A communication system able to provide multiple path communication between a plurality of stations operating on a single channel. The stations are synchronized and a cyclically repeating series of time slots is defined. One time slot in each cycle is reserved for the transmission of synchronization information by a station designated the master station for reception by the other stations, designated slave stations, and maintaining synchronization therein. Another time slot is reserved for any sl...

A communication system for communicating data such as image data has a transmitter and a receiver connected through a communication line. Each transmitter or receiver has an NCU, a modem, a control unit, a reader, a recorder, and a console unit. A sound output unit for producing a sound representing the state of a received image (the number of errors in the received image data) can be included in the transmitter or the receiver. After an operator at the transmitter sends data, the operator is ca...

In a communication system such as the videotext system, the data are prepared according to the so-called ISO layer model before such data are transmitted via a conventional telephone circuit. The fact that telephone circuits may be tapped constitutes a danger in that unauthorized persons may gain access to data relating to individuals. According to the invention, a selectively connectable coding and decoding module of the bypass-type is provided between the third layer and the active layer of th...

Disclosed is a communication receiver for use in a burst communication system. A typical system is composed of a transponder and an interrogator. The transponder receiver and interrogator receiver operate in an asynchronous communication mode. The incoming coded signal is down converted to an i.f. frequency compatible with surface acoustic wave (SAW) convolvers. The i.f. signal is then divided between two SAW convolvers, each having a convolution interval of two times the message symbol length (...

A method of communicating between two control units includes transmitting a message from one control unit to the other, checking the message at the other control unit for proper reception, if the reception is not proper, sending a NAK signal from the other to the one control unit, if the reception is proper, sending an ACK signal from the other to the one control unit, and upon receiving an NAK at said one control unit, resending the original message.

In a dynamic frame length slotted ALOHA system the synchronizing signals are transmitted by a base station at different frequencies (each having a period equivalent to a multiple of the time slot period). The different frequencies denote different frame lengths and the central stations detect these frequencies and select a frame length accordingly.

There is disclosed a communication system, such as a telephone exchange with an automatic dialling function, in which the telephone number of the destination called by automatic dialling is made known to the calling terminal or telephone, so that the user can confirm the destination in advance before the communication is made.

A communication network is provided for transmitting data in a hostile electromagnetic environment. Master and slave units are coupled to a data path by transformer coupling. The slave units can be turned on by applying a DC voltage between transfomer taps at the master, and detecting the voltage at corresponding taps at the slave. Separate pairs of conductors are used to carry signals transmitted by the master and signals transmitted by the slave. The conductors form a closed loop data path ena...

A communication system and communication method having protocols used are to priorly process real-time data without delay. Information of a protocol header of data to be sent or received is used as priority decision information to decide whether or not the data should be priorly send- or receive-processed. The information to be priorly processed of combination of the priority decision information is registered and managed as priority data information before being stored. The data send or receive...

Independent communication systems are provided with additional receivers that allow the systems to monitor one another's outbound control signalling channels. Secondary control signalling can be interleaved with the primary control signalling information on this communication resource, which secondary control signalling information is intended for reception and use by the monitoring system.