System for processing data signals for insertion in television signals
First Claim
1. A signal processing system for the compilation and processing of a supply of data signals representing the data for a set of pages of data each for display, separately from the other pages, upon television receiver screens, to provide output signals for insertion in a transmitted television signal during periods of the transmitted television signal which are unoccupied by video signals, said system comprising a main store for storing the supply of data signals in digitized form, at least one peripheral data generating device for supplying data signals to the main store, a second store having a data storage capacity which is small compared with the storage capacity of the main store, transfer means operable to read out portions of the data signals in digitized form from the main store in a sequence for temporary storage of said portions in the second store, an output, discharge means operable to clock out the portions of the data from the second store and feed them to the output in series digital form at a rate and at times such that the discharged signals in said series digital form can be accommodated in said television signal during said periods, each said portion representing a part of one of said pages, said sequence being such that the supply of data signals representing the data for the set of pages is transferred to the second store in a repeated cycle, said second store and said discharge means cooperating in order that each portion is fed to the output once only per cycle and means at the output for also providing a clock run-in signal and a start code signal for accommodation in said television signal during said periods and before each said portion.
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Abstract
In any television transmission system there are periods during which the wide-band picture signals are absent. The invention provides a signal generator system for the transmission of digital information representing a series of pages of alphanumeric or graphical symbols piecewise during these periods. At least one peripheral generating device is provided for supplying digitized data to a main storage device (conveniently of the magnetic disc type) and transfer means is operable to read out portions of the data from the main storage device and store them temporarily in a second storage device. Discharge means is operable to discharge portions of the data from the second storage device at intervals to provide output signals for insertion in a television signal during periods as aforesaid.
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Citations
21 Claims
- 1. A signal processing system for the compilation and processing of a supply of data signals representing the data for a set of pages of data each for display, separately from the other pages, upon television receiver screens, to provide output signals for insertion in a transmitted television signal during periods of the transmitted television signal which are unoccupied by video signals, said system comprising a main store for storing the supply of data signals in digitized form, at least one peripheral data generating device for supplying data signals to the main store, a second store having a data storage capacity which is small compared with the storage capacity of the main store, transfer means operable to read out portions of the data signals in digitized form from the main store in a sequence for temporary storage of said portions in the second store, an output, discharge means operable to clock out the portions of the data from the second store and feed them to the output in series digital form at a rate and at times such that the discharged signals in said series digital form can be accommodated in said television signal during said periods, each said portion representing a part of one of said pages, said sequence being such that the supply of data signals representing the data for the set of pages is transferred to the second store in a repeated cycle, said second store and said discharge means cooperating in order that each portion is fed to the output once only per cycle and means at the output for also providing a clock run-in signal and a start code signal for accommodation in said television signal during said periods and before each said portion.
- 15. A method for the compilation and processing of data for a series of pages of characters and preparing the compiled data for transmission which comprises generating the data for said pages using at least one peripheral generating device, compiling the generated data by transferring it to a main store, reading out portions of the compiled data from the main store at a first rate and temporarily storing said data in a second store, periodically discharging the portions from the second store at a second rate and inserting said portions, in series digital form, in a television signal during regularly recurrent periods of said signal which are free from video signals, said second rate being greater than said first rate and being such that the portions, when inserted in the television signal in series digital form, have a bit rate requiring a transmission band width comparable with the transmission band width required for the video signals of the television signal and the reading out of the portions of the compiled data from the main store being performed in a cyclic manner such that the data for the whole series of pages is inserted in the television signal in a sequence.
Specification