Abstract: An analog-to-digital converter is provided. The analog-to-digital converter includes: a sample/hold circuit; a digital-to-analog converter; a plurality of comparison circuits; a control logic; and a digital register, wherein the plurality of comparison circuits include: a first comparison circuit configured to output a first comparison result signal in a first operation period; a second comparison circuit configured to, in a second operation period, calibrate an offset of a second comparison result signal based on a reference signal corresponding to the first comparison result signal among a plurality of reference signals and output the calibrated second comparison result signal; and a third comparison circuit configured to, in a third operation period, calibrate an offset of a third comparison result signal based on a reference signal corresponding to the calibrated second comparison result signal and output the calibrated third comparison result signal.

Abstract: A method for analog transmission of video from a transmitter using multiple transmit antennas includes transmitting analog video signals through at least two antennas to a receiver, monitoring at the receiver an attribute of the channels between the transmit antennas and an antenna of the receiver, and changing a phase and magnitude of an analog video signal being transmitted through at least one of the at least two antennas responsive to the monitoring. Additionally, a method for analog transmission of video signals using multiple transmit antennas includes space-time coding.

Abstract: Methods and apparatus for providing access to program channels, e.g., high definition programs and program channels which corresponding to a standard definition program and/or program channels are described. In accordance with the invention, a high definition auto tune function is supported. When enabled, in one exemplary embodiment, if a user selects a standard program definition channel, a check is automatically made to determine if a corresponding high definition program channel is available. The corresponding high definition program channel is a channel which provides the same program as on the selected standard definition channel but in high definition. When the auto tune function is enabled and a corresponding high definition channel is available, the device, e.g., set to box or tuner implementing the auto tune feature of the present invention, automatically tunes to the high definition channel instead of the standard definition channel.

Abstract: A chromaticity correction device corrects chromaticity of a video signal displayed on a display panel of a display device to correspond to a change in a luminance value of the display panel. The chromaticity correction device includes a luminance detection unit which detects the luminance value, a backlight driving level detection unit which detects a backlight driving level, a temperature detection unit which detects an internal device temperature or an ambient temperature, a reference luminance value calculation unit which estimates a reference luminance value in a characteristic of an initial state, a chromaticity calculation unit which obtains a chromaticity change amount of white point chromaticity and estimated white point chromaticity that is an estimated value of current white point chromaticity, a chromaticity correction value calculation unit which obtains a chromaticity correction value and a chromaticity correction circuit which corrects the chromaticity of the video signal.

Abstract: According to one embodiment, a color correction apparatus includes an input portion, a storing portion and a correction portion. The input portion inputs color image signals which correspond to recording color material amounts. The storing portion stores a standard color reproduction parameter for calculating a standard color reproduction chromaticity and reference chromaticity deviation amounts at a plurality of reference color points in recording color material amount coordinate space. The correction portion estimates chromaticity deviation amounts of the input color image signals on the basis of the reference chromaticity deviation amount, calculates a standard chromaticity which corresponds to the input color image signals on the basis of the standard color reproduction parameter and corrects the input color image signals on the basis of the estimated chromaticity deviation amounts and the standard chromaticity.

Abstract: According to one embodiment, an electronic device includes a reproduction controller and a transmitter. The reproduction controller is configured to reproduce a first type of information of a first content. The first content includes a plurality of types of information. The transmitter is configured to transmit an instruction to reproduce a second type of information of the first content to other electronic device.

Abstract: Methods and apparatus for providing access to program channels, e.g., high definition programs and program channels which corresponding to a standard definition program and/or program channels are described. In accordance with the invention, a high definition auto tune function is supported. When enabled, in one exemplary embodiment, if a user selects a standard program definition channel, a check is automatically made to determine if a corresponding high definition program channel is available. The corresponding high definition program channel is a channel which provides the same program as on the selected standard definition channel but in high definition. When the auto tune function is enabled and a corresponding high definition channel is available, the device, e.g., set to box or tuner implementing the auto tune feature of the present invention, automatically tunes to the high definition channel instead of the standard definition channel.

