Video system for conveying digital and analog information
Signal presence detector and method
Simultaneous transmission of two information signals within a band-limited communications channel
Synchronous tracking device for direct spread spectrum receiver
Cable television spread spectrum data transmission apparatus
Embedment of data in a video signal Patent #: 4969041
ApplicationNo. 811805 filed on 12/20/1991
US Classes:348/473Including additional information
ExaminersPrimary: Groody, James J.
Assistant: Harvey, David E.
Attorney, Agent or Firm
International ClassH04N 007/08
AbstractA co-channel communication system allows transmission of one or more data signals in an active or visible portion of a video raster in a manner that is imperceptible to a viewer. More particularly, the data signal is transmitted over a preselected active video lines of a video raster. In order to reduce the perceptibility of the data signal, the video lines over which the data signal is transmitted is varied according to a random sequence. In an alternate embodiment, the data is also modulated at relatively low modulation levels, for example, by converting the data signal to a spread spectrum signal.