Abstract: An interface for a communications receiver such as a cable or satellite television receiver allows control between the receiver and an external device. The external device can supplement the services provided by the receiver. The interface includes a bidirectional control port for coupling the external device to the communications receiver. Ports for isochronous data and high speed data are also provided. The external device can simulate commands available via a user interface for the receiver, such as remote control actuations. In this manner, the external device can access information and control the receiver (e.g., to tune to a specific television or data channel) via the bidirectional control port. The interface enables the external device to use the full capabilities of the communication receiver for data acquisition and processing. The acquired and processed data is then delivered to the external device via the interface.

Abstract: Impulse purchasing is provided for packages of services offered to consumers via an information network. A plurality of services is offered for individual purchase on an impulse basis via a user terminal coupled to the information network. The plurality of services is offered for purchase as a package on terms that may be more favorable than when the services are purchased individually. Upon purchase of a package, a package record is established for access by the user terminal. The package record provides cryptographically secure access to services provided in the package during a defined time period over which the package is valid.

Abstract: Limited duration previews of program offerings available for purchase via a communication network are provided in a cryptographically secure manner at virtually any time during the service. The invention has particular applicability to the provision of video services on a pay-per-view basis. Such a video service is provided during a program epoch. A fixed period is defined during the program epoch when portions of the video service are available for viewing on a preview basis. A consumer is allowed to preview, without purchase, portions of the video service at any time during the fixed period for up to a maximum preview duration that is shorter than the fixed period. The consumer can then purchase the video service for viewing during the program epoch after previewing portions thereof. A plurality of records is maintained to service different previewable programs concurrently.

Abstract: A system is provided for selectively transmitting horizontal television lines including video and digital audio components or equivalent digital data lines containing a plurality of audio program signals. A conventional television signal transmission places a digital audio signal in the horizontal blanking interval, followed by analog video information. In accordance with the present invention, the "window" containing the analog video information is replaced with a plurality of digital audio signals that are time division multiplexed within the window. An additional audio channel is placed in the horizontal blanking interval, at the same location the audio is placed when video information is transmitted. Selector switches are provided in the encoder and decoder for processing a composite waveform as either a video signal with an associated audio channel, or as a multiple channel digital audio signal. Independent encryption and decryption of each of the multiple audio channels is provided.