Etablissement Public De Diffusion Dit 'telediffusion De France'

L'etat Francais, Represente Par Le Secretaire D'etat Aux Postes Et

Other

L'etat Francais

Etablissement Public Dit Telediffusion De France

L'etat Francais, Represente Par Le Ministre Des P.t.a. (centre National D'e

L'etat Francais, Represente Par Le Secre-d-etat Aux Postes Et

La Telediffusion Centre National

Yves M Noirel

Yves Maurice Guinet

Jean-Claude Vardo

Jean-Pierre Bauduin

Joseph Blineau

Pierre Leray

Gerard Chevee

A field of useful data is split into a number of basic entities, called 'data groups'. Each data group is, in turn, split into smaller basic entities or 'data blocks'. Each resulting data block is inserted in a data packet to be transmitted through a teletext or videotext network. Therefore, an input coupler has two functional parts: a data group generator and a data packet generator.

One-way data packet transmission system for processing data arranged in

According to this invention, a field of useful data is split into a number of basic entities, called 'data groups'. Each data group is, in turn, split into smaller basic entities or 'data blocks'. Each resulting data block is inserted in a data packet to be transmitted through a teletext or videotext network. Therefore, an input coupler has two functional parts: a data group generator and a data packet generator.

One-way data transmission system

A system broadcasts videotext data in the form of data packets originating from numerical data coming from several paths. Each packet has a prefix which contains synchronization and path identification code signals, a format signal which indicates the length of the data which follow the prefix. The transmitting station has as many coupling devices as there are paths for originating data. The coupling device has a data memory coupled to drive to a multiplexing circuit under the control of a common governing circuit. An inhibition order is given either as soon as the memory is full, or as soon as a counter has reached a pre-determined count. Then, the memory is connected to the multiplexing circuit, into which the stored data is emptied. The system is characterized in that a small capacity buffer is used between the memory and the input circuit for reading data out of the buffer memory responsive to a programmer. A transcoder treats the broadcast data to fit it into the system format.

Unidirectional data transmission system

This test equipment permits a testing of the demodulator of a teletex television receiver. It consists of a digital test signal generator, the output of which is connected to the HF input of the television, and a receiver, the input of which is connected to the video output of said receiver. The generator tramsmits pseudo-random data packets having a first frequency of binary elements, with two double-intervaled binary elements at two predetermined instants t.sub.1 and t.sub.2 for each packet. The receiver has a data regeneration circuit whose threshold varies line by line from a maximum value to a minimum value. The sampling clock of the receiver is at a second frequency lower than the first by the ratio (n-2)/n, where n is equal to the integral ratio of the first frequency to the line frequency of the television. A suitable means insures resynchronization of the sampling clock at the middle of each line. A receiving circuit for the pseudo-random data detects the errors which are transmitted to the video input of the television.

Test equipment for a teletex television receiver

There is provided a one-way data transmission system wherein a transmitter station transmits in the form of data packs data from a plurality of channels, the said packs being time multiplexed. One channel amongst the plurality of channels is allotted to transmitting date information. In the receiver equipments, the dead memory stores not only the channel code, but also a subscription period information which permits to validate the channel code depending on the date information received from the date channel. Automatic dead-memory distributors are provided which receive data from a control channel transmitted by the system, like other channels. The system is compatible with television systems.

One way data transmission system

Growing community of inventors

Montfort, France

Yves M Noirel