Abstract: Provided is an analog front end of a digital TV, a digital TV system having the same, and a method of operating the same. The analog front end includes: a first selection circuit which selectively outputs differential sound intermediate frequency signals or differential TV broadcast signals in response to a first selection signal; a second selection circuit which outputs a clock signal among a plurality of clock signals having a different sampling frequencies, in response to a second selection signal; and an analog-to-digital converter which converts output signals output from the first selection circuit to a digital code, according to a sampling frequency of a clock signal output from the second selection circuit.

Abstract: A video signal processing apparatus may include a frame memory and a separator and deinterlacer circuit. The frame memory may store an interlaced video signal. The separator and deinterlacer circuit may execute operations of separating and deinterlacing the interlaced video signal stored in the frame memory. The apparatus may output a sequential video signal. A data processing system may include the video signal processing apparatus. A method for processing video signals may include storing an interlaced video signal in a frame memory and executing operations of separating and deinterlacing the interlaced video signal stored in the frame memory. The method may also include outputting a sequential video signal.

Abstract: A method for searching a signal source suitable for a multimedia apparatus with multiple signal terminals is disclosed. The method provides an ordered search list of the signal terminals to save the search sequence of the signal terminals. The multimedia apparatus sequentially detects the signal terminals according to the ordered search list of the signal terminals to identify whether an input signal is available. When a specific signal terminal of the signal terminals is found to have an input signal, the sequence of the specific signal terminal in the ordered search list of the signal terminals is set as the first sequence position.

Abstract: A tuner and a demodulating unit thereof are provided. A trap filter for a specific frequency is installed in the IF demodulating unit so as to eliminate a frequency signal acting as a beat component.

Abstract: Base band compensation for an IF stage in a television provides significant advantages over compensation applied to the composite signal. Each base band color difference signal is filtered to obtain cross-talk elements, which are then applied to the opposite channel to eliminate the cross-talk components from the color difference signal channels. The compensation technique is applicable to IF stages generally, including those based on SAW filters. High and low gain compensation of the cross-talk compensated signals may also be performed to reduce distortion in the compensated signals. The base band compensation tends to reduce or eliminate visual artifacts in a television image, especially where sharp contrast transitions occur in the image.

Abstract: An analog TV receiver implementation on DSP allows mobile platforms to view analog TV broadcasting on LCD displays. The analog television receiver includes a demodulator for demodulating a received analog television signal, an analog to digital converter for digitizing the demodulated television signal and a digital signal processor for producing display signals from the digitized television signals. The digital signal processor being programmed to search for a horizontal synchronization signal in the television signal, track the horizontal synchronization signal and search for a vertical synchronization signal in the television signal. Next the processor separates a luminance and a pair of chrominance components of the television signal and demodulates the pair of chrominance components. Red, green and blue values are constructed from the demodulated chrominance components and the luminance components. Display signals are produced from the red, green and blue values.

Abstract: A time-based, digital FM demodulator circuit receives a stream of digital samples corresponding to an analog FM waveform. The samples are provided to a zero crossing detector, which allows a counter to determine a number of clock cycles between zero crossings. The resolution of this coarse period determination is further refined by an intercept calculation, which further localizes the zero crossing of the FM waveform based on interpolation between samples on either side of the zero crossing. Accuracy of the period determination may be further enhanced by use of a sinusoidal correction filter, which minimizes error caused by the linear interpolation performed on the sinusoidal waveform. Although the FM demodulator circuit is particularly suitable for demodulation of the chroma component of a SECAM video signal, it may advantageously be applied in a wide variety of FM demodulation applications.

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 method of scanning channels in a digital television including (a) setting a starting frequency; (b) searching for a first available digital channel by searching a search frequency that is the starting frequency; adding a predetermined scan step to said search frequency if the first available channel is not found at the starting frequency, and adding additional predetermined scan steps to the search frequency until the first available channel is found if the first available channels is not found at the starting frequency plus the scan step; and (c) searching for a second available digital channel by searching at a first main frequency, which is the first available channel frequency plus a first predetermined bandwidth, wherein the step of searching for the second available digital channel includes searching at a plurality of scan steps around the first main frequency.

Abstract: A device and method are provided for implementing digital baseband separation of composite video signals with reduced memory requirements. The method and device require that only the composite signal be stored in a large delay element. Multiple quadrature demodulators are employed to generate multiple delayed complex baseband signals. Therefore, no large complex baseband delay element is required.

