Title: Scrambler and decoder for a television signal

Abstract: An improved scrambler and decoder for a television signal is described wherein a television carrier is inverted in phase and subjected to low frequency amplitude modulation to obtain enhanced channel security. The carrier amplitude modulation is obtained with a coding signal which is transmitted as a pilot signal in the form of frequency modulation of the carrier. The coding signal is recovered at the decoder with a phase lock network and used to regenerate an unscrambled carrier. The coding signal provides information for special functions such as subscriber access control, program selection and the like.

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Inventors: Aaronson, Gerald (Brookline, MA, US)
Murphy, William D. (Burlington, MA, US)

Application Number: 494653
Filing Date: 1974-08-05
Publication_date: 1976-02-03
Assignee: GTE Laboratories Incorporated (Waltham, MA)
Primary Class(es): 380/219 380/235, 380/240, 455/109
Other Classes:
US Patent Ref:

2709218	May, 1955	Gabrilovitch	179/1.
3180927	Apr, 1965	Heppe et al.	325/34.
3500250	Mar, 1970	Frerking	325/138.
3729576	Apr, 1973	Court	178/5.
3852519	Dec, 1974	Court	178/5.

Other Refs:
Primary Examiner: Farley, Richard A.
Assistant Examiner: Buczinski, S. C.
Attorney: Kriegsman; Irving M, Hart; Leslie J.