Combined television/data transmission system

• US 3,982,064 A
• Filed: 09/05/1974
• Issued: 09/21/1976
• Est. Priority Date: 09/04/1973
• Status: Expired due to Term

• Current Assignee: General Electric (Shanghai) Co., Ltd. (GE Aerospace)
• Original Assignee: General Electric (Shanghai) Co., Ltd. (GE Aerospace)
• Inventors: Barnaby, Bernard Sydney
• Primary Examiner(s): Griffin, Robert L.
• Assistant Examiner(s): Martin, John C.
• Application Number:
  US05/503,376
• Time in Patent Office: 747 Days
• Field of Search: 178/5.6, 178/5.8, 178/DIG. 23, 178/69.5 R, 178/69.5 TV, 178/6, 178/6.8, 340/324 AD, 340/33
• US Class Current: 348/467
• CPC Class Codes: H04N 7/0882 for the transmission of character code signals, e.g. for teletext circuits for the digital non-picture data signal H04N7/035

Abstract

A television transmission system of the kind in which some of the line scan periods of a conventional transmission that are left blank (as far as picture content is concerned) between successive frame transmissions are utilized for signalling data for selective display on the screen of a television receiver. The improvement over previous systems is that the information to be displayed as a line of data may be transmitted in a single line scan period. This is achieved by transmitting in a line scan period a page number and then in subsequent line scan periods the lines of data for that page. New page numbers are then transmitted followed by their respective lines of data in sequence. A receiver for the transmission system is described.

Claims

1. A combined television/data transmission system for a television signal in which information characterizing a page of data to be displayed is digitally coded and transmitted in line scan periods that do not have picture information, in which each said page of data comprises a number of rows of data, each page of data being transmitted by transmitting a respective page address in a first said line scan period that does not have picture information, one or more subsequent periods of said line scan periods being utilized to transmit information relating to said rows of data, the information transmitted during each subsequent line scan period relating to a complete row of data in said respective page and containing in addition the row address in digitally coded form but not said respective page address, the end of transmission of a page of data being identified by a further one of said line scan periods in which a further page address is transmitted.

2. A combined television/data system as claimed in claim 1 in which in a line scan period in which a page address is signalled a synchronizing signal is transmitted followed by a start signal prior to transmitting the page address signal and in which in a line scan period in which a row of data is signalled a synchronising signal is transmitted followed by a start signal prior to transmitting the row address signal.

3. A combined television/data transmission system as claimed in claim 1 in which during said first line scan period subsequent to said transmission of said page address digital coded signals relating to auxiliary information are transmitted.

4. A combined television/data transmission system as claimed in claim 3 in which the correct time is transmitted as said auxiliary information.

5. A combined television/data system as claimed in claim 1 in which the information for display is in alpha-numeric form.

6. A combined television/data system as claimed in claim 1 in which the information for display is in graphical form.

7. A transmitter for a combined television/data system in which information characterizing a page of data to be displayed is digitally coded and transmitted in television line scan periods that do not have picture information in which each page of data comprises a number of rows of data, each page of data being transmitted by transmitting a respective page address in a first said line scan period that does not have picture information, one or more subsequent periods of said line scan periods being utilized to transmit information relating to said rows of data, the information transmitted during each subsequent line scan period relating to a complete row of data in said respective page and containing in addition the row address in digitally coded form but not said respective page address, the end of transmission of a page of data being identified by a further one of said line scan periods in which a further page address is transmitted, said transmitter including

A. line and frame synchronizing means to synchronize the transmission of the television video signals on a suitable video carrier frequency signal,

B. a timing circuit to synchronize transmission of data signals during one or more specified line scan periods during the vertical blanking interval of said television video signals,

C. a parallel-to-serial shift register into which data to be transmitted is fed in parallel,

D. a page counter,

E. a row counter controlled by said timing circuit,

F. a random access memory, the outputs of said page and line counters being used to address associated portions of said random access memory, the information from said memory being stored in a part of said register,

G. a synchronizing and start circuit being connected to feed synchronizing and start signals into a further part of said register,

H. a combining circuit, said information in said register being combined with said video carrier frequency signal in said combining circuit under the control of said timing circuit to produce an output data signal during one or more specified line scan periods during said vertical blanking interval, in which in each portion of said memory associated with the first row of each page the page address is stored in digital form together with auxiliary information in digital form and in which in the portions of said memory associated with the subsequent rows of each page the row address is stored in digital form together with the data contained in each respective row in digital form, and in which the information contained in the associated portions of said memory is transferred to said register under the control of said page and line counters for transmission during said first and said subsequent line scan periods.