Abstract: A luminance component of a video signal is modulated in a first frequency band. A first chrominance component of the video signal is modulated in a second frequency band and is mixed with an audio component. A second chrominance component of the video signal is modulated in a third frequency band. The modulated luminance component, the first modulated chrominance component, and the second modulated chrominance component are then transmitted across a communication link.

Abstract: A luminance component of a video signal is modulated in a first frequency band. A first chrominance component of the video signal is modulated in a second frequency band and is mixed with an audio component. A second chrominance component of the video signal is modulated in a third frequency band. The modulated luminance component, the first modulated chrominance component, and the second modulated chrominance component are then transmitted across a communication link.

Abstract: Device and method for tracking a phase error in a digital TV receiver, wherein a phase noise compensated I signal is subtracted from I level reference signals of VSB signal, to obtain an error of the I signal, a sign of the Q signal having a phase noise thereof compensated is multiplied to the error of the I signal from the error determining part, to estimate a basic phase error, and a phase error compensating area is determined, a preset constant ‘?’ is multiplied to the basic phase error to provide a final phase error in the determined phase error compensating area, and the basic phase error is provided as it is as the final phase error in other areas, thereby estimating the phase error more accurately.

Abstract: A luminance component of a video signal is modulated in a first frequency band. A chrominance component of the video signal is modulated in a second frequency band. The modulated luminance component and the modulated chrominance component are then transmitted across a communication link.

Abstract: A chroma-decoder 1 has two SRCs 17 and 21. The first SRC 17 performs down-conversion, changing the sampling rate of a composite video signal sampled with a system clock signal Cs to the sampling rate (14.3 MHz) of an NTSC signal. The signal generated by the SRC 17 is output in synchronism with the system clock signal Cs. The signal is then divided into a luminance signal Y and a color-difference signal C, which are subjected to chroma decoding. The second SRC 21 performs down-conversion, changing the sampling rate of the luminance signal and color-difference signal of the NTSC signal to the sampling rate (13.5 MHz) of an ITU-R601 standard.

Abstract: A SECAM decoder and an FM modulator therefor are disclosed, in which a demodulated color signal is provided to indicate deviations in the frequency of modulated color information from a nominal subcarrier frequency. The demodulator comprises numerator and denominator filters operating on the modulated color information, and a divider providing a ratio result by dividing the numerator filter output by the denominator filter output. The demodulator may include two sets of numerator and denominator filters offset in phase from one another, where one of the two sets is selectively employed in order to mitigate divide-by-zero problems. Also disclosed are methods for demodulating digitized FM color signals in a SECAM decoder.

Abstract: A digital television receiver and antenna control method in the digital television receiver are disclosed. The digital television receiver includes and antenna having directivity according to a control signal for switching patterns of the antenna. A receiving section receives and processes channel signals for digital television broadcasting through the antenna. An antenna control section generates the control signal for switching the patterns of the antenna based on channel information according to the received channel signal. An antenna switching control section switches the patterns of the antenna during a sync signal period of the received channel signal when the control signal is generated.

Abstract: A color demodulation apparatus having color demodulation capabilities as the conventional ones, with its size reduced by sharing part of processing circuit therein is provided. An adder circuit 10 and a SW circuit 11 shift the phase of a ramp wave generated by a VCO circuit 9 alternately 90 degrees and 180 degrees for each clock. A SIN data generator circuit 12 generates a phase alternate SIN wave signal from the shifted ramp wave. A multiplier circuit 3 performs R-Y and B-Y demodulation through multiplexing based on the phase alternate SIN wave signal. An accumulator circuit 6 accumulates burst signals of each of R-Y and B-Y signals of the demodulated, multiplexed signal. A second load hold circuit 8 separately outputs an R-Y burst signal to the VCO circuit 9, and a B-Y burst signal to a comparator circuit 13, constituting two feedback loops. A first load hold circuit 5 separates R-Y and B-Y signals from the multiplexed signal, and outputs these two signals.

