| 摘要 |
<p>In order to gather information on the reception of video channels in a household or other location equipped with a television receiver, partinent data such as identification and viewing time are injected into an assigned minor area of the TV picture at the receiving location. The injected data, appearing in digitized form in the assigned area where the TV picture has been blocked out, are picked up by a photosensor juxtaposed with the CRT screen of the receiver, or possibly from a video output thereof, and are fed to a processor for transmission over a telephone line with or without intermediate storage to an evaluation center. A data injector inserted between an antenna and an input terminal of the receiver blanks the incoming video signal of a selected channel during a small fraction of a frame-scanning cycle, while the CRT beam sweeps the assigned area, and replaces it with the digitized data. Alternatively, the blanking of the assigned area and insertion of channel identification may take place at the transmitting station.</p> |
