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Method and apparatus for monitoring TV channel selecting status

  • US 6,487,719 B1
  • Filed: 03/22/1999
  • Issued: 11/26/2002
  • Est. Priority Date: 03/23/1998
  • Status: Expired due to Fees
First Claim
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1. A method for monitoring the channel selecting status of a TV set which has a plurality of video/audio sources built-in and at least one video/audio input terminal for inputting video and audio signals from at least one external video/audio source, said TV set being capable of providing a display and an acoustic output of video and audio signals supplied from a user'"'"'s arbitrarily selected one of said video/audio sources, said method comprising the steps of:

  • (a) detecting vertical and horizontal sync signals of a video signal applied to a cathode-ray tube of said TV set;

    (b) detecting video signals output from said plurality of video/audio sources built in said TV set;

    (c) detecting a video signal output from said video/audio source connected to said video/audio input terminal of said TV set;

    (d) sequentially selecting said video signals detected in said steps (b) and (c);

    (e) separating vertical and horizontal sync signals from each of said video signals sequentially selected in said step (d);

    (f) measuring the time difference between said vertical and horizontal sync signals detected in said step (a) and said vertical and horizontal sync signals selected in said step (e);

    (g) correcting said time difference measured in said step (f) in accordance with a premeasured delay time inherent in each of said plurality of video/audio sources, and determining that one of said video/audio sources for which said corrected time difference is minimum is the video/audio source currently selected by said user;

    (h) controlling a plurality of reference receivers to sequentially generate video signals of channels receivable from that one of said video/audio sources which was determined to be currently selected by said user in said step (g), said plurality of reference receivers being capable of generating video signals of each channel of each TV broadcast independently of said TV set;

    (i) separating vertical and horizontal sync signals from each of said video signals generated in said step (h);

    (j) measuring the time difference between vertical and horizontal sync signals of said video/audio sources determined to be currently selected by said user in said step (g) and said vertical and horizontal sync signals separated in said step (i); and

    (k) correcting said time difference measured in said step (i) in accordance with a premeasured delay time inherent in each of said plurality of video/audio sources, and determining that a channel for which said corrected time difference is smaller than a predetermined threshold value is a candidate for a channel currently selected by said user.

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