Abstract: A clamp circuit includes a coupling capacitor connected between signal input and signal output terminals. A constant current sink and a controlled current source are connected to the output terminal. A comparator, coupled to the output terminal via a lowpass filter, generates signals for conditioning the controlled current source to source current whenever the output terminal exhibits a potential which differs from a predetermined reference in a predetermined polarity sense.

Abstract: A detector for detecting motion in an image represented by a video signal includes delay elements for providing lines of signal from five consecutive fields. Sums of signals from first and second fields are subtracted from sums of signals from third and fourth fields to generate first motion indicators. Differences of signals from the first and second fields are subtracted from differences of signals from the third and fourth fields to generate second motion indicators. Differences of signals from the first and fifth fields are generated to form third motion indicators. The first, second and third motion indicators are compared and the largest is provided as a motion signal which is subsequently limited, spread and scaled. Signals used in forming the motion indicators are selected to substantially reject any adverse influence of the chrominance subcarrier.

Abstract: In a video signal processing system apparatus for differentiating between video field types includes circuitry for measuring an interval between a vertical signal component and a predetermined transition of a horizontal signal component. Measured values from successive fields are compared to provide a signal related to the respective field type, e.g., odd/even.

Abstract: An NTSC compatible, single broadcast channel, widescreen EDTV system encodes and decodes a television signal comprising four components: (1) a main, standard format NTSC signal with low frequency side panel image information compressed into the overscan regions thereof; (2) time expanded high frequency side panel image information; (3) extended high frequency horizontal luminance image information; and (4) vertical-temporal luminance image information. Components (2) and (3) are intraframe averaged and quadrature modulate an alternate subcarrier, e.g., at 3.108 MHz, to produce a modulated signal. The modulated signal is summed with component (1) after intraframe averaging to produce an NTSC compatible 4.2 MHz baseband signal. This signal and component (4) quadrature modulate an RF picture carrier to produce an NTSC compatible RF broadcast signal for transmission via a single broadcast channel.

Abstract: An improved color picture tube includes a rectangular faceplate panel having two long sides and two short sides. A rectangular shadow mask is suspended at its four corners by support means within the panel adjacent to a cathodoluminescent screen located on the panel. The tube has three principal axes that are mutually orthogonal to each other. These axes include a longitudinal axis which extends through the center of the tube perpendicularly to the center of the panel, a major axis which passes through the center of the panel paralleling the long sides of the panel, and a minor axis which passes through the center of the panel paralleling the short sides of the panel. Each of the support means has a central support axis. The improvement comprises the two support axes on each side of the minor axis crossing a plane containing the longitudinal and major axes at a point located between the minor axis and a short side of the panel.

Abstract: Apparatus for generating a signal having a predetermined frequency relationship with a subcarrier includes a counter for counting cycles of said subcarrier. Count values from the counter are coupled as address values to a memory circuit. The memory circuit is preprogrammed to provide a signal having the desired frequency responsive to successive address values applied by the counter.

Abstract: An amplifier loaded with a constant bandwidth tuned circuit is provided with an output series coil, and with a resistance in series with the output coil and a subsequent load to provide attenuation at high frequencies for maintaining the total overall gain of the amplifier and tuned circuit load constant with increasing frequency while simultaneously maintaining the bandwidth of the tuned circuit constant with increasing frequency.

Abstract: A channel number data entry system for a television receiver employing a numeric keyboard allows the selection of cable channels having channel numbers greater than 99, without the use of a separate ENTER or 100s key. Specifically, if a predetermined unused or invalid channel number, such as 00, is entered, then the on-screen display message 1.sub.-- is generated, and a three digit channel entry mode is enabled. If a valid and used two digit channel number is entered, then a two digit channel entry mode is enabled. In both modes, the desired channel is tuned upon receipt of the final digit of the channel number.

Abstract: A channel number data entry system for a television receiver employing a numeric keyboard allows the selection of cable channels having channel numbers greater than 99, without the use of a separate ENTER or 100s key. Specifically, if the leading digit of a desired channel number is a number one, a measurement is made of the time interval during which the number one key is activated. If the measured time interval exceeds 2 seconds, then a three digit channel entry mode is enabled. If the measured time interval does not exceed 2 seconds, then a two digit channel entry mode is enabled. In both modes, the desired channel is tuned upon receipt of the final digit of the channel number.

Abstract: Active turn-off or disabling circuits respond to control signals from a control unit which defines the mode of operation of a receiver. In response to a designation of a standby mode of operation the active disabling unit actively disables a pulse width modulator to prevent pulses from being produced based upon an input of ringing signal. In addition, the active disabling circuits prevent such ringing signal from negatively effecting pincusion protection circuits. The ringing signal is produced in a horizontal flyback transformer during a transition interval that follows a transition to standby mode of operation.

