APPARATUS FOR SYNCHRONIZED GENERATION OF A SIGNAL FROM A COMPOSITE COLOR VIDEO SIGNAL SUBJECTED TO SIGNAL PERTURBATIONS

• US 3,578,902 A
• Filed: 08/28/1968
• Issued: 05/18/1971
• Est. Priority Date: 08/28/1968
• Status: Expired due to Term

• Current Assignee: RCA Corporation
• Original Assignee: John Monsay
• Inventors: Monsay, John
• Application Number:
  US04/755,895
• Time in Patent Office: 993 Days
• US Class Current: 386/274
• CPC Class Codes: H03L 7/083 the reference signal being additionally directly applied to the generator
• CPC Class Codes: H04N 9/455 Generation of colour burst signals; Insertion of colour burst signals in colour picture signals or separation of colour burst signals from colour picture signals H04N9/45 takes precedence

Abstract

A technique is disclosed for providing a local reference signal in response to a composite color video signal. The frequency and phase of the reference signal are determined by certain signal portions of the composite signal. The nominal frequency of the reference signal is made to conform to a multiple of the horizontal synchronizing signal frequency portion of the composite signal. The reference signal is further influenced by the presence of the color burst signal portion of the composite signal, to synchronize the reference signal in phase and frequency to the burst signal.

Claims

1. Apparatus for providing in response to a composite color video signal, which has been subjected to signal perturbations, an output signal which is synchronized in phase and frequency with the color burst and horizontal sync signal portions of said composite video signal, comprising:

means for separating said horizontal synchronizing signal portion from said composite signal;

means for separating said burst signal from said composite signal;

a signal generator having control means for establishing an operating frequency of said generator in response to a first signal applied to one input thereof, said generator including means responsive to the presence of a further signal at a second input thereof causing the output signal of said generator to be conformed in phase and frequency to said further signal;

means responsive to said burst signal for providing said further signal to the second input of said generator; and

frequency difference determining means coupled to the output of said generator and responsive to the frequency of said horizontal synchronizing signal portion for providing said first signal input to said generator, said first signal being such as to establish the operating frequency of said generator at a value enabling the generator output to be conformed in phase and frequency to said burst signal and maintained close to the frequency of said burst signal in the absence of said burst signal, regardless of perturbations of said composite video signal.

2. In combination with a system for recording and reproducing a composite color video signal, wherein said composite signal including frequency related color burst and horizontal synchronizing signal portions are subjected to common perturbations by virtue of said recording and reproducing process, apparatus for providing and maintaining a continuous local color reference signal having the phase and frequency of said reproduced burst signal in the presence of said perturbations, comprising:

first means for separating the reproduced horizontal synchronizing signal portion of said composite signal as modified by said perturbations;

second means for separating the reproduced color burst signal portion of said composite signal as modified by said perturbations;

an oscillator with first and second inputs and an output and having a frequency determining network including a voltage controlled tuned means, said oscillator providing an output frequency established by a signal applied through said first input to said voltage controlled tuned means, and synchronized in phase and frequency in the presence of a further signal applied through said second input to said frequency determining network;

means for applying said modified color burst signal portion to the second input of said oscillator;

frequency divider means coupled to said oscillator output for providing a submultiple frequency of said oscillator output signal;

phase detector means coupled to the output of said divider means and said first means, for providing to said first input of said oscillator a continuous signal whose magnitude is indicative of the deviation of the output frequency of said oscillator from a multiple of said modified horizontal synchronizing signal, said first input signal establishing said oscillator output at a frequency multiple of said modified horizontal synchronizing signal portion which is approximately equal to the frequency of said modified color burst portion, to enable said oscillator output to be phase and frequency synchronized by the presence of said color burst portion, and maintained at said established frequency between the periodic occurrences of said color burst portion.

3. The invention as claimed in claim 1 wherein said frequency difference determining means includes:

a frequency divider circuit coupled to the output of said signal generator; and

a phase error detector having a first input coupled to the output of said divider and a second input coupled to said horizontal synchronizing signal separator.