Abstract: A video-scrambling system induces a random wobble i.e., time shifting, in the location of active portion of the video frame, without affecting the horizontal sync signal and colorburst in each video line, thus providing both security and concealment. The security is enhanced by filling in the gap between the nominal beginning of active video and the actual beginning of active video with a synthesized video signal which replicates the adjacent active video using a digitally generated filling pattern. Also, a random noise overlay further conceals the location of the gap. Additional concealment is provided by wiggling in time the location of the horizontal sync signal using one or two frequencies and also by randomly altering the location of the vertical sync signal. The NTSC digital encoding in accordance with the invention is simplified by using only two channels, chrominance and luminance, and by a heterodyne circuit for chrominance stability.

Abstract: A radio receiver receives FM subcarrier transmissions, and stores the transmitted textual information in a random access memory. The information is typically news, weather, sports, entertainment or other information of interest. A user interface allows selection from the memory of the stored information via a set of menus controlling a hierarchical database, so as to access particular items of information. A speech synthesizer accepts the accessed textual information items and transforms them into spoken speech. The user interface is either by voice or a single or multi-position switch allowing scanning through and selection from the menu items.

Abstract: A hybrid digital/analog video recorder prevents both analog and digital copying. The recorder (including a digital tape deck) inputs and outputs both analog and digital video signals. At the analog input, a detector detects conventional copy protection in the analog input video, and in response disables recording thereof. At the digital input, a first detector detects anti-copy bits present in the input material and in response prevents recording. A second bit detector detects serial copy prevention scheme bits, and in response adds an anti-copy bit to the input digital stream, preventing later copying of such material. When another bit detector detects anti-copy bits present in the playback digital data stream prior to conversion to analog, an analog copy protection signal modifies the output analog signal, inhibiting copying of the output signal. In another version, a specially adapted video recorder or playback device copy protects video source material which for technical reasons is not copy protectable.

Abstract: Copy protected video signals employing field-length-modulation (FLM) are effectively recorded by a VCR by stripping the rate-varying vertical sync pulses from the FLM video and reinserting constant rate vertical sync pulses having a rate equal to the mean frequency or half the mean frequency of the FLM sync pulses. Display of the recorded video on a conventional television monitor or set is achieved by removing the constant rate vertical sync pulses and reinstating the rate-varying FLM sync pulses. Timing marks placed at locations of stripped FLM sync pulses are used to position reinserted FLM sync pulses during playback of recorded video. Video gaps created by removed constant rate sync pulses are filled either with video information from a contiguous scan line or a filler signal to improve the appearance of the picture.

Abstract: A video signal is modified so that a television receiver still produces a normal color picture from the modified signal, whereas a videotape recording of this signal produces generally unacceptable pictures. This invention relies on the fact that videotape recorders feature some form of automatic level control circuit. These automatic level control circuits measure the sync pulse level in the video signal and develop a gain correction signal for keeping the video level applied to an FM modulator in the videotape recording system at a fixed predetermined value. In accordance with the present invention either a positive or a negative pulse is added to the video signal immediately following the trailing edge of sync. The effect of these added pulses is to cause the automatic level control circuit in the recorder to assess the video level at either many times its actual value or as a fraction of its actual value.

Abstract: A technique for encrypting and decrypting information signals normally arranged as a succession of lines of active information, with each line having a line timing reference, such as color video information signals. The active video portion is time shifted with respect to the horizontal sync portion of the corresponding line using a predetermined slowly varying time shifting function. The time shifting information is conveyed to the decryption site by encoding the instantaneous vlue of the time shifting wave form for the beginning of each field in the vertical blanking portion of that field. To provide a reasonable maximum time shifting range, portions of the trailing edge of the active video in the preceding line and portions of the leading edge of the active video in the current line are discarded. During decryption, the original line timing and color burst signals are discarded and new signals are generated which are time displaced from the actie video portion by the original amount before encryption.

