| 摘要 |
A method of providing a multilevel quality signal comprises separating out a component of the signal, encrypting the separated out component and then recombining the signal components. The resulting signal has two quality levels, a high quality level, for example CD quality, and a lower but still acceptable level, over a single channel. A decrypting key can be provided to selected receivers, i.e., payee receivers, for reception of the high quality signal.
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