Ampex Corporation

Martin A Lilley

Jan S Wesolowski

A method and system for encoding color frame polarity information into composite sync signals. Also, a method and system for detecting color frame polarity information which has been encoded into composite sync signals and for restoring the encoded composite sync into its normal non-encoded form.

Composite sync color frame encoder and decoder

Digital-based phase control system

A method and apparatus for producing a video composite blanking signal which provides for selectively unblanking lines of video information which would normally be blanked according to a predetermined television standard. Each line in a frame of video data is assigned a line type based on its location in the sequence of lines of video information. Those lines that are in the vertical blanking period are assigned a different line type than those which are not. In response to unblanking selection data, line types of lines which are normally blanked are selectively modified to the line types of those lines which are not normally modified. The vertical interval blanking signal is produced only for those line types for line in the vertical blanking period.

Method and apparatus for selectively unblanking special signals inserted

A method and system for composite system phase control in a signal processor such as a television video recorder operating in a genlocked system. A synchronizing signal, preferably a frame-rate horizontal reset pulse, is generated in response to coincidence between predetermined parts of two timing reference signals, in particular color television frame-rate horizontal line reference pulses and clock pulses derived from the color subcarrier. Possible coincidence ambiguity between the two timing reference signals exists when transitions in the two signals occur within a predetermined time period. The phase of one of the reference signals, the subcarrier frequency clock, is shifted 180 degrees (one-half cycle) to eliminate the potential coincidence ambiguity. Simultaneously, the phase of the generated synchronizing signal, the horizontal reset pulse, is shifted by one-half cycle of the subcarrier-related clock signal in a direction to compensate for the phase shift of that reference signal so that the phase shift of the generated synchronizing signal is transparent, i.e. there is no apparent change in the position of the generated sychronizing signal.

System for generating a synchronizing signal in response to two timing

A switched RF signal, formed of modulated RF and blanking level signals, is selectively phase inverted on alternate pairs of television lines to provide, after FM detection, a video signal containing alternating positive and negative offset errors. The video signal is integrated to average and thus, in effect, minimize the alternating errors.

Circuit for reducing AFC offset error

Time base errors in PAL subcarrier reference bursts, created in part by the operation of a video tape recorder, are detected by the recorder and used for detecting the phase shift error in phase angle switching between bursts on adjacent video signal lines which existed before the video signal was recorded. The video tape recorder timing errors detected on the bursts are first detected after the 90.degree. phase angle between successive bursts has been eliminated. Two sample and hold units then are alternately strobed, each at a point in time during a given tape recorder head pass wherein the error signals are normally most accurate, such that a first burst timing error is retained in one such unit and a next burst timing error is retained in said second unit. The outputs of these two sample and hold units are filtered and combined in an integrator for generating a voltage control signal whose amplitude varies as a function of the pre-existing burst shift error. This control voltage is fed to a phase shift unit which operates in response thereto to modify the phase of subsequent off-tape color reference bursts before error detection has been performed on such subsequent bursts.

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Fremont, CA, United States of America

Martin A Lilley