Abstract: In the disclosed communication system the digital message bits (e.g., data bits) to be transmitted to a particular receiver are individually encoded in the digital address (of K bits) of that receiver. The receiver has a K(stage) correlation circuit which serves to correlate all incoming message information with its own digital address. In the case of a match, autocorrelation peaks appear at intervals determined by the digital message. A feature is to transmit each address sequence a number of times (e.g., 8) so as to reduce the likelihood of error.

Abstract: It has been found that in a profiled optical waveguide for guiding a finite spectrum of light, reduction of total dispersion is possible by forming the overall profile in the waveguide as a composite of at least two profiles of different contour. The profiles contributing to the composite are formed for example through polarizability or density gradations in the waveguide.