Abstract: Receiving apparatus for digital television signals digitizes a final intermediate frequency signal supplied from a triple-conversion radio receiver and synchrodynes the digitized final intermediate frequency signal to baseband. The triple-conversion radio receiver selects one of a plurality of digital television signals for upconversion to that portion of the electromagnetic frequency spectrum above the channels that are used for television broadcasting, amplifies a first intermediate-frequency signal in a first intermediate frequency band generated by that upconversion, amplifies a second intermediate-frequency signal in a second intermediate frequency band generated by downconverting the amplified first intermediate-frequency signal, and supplies a third intermediate-frequency signal in a third intermediate frequency band generated by downconverting the amplified second intermediate-frequency 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: A dual-loop PLL circuit is provided with a clamping circuit 12, an A/D conversion circuit 14, a reference color burst outputting circuit 18, a PLL circuit 24, and phase detecting circuit 34. The phase of a reference color burst KK outputted from the circuit 18 is changed at a slice level SL, and the level SL is changed by a reference phase value in the phase detecting circuit 34. The sampling clocks outputted from the PLL circuit 24 to the A/D conversion circuit 14 are converted to a signal of a frequency of 4 Fsc, and the phase of the signal can be changed continuously by using the reference phase value. In addition, since the phase of the sampling clocks can be adjusted to a desired value and the output signal of the A/D conversion circuit 14 can be converted onto a prescribed color difference signal by a signal conversion circuit and outputted, the color difference signals can be demodulated easily with high accuracy.

Abstract: A chroma-decoder 1 has two SRCs 17 and 21. The first SRC 17 performs down-conversion, changing the sampling rate of a composite video signal sampled with a system clock signal Cs to the sampling rate (14.3 MHz) of an NTSC signal. The signal generated by the SRC 17 is output in synchronism with the system clock signal Cs. The signal is then divided into a luminance signal Y and a color-difference signal C, which are subjected to chroma decoding. The second SRC 21 performs down-conversion, changing the sampling rate of the luminance signal and color-difference signal of the NTSC signal to the sampling rate (13.5 MHz) of an ITU-R601 standard.

Abstract: The demodulating device for a chrominance signal includes an oscillator with a controlled frequency, and an adjuster for adjusting the oscillator frequency as a function of a charge voltage of a memory capacitor. The adjuster preferably includes a fine adjustment channel to output a first adjustment value that depends on the charge voltage of the memory capacitor, and a coarse adjustment channel to output a second adjustment value. The second adjustment value is modified when the charge voltage of the memory capacitor is not within a given range. The device is used, for example, in integrated SECAM decoders.

Abstract: In a television tuner system, a printed board is disposed within a frame having a side plate. A tuner and an intermediate frequency circuit are disposed adjacent to each other on the printed board. The tuner has a mixer and a local oscillator. The intermediate frequency circuit includes at least a SAW filter having a plurality of terminals. A first ground conductor is formed between the tuner and the intermediate frequency circuit. A second ground conductor is formed at a peripheral edge of the printed board. The SAW filter is placed along the second ground conductor in such a manner that the terminals of the SAW filter are arranged substantially parallel to the side plate. The local oscillator is disposed substantially on a line extending from the arrangement of the terminals of the SAW filter. With this arrangement, the distance between the output terminals and the local oscillator is greater than that between the input terminal and the local oscillator.

Abstract: There is disclosed a digital filter cell capable of processing in a first mode a first signal having real data components only and processing in a second mode a second signal having real data components and imaginary data components. The digital filter cell comprises: 1) a plurality of serially coupled coefficient registers for receiving a sequence of coefficients; 2) a plurality of serially coupled data registers for receiving a sequence of digital data samples, each register having a tap output; 3) a data multiplexer having a plurality of input channels for receiving the tap outputs from the plurality of serially coupled data registers; and 4) a product summation circuit having a first input coupled to an output of the data multiplexer and a second input coupled to an output of a selected one of the plurality of serially coupled coefficient registers.

Abstract: A demodulator circuit including: a signal generating circuit for generating a sine-wave signal and a cosine-wave signal whose frequencies are same as that of the carrier wave of a modulated signal, a multiplying circuit for multiplying the modulated signal by the sine-wave signal and the cosine-wave signal generated by the signal generating circuit, and a filtering circuit for eliminating the frequency twice as high as that of the carrier wave from each of the results of the computation conducted by the multiplying circuit. Due to this, no restriction is imposed by the frequency of the system clock signal in configuring the system as a whole.

