Method and apparatus for extracting binary signals included in vertical blanking intervals of video signals

Apparatus for extracting binary signals occurring in an information signal reproduced from a tape transported over a range of velocities and in forward or reverse directions past a transducer rotated at a fixed velocity relative to the tape, said information signal reproduced at a rate which varies as a function of the tape velocity to the transducer velocity, each binary signal having a selected number of bits at regular intervals with certain of the bits forming a known bit pattern in each binary signal, and each binary signal having a bit rate which varies as the rate of reproduction of the information signal, comprising:

• means for generating a control signal having a rate proportional to the velocity at which the tape is transported past the transducer;
• means for supplying signal indicative of the direction that the tape is being transported;
• a clock generator responsive to the control signal and the direction signal for generating a clock signal having a rate corresponding to the bit rate at which the binary signal is reproduced from the tape by the transducer as said tape is transported in said direction at the velocity proportional to the control signal rate;
• and
• a binary signal detector coupled to receive the reproduced information signal, and responsive to said clock signal and the occurrence of the known bit pattern, for detecting the occurrence of the binary signal in the received information signal.

A method for extracting binary signals occurring in an information signal reproduced from a tape transported over a range of tape velocities past a transducer rotated at a fixed velocity relative to the tape, said information signal being reproduced at a rate which varies as the tape transport velocity varies, each binary signal having a selected number of bits at regular intervals with certain of the bits forming a known bit pattern in each binary signal, and each binary signal having a bit rate which varies as the rate of reproduction of the information signal, comprising:

• supplying control signals indicative of the velocity and direction of the tape transport as the information signal is reprdouced from the tape;
• generating in response to the control signals a relative signal indicative of the relative tape to transducer velocity and of the direction of the tape;
• generating in response to the relative signal a timing signal having a rate corresponding to the rate at which the information signal is reproduced from the tape over said range of tape velocities;
• examining the reproduced information signal at the rate of the timing signal;
• and
• identifying the ocurrence of the binary signal in the reproduced information signal upon examination of an interval of reproduced information signal that includes the known bit pattern.

Apparatus for extracting binary signals included in the vertical blanking intervals of a video signal reproduced from a tape transported over a range of velocities past a transducer rotated at a fixed velocity relative to the tape, the velocity of tape transport and the velocity of rotation of the transducer defining a relative tape to transducer velocity that varies as the velocity of tape transport varies, said video signal reproduced at a rate which varies as the relative tape to transducer velocity varies, each binary signal having a selected number of bits at regular intervals with each bit represented by one of two signal amplitude levels, certain of the bits of each binary signal at the same levels to form a known bit pattern in each binary signal, and each binary signal having a bit rate which varies as the rate of reproduction of the video signal, comprising:

• means for generating a control signal having a rate proportional to the velocity at which the tape is transported past the transducer;
• a clock generator responsive to the control signal for generating a clock signal having a rate corresponding to the bit rate at which the binary signal is reproduced from the tape by the transducer as said tape is transported at the velocity proportional to the control signal rate;
• wherein said clock generator comprises a tape speed detector responsive to the control signal for producing an output corresponding to tape speed, a tape to transducer velocity detector responsive to the tape speed detector output for producing an output corresponding to tape to transducer velocity, and a pulse generator responsive to the tape to transducer velocity detector output for generating said clock signal;
• wherein said tape speed detector further comprisess, a down counter responsive to a reference clock for generating a tape speed detector clock, and an up counter responsive to the control signal for producing a tape speed value, the up counter being reset by the tape speed detector clock;
• means responsive to the video signal reproduced by the transducer for generating a stream of binary data therefrom having a first level corresponding to one of said two signal amplitude levels when said video signal has an amplitude above a selected reference level and a second level corresponding to the other of said two signal amplitude levels when said video signal has an amplitude below the selected reference level;
• a binary signal detector coupled to receive the stream of binary data and the clock signal, said detector responsive to said clock signal and the occurrence of the known bit pattern of the binary signal for detecting the occurrence of the binary signal in the received stream of binary data;
• and
• a decoder coupled to receive and decode the detected binary signal.

Apparatus for extracting binary signals included in the vertical blanking intervals of a video signal reproduced from a tape transported over a range of velocities past a transducer rotated at a fixed velocity relative to the tape, the velocity of tape transport and the velocity of rotation of the transducer defining a relative tape to transducer velocity that varies as the velocity of tape transport varies, said video signal reproduced at a rate which varies as the relative tape to transducer velocity vasries, each binary signal having a selected number of bits at regular intervals with each bit represented by one of two signal amplitude levels, certain of the bits of each binary signal at the same levels to form a known bit pattern in each binary signal, and each binary signal having a bit rate which varies as the rate of reproduction of the video signal, comprising:

• means for generating a control signal having a rate proportional to the velocity at which the tape is transported past the transducer;
• a clock generator responsive to the control siganl for generating a clock signal having a rate corresponding to the bit rate at which the binary signal is reproduced from the tape by the transducer as said tape is transported at the velocity proportional to the control signal rate;
• wherein said clock generator comprises a tape speed detector responsive to the control signal for producing an output corresponding to tape speed, a tape to transducer velocity detector responsive to the tape speed detector output from producing an output corresponding to tape to transducer velocity, and a pulse generator responsive to the tape to transducer velocity detector output for generating said clock signal;
• transducer velocity means for producing an output corresponding to transducer velocity, wherein said tape to transducer velocity detector comprises means for combining the tape speed detector output with the transducer velocity means output to produce the tape to transducer velocity;
• means responsive to the video signal reproduced by the transducer for generating a stream of binary data therefrom having a first level corresponding to one of said two signal amplitude levels when said video signal has an amplitude above a selected reference level and a second level corresponding to the other of said two signal amplitude levels when said video signal has an amplitude below the selected reference level;
• a binary signal detector coupled to receive the stream of binary data and the clock signal, said detector responsive to said clock signal and the occurence of the known bit pattern of the binary signal for detecting the occurrence of the binary signal in the received stream of binary data;
• and
• a decoder coupled to receive and decode the detected binary signal.