System for broadcasting audio-visual television signals synchronized by a pilot frequency and method for the application of said system
AssigneeThomson-Brandt
InventorRene Romeas
Life of this patent
Estimating the term…
Abstract
In a system for broadcasting audio-visual television signals, a pure-frequency pilot signal is recorded concurrently with the video signals. The synchronizing signals which are necessary for reproduction of the aduio-visual signals are reconstituted from the pilot signal during the reading process.
Claims9
A system for broadcasting audio-visual signals representing television pictures defined by fields, each field divided into scanning lines, said audio-visual signals including a video signal component, comprising:
- a recording section including a first frequency-modulation circuit for producing a carrier wave modulated by said video signal,
- a second circuit for producing a continuous sine wave pilot signal having a frequency that is a multiple of the line scanning half frequency of the pictures,
- a third circuit for combining said carrier wave, as modulated by said video signal with said continuous sine wave pilot signal for producing a composite signal,
- a fourth circuit for width-modulating and amplitude-limiting said composite signal,
- an information medium provided with a track for recording said composite signal, and
- a reading section comprising:
- filter circuits for extracting said continuous sine-wave pilot signal from said composite signal and
- means for generating from said continuous sine wave pilot signal standard synchronizing signals used in conventional television systems.
A method for broadcasting audio visual signals representing television pictures defined by fields, each field being divided into scanning lines, said audio visual signals including a video signal component, comprising the steps of:
- inserting a single train of bits representing an image-commencement synchronizing binary code within an interval corresponding to the blanking of one of said fields constituting an image;
- frequency modulating a principal carrier wave by said video signals;
- generating a continuous sine-wave pilot signal that is an exact multiple of the line-scanning half-frequency;
- weighting the amplitudes of said carrier wave and of said sine-wave pilot signal by predetermined coefficients;
- combining said principal carrier wave with said continuous sine-wave pilot signal to obtain a composite signal;
- width-modulating and amplitude-limiting said composite signal;
- recording said composite signal onto a recording medium;
- reading the composite signal from said recording medium;
- extracting said continuous sine-wave pilot signal from said composite signal read from said recording medium;
- and generating
- from said continuous sine-wave pilot signal so extracted standard synchronizing signals used in conventional systems.
Dependencies are inferred from the claim text.