| 摘要 |
Various methods and systems for television transmission, as well as for scrambling a plurality of input signals (10, 18) for secure transmission thereof, are disclosed. The scrambling technique, in one form, includes modulating (46A) an in-phase component (48) of at least one carrier signal in response to one and then another of a plurality of input signals (10) in a sequence of time intervals (64) 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 (48) of the carrier signal is similarly modulated (46B) in response to the one and another (60, 62) of the plurality of input signals in the sequence of time intervals 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 (12) for transmission (16). A decoder (26, 30) for unscrambling the plurality of signals and selecting one 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 multilingual program service as well as other services can be provided. |
