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: A digital television tuner is realized in which the construction of a baseband signal processing portion is simple, it is difficult for a local oscillation signal to leak to the input end side, and in which image interference is suppressed.

Abstract: An analog television is digitally enabled so that both analog video received in an analog broadcast signal and data received in data packets of a digital broadcast signal can be displayed on the same display. The analog television is digitally enabled by including digital television tuning and demodulation equipment either in the cabinet of the analog television or in a set top box coupled to the analog television.

Abstract: Frequency conversion into a first intermediate frequency which is higher than a received frequency band is performed for a received signal by using a mixer 63 and a PLL 64. Next, an output of the mixer 63 is frequency converted into a second intermediate frequency of base band by using a quadrature mixer formed by mixers 67, 68 and a phase shifter 70. At this time, a frequency of local oscillation signal of a PLL 69 supplied to the quadrature mixer is controlled so as to be switched, depending on a position of received segment, between a frequency which is higher than the first intermediate frequency and a frequency which is lower than the same.

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 method of receiving and demodulating a plurality of digital signals transmitted with different respective carrier frequencies and a digital receiver for receiving and demodulating a plurality of digital signals transmitted with different respective carrier frequencies wherein the carrier frequency signals are down converted to respective base-band signals and digitized and a common demodulator is provided to demodulate the respective digitized base-band signals in a time division manner.

Abstract: Reduction in the time required for an Advanced Television Standards Committee (ATSC) digital television tuner to equalize, converge, and acquire a digital television signal suitable for viewing, wherein early model ATSC tuners also include a National Television Standards Committee (NTSC) analog tuner, is achieved by using a microprocessor to control use of the NTSC tuner to scan television channels. A channel measurement module converts the scanned analog signal to a digital signal, and the equalization coefficients for the resultant digital signal are stored in memory. The equalization coefficients stored in memory are then accessed and utilized to tune in new channels on the ATSC tuner. The amount of time necessary for the ATSC tuner to tune in a new channel is thus reduced. When the ATSC tuner is in use, the equalization coefficient data stored in memory are periodically updated.

Abstract: Apparatus for reproducing data from a selected digital television signal, transmitted in packet form as vestigial-sideband (VSB) amplitude-modulation (AM) of a carrier, has a tuner for selecting a digital television signal and converting it to a final intermediate-frequency signal, which is digitized by an analog-to-digital converter before synchrodyning to baseband in the digital regime. VSB synchrodyning circuitry synchrodynes the digitized final intermediate-frequency signal to baseband in the digital regime to generate in-phase and quadrature-phase baseband signals. The quadrature-phase baseband signal is lowpass filtered to generate an automatic frequency and phase control (AFPC) signal for controlling a local oscillator in the tuner, so that the in-phase baseband signal comprises digitized VSB symbol coding. Symbol decoding circuitry responsive to the VSB symbol coding generates a digital data stream.

Abstract: A demodulation circuit that does not produce Nyquist buzzing. After IF signals output by bandpass filter (16) are multiplied by first and second multipliers (31) and (32) with a carrier wave reproduced by carrier wave reproduction part (7) and a carrier wave whose phase is shifted &pgr;/2, respectively, they are squared by first and second square-law circuits (33) and (34) and added together by addition adder (35). The error produced by the Nyquist slope is removed from the output of adder (35).

Abstract: A plural-conversion digital television signal receiver that embodies the invention upconverts digital television signal from a selected television channel to a UHF initial I-F signal. After image-rejection filtering there is a single-step downconversion of the initial UHF first I-F signal to a low-band final I-F signal, the uppermost frequency of which is in the high-frequency band. The low-band final I-F signal is digitized and demodulated in the digital regime to generate a baseband signal.

