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US 4,366,451 AGranted
Chrominance subcarrier regeneration network
AssigneeNone recorded
InventorLeonard Kowal
Life of this patent
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AssigneeNone recorded
InventorLeonard Kowal
Estimating the term…
A chrominance subcarrier regeneration network having high stability, the network being adapted for use in a video tape recorder and including a phase detector for comparing the phase of a gated subcarrier burst of a video signal with that of a subcarrier regenerated signal to develop an error signal; a voltage controlled oscillator driven by the error signal to develop a corrected signal at a frequency substantially below that of the subcarrier burst; and a crystal oscillator, mixer and filter for translating the frequency and filtering the corrected signal to develop the regenerated signal.
A phase-locked loop for generating at an output terminal an output signal which tracks in phase and frequency a coherent component of a gated input signal derived from a video tape recorder, the loop comprising in combination:
A phase-locked loop for generating at an output terminal an output signal which tracks in phase and frequency a coherent component of a gated input signal derived from a signal source in which the frequency stability has been degraded, the loop comprising in combination:
A chrominance subcarrier regeneration network for generating at an output terminal a regenerated signal which tracks in frequency and phase a subcarrier burst signal reproduced from a video tape, the network comprising in combination:
Dependencies are inferred from the claim text.
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From the US filing history. Foreign family members aren’t listed.
Details of the phase-locked loop: concerning mainly a recovery circuit for the reference signal
Regeneration of colour television signals: regeneration of a colour reference signal, e.g. the colour synchronisaton burst signal, the chrominance…
Automatic control, starting, synchronisation or stabilisation of generators of electronic oscillations or
Pictorial communication
Term ended 28 Dec 1999 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
1. Field of the Invention
The present invention relates generally to videotape recorders and more specifically to a high stability chrominance subcarrier regeneration network employing a reduced frequency voltage controlled oscillator circuit, the output of which is translated to the subcarrier frequency by a higher frequency crystal oscillator.
2. Description of the Prior Art
FIG. 1 is a block diagram of a chrominance subcarrier regeneration network for use in a video tape recorder in accordance with the present invention;
FIG. 2 is a schematic diagram further illustrating the amplifiers, filter, clamping circuit and one-shot multivibrators shown in FIG. 1;
FIG. 3 is a schematic diagram further illustrating the gate and the phase detector of the chrominance subcarrier regenerating network shown in FIG. 1; and
A chrominance subcarrier regenerating network in accordance with the present invention is illustrated in FIG. 1, and generally designated by the number 10. As an aid to the understanding of the present invention, a number of associated components are illustrated and generally designated by the number 12. The associated components 12 are adapted to derive those signals required by chrominance subcarrier regenerating network 10 from the color video signal developed on input line 14. The illustrated associated components include an amplifier 16, a filter 18, amplifier 20, a clamping circuit 22, and a pair of one-shot multivibrators 24 and 26.
Amplifier 16 has a single emitter follower stage operating as a buffer for coupling video signals developed on line 14 to a line 28. Coupling the chrominance portion of the video signals developed on line 28 to a line 30, filter 18 has a two-stage band pass filter tuned to 3.58 megahertz.
The video signals developed on line 14 are also amplified and buffered by amplifier 20 before being coupled to a line 32. Amplifier 20 has two stages, including a common emitter stage providing a small voltage gain followed by an emitter follower. Additionally, amplifier 20 has a resistance-capacitance (RC) network for attenuating higher frequency components of the video signals.