Abstract: A method and apparatus are described for preventing a dual deck video recorder from being used to record a copy-protected video signal. A switch is included on the recorder to indicate whether a video signal input to one of the deck locations for recording originates externally of the machine or internally at another deck location. Recording is prevented whenever the switch indicates that the video signal originates from the other deck location if the video signal at such location includes a selected copy-protect signal. If a video signal to be recorded comes from externally of the machine, copying of the same is prevented if (1) the video signal includes the copy-protect signal; or (2) the video signal to be copied is the same as the play back video signal and the latter has the selected copy-protect signal.

Abstract: Time sequential information signals, such as color video signals having a line timing reference and an active video portion, are encrypted by time shifting the active video signal portion towards and away from the line timing reference signal in psuedo-random fashion prior to broadcasting or recording on tape or disk and transmittal to the user. The signals are decrypted by an inverse time shifting technique. By limiting the amount of time shifting between lines, potential signal degradation for color video signals is minimized, and drop out compensation processing is minimally affected, so that the color resolution and picture quality are substantially unaffected.

Abstract: A video signal is modified so that a television receiver will still provide a normal color picture but which a video tape recorder will detect and prohibit its being recorded. A plurality of ordered pairs of pseudo-sync and positive pulses are added to the video signal vertical blanking interval following the normal sync pulse. A disabiling circuit associated with a recorder detects the modified signal. This detection may be by comparing the voltage differential between the pseudo-sync pulse tip and the positive pulse relative to the normal voltage differential between the sync pulse tip and the back porch of the blanking interval. Alternatively, the modified signal can be detected by identifying the pulse frequency of the signal in the blanking interval. A high frequency is indicative of the presence of the modified signal. Detection is also shown by peak-detecting the video signal and sampling this peak-detected signal during the vertical blanking period.

Abstract: A video signal is modified so that a television monitor/receiver still produces a normal picture from the modified signal, whereas a videotape recording of this signal produces generally unacceptable pictures. Videotape recorders have an automatic gain control circuit which measures the sync pulse level in a video signal and develops a gain correction signal for keeping the video level applied to an FM modulator in the videotape recording system at a fixed, predetermined value. A plurality of positive pulses are added to the video signal with each immediately following a respective trailing edge of a normally occuring sync pulse. These added pulses are clustered at the vertical blanking interval of each field to minimize the affect of the same on the viewability of the picture defined by the signal while still causing the automatic level control circuit in a recorder to assess the video level at many times its actual value.

Abstract: Added pseudo-sync pulses and AGC pulses are removed from a video signal to enable acceptable video recording thereof. The added signals previously interfered with acceptable video recording of the video signal because the automatic gain control of videotape recorders sensed false recording levels, while conventional televisions receivers were unaffected by those modifications to the video signal. Removal of the added pulses permits acceptable video recording of the previously modified video signal. A selectively-operable clipping circuit is used to remove selected negative-value components (i.e. pseudo-sync pulses) from the video signal, while added AGC pulses are effectively blanked from the video signal with an electrically-operable switch. Both the blanking and clipping functions are selectively achieved by sensing both the normal sync pulses of the video signal and the added pseudo-sync pulses.

Abstract: A video signal is modified so that a television receiver will still provide a normal color picture from the modified video signal while a videotape recording of the modified video signal produces generally unacceptable pictures. This invention relies on the fact that typical videocassette recorder automatic gain control systems cannot distinguish between the normal sync pulses (including equalizing or broad pulses) of a conventional video signal and added pseudo-sync pulses. Pseudo-sync pulses are defined here as any other pulses which extend down to a normal sync tip level and which have a duration of at least 0.5 microseconds. A plurality of such pseudo-sync pulses is added to the conventional video signal during the vertical blanking interval, and each of such pseudo-sync pulses is followed by a positive pulse of suitable amplitude and duration.

