Independent Broadcasting Authority

Philip John Dodds

Peter Richard Hutt

Gunter Von Cavallar

Brian Neil Douglas

Alan Ronald Blake

John B Watson

Apparatus for deriving a parameter indicative of the quality of parts of, or the whole of, a television system from an insertion test signal repeated at regular intervals during field blanking periods of a transmitted signal includes a sampling means for providing a digital signal representing the amplitude at a sampling position of the test signal, means for actuating the sampling means, and a computer. The computer is programmed to caculate the quality parameter from a number of the amplitude representative digital signals taken at different sampling positions by the sampling means, to provide the calculated parameter as an output, and to respond to timing origins included in the television signal to thereby control the actuating means. The actuating times are so related to the timing origins that the digital amplitude signals are provided at an average rate which is low compared with the rate at which the signals occur during a single test signal. A digital store is connected between the sampling means and the computer for storing a number of the digital amplitude signals and also for storing request signals for the amplitude signals in such a way that the sampling means is enabled to operate during a line period at a greater rate than the computer. The digital store may be in the form of a first-in-first-out store.

Television systems

According to the invention, a television receiver system comprises selector equipment for selecting information in the form of coded characters, received separately from any picture signals, from a single information channel or a small number of information channels and routing the selected information to a storage device, and a reading device operable, when actuated, to read the information from the storage device repeatedly and feed it, via a character generator, for display by an intensity modulated raster.

Television receiver system having facility for storage and display of

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.

System for processing data signals for insertion in television signals

Apparatus for processing groups of digital data for transmission comprises a run-in signal generator for providing at the output of the apparatus an output in which the groups of data are each preceded by a run-in signal, said apparatus being so constituted that the output is in the form of digital signals of the complemented type, and a start code generator operable to provide a start code with at least one break of complementation and arranged to insert a start code between each group and its preceding run-in signal. The apparatus is especially suitable for the transmission of data intermittently, e.g. during periods of a television signal unoccupied by wide-band picture signals. Because of the complementation break, the start code cannot arise from a data combination. Good reliability of reception is achieved on channels susceptible to interference. An apparatus for reception comprises a memory device controlled by a clock circuit responsive to the run-in signal, and means responsive to the start code to route the data for display purposes.

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Southampton, United Kingdom

Philip John Dodds