Abstract: A carrier sense multiple access with collision detection strategy ascertains for a particular network configuration the network propagation time, and promulgates a parameter p providing an indication thereof to each station of the network. Each station of the network stores p for use in making decisions about collisions. Whenever a modification of the network is made changing the propagation time, a new value of p is promulgated to the stations of the network so that the collision related decisions made by each stations's interface controller will reflect the new network configuration. Communications are formed in packets with a preamble long enough to propagate the network. The controllers analyze the signals they receive to discern whether a packet has been contaminated by an interference.

Abstract: A broadband data communication system provides effective increased bandwidth for the transmission of electrical information signals in the system. The signal transmission medium is a coaxial cable having main receive and transmit branches, and having drop line pairs connected to the main branches at junction points. A plurality of user devices is connected to each drop line pair, including a particular set connected to a particular pair. Each user device of the set can transmit and receive signals of local frequencies in a selected bandwidth. Frequency isolation means is connected to the particular drop line pair adjacent its junction point, and passes signals of the local frequencies only from the transmit drop line to the receive drop line, while blocking signals of the local frequencies from transmission over the main cable branches. The particular set of user devices and the filter isolation means together define a subnet.

Abstract: A pattern recognition system has both coarse and fine levels of analysis in which a coarse array representation of a workpiece pattern is formed and used to identify the workpiece pattern as either a referench character or as a member of an ambiguous set of reference characters which are represented by identical coarse array representations. At least portions of a fine array representation of a workpiece pattern which has been classified as a member of a set of reference characters are compared to corresponding portions of fine array representations of reference characters in the set identified by the classification. The pattern recognition system has a learning system through which reference characters may be introduced into the recognition system and through which a representation of a workpiece pattern which was not identified may be incorporated into an existing set of reference characters of the recognition system.