Eric L Ingram

US Patent:

54284040, Jun 27, 1995

Filed:

Jan 29, 1993

Appl. No.:

8/010771

Inventors:

Eric J. Ingram - Lilburn GA
James O. Farmer - Lilburn GA

Assignee:

Scientific-Atlanta, Inc. - Atlanta GA

International Classification:

H04N 540
H04N 5455

US Classification:

348726

Abstract:

An apparatus and method for demodulating and remodulating a transmitted signal prior to presentation to a television receiver, the transmitted signal comprising a video signal, a first channel signal, and a second channel signal, wherein one of the two channel signals is selected, demodulated and remodulated with the video signal prior to presentation to the television receiver. The apparatus allows the viewer of a television receiver which accepts a single channel signal to select between one of two alternate channel signals associated with a video broadcast without the need to modify the television receiver. The apparatus is particularly well suited for television broadcasts using a dual carrier transmission format. A novel varactor diode tuning means is used in one embodiment for changing the center frequency of a frequency modulation demodulator. The disclosed apparatus also transparently allows stereo demodulation for television receivers which are capable of such stereo demodulation.