US4829377A — Horizontal synchronization, clock synchronization…

Claim 1

Independent Claim 168 words

In an analog TV transmission system of the type which produces a video signal transmitted to a receiver, said video signal being in the form of a raster scanning pattern of horizontal scan lines of video information with a horizontal blanking interval between scan lines during which interval synchronizing signals, including horizontal synch pulses, are transmitted, the improvement comprising: means for generating a horizontal unique pulse sequence during each horizontal blanking interval, the amplitudes of the pulses forming said pulse sequence being modulated to produce a horizontal unique word defining a horizontal line time base, the frequency of the pulses of the pulse sequence being proportional to the frequency of the TV system color subcarrier signals to provide a color subcarrier phase reference, an average level of the pulses of the pulse sequence being at a desired DC level of the video signal at the receiver, and a peak amplitude of the pulses of the pulse sequence defining a reference level for automatic gain control at the receiver.

Claim 2

Dependent Claim 168 words

In an analog TV transmission system of the type which produces a video signal transmitted to a receiver, said video signal being in the form of a raster scanning pattern of horizontal scan lines of video information with a horizontal blanking interval between scan lines during which interval synchronizing signals, including horizontal synch pulses, are transmitted, the improvement comprising: means for generating a horizontal unique pulse sequence during each horizontal blanking interval, the amplitudes of the pulses forming said pulse sequence being modulated to produce a horizontal unique word defining a horizontal line time base, the frequency of the pulses of the pulse sequence being proportional to the frequency of the TV system color subcarrier signals to provide a color subcarrier phase reference, an average level of the pulses of the pulse sequence being at a desired DC level of the video signal at the receiver, and a peak amplitude of the pulses of the pulse sequence defining a reference level for automatic gain control at the receiver.

Claim 3

Dependent Claim 65 words

A TV transmission system as claimed in claim 1, wherein said unique pulse sequence generating means comprises a multi-stage decoder means receiving a horizontal time base signal of said TV transmission system, switch means for selectively passing an output from each stage of said decoder and gate means for passing the unique pulse sequence determined by the states of the switches of said switch means.

Claim 4

Dependent Claim 99 words

A TV reception system as claimed in claim 2 further indicating an AGC circuit comprising a gain control means, rectifier means for rectifying the output from said gain control means, a difference circuit receiving this output from said rectifier means and a local reference level, switch means responsive to an AGC timing signal derived from said horizontal time base for selectively passing the output from said difference circuit, integrator means responsive to the signals passing through said switch means the output of said integrator means being an input to said gain control means, another input being the video signal.

Claim 5

Dependent Claim 204 words

In a TV reception system of the type receiving a video signal in a raster scanning pattern of horizontal scan lines, with a horizontal blanking interval between scan lines, said horizontal blanking interval containing a horizontal unique pulse sequence, said horizontal unique pulse sequence being transmitted as a data signal and containing a horizontal unique word defining a horizontal time base, the frequency of the pulses of the sequence being proportional to the frequency of the color subcarrier signals thereby providing a color subcarrier phase reference, an average level of the sequence pulses being at a desired DC level of the video signal, a peak amplitude of the sequence pulses defining a reference level for automatic gain control, receiving apparatus comprising: means for demodulating the data from the received video signals; means, responsive to the demodulated data, for detecting the horizontal unique pulse sequence; means responsive to detection of the horizontal unique pulse sequence for producing a horizontal time base signal; means responsive to the produced horizontal time base signal for producing an AGC reference level, a DC level clamp reference, and a subcarrier phase reference; and means responsive to the produced horizontal time base signal for producing the horizontal and vertical sync pulses.

Claim 6

Dependent Claim 204 words

In a TV reception system of the type receiving a video signal in a raster scanning pattern of horizontal scan lines, with a horizontal blanking interval between scan lines, said horizontal blanking interval containing a horizontal unique pulse sequence, said horizontal unique pulse sequence being transmitted as a data signal and containing a horizontal unique word defining a horizontal time base, the frequency of the pulses of the sequence being proportional to the frequency of the color subcarrier signals thereby providing a color subcarrier phase reference, an average level of the sequence pulses being at a desired DC level of the video signal, a peak amplitude of the sequence pulses defining a reference level for automatic gain control, receiving apparatus comprising: means for demodulating the data from the received video signals; means, responsive to the demodulated data, for detecting the horizontal unique pulse sequence; means responsive to detection of the horizontal unique pulse sequence for producing a horizontal time base signal; means responsive to the produced horizontal time base signal for producing an AGC reference level, a DC level clamp reference, and a subcarrier phase reference; and means responsive to the produced horizontal time base signal for producing the horizontal and vertical sync pulses.

Claim 7

Dependent Claim 108 words

A TV reception system as claimed in claim 4, wherein said horizontal unique pulse sequence detecting means comprises register means having a number of register stages equal to the number of bits in the unique pulse sequence, each stage having a logic high and a logic low output, switch means selectively supplied to either the logic high or the logic low output of each register stage such that the output of the switch means is a logic high when the horizontal unique sequence is in the register means, and gate means producing a logic high in response to a logic high at the output of the switch means.

Claim 8

Dependent Claim 110 words

A TV reception system as claimed in claim 5 further including a horizontal loss of sync detector comprising a first counter producing a reference period, a second counter receiving said horizontal time base as a clock input thereto, means for producing a correct horizontal sync pattern, means responsive to the demodulated data and the correct horizontal sync pattern for indicating non-coincidence between data signals and the correct horizontal sync pattern, second counter means responsive to said indicating means for counting non-coincidence between the data signals and said correct horizontal sync pattern, and comparator means for comparing the count in said second counter over the reference period against a reference level.

Claim 9

Dependent Claim 50 words

A TV reception system as claimed in claim 6 wherein said data signal includes a vertical unique word, and further comprising means responsive to the demodulated data for detecting the vertical unique word and means responsive to the detection of the vertical unique word for producing a vertical time base.

Claim 10

Dependent Claim 21 words

A TV reception system as claimed in claim 7 wherein said means for producing a horizontal sync pulse includes a ROM.

Claim 11

Dependent Claim 75 words

A TV reception system as claimed in claim 4 further including a subcarrier phase reference circuit comprising a phase detector receiving the video signal and a reference signal, switch means response to the subcarrier phase reference signal derived from said horizontal time base for selectively passing the output from said phase detector and a voltage controlled oscillator for producing a signal having a frequency proportional to and in phase with the transmitted subcarrier reference signal.

Claim 12

Dependent Claim 62 words

A TV reception system as claimed in claim 4 further including a DC level clamp circuit comprising a difference circuit, switch means response to the DC level clamp timing signal derived from said horizontal time base, integrator means coupled to said switch means, the output of said integrator being one input to the difference circuit, another input thereto being the video signal.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1992-05-08	1992-11-07	1993-05-09	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1996-05-08	1996-11-07	1997-05-09	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2000-05-08	2000-11-07	2001-05-09	$7700.00	Window Closed / Lapsed

Horizontal synchronization, clock synchronization, D. C. restoration and gain control scheme for an analog TV system

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