Abstract: A crosstalk detector for detecting the crosstalk of signals optically read from a recording medium having a plurality of tracks. A changeover circuit selects one of first and second signals generated by first and second oscillators. The amplitude of a signal of a predetermined center frequency is extracted from the selected signal and RF signal and that amplitude is compared with a control signal that inverts at every horizontal synchronizing period of a video signal demodulated from the RF signal.

Abstract: In a television system including a source of an intermediate frequency (IF) signal, which signal includes an IF picture carrier amplitude modulated with video information, synchronous demodulator means responds to the IF signal, for providing an in-phase first output video signal that has both luminance and chrominance components, and for providing a quadrature-phase second output video signal that has a chrominance component but substantially no luminance component. Chroma circuitry is responsive to the quadrature-phase second output video signal for generating first and second color-difference signals.

Abstract: An HDTV receiver takes advantage of the detailed structure of the NTSC signal, namely the periodicity of the signal caused by the horizontal scan rate, in order to remove co-channel interference. A feedforward circuit is used to form an estimate of a current co-channel interference value from co-channel interference values occurring on previous scan lines. The estimate is subtracted from the signal to remove the co-channel interference at the expense of generating intersymbol interference. The circuit uses a form of decision-feedback equalization (DFE) in order to remove the intersymbol interference. The periodicity of the NTSC signal is exploited to allow the use of a high-rate trellis code in the DFE circuit.

Abstract: A noise canceler for a video signal includes: a delay circuit for outputting a succeeding line video signal, a present line video signal and a preceding line video signal: a minimum value detector which compares the succeeding line video signal with the present line video signal, and the present line video signal with the preceding line video signal, so as to output the lower-level minimum value; a maximum value selector for comparing the minimum values so as to select the higher-level maximum value; a maximum value detector which compares the succeeding line video signal with the present line video signal, and the present line video signal with the preceding line video signal, so as to output the higher-level maximum value; a minimum value selector for comparing the maximum values so as to select the lower-level minimum value; an adder for summing the maximum value output from the maximum value selector and the minimum value output from the minimum value selector so as to output a signal containing correlati

Abstract: An apparatus and method for generating a modified video signal consisting of a correction signal and a video input signal. The correction signal is derived from a digitized video input signal by at least a frequency-band limiter and an amplitude limiter. The video input signal is delayed by the processing time of the correction signal before the two signals are combined. To avoid unwanted harmonics the amplitude limiter uses a transfer function which can be exactly described by a rational integral function of the nth degree,y=a.sub.0 +a.sub.1 *x+a.sub.2 *x.sup.2 +a.sub.3 *x.sup.3 . . . a.sub.n *x.sup.nwith 1<n<f.sub.n /f.sub.s, where f.sub.n is the Nyquist frequency, f.sub.s is the maximum frequency of the frequency-band-limited video signal, x is the input to the amplitude limiter a.sub.0 to a.sub.n are scale factors, and y is the output of the amplitude limiter.

Abstract: A high-performance television receiver synchronously detects the picture IF signal. A synchronous impulse noise in the IF signal generates either positive-going noise or negative-going noise in the video signal supplied from a synchronous video detector, which noise is subsequently replaced by a value of video signal occurring previous to the impulse noise in the following manner. The video signal contaminated with impulse noise is supplied as input signal both to an impulse noise detector and to a delay line. The output signal from the delay line, delayed by about 240 ns, is supplied as the signal for tracking by a track-and-hold circuit. The detected impulse noise signal is used to actuate the hold condition in the track-and-hold circuit. By stretching the pulse from the impulse noise detector for the 600-800 ns duration overlapping the duration of most impulse noise, the track-and-hold circuit replaces most impulse noise with previously stored values of the delayed video signal.

Abstract: A method and apparatus serves for filtering signals, whereby signal amplitudes can be allocated to a quantized, two-dimensional reference plane. For intensifying a useful signal part, a filtered signal can be added to an unfiltered input signal after constant parts as well as high-frequency parts have been filtered out. After a frequency-dependent filtering of the signal part to be filtered, components of the signal part to be filtered which have an amplitude above a prescribable threshold are eliminated in at least one contour filter stage. The threshold is adaptively adjusted dependent on an amplitude of the input signal. Over and above this, the output signal of the contour filter stage is subtracted from the output signal of the frequency-dependent filter for generating the overall filter signal.

