There is disclosed optical communication apparatus for transferring digital information at high rates, as high as 10.sup.10 bits per second. The communication channel is a mode-or phase-locked CW laser which generates optical pulses of very short duration, typically of 10.sup..sup.-9 seconds, at short intervals. Typically 10.sup.8 pulses are transmitted per second. Each pulse is subdivided into time-spaced sub-pulses by beam splitters and each sub-pulse, in its turn, is incident on one of an arr...

A communication system wherein a relay station comprising a single receiver and a single transmitter is adapted to selectively monitor a plurality of frequencies and transmit the monitored signal in one of a plurality of predetermined frequencies. To accomplish this end a sensing system is operated in conjunction with the receiver and transmitter to sense the incoming signal and lock the receiver and transmitter in an operating condition corresponding to the sensed incoming signal. Assuming that...

A bilateral repeater for connection in a transmission line arranged to transmit data between two spaced points includes a network having two inputs and two outputs. Each output is connected to a corresponding input at a terminal arranged for connection to the transmission line. The repeater also includes bilateral circuitry responsive to an initiating data signal applied via either of the terminals to an input for transmitting a corresponding data signal via an output to the other of the termina...

A communication system featuring a pyramid structured interconnecting network, adjacent levels of the interconnecting network being coupled together with single channel links. The system permits lateral signal routing once a common or linking level is reached. The base level of the pyramid structure contains message stations, with each higher level comprised of control stations. Each control station is controlled by the next higher level control station to which it is coupled while simultaneousl...

A threshold detector sorts each of a plurality of n-bit binary code blocks representative of redundantly encoded information into correct bits and, if present, a bit ambiguous as to information content. The latter bit is transformed into an erased word. The correct digits and erased word forming one signal sequence are registered in a shift register with a corresponding checking code. Upon detecting the erased word, a correction circuit responds to the checking code to calculate the original exa...

A technique for communicating binary data comprising adding the transmitted data signals to develop a check sum, transmitting the check sum immediately following the "end-of-transmission" signal, receiving the transmitted data signals together with said check sum, adding the data signals received to develop a received signal sum, and comparing said received signal sum with said check sum to verify message integrity. Both method and apparatus are disclosed.

A communication system by which a plurality of substantially simultaneously transmitted different subscription programs may be selectively individually displayed on a common display channel. A multiplexed communication signal containing a plurality of different program information signals and a plurality of command signals is provided to a plurality of display devices which are capable of displaying different selected program information displays from the plurality of such signals in response to...

A transmitter for use in a communication system in which successive frames of coded data are transmitted over a multi-channel link from a transmitting station to a receiving station includes a code generator for generating the successive frames of coded data and means for jittering the start of the successive frames of coded data such that the start of each frame is delayed by a random amount.

Communication apparatus in which an operator selects information items or characters which are visually displayed in groups sequentially. The operator observes the sequential display of the groups and selects the group containing the character he desires to communicate by operating a single switch mechanism in coincidence with the visual display of that group. The apparatus then sequentially displays the characters within the selected group. The operator then selects his desired character by ope...

An automatic communication system and method for generating information recorded on record cards by automatically reading individual cards, and transmitting the information generated as electrical signals to one or more receiving stations where it is automatically recorded. The system includes means for automatically effecting a communication link between the output of the card reader and a selected receiving station and, after automatically establishing that the communication link is in effect,...