| 摘要 |
A method and system for scrambling a plurality of input signals for secure transmission thereof, as well as various methods and systems for television transmission, are disclosed. The disclosed scrambling technique, in one form, includes modulating an in-phase component of at least one carrier signal in response to one and then another of a plurality of input signals in a sequence of time intervals such that parts but not all of the one and another of the input signals are carried by the in-phase component. A quadrature component of the at least one carrier signal is modulated in response to the one and another of the plurality of input signals in the sequence of time intervals such that parts but not all of the one and another of the input signals are carried by the quadrature component and such that the in-phase and quadrature components together carry the one and another of the input signals in their entireties. The modulated in-phase and quadrature components are combined for transmission. A decoder for unscrambling the plurality of signals is also disclosed. The various television transmission methods and systems involve provision of additional audio signals, in scrambled or unscrambled form, with the normal television audio and video signals so that multi-lingual program service as well as other services can be provided. |