Abstract: During the reception of VSB DTV signal, the channel equalizer for a QAM/VSB DTV signal receiver the equalizer is operated to equalize only the real sample stream of VSB symbol code, rather than being operated as a complex equalizer. During the reception of QAM DTV signal, the real sample stream of QAM symbol code and the imaginary sample stream of QAM symbol code are time-division-multiplexed together on an alternate sample basis to generate input signal for the channel equalizer, which is operated as a dual-phase filter. After equalization, the time-division-multiplexed real and imaginary samples of QAM symbol code are de-multiplexed to recover parallel real and imaginary sample streams of QAM symbol code that are independent of each other, but have been subjected to similar equalization. Supposing that the QAM DTV symbol code rate is half the VSB DTV symbol code rate, the minimum sampling rate for operation of the channel equalizer is the same for both types of symbol code.

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: In a circuit arrangement for demodulating an intermediate-frequency video signal generated while using a Nyquist edge, having a phase-locked loop (1) including a phase detector (3), a loop filter (4) and a voltage-controlled oscillator (5), and a video demodulator (2), the intermediate-frequency video signal being applied to the phase detector (3) and the output signal of the phase-locked loop (1) being applied to the video demodulator (2), which converts the intermediate-frequency video signal into a baseband video signal, phase fluctuations contained in the carrier of the intermediate-frequency video signal due to its generation while using a Nyquist edge are compensated in that the phase comparator (3) operates, by approximation, independently of modulation in the control range of the intermediate-frequency video signal, in that the baseband video signal is present in an inverted form with respect to the intermediate-frequency video signal, and in that a correction signal is derived from the baseband video

Abstract: The SECAM chrominance signal demodulator includes an oscillator with a controlled frequency, a phase comparator with a first input connected to an oscillator output, a second input to receive a chrominance signal, and an output connected to an input loop of the oscillator. The demodulator further includes a fixed current source, also connected to the loop input, a current mirror to copy a current equal to the sum of the fixed current and a comparator output current in the output branches comprising first and second calibration resistors respectively, in series with a common resistor. Output voltages corresponding to the red and blue components of the chrominance signal are measured at the terminals of the calibration resistors respectively. The demodulator is used in television sets, for example.

Abstract: A method and apparatus for masking program selection latency in an MPEG-like information stream receiver, such as an ATSC or DVB television receiver. An information stream receiver receives VSB- or QAM-modulated signals comprising an MPEG-like system streams including program transport streams. In a channel scanning mode of operation, a plurality of identified program transport streams (i.e., channels) are sequentially retrieved from one or more system streams. A portion of each retrieved program transport stream, such as an intra-frame encoded video frame within an included elementary video stream, is extracted and stored in a memory. In a channel changing mode of operation, if a desired channel is one of the sequentially scanned channels, then the stored I-frame is retrieved and coupled to a decoder while the desired channel is re-acquired by tuning, demodulating, and demultiplexing operations.

Abstract: A video processing system that automatically adjusts video processor parameters depending upon the format of a received video signal in, e.g., a television receiver capable of receiving a multiplicity of video formats.

Abstract: A video signal processor which includes a reference signal generating circuit provided with at least an oscillation circuit for generating a reference signal corresponding to a burst signal and a Y/C separation circuit for separating a video signal into a luminance signal and a chrominance signal with an output of the reference signal generating circuit as a clock signal, and uses a microcomputer for controlling the entire operation of the video signal processor. In the video signal processor, an output of the reference signal generating circuit is also supplied to the microcomputer as a clock signal.

Abstract: An IF demodulator circuit with IF gain control at a variable time constant, which receives an IF carrier including synchronizing pulses, a black porch and picture information with a positively modulated picture signal, in which the IF picture signal is amplified to a nominal amplitude value by the gain control, and which includes an IF demodulator (3) which demodulates the IF picture signal and supplies a picture signal from the output, while, for a gain control which is independent of DC offsets that may occur in the picture signal, the demodulator circuit is constructed in such a way that a black level detector (8) for generating a black level signal used as a threshold value signal in conformity with the amplitude value of the black porch of the picture signal supplied by the amplitude demodulator (3) is provided, that a DC offset circuit (4) is provided, which raises the DC component of the picture signal and/or lowers the DC component of the threshold value signal in such a way that both signals are offs

Abstract: A digital sampling and separation unit (12) for a television receiver (10) of a composite video signal, such as an NTSC signal, which has a color subcarrier. The video signal is sampled at a frequency selected in accordance with the invention. This frequency provides samples having a definite and repeating phase relationship with the subcarrier signal. (FIG. 4). As a result, phase reference values can be used to convert the samples into correct color difference values.