Abstract: In a digital TV receiver a single digital complex multiplier is used for digitally synchrodyning digital intermediate-frequency signal to baseband both during the reception of VSB digital television signals and during the reception of QAM digital television signals. The component digital multipliers of the complex multiplier are provided by read-only memories (ROMs). The complex digital carriers used by the complex multiplier are supplied from further read-only memory storing sine/cosine look-up tables for the QAM carrier and for the VSB carrier as,translated to the final intermediate-frequency band. This further read-only memory is addressed by a sample count and an indication of whether VSB or QAM digital television signal is currently being received.

Abstract: A signal to be displayed that is output from a display signal source is upconverted and transmitted in the form of a millimeter-wave which is in turn downconverted and supplied to a flat display and displayed there.

Abstract: A transmitter transmits, and a receiver receives, a data frame is transmitted into an 8 MHZ channel. The data frame contains a plurality of data segments, where each of the data segments contain DS symbols. The DS symbols include data symbols, priming symbols, and segment synchronization symbols. The transmitter trellis encodes the data symbols, priming symbols, and segment synchronization symbols. The receiver trellis decodes the data symbols, priming symbols, and segment synchronization symbols. The data frame also contains a mode control ID which the receiver uses in trellis decoding the data symbols, priming symbols, and segment synchronization symbols.

Abstract: In a receiver for processing a VSB modulated signal containing terrestrial broadcast high definition television information including data packets, the received signal is converted to a digital signal (19), demodulated (22) and equalized by an adaptive channel equalizer (34). An equalized signal is processed by decoding networks including a Reed-Solomon FEC error detecting and correcting network (44). The equalizer filter coefficient step size is dynamically adjusted during the adaption process as a function of the packet error rate. A local microcontroller (60) monitors the packet error rate at the Reed-Solomon error detector and instructs the equalizer to adjust the coefficient step size in a direction to reduce the packet error rate.

Abstract: The combined TV receiver can receive and process an analog broadcasting signal as well as a digital broadcasting signal, and includes a controller determining whether a channel selected by a user is a digital broadcast or an analog broadcast. The controller generates station selection data on the selected channel and a control signal pertinent to the determination. A tuner receives the station selection data and tunes to a broadcasting signal associated with the selected channel, out of signals received through an antenna. A switch unit forwards the broadcasting signal tuned at the tuner, in response to the control signal, to either an analog broadcasting processor or a digital broadcasting processor. An AGC (auto-gain controller) receives a gain signal either from the analog broadcasting processor or from the digital broadcasting processor, and adjusts a signal gain of the broadcasting signal tuned at the tuner, thereby allowing reception of both analog and digital signals.

Abstract: An NTSC co-channel interference detector (44) detects the presence of an interfering NTSC signal in the received Q-channel signal that is orthogonal to the received I-channel signal, rather than detecting the presence of an interfering NTSC signal in the received I-channel signal. By determining whether or not a significant amount of NTSC co-channel interference accompanies the received Q-channel signal, it is inferentially determined whether or not a significant amount of NTSC co-channel interference accompanies the received I-channel signal, such as to cause too many errors in the trellis decoding of equalized received I-channel signal to be corrected by the Reed-Solomon decoder (40) following the trellis decoder (34). The accurate determination of co-channel NTSC interference levels is simplified, because essentially no direct bias arises from the quadrature-phase synchronous detection of the pilot carrier of the VSB AM digital television signal.

Abstract: A method and apparatus for a demodulator circuit in a communication system is described. The invention relates to a demodulator circuit in a communication system using a multi-carrier modulation scheme. The demodulator makes efficient use of channel state information for respective carriers in the multi-carrier modulation to de-map the received data. An efficient method of calculating channel state information is also disclosed.

Abstract: An integrated receiver with channel selection and image rejection substantially implemented on a single CMOS integrated circuit is described. A receiver front end provides programable attenuation and a programable gain low noise amplifier. Frequency conversion circuitry advantageously uses LC filters integrated onto the substrate in conjunction with image reject mixers to provide sufficient image frequency rejection. Filter tuning and inductor Q compensation over temperature are performed on chip. The filters utilize multi track spiral inductors. The filters are tuned using local oscillators to tune a substitute filter, and frequency scaling during filter component values to those of the filter being tuned. In conjunction with filtering, frequency planning provides additional image rejection. The advantageous choice of local oscillator signal generation methods on chip is by PLL out of band local oscillation and by direct synthesis for in band local oscillator.

