1
Robert A Dougherty: Apparatus and method for injecting an ancillary signal into a low energy density portion of a color television frequency spectrum. A C Nielsen Company, Marshall O Toole Gerstein Murray & Borun, May 13, 1997: US05629739 (160 worldwide citation)

An ancillary signal is injected into a program signal within the frequency band normally occupied by the program signal alone. The program signal includes a modulated carrier having a carrier frequency and a low energy density portion of the frequency band. The ancillary signal is selectively added ...


2
Robert A Dougherty, David A Kiewit, Daozheng Lu, Henry B Wheeler: Co-channel transmission of program signals and ancillary signals. Nielsen Media Research, Marshall O Toole Gerstein Murray & Borun, April 7, 1998: US05737025 (112 worldwide citation)

In the present invention, an ancillary code is added to a composite video signal in its active video portion. The ancillary code may be spread over several frequencies and summed at the output of a decoder to enhance the legibility of the ancillary code at the output of the decoder. Frequency-steppi ...


3
Daozheng Lu, Henry B Wheeler, Edgar W Aust, Robert A Dougherty: Video and data co-channel communication system. Nielsen Media Research, Marshall O Toole Gerstein Murray & Borun, April 7, 1998: US05737026 (54 worldwide citation)

In the present invention, ancillary data is modulated onto a carrier frequency which is within a low energy density portion of a frequency band of a video signal, and the modulated carrier data is combined with the video signal so that the modulated carrier is in an overscan region of the video sign ...