A billing system for billing for the use of television sets in a hospital, hotel or the like includes a computer located in a billing office and television sets located in various rooms. Command signals from the computer, video signals, and power for powering the television are all delivered to each television set over a single coaxial cable. Each television set includes a microprocessor, a modem and logic circuits which remain active even if a user turns off his television receiver. The computer may assume control over any one or more of the television receivers by issuing a slave command which, at a time specified in the command (1) turns an addressed television receiver on if it is off and (2) tunes the addressed receiver to a specific channel. The slave commands may be of two types. One type permits no control over the TV receiver by a user and the other permits a user to override the slave command. Billing for TV usage is stored in the TV set and is transferred to the computer in response to a command from the computer. Billing information in one TV set may be transferred to another set if a user should move from one room to another. In a second embodiment, power is provided from a conventional AC wall outlet but in this case the slave commands are not executed if the television receiver is unplugged.

System for controlling television and billing for its use

In the known color stripe process for preventing recording of video signals, the color burst present on each line of active video is modified so that any subsequent video tape recording of the video signal shows variations in the color fidelity that appear as undesirable bands or stripes of color error. This color stripe process is defeated first by determining the location of the video lines including the color stripe process, either by prior experimentation or by on-line detection. Then some or all of the lines including the modified color bursts are modified so as to render the overall video signal recordable. The modification is accomplished in a number of ways, including phase shifting the color stripe burst into the correct phase, replacing some of the color stripe bursts or a portion of particular color stripe bursts so that they are no longer effective, and mixing the color stripe burst with color stripe signals of the correct phase so as to eliminate most or all of the phase error present. The modified color bursts are defeated, in other versions, by modifying the horizontal sync pulse signals immediately preceding the modified color bursts so that the modified color bursts are not detected by a VCR and hence have no effect.

Method and apparatus for defeating effects of color burst modifications to a video signal

Method and apparatus for modifying the effects of color burst modifications to a video signal

The quality of sound delivered to a subscriber viewing a channel which has been scrambled using sync suppression scrambling, particularly when the program is being transmitted with stereo sound, is improved by processing the aural component of the TV signal at the head end of the system prior to transmission over the cable or other communication link to the subscribers. The amplitude of the aural signal is reduced so as to compensate for the increase in amplitude which occurs when the composite TV signal is descrambled by restoring the amplitude of the suppressed synchronizing signals thereof. No changes are required in the existing subscriber equipment and the subscribers may continue to use the descramblers supplied to them without any modification thereof. Noises, such as are perceived as a "buzz" like sound, and loss of stereo separation of the aural signal upon descrambling are avoided.

Sync suppression scrambling and descrambling of television signals for subscription TV

An analog color video signal is prevented from being satisfactorily copied by inserting a phase-shifted color burst signal of predetermined duration into a predetermined location of the usual burst interval of that analog color video signal. The predetermined location may precede the normal color burst signal, or it may follow the normal color burst signal or it may be located in the middle of the burst interval.

Copy protection by inserting a phase-shifted color burst signal into the burst interval of an analog color video signal

Of the scrambling systems used in CATV and direct satellite broadcasting systems, the invention pertains to the transmission of a keying signal for demodulation. The keying signal, as a carrier wave displaced 90° in phase from a picture carrier wave, is superimposed on the conventional sync signal suppression period with no sound carrier wave being processed, thereby avoiding the generation of buzzing noise which would occur when the keying signal is superimposed on the sound carrier wave. With this invention, not only can the generation of buzzing noises be eliminated, but also even in multiplex sound systems the sound signal can be transmitted without the sound quality being adversely affected. Also, no synchronizing signal can readily and easily be detected and, therefore, subscription TV programs can not be viewed by unauthorized persons.

Apparatus for scrambling and descrambling communication signals

A one-way addressable system includes a broadcasting center from which pay television signals and time codes representing time are produced, and subscriber's television receivers. The receiver includes a detector which produces a failure signal upon detection of a failure of a power supply along a primary power line, and produces an establish signal upon detection of an establish of the power supply along the primary power line. A secondary power source is provided for supplying power to the receiver when the failure signal is produced. A buffer is provided for storing newly received time code while the establish signal is present and for holding the same time code, which is received immediately before the generation of the failure signal, while the failure signal is present. A memory is provided for storing the time code shifted from the buffer in response to the receipt of a new time code to the buffer. A microcomputer calculates a time difference between the time codes maintained in the buffer and in the memory, thereby enabling the time count during the failure signal is present.

Hitoshi Mori

Papers

Apparatus for scrambling and descrambling communication signals

One-way addressable system