receiving a continuous carrier in the preamble field of each communication frame.