Abstract: A PAL signal demodulating apparatus comprises BPF filters that perform band pass filtering to pass a chroma band for frames 1 to 5, thereby producing the BPF output signals for the frames, a 3D color phase distortion correcting color signal acquiring unit that calculates correlations between frames 1 and 3 and between frames 3 and 5 and takes a weighted average of the BPF output signals for frames 2 and 4 with weights according to the two calculated correlations, thereby producing a 3D color phase distortion correcting color signal N, and a carrier chrominance signal extracting unit that takes the addition/subtraction of the BPF output signal for frame 3 and the 3D color phase distortion correcting color signal, thereby extracting carrier chrominance signals, to perform correctly U/V separation for a line different in color from its preceding and following lines in the same frame.

Abstract: A PAL signal demodulating apparatus comprises BPF filters that perform band pass filtering to pass a chroma band for frames 1 to 5, thereby producing the BPF output signals for the frames, a 3D color phase distortion correcting color signal acquiring unit that calculates correlations between frames 1 and 3 and between frames 3 and 5 and takes a weighted average of the BPF output signals for frames 2 and 4 with weights according to the two calculated correlations, thereby producing a 3D color phase distortion correcting color signal N, and a carrier chrominance signal extracting unit that takes the addition/subtraction of the BPF output signal for frame 3 and the 3D color phase distortion correcting color signal, thereby extracting carrier chrominance signals, to perform correctly U/V separation for a line different in color from its preceding and following lines in the same frame.

Abstract: Systems and methods are provided for correcting color phase error in a video decoder system. A demodulator system demodulates the composite input signal and the at least one delayed signal to produce sets of baseband chroma components based on a phase correction value. Color phase correction logic determines the phase correction value for the demodulator system based upon characteristics of the baseband chroma components associated with a series of at least two consecutive frames.

Abstract: An NTSC system chrominance signal demodulation apparatus is provided with a clock timing change circuit for burst-locking an input signal under the state where the phase is shifted by 90 degrees for every line, and phase axis rotation circuits for performing phase axis rotation, thereby to enable conversion of the phase axis of the burst signal. Therefore, demodulation of a PAL system chrominance signal can be carried out as well as demodulation of an NTSC system chrominance signal, and thereby demodulation of chrominance signals can be carried out using a common device regardless of the broadcast systems such as NTSC and PAL. Further, demodulation of chrominance signals can be carried out even under adverse conditions such as weak electric field or level compression of the burst signal.

Abstract: A color demodulation device having an AD converter, a phase signal generator, a burst data generator and a multiplier. The AD converter produces digital samples of chrominance signal at a frequency four times a color subcarrier frequency, and the phase signal generator generating a phase signal for identifying phases of a burst signal and color subcarrier signals modulated by respective B-Y and R-Y signals. The burst data generator produce burst data corresponding to the burst signals which have predetermined phase relationships with the respective color subcarrier signals according to the phase signal. The multiplier produces products of the burst data and the digital samples of the chrominance signal, from which digital samples of the respective R-Y and B-Y signals are produced.

Abstract: The key component of a digital PAL or NTSC color decoder is a quadrature demodulator for these AM modulated signals. For a SECAM color decoder, however, an FM demodulation is required which is conventionally implemented using a Hilbert filter which is followed by a CORDIC processor and a differentiation stage. It would be advantageous if for multi-standard applications a general-purpose color demodulator for PAL, NTSC and SECAM systems could be implemented on one chip having as much as possible common demodulation processing stages. According to the invention a single common quadrature mixer is used for all three color systems. A resulting bias effect caused by the use of a single mixing frequency is corrected in a clamping stage. The bias effect can also be used for line identification.

Abstract: A color system determination circuit for use with an input video signal having a frequency component is disclosed. The circuit includes a color trap filter for attenuating the frequency component in the input video signal with the color trap filter providing a color burst output signal, a comparator for comparing the color burst output signal of the color trap filter and the frequency component of the input video signal, a maximum value detector which receives the color burst output signal of the color trap filter and a color burst sampling signal and detects a maximum value of the color burst output signal of the color trap filter during a period of the color burst sampling signal, and another maximum value detector which receives the video signal and the color burst sampling signal and detects a maximum value of the video signal during the period of the color burst sampling signal.

