An optical communication system using techniques borrowed from UWB radio technology, such as correlating a received PPM signal with a stored training signal

摘要

The invention is applicable to wired or wireless optical data communications, preferably using infra-red radiation. In one embodiment the data is transmitted using pulse position modulation (PPM). A training sequence is sent from the transmitter to the receiver and the receiver stores an electrical representation of the received training sequence, or information deduced using the training sequence, in memory as a reference signal. The applicant refers to the reference signal as a "reference channel response signal". Received electrical representations of the PPM signals are correlated with the reference signal to detect pulse positions and thus demodulate the data. In one embodiment the transmitter modulates the PPM data with a pseudo-random sequence in a time domain spreading technique. The correlation operation is preferably performed on digitised signals. The optical receiver of the invention may be combined with a UWB radio system, preferably for use in a home network.