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Scan converter utilizing discrete differentially coded signals

  • US 4,271,431 A
  • Filed: 10/11/1978
  • Issued: 06/02/1981
  • Est. Priority Date: 10/11/1978
  • Status: Expired due to Term
First Claim
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1. A scan rate converter, comprising:

  • (A) input section means operable in both a fast scan conversion and a slow scan conversion mode, said input section means for;

    (1) sampling an input FSTV signal at a fast scan rate when said input section means is operated in said fast scan conversion mode, said input FSTV signal including a plurality of lines of video information;

    (2) sampling an input SSTV signal at a slow scan rate when said input section means is operated in said slow scan conversion mode, said input SSTV signal including a plurality of lines of video information; and

    (3) generating a discrete differential coded signal responsive to each said sampling of said input FSTV and input SSTV signals when said input section means is operated in said fast scan and slow scan modes of operation, respectively, such that each line of video information being sampled is divided into a plurality of discrete differential coded signals, each of said discrete differential coded signals having a magnitude determined by the difference between the actual magnitude of the FSTV or SSTV signal being sampled at the sampling instant corresponding to the discrete differential coded signal in question and a predicted magnitude of the FSTV or SSTV signal being sampled at the sampling instant corresponding to the discrete differential coded signal in question, the value of said predicted magnitude of the FSTV or SSTV signal being sampled being reset to a predetermined value at each sampling instant corresponding to the first discrete differential coded signal in a line of video information being sampled,(B) memory section means operable in a read and a write mode of operation, said memory section means for;

    (1) storing each of said discrete differential coded signals generated by said input section means when said memory section means is operated in said write mode; and

    (2) reading said discrete differential coded signals stored in said memory section means out of said memory section means when said memory section means is operated in said read mode, said discrete differential coded signals stored in said memory section means being read out of said memory section means at both said fast scan and said slow scan sampling rates in a time multiplexed manner; and

    (C) output section means for;

    (1) converting said discrete differential coded signals read out of said memory section means at said fast scan rate into an output FSTV signal; and

    (2) converting said discrete differential coded signals read out of said memory section means at said slow scan rate into an output SSTV signal.

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