Unidirectional data transmission system

• US 4,420,833 A
• Filed: 09/22/1980
• Issued: 12/13/1983
• Est. Priority Date: 09/27/1979
• Status: Expired due to Term

• Current Assignee: Nications)
• Original Assignee: Etablissement Public de Diffusion DIT "Telediffusion de France", L'Etat Francais Represente PAR Le Secretaire D'Etat AUX Postes et Telecommunications et A La Telediffusion
• Inventors: Noirel, Yves M.
• Primary Examiner(s): Olms, Douglas W.
• Application Number:
  US06/189,080
• Time in Patent Office: 1,177 Days
• Field of Search: 370/83, 370/82, 370/79, 358/142, 358/147
• US Class Current: 370/349
• 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

Abstract

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.

Claims

1. A system for broadcasting data in the form of data packets sent from a transmitting station;

said data packets including numerical data received from at least one of a plurality of incoming paths and combining such data into a format comprising a prefix containing synchronization and path identification code signals, said packet also including a format signal indicating the length of the successive data words which follow the prefix;

said system comprising;

a transmitting station having a plurality coupling means, one coupling means being individually associated with each of said incoming paths;

common governing means for controlling all of said plurality of coupling means, each of said coupling means having an individual input circuit menas coupled to receive data over the incoming path which is individually associated with the coupling device;

multiplexing means for preparing said data packets for transmission;

data memory means individually associated with each of said input circuit means for driving said multiplexing means under control of said common governing means;

counter means operated at a pre-determined bit clock rate for retaining a memory of the amount of data stored in said data memory;

means responsive to at least a partial filling of said data memory means as indicated by said counter means for inhibiting the input circuit means associated therewith;

means responsive to said inhibiting of said input circuit means for connecting said data memory means to the multiplexing means and emptying the data memory means, and for resetting the counter means, the inhibition being removed on the emptying of said memory means;

a register means having an adjustable maximum capacity for causing said inhibition order to be given when the count of said data again reaches a pre-determined value; and

a small capacity buffer memory means interposed between said input circuit means and its individually associated data memory means for smoothing the flow of said data into said data memory means, the reading of the data into and out of the buffer memory being governed by a programmer means associated with said coupling means.

2. The system of claim 1 and means for sending the signals which follow the prefix into said buffer memory when said prefix is accepted;

transcoding circuit means for converting the format signal;

format signal register means responsive to said transcoding means for storing the format signal of each data packet as it is received,

means responsive to said counter means reaching a maximum count for emptying data from the buffer memory means and into the output circuit means, the length of the emptying data being limited by the content of said format signal register means.