Abstract: A convergence device 10 for assembly an LCD imaging device 14 to a fixed housing 12. The convergence device 10 has a frame 25 with a plurality of retention arms 26 protruding therefrom. Each of the retention arms 26 has a retention barb 27 for hooking behind a retention land 28 on the imaging device 14. The imaging device 14 has a retainer 18 with a plurality of preload flexures 24 for providing some outward pressure on the frame 15 of the convergence device 10. After the imaging device 14 is positioned on the fixed housing 12, an adhesive 30 is applied to a housing adhesive gap 32 and to a plurality of imager fixing adhesive gaps 34 to hold the convergence device 10 in place relative to the fixed housing 12 and further to hold the imaging device 14 in place relative to the convergence device 10.

Abstract: A receiver for processing a VSB modulated signal containing terrestrial broadcast high definition television information includes an input analog-to-digital converter (19) for producing a digital datastream. A symbol timing recovery and segment sync recovery network (24; FIG. 3, 4) develops a properly timed sampling clock for the digital converter (19). The symbol timing recovery network (310) responds to an output from the segment sync recovery network (328), which in turn responds to an equalized signal from an adaptive channel equalizer (34). A controlled oscillator (336) generates the sampling clock for the digital converter. A control network (340, 344, 348; FIG. 3) shifts the frequency range of the oscillator to maintain desired linear operation to enhance symbol timing acquisition.

Abstract: A VSB demodulating device and method in a DTV receiver is disclosed, in which a VSB signal is received for independent carrier wave recovery and symbol clock recovery. An A/D converter samples the output of a SAW filter with a fixed frequency and converts the resultant value to a digital signal. A carrier wave recovery portion recovers a carrier wave from a base band pilot signal output from a multiplier, and a timing recovery portion recovers a symbol clock used for a transmitter using the output of a matched filter disposed in a base band. In this case, the carrier wave recovery portion and the timing recovery portion are independently operated without affecting each other. Thus, the carrier wave recovery portion is operated stably even in case where a fatal ghost exists in a band used for timing recovery.

Abstract: A method and apparatus for performing phase detection and timing recovery for a vestigial sideband (VSB) signal by processing a complex valued passband VSB signal using a high order non-linearity to detect the phase of the VSB signal. As such, an all digital solution to timing recovery for a high definition television is provided.

Abstract: The invention relates to a digital video and/or audio transmission system. To improve such a system the invention proposes to use for the compressing/decompressing the so-called DVCPRO standard (till the error correction) and use the so-called COFDM standard for the modulation/demodulation.

Abstract: A digital broadcasting reception unit includes a tuner unit and a demodulation unit. Analog terminals of the tuner and demodulation units are arranged in frames defined on the tuner and demodulation units near one ends of the frames, respectively, whereby a first region containing the analog terminals is formed. Digital terminals of the tuner and demodulation units are arranged in frames defined on the tuner and demodulation units near the other ends thereof, respectively, whereby a second region containing the digital terminals is formed. An analog signal wiring-pattern for connecting the analog terminals of the tuner unit to those of the demodulation unit is formed. A digital signal wiring-pattern for connecting the digital terminals of the demodulation unit to a digital signal processing circuit is formed. Furthermore, ground patterns are formed.

Abstract: Circuitry for identifying digital data packets, each comprising a useful signal and a header signal containing data pertaining to the contents of the useful signal is provided. The circuitry includes a means (30) for extracting data from each header signal, which data is representative of a corresponding useful signal, a means for storing reference data in a memory, at addresses each corresponding to a packet type, and a means for comparing the data extracted from each header signal with said reference data stored in memory, and for the delivery, to a data processing unit (32,34), of an address signal indicating the nature of the corresponding packet. The data storage means and the comparison means preferably employ an associative memory (38) adapted to ensure the simultaneous comparison of the data extracted from each header signal with the reference data stored in memory.

