| US 7,587,121 B1 | ||
| Method and system for multiple field modulation | ||
| Michael S. Gramelspacher, St. Louis, Mo. (US); Christopher E. Chupp, St. Louis, Mo. (US); Yousri H. Barsoum, St. Louis, Mo. (US); Jesse J. Chounard, II, Ballwin, Mo. (US); and Michael C. Reynolds, Ballwin, Mo. (US) | ||
| Assigned to Koplar Interactive Systems International, L.L.C., St. Louis, Mo. (US) | ||
| Filed on Oct. 20, 2004, as Appl. No. 10/969,708. | ||
| Claims priority of provisional application 60/513651, filed on Oct. 23, 2003. | ||
| Int. Cl. H04N 5/91 (2006.01) | ||
| U.S. Cl. 386—46 [386/94] | 19 Claims |
| 1. A method for detecting a signal presence in a modulated video signal, the modulated video signal having a plurality of
encoded fields and a plurality of unencoded fields, the plurality of unencoded fields having a first field, the method comprising:
decoding the first field of the modulated video signal to determine a previous field signal strength;
comparing the previous field signal strength with a current field signal strength for the plurality of unencoded fields and
the plurality of encoded fields by alternating between a reference detection step and an auxiliary detection step to generate
an encoded average intensity value for the plurality of the encoded fields and an unencoded average intensity value for the
plurality of the unencoded fields; and
verifying a signal presence in the modulated video signal by determining whether the encoded average intensity value is greater
than the unencoded average intensity value plus a significance value in the modulated video signal.
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