One-way data transmission systems

• US 4,496,975 A
• Filed: 05/10/1982
• Issued: 01/29/1985
• Est. Priority Date: 05/14/1981
• Status: Expired due to Fees

• Current Assignee: Etablissement Public de Diffusion DIT Telediffusio, L'Etat Francais Represente PAR Le Ministre Des PTT
• Original Assignee: L'Etat Francais Represente PAR Le Ministre Des PTT
• Inventors: Noirel, Maurice Y.
• Primary Examiner(s): Chin, Tommy P.
• Application Number:
  US06/376,790
• Time in Patent Office: 995 Days
• Field of Search: 358/142, 358/86, 358/11, 358/12, 358/84, 358/117, 358/140, 358/141, 370/82, 370/83, 370/79
• US Class Current: 348/467
• CPC Class Codes: H04J 3/24 in which the allocation is indicated by an address the different channels being transmitted sequentiallyH04J3/17 takes precedence; in computers G06F12/00, G06F13/00 code multiplex systems H04J13/00; selecting techniques H04Q; relay systems H04B7/14
• CPC Class Codes: H04N 7/025 Systems for the transmission of digital non-picture data, e.g. of text during the active part of a television frame transmission of digital non-picture data during the vertical blanking interval only H04N7/088
• CPC Class Codes: H04N 7/0888 Subscription systems therefor
• CPC Class Codes: H04N 7/163 by receiver means only

Abstract

A one-way teletext data transmission system is an improvement over a knowneletext system sold under the trademark "ANTIOPE" which transmits data having error correction and ciphering. The length of the transmitted data pack is always the maximum pack length and the value of the format byte is nil. A wire is connected from every channel to its individually associated coupler. That wire may be at either of the binary levels "1" or "0". The coupler comprises a first switch for switching between a counter and a memory. The memory stores a format byte, the value of which is nil. A second switch connects the memory to a data memory when any data packet transmission occurs, if the wire is at a predetermined binary level "1". The reception equipment is similar.

Claims

1. A one-way data transmission system wherein a transmitting station transmits packs of digital data, from at least one of several channels, each data pack including a prefix containing synchronism signals and channel identification code signal, a data pack format signal indicating the length of the data sequence following the prefix when the transmitted data are teletext data, the transmitted data have a structure such that they provide possible error corrections and ciphering, the length of the transmitted packs always being a maximum and the format of the byte value being nil, the transmitting station comprising a coupler means associated with each of said channels, each of said coupler means having an input circuit means with an input coupled to receive signals of a channel associated therewith, data memory means coupled to an output of said input circuit means, multiplexing circuit means coupled to an output of said data memory means, control circuit means, common to all of said coupler means, counter means fed at a predetermined rate, means responsive to a full memory for delivering an inhibition control signal to said input circuit means, means for connecting said data memory means to said multiplexing circuit and then reading out and resetting said counter and thereafter suppressing said inhibition control signal, register means having a settable maximum capacity coupled to said means for delivery said inhibition control signal to deliver said inhibition control signal when the count of said data reaches a predetermined value, small capacity buffer memory means coupled between said data memory means and said input circuit means controlled by a programmed control circuit means for controlling the read out of data from said buffer memory, a wire coupled between each channel equipment and the coupler means associated therewith, said wire being switchable a level "1", or "0", each coupler means further including first switching means for switching off said counter means and buffer memory means, and format byte memory means storing the value "nil", and second switching means for connecting said format byte memory means to said data memory means for each data pack transmission when said wire is at level "1" or "0", said first and second switching means being at rest when said wire is at level "0" or "1".

2. A one-way data transmission system according to claim 1, and reception equipment means for receiving signals from the said data one-way transmission system, means responsive to an acceptance of said data sequence following said prefix for storing said accepted data sequence in a buffer memory means, output circuit means responsive to said buffer memory, pack format signal register means for storing a format signal of each received data pack prefix, counter means fed by a byte clock signal for controlling a read out of a data sequence from said buffer memory means into said output circuit means, as soon as said counter means has reached a predetermined maximum count, the length of said data sequence being limited by the contents of said format signal register means, transcoding circuit means for processing the transmitted format signal and including means for recognizing the value "nil" of a format byte, means for converting that value into the value "Nmax" that is transmitted to the format signal register means, and an output wire connected to said output circuit.