Abstract: A field recursive type noise reduction apparatus is disclosed in which the field difference is divided into a plurality of frequency components by means of the Hadamard transformation and the existence of a boundary of an oblique line in the proximity of pixels to be processed is detected from frequency components remaining by removing minimum and maximum horizontal frequency components by an oblique line detection circuit. In the location where the existence of the boundary of oblique line is detected, a feedback rate of the apparatus is reduced to avoid deterioration of the image quality by nonlinear processing means and in other locations the feedback rate is increased to improve the S/N, so that a noise reduction apparatus is realized having excellent improvement of the S/N as compared with a conventional field recursive type noise reduction apparatus.

Abstract: A noise eliminating circuit comprising a noise eliminating filter for moving image part to be used when an input image is of the moving image part, a noise eliminating filter for stationary image part to be used when the input image is of the station image part, these filters being adaptively selected between according to a motion of the input image, a detecting circuit for detecting the motion of the input image, and a selecting circuit for selecting between outputs of these filters based on an output of the detecting circuit, wherein the noise eliminating circuit for stationary image part outputs an average input image of number of stationary frames n to be entered. The novel constitution effectively suppresses a noise introduced in a moving image or a stationary image, generating an output signal with a good picture quality.

Abstract: An arrangement for enhancing an image corresponding to a television signal including a digital component includes a variable bandwidth filter and a control unit for controlling the bandwidth of the filter in response to the bit error rate (BER) of the digital component of the television signal. The control unit increases the bandwidth as the BER and therefore the signal quality increases and decreases the bandwidth as the BER and therefore the signal quality decreases. In one embodiment, the control unit is responsive to both the BER and the "darkness" of the image represented by the television signal so as to restrict the bandwidth more for relatively dark areas than for relatively light areas.

Abstract: A frame image signal which is output cyclically is converted to a digital signal and input to a first multiplier in a digital filter. The first multiplier multiplies a digital image signal Y.sub.i of each frame by (1-a), and supplies the product (1-a).multidot.Y.sub.i to a first input terminal of an adder. The coefficient a is a negative coefficient whose absolute value is not more than 1, so that (1-a) becomes a positive coefficient of not less than 1. An output of the adder serves as an output Y.sub.i ' of the digital filter from which the residual image has been erased, and is supplied to a subsequent unit, e.g., a display unit (not shown) connected to the output of the adder. The output Y.sub.i ' of the adder is also supplied to a frame memory and is delayed by one frame period. Therefore, an output Y.sub.i-1 ' of the frame memory is a one-frame preceding image output. The signal Y.sub.i-1 ' is input to a second multiplier and is multiplied by the coefficient a.

Abstract: A high-performance television receiver synchronously detects the picture IF signal. A synchronous impulse noise in the IF signal generates either positive-going noise or negative-going noise in the video signal supplied from a synchronous video detector, which noise is subsequently replaced by a value of video signal ocurring previous to the impulse noise in the following manner. The video signal contaminated with impulse noise is supplied as input signal both to an impulse noise detector and to a delay line. The output signal from the delay line, delayed by about 240 ns, is supplied as the signal for tracking by a track-and-hold circuit. The detected impulse noise signal is used to actuate the hold condition in the track-and-hold circuit. By stretching the pulse from the impulse noise detector for the 600-800 ns duration overlapping the duration of most impulse noise, the track-and-hold circuit replaces most impulse noise with previously stored values of the delayed video signal.

Abstract: A motion adaptive vertical filter is used to filter an interlaced video signal on a frame basis in areas of the image that are not in motion and on a field basis in areas that are in motion. A soft switch mixes the field filtered data and the frame filtered data in areas where there is relatively little motion to prevent artifacts which may be caused by abruptly switching between the two vertical filtering schemes. The frame vertical filter reduces the vertical resolution of still NTSC images to 180 cycles per picture height (CPH) while the field filter reduces the vertical resolution to 90 CPH.