Patent ID: 6813326
Filing Date: 2004-11-02
Classification: H04H,H04L

Abstract:
A communication station in a data transmission system for transmitting data between communication stations located away from each other, comprising;a transmitter having circuits for transmitting together a main signal having a carrier modulated with main data to be transmitted and a sub-signal having frequency information to be used to conduct frequency conversion at a receiver of another communication station, said sub-signal being generated by modulating a carrier having a predetermined frequency outside of a frequency band of said main signal with sub-data different from said main data; a receiver having a circuit for receiving a receive signal from a transmitter of another communication station and extracting a sub-signal from said receive signal and a circuit for generating a reference signal when conducting frequency conversion of said receive signal to a signal of a predetermined frequency based on frequency information included in the extracted sub-signal; and a second transmitter for receiving the receive signal from the transmitter of another communication station, converting the received signal to a signal of a frequency band lower than the receive signal and transmitting the converted signal.