Abstract: A television for storing and displaying a stored still picture, which includes: a memory for storing a still picture of a desired scene; a decoder for separating a video signal of a broadcast channel into an RGB signal and a synchronizing signal; a synchronizing signal detector for outputting a detection signal according to the existence of the synchronizing signal; a microcomputer for controlling so that the RGB signal output from the decoder can be displayed on a picture tube by recognizing the detection signal when a normal broadcast signal is input and so that the still picture stored in the memory can be displayed on the picture tube when a normal broadcast signal is not input. Thus, if a broadcast channel goes off the air, or a channel which is not on the air is selected, a selected picture is retrieved from the memory and displayed on the television screen, thereby reducing eye fatigue.

Abstract: A video signal decoder using a sample clock tied to a frequency that is an integer multiple of four times the color subcarrier (4*Fsc). By using a 4*Fsc rate on a given input wave, the decoder determines the phase shift between the sample clock and the original wave being sampled. Then, the decoder calculates the color based upon that shift. Circuitry for implementing the decoder contains two major circuit paths. The decoding process consists of two main phases and each path performs a different function during each phase. During the first phase, the first path calculates constants based upon a user's hue and saturation adjustments used for chroma demodulation. Also during the first phase, the second path examines the color burst signal and from that signal finds the black level of the incoming video signal. During the second phase, the first path decodes the color in the TV signal using the constants calculated during the first phase.

Abstract: A circuit arrangement for the digital identification of television transmission standards, particularly PAL, SECAM and NTSC. Provision is made for transmission standard demodulation stages connected in parallel to which a signal composed of a chromaticity signal and a synchronizing character is directed and which are each cyclically activated by control signals for a certain period of time. A trigger is also provided, together with an up-down counter, a circuit arrangement for the evaluation of the value delivered by the up-down counter, and a control logic.

Abstract: An AFC filter for an FPLL comprises a filter formed of a network of resistors and capacitors exhibiting a predetermined phase response characteristic. The phase response characteristic is limited with increasing frequency to a value of about 90.degree. during a start-up interval.

Abstract: A dual chrominance signal processor is disclosed which may be used in a combination television and video cassette recorder system, for example. Such a chrominance signal processor includes first and second modulated chrominance signal sources, and first and second demodulating carrier signal sources, corresponding to the first and second modulated chrominance signal sources, respectively. A demodulator is responsive to a chrominance signal and a demodulating carrier signal, for demodulating the chrominance signal. A signal selector is coupled between the signal sources and the demodulator, and selectively couples one of the first and second chrominance signal sources, and the corresponding one of the first and second demodulating carrier signal sources, to the demodulator in response to a selection 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: A QAM demodulator that samples an IF input modulated with data at a fractional complex sampling rate between one and two times the data rate. The use of a fractional sampling rate significantly reduces the number of components necessary to implement the demodulator, particularly in the equalizer section of the demodulator which corrects for channel distortion. The fractional sampling rate demodulator architecture of the invention provides a significant reduction in integrated circuit surface area needed in a VLSI implementation.

Abstract: A synchronous detector for demodulating and decoding a digital data signal modulated either according to a vestigial sideband or a quadrature amplitude modulation scheme is based upon the principle of recognizing that a vestigial sideband signal may be regarded and treated as an offset-keyed QAM signal. The detector comprises a tuner for tuning to a center frequency symmetrically displaced within the transmitted digital data signal frequency spectrum and a decoder circuit selectively operating to reconstruct the transmitted digital data stream according to the duration of a transmitted data symbol. A related method of demodulating and decoding a modulated digital data stream comprises analogous steps of tuning to a center carrier frequency and selectively switching between in phase and quadrature arms of the demodulator such that the switch resides in one position or the other for a duration equal to half the duration of a transmitted data symbol.