Scrambling and descrambling a high definition TV signal

A method of descrambling a scrambled high definition television (HDTV) signal, the scrambled HDTV signal having, in its active picture portion, video lines time shifted relative to the line timing reference of each video line, and having an indication of the amount of the time shifting associated with the HDTV signal in such a manner as not to be recordable by at least some video recorders, the descrambling comprising the acts of:

• receiving the scrambled HDTV signal;
• extracting from the scrambled HDTV signal the indication of the amount of time shifting;
• generating a new line timing reference;
• and
• establishing a stable relationship between the generated line timing reference and the active picture portion of the video lines, using the extracted indication of the time shifting.

A high definition television (HDTV) receiver adapted to descramble a scrambled HDTV signal, comprising:

• an input terminal for receiving the HDTV signal;
• a separator circuit coupled to the input terminal and which extracts from the HDTV signal indications of time shifting of the active picture portion of video lines of the HDTV signal relative to the line timing reference of each line;
• a phase lock loop coupled to the separator circuit, which generates a new line timing reference and establishes a stable relationship between the generated line timing reference and the active picture portion of the video lines using the extracted indications;
• and
• a deflection circuit having an input terminal coupled to the phase lock loop and having an output terminal coupled to drive a television display.

An apparatus for scrambling a high definition television (HDTV) signal, comprising:

• an input terminal for receiving the HDTV signal;
• a source of a time varying signal;
• a storage coupled to the source of the varying signal and coupled to the input terminal, which time shifts the active portion of video lines of the HDTV signal by an amount determined by the varying signal, relative to the line timing reference of each video line;
• a switch coupled to the storage and to the source of the time varying signal, thereby to insert into the HDTV signal an indication of the amount of the time shifting in such a manner as not to be recordable by at least some video recorders;
• and
• an output terminal coupled to the switch and which outputs the time shifted HDTV signal with the inserted indication.

A method of coupling a scrambled high definition television (HDTV) signal between a source and an HDTV receiver, wherein a coded pulse for descrambling the HDTV signal is located at a predetermined portion of a blanking interval of the scrambled HDTV signal, comprising the acts of:

• transmitting the HDTV signal in analog form from the source;
• conveying the transmitted HDTV signal on a conductor to the receiver;
• except when the predetermined portion of the HDTV signal is being conveyed, providing a standard video connection on the conductor between the source and the receiver;
• and
• when the predetermined portion is being conveyed, transmitting that portion of the HDTV signal as a current signal on the conductor.

An output interface in a source of scrambled high definition television (HDTV) signal wherein a coded pulse for descrambling the HDTV signals is located at a predetermined portion of a blanking interval of the scrambled HDTV signal, the interface comprising:

• an input terminal for receiving the scrambled HDTV signal;
• an output terminal for connecting to a HDTV receiver;
• and
• an interface circuit coupled to a node between the input and output terminals and having a control terminal coupled to receive a control signal, wherein during the predetermined portion of the blanking interval, in response to the control signal, the interface circuit provides a current signal to the output terminal to be included in the scrambled HDTV signal to be output to the HDTV receiver on the output terminal.

An input interface in a high definition television (HDTV) receiver adapted for descrambling a received scrambled HDTV signal including a coded pulse located at a predetermined portion of the scrambled HDTV signal, the interface comprising:

• an input terminal for connecting to a source of the scrambled HDTV signal;
• an output terminal connected to display circuitry of the receiver;
• and
• an interface circuit coupled to a node between the input and output terminals and having a control terminal for receiving a control signal indicating the predetermined portion of the HDTV signal, wherein during the predetermined portion, in response to the control signal and an input current signal, the interface circuit provides a corresponding signal to the output terminal.

A method of modifying a high definition television (HDTV) signal which has been subject to time shifting of the active video in a video line relative to a timing reference of the line, wherein an indication of the amount of time shifting is associated with the HDTV signal and not recordable by at least some video recorders, for inhibiting the making of acceptable recordings of the HDTV signal therefrom, the method comprising the acts of:

• receiving the HDTV signal including the associated indication of the amount of time shifting;
• modifying the HDTV signal so that the indication of the amount of time shifting is recordable;
• and
• recording the HDTV signal along with the indication of the amount of time shifting, thereby to permit later playback of a more acceptable video recording of the HDTV signal.

An apparatus for modifying a high definition television (HDTV) signal which has been subject to time shifting of the active video in a video line relative to a timing reference of the video line, wherein an indication of the amount of the time shifting is associated with the HDTV signal and not recordable by at least some video recorders, for inhibiting the making of acceptable recordings of the HDTV signal therefrom, the apparatus comprising:

• an input terminal for receiving the HDTV signal including the associated indication of the amount of time shifting;
• modifier circuitry coupled to the input terminal and processing the HDTV signal so the indication of the amount of time shifting is modified so as to be recordable;
• and
• an output terminal coupled to the modifier circuitry for outputting the modified HDTV signal to a video recorder.