Abstract: A network interface in a local area network system for transferring a message from a first terminal to a second terminal at high speed comprises a receiving section for receiving the message from the first terminal, a first sending section for sending the received message to a first network on the basis of a first control instruction, a second sending section for sending the received message to a second network on the basis of a second control instruction, and a network control section for detecting a message size of the received message and for outputting the first and second control instruction to the first and second sending section in accordance with the message size.

Abstract: A redundant common communication system for a distributed process control or data processing system has multiple stations which are coupled to at least two redundant communication channels (such as communication busses). Each station includes a transmitter for transmitting data packets and a receiver for receiving data packets. Each data packet includes a channel selection field which identifies a selected channel to be used by all station during a succeeding transmission of a data packet. Each station makes an assessment of quality of each channel based upon the occurrence of errors when that channel is in use. The station computes a margin value based upon assessed quality factors. When the station gets an opportunity to transmit, the channel selection field of the transmitted packet identifies a channel which is selected based upon the margin value and the frequency of previous use of each of the channels.

Abstract: Conventional telephone systems including terminal equipments interconnected by a communications channel typically employ a supervisory tone transmitted by each terminal equipment to indicate its idle condition. Because the fraction of idle terminal equipments may be high, the total energy carried over the channel is substantially determined by these tones. The apparatus of the type disclosed herein, employed in association with each terminal equipment, effects a reduction in the channel power loading due to those tones. The apparatus includes circuits for detecting the presence of the idle state supervisory tone being transmitted from or received by the associated terminal. If the tone is present on either the transmit or received lead, the signal transmitted by the terminal into the channel is attenuated by a fixed power ratio and the signal received by the terminal from the channel is amplified by the same fixed power ratio.

Abstract: In order to suppress noise due to reflected outgoing signals in a telephone receiver of a system for the bidirectional transmission of digitized voice signals over a two-wire telephone line connected by a hybrid coil to an outgoing section and an incoming section of a subscriber station or of an exchange, a shift register loaded with several (e.g. five) consecutive transmitted bits from the outgoing section addresses the cells of a memory containing the digitized amplitudes of corrective signals assigned to the several bit combinations which may be present at any time in that register. The corrective signal read out from the memory during each bit period is subtracted in the incoming section from an arriving signal and the result is fed on the one hand to a receiver and on the other hand to an algebraic adder as a modifying signal incrementing or decrementing, if need be, the contents of the corresponding cell during a writing interval which is a small fraction of a bit period.

Abstract: An optical multiplexer whereby the light from a plurality of optical fibers can be combined in an optical transmission fiber via an input lens, a prism and an output lens. The lenses are preferably ball-lenses. The multiplexer does not comprise any color-selective elements.

Abstract: There is disclosed a method and apparatus for providing call clearance in a packet-switched data communications system. The apparatus disclosed detects the request of an originating terminal to end a call and delays the request for a predetermined calculated time period. The period is determined according to the length of the message being transmitted, the number and type of transmission links being traversed and the speed of transmission of the sending and receiving terminals. At the termination of this period the apparatus issues a normal clear request which then disconnects the connection while assuring that any data which may have been delayed reaches the destination terminal.