Abstract: A two-dimensional contour enhancement is performed along a plurality of lines on a two-dimensional frequency characteristic chart, the line intersecting with each other at middle points between successive color cross generating regions and not passing through an origin. Then, the contour enhancement can be carried out in a frequency region of 3-4 MHz in which a visual effect of contour enhancement appears most effective, while the enhancement in the cross color generating regions can be suppressed.

Abstract: A PAL system demodulator capable of delivering high quality color signals even in the cases of poor vertical correlation comprising 1H delay line 1 delaying the chroma signal by one horizontal period, 1H delay-line 2 delaying a reference signal by one horizontal period wherein the output of the 1H delay line 1 is defined by reference signal, color demodulating circuit 3 canceling hue error by conducting an operation between the scanning lines covering from the input and the output of the 1H delay line 1, color-demodulating circuit 4 canceling the hue error by conducting an operation between the scanning lines covering from the input and the output of the 1H delay line 2, vertical correlation detecting circuit 5 detecting the vertical correlation between the chroma signal of the reference signal and the chroma signal of the adjoining line or the chroma signal of the adjoining line separated by one-line, and selector 6 selecting the output of the color demodulating circuit 3 or the output of color demodulating

Abstract: An adaptive type color demodulation apparatus for the PAL system includes a first color demodulating circuit (PAL-D) for demodulating a PAL system chrominance signal between scanning lines and a second color demodulating circuit (PAL-S) for demodulating the PAL system chrominance signal on a scanning line. Also included is a vertical correlation detecting circuit for detecting a vertical correlation between chrominance signals which are separated by two horizontal periods and a selector for selecting either an output of the first color demodulating circuit or an output of the second color demodulating circuit in response to the detected result of the correlation detecting circuit. Accordingly, hue distortion of the chrominance signal which occurs during signal transmission is cancelled even if the phase distortion is large and a precise color signal is demodulated even if there is no correlation between adjacent scanning lines.

Abstract: A signal demodulator apparatus comprises: an input terminal (11) for inputting an external signal; a delay line (12) connected to the input terminal, for outputting a first delay signal obtained by delaying the external signal by a predetermined time; a phase corrector (13) responsive to the first delay signal outputted by the delay line, for correcting phase of the first delay signal on the basis of a phase difference detection signal and outputting the first phase-corrected delay signal as a second delay signal; and a phase difference detector (16, 15, 19, 20) for detecting a phase difference between the second delay signal outputted by said phase corrector and the external signal inputted through the input terminal and for outputting the phase difference detection signal to the phase corrector to correct the phase difference to a predetermined value.

Abstract: A PAL encoder comprises phase converter, first and second low-pass filters, a burst signal adder, a chrominance subcarrier generator, and a modulator. The phase converter converts digital first and second color-difference signals into digital U-axis and V-axis signals. The first and second low-pass filters pass low-frequency components of the digital U-axis and V-axis signals to produce band-rejected U-axis and V-axis signals, respectively. The burst signal adder adds a predetermined burst signal to the band-rejected U-axis and V-axis signals to produce burst-added U-axis and V-axis signals, respectively. The chrominance subcarrier generator outputs digital sine and cosine signals of the chrominance subcarrier. The modulator multiplies the burst-added U-axis signal by the sine signal and the burst-added V-axis signal by the cosine signal and adds the multiplied results to produce a digital chroma signal.

Abstract: A system converts PAL and NTSC pixel clock signals to signals (in a studio, digital or square pixel format) at a sub-carrier frequency individual to the PAL and NTSC formats. The system includes a first register for providing a particular increase in the register count upon each occurrence of a pixel clock signal. Any remainder in the first register upon the production of the output signal is introduced to the register upon the occurrence of the next pixel clock signal. The particular increase in the first register count is controlled by a value in a second register, this value being adjustable dependent upon the system format and mode. A sequence of registers may be substituted for the first register with each register receiving an output from the previous register in the sequence. The system also converts signals representing the primary colors to luminance and chrominance signals.