Abstract: A sampled data interpolator includes a linear interpolator coupled in parallel with a nonlinear compensation signal path. The nonlinearly processed signals and the linearly interpolated signals are summed to produce interpolated samples. The nonlinear compensation signal path includes a finite impulse response filter having tap weights conforming to a sinc function, and a weighting circuit for scaling filtered samples by a normalized sinc function.

Abstract: A multimode comb filter for comb filtering, e.g., NTSC and/or PAL video signals includes delay means for concurrently providing video signals representing first, second and third adjacent horizontal lines. First and second combining means coupled to the delay means provide alternate 1-H comb filtered signals in both the NTSC and PAL modes. Control circuitry coupled to the delay means generates a control signal for adaptively selecting the one of the alternate 1-H comb filtered signals or appropriate proportions of both alternate 1-H comb filtered signals to form an output comb filtered signal. In the NTSC mode the control circuitry generates the control signal from sums of vertically aligned pairs of samples from said first and second lines and from said second and third lines. In the PAL mode the control signal is generated from alternating sums and differences of vertically aligned pairs of samples from said first and second lines and from said second and third lines.

Abstract: An improved color picture tube includes an evacuated glass envelope having a rectangular faceplate panel. The panel includes a shadow mask assembly mounted therein by support means located at peripherally spaced positions within the panel. The support means at each of the spaced positions includes a stud, attached to the glass envelope, and a spring, having an aperture therein that engages the stud. The spring is interconnected with the shadow mask assembly. The improvement comprises the spring including a first portion interconnected with the shadow mask assembly, an elongated second portion extending from the first portion toward the stud, a third portion interconnected with the second portion and including an aperture engaging the stud, and an offset section that positions the center of the aperture on a central longitudinal plane passing through the second portion.

Abstract: A horizontal deflection circuit output stage generates a retrace pulse in a tertiary winding of a flyback transformer. A flyback pulse that is substantially wider than the retrace pulse is produced in a winding of a second transformer that is coupled in series with the tertiary winding such that the retrace pulse occurs when a peak portion of the flyback pulse is already relatively "flat". The amplitude of the flyback pulse is controlled in a negative feedback loop for stabilizing an ultor voltage.

Abstract: A color picture tube includes a screen and an improved inline gun for generating and directing three inline electron beams along separate paths toward the screen. The gun includes a plurality of cathodes and at least six electrodes longitudinally spaced from the cathodes. The improvement comprises the first, second and fourth electrodes from the cathodes being of materials having lower coefficients of thermal expansion than the coefficients of thermal expansion of the materials of the other electrodes.

Abstract: A multimode comb filter for comb filtering, e.g., NTSC and/or PAL video signals includes delay means for concurrently providing video signals representing three adjacent horizontal lines. First and second combining means coupled to the delay means provide alternate 1-H comb filter signals in both the NTSC and PAL modes. Control circuitry coupled to the delay means generates a control signal for adaptively selecting the one of the alternate 1-H comb filtered signals or appropriate proportions of both alternate 1-H comb filtered signals to form an output comb filtered signal.

Abstract: An apparatus and method for improvement of stereophonic sound. A source of stereophonic sound is provided with two internal loudspeakers and external access to the stereophonic signal. A "wall of sound" effect is achieved by coupling of the sterophonic signal to at least two external loudspeakers with the internal loudspeakers being fed a mixture of the sterophonic signal at reduced power.

Abstract: A television system is disclosed including sections for limiting peak white drive to a display device (e.g., of the direct view of projection type) while maintaining relatively high subjective image contrast and brightness. Specifically, the system includes an automatic contrast control section for controlling the amplitude of the luminance signal in response to the peak value of a luminance-representative image component signal preceded by a "white-stretch" control section for emphasizing mid-range luminance components relative to high-range luminance components as a function of the average value of the luminance-representative image component. In this way, spot blooming and display driver saturation can be minimized while providing subjectively sharp, bright pictures.

Abstract: A digital signal clamp circuit is realized using an adder and an up/down counter. The digital signal is coupled to one input of the adder and the counter output is coupled to a second input of the adder. The up/down counter is enabled to count only during signal intervals exhibiting the desired clamping level. The counter is controlled to count up or down depending on the polarity of the signal provided by the adder. The count value in the counter is continuously applied to the adder to provide clamping. Using a truncated count value from the counter enhances clamping performance.

Abstract: The present invention provides an improved cathode-ray tube. The neck of the tube envelope is closed at one end by a stem that includes a plurality of electrically conductive pins extending therethrough. The pins are interconnected to various electrodes of the gun by electrical leads that are welded to respective pins. The improvement comprises at least one of the leads having a bend therein that positions a nonwelded portion of the lead between a lead-to-pin weld location and the neck of the tube.