Abstract: A video signal of the type having phase modulation induced in the color burst component thereof to inhibit video tape recording, is modified to remove the phase modulation and permit acceptable video tape recording. The phase modulated color burst component of an incoming video signal drives a phase lock loop, which regenerates a color burst component free of the modulation for insertion into the video signal.

Abstract: For each magnitude of charge stored on a section of a target of a photoelectric tube due to the action of incident light thereon, there is a specific value of cathode voltage which ensures the discharge of the section in one pass of the scanning beam. It follows that if the cathode receives a voltage whose instantaneous value is proportional to the magnitude of the charge stored on the corresponding portion of the target, the complete discharge of the target is effected in one pass of the scanning electron beam. Since the output voltage of a camera preamplifier at any instant is directly related to the magnitude of the charge stored on the corresponding portion of the target of the same tube or a different tube viewing the same scene, the preamplifier output voltage herein is selectively applied to the tube cathode, preferably with an appropriate transfer function, whereby lag in the tube is eliminated.

Abstract: A method and apparatus which modifies a color video signal in such a manner that a conventional television receiver produces a normal color picture from the modified signal, whereas a videotape recording made from the modified signal exhibits annoying color interference. This is achieved by phase modulating the color burst component of the video signal with a noise signal. A videotape recorder interprets the phase variation as a velocity error and alters the chrominance signal, giving rise to color noise in the videotape recording. The characteristics of the noise signal are chosen to preclude interfering with the receiver's subcarrier regenerator.

Abstract: During the horizontal retrace scan period of a scanning beam in a television pickup tube, the beam current is increased to the maximum possible value to recharge the target layer, and the cathode voltage is raised by a few volts to prevent readout of normal video. Also, the scanning beam path may be modified to insure that every area of the image is scanned by the retrace scan prior to being scanned by the active picture scan.

Abstract: A simple demodulator circuit for demodulating high frequency pulse width modulated carrier signals, includes means for charging a capacitor to charge levels commensurate with the pulse widths. Output switch means, biased at the verge of conduction, discharge the capacitor charge at the ends of the pulses as an exponential signal with given time constant. Since the amplitudes of successive exponential signals are proportional to the respective capacitor charge levels, the charge levels are simultaneously read during the discharge process, thereby allowing demodulation at very high speeds.

Abstract: The scanning process of a television camera is modified so that scanning is inhibited for N successive scan periods and is enabled during the next scan period, in a repeating cycle of (N+1) periods duration. The signal output generated during the N inhibited scan periods is zero but, during the enabled scan period, is (N+1) times greater than the corresponding signal which would be generated by conventional scanning action.

Abstract: Selected additional voltages are utilized to modify the respective horizontal and vertical sawtooth waveforms which generate the horizontal and vertical electron beam scans in a photoelectric tube. The added voltages are selectively applied during the respective horizontal and vertical blanking intervals, whereby the speed of the scan is doubled, tripled, etc., during the blanking intervals. Since the time available during blanking is still the same, increasing the speed of the beam scan causes the beam to scan correspondingly further into the non-scanned target portion. Thus, corresponding greater distances into the surrounding target are discharged which, in turn, circumvents charge bleeding into the active picture area, thereby precluding edge hooking.

Abstract: A technique for encrypting and decrypting information signals normally arranged as a succession of lines of active information, with each line having a line timing reference, such as color video information signals. The active video portion is time shifted with respect to the horizontal sync portion of the corresponding line using a predetermined slowly varying time shifting function. The time shifting information is conveyed to the decryption site by encoding the instantaneous value of the time shifting wave form for the beginning of each field in the vertical blanking portion of that field. To provide a reasonable maximum time shifting range, portions of the trailing edge of the active video in the preceding line and portions of the leading edge of the active video in the current line are discarded. During decryption, the original line timing and color burst signals are discarded and new signals are generated which are time displaced from the active video portion by the original amount before encryption.