Abstract: At the transmitter side, carrier waves are modulated according to an input signal for producing relevant signal points in a signal space diagram. The input signal is divided into, two, first and second, data streams. The signal points are divided into signal point groups to which data of the first data stream are assigned. Also, data of the second data stream are assigned to the signal points of each signal point group. A difference in the transmission error rate between first and second data streams is developed by shifting the signal points to other positions in the space diagram expressed at least in the polar coordinate system. At the receiver side, the first and/or second data streams can be reconstructed from a received signal. In TV broadcast service, a TV signal is divided by a transmitter into, low and high, frequency band components which are designated as a first and a second data streams respectively.

Abstract: A signal of a vestigial sideband modulated wave is generated by use of a first oscillator, an amplitude-modulator and a surface acoustic wave filter for vestigial sideband filtering at a frequency being higher than the carrier frequency of a video signal, the signal is frequency-converted to a given transmission channel by use of a first PLL frequency synthesizer, a first control circuit, a frequency converter and a filter.

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 received signal passed through an HPF is supplied to an input switching circuit where the signal is switched to any of HIGH BAND, MID BAND and LOW BAND circuitry. The received signal of each band circuitry is band-switched by an RF amplification input BPF, RF-amplified by an RF amplifier and then a resultant received signal is supplied from an RF amplification output BPF. The received signal is mixed with a local oscillation signal from a local oscillator circuit by a mixer circuit to generate an intermediate-frequency signal. The intermediate-frequency signal is supplied to an IF amplifier circuit, a SAW filter and an IF amplifier circuit. A PLL channel select circuit outputs a switching voltage for each band and conduct PLL control for the local oscillator circuit.

Abstract: A decoder has a DRAM used as a work area in processing such as decompression and an MPEG decoder including an OSD processing unit. The MPEG decoder has a function to decompress data completing MPEG compression and a graphic function to display information such as an EPG (Electronic Program Guide). A control unit generates display data from presentation information conveyed by a digital television broadcast by using the OSD processing unit employed in the MPEG decoder and the DRAM in order to display the presentation information. With such a decoder, it is possible to provide a receiver with a new function to use presentation information conveyed by a digital television broadcast without entailing an increase in cost.

Abstract: An integrated receiver with channel selection and image rejection substantially implemented on a single CMOS integrated circuit is described. A receiver front end provides programable attenuation and a programable gain low noise amplifier. Frequency conversion circuitry advantageously uses LC filters integrated onto the substrate in conjunction with image reject mixers to provide sufficient image frequency rejection. Filter tuning and inductor Q compensation over temperature are performed on chip. The filters utilize multi track spiral inductors. The filters are tuned using local oscillators to tune a substitute filter, and frequency scaling during filter component values to those of the filter being tuned. In conjunction with filtering, frequency planning provides additional image rejection. The advantageous choice of local oscillator signal generation methods on chip is by PLL out of band local oscillation and by direct synthesis for in band local oscillator.

Abstract: A receiver system automatically adaptively tunes to broadcast signals that are variable in the number of channels that are transmitted, their signal coding type and their modulation format. A system receives a digital bitstream representing video information encoded in one of a plurality of different formats, and transmitted on one of a plurality of transmission channels. In the system, a method for acquiring data transmitted on a transmission channel involves selecting a transmission channel from the plurality of channels and selecting a modulation format. The method also involves tuning to receive the modulation format and determining whether valid data is being received on the selected transmission channel. The method steps are repeated until valid data is received. The method may also involve selecting a coding type, and tuning to receive the coding type.

Abstract: A phase synchronous circuit includes a comparing unit for comparing an output of a low-pass filter with a reference voltage which causes the central frequency of a voltage-controlled oscillator to be set as well as generating a compared output voltage by integrating a compared output current, a frequency oscillator for generating a frequency signal to frequency-modulate an output of the voltage-controlled oscillator and a switching unit for, in the presence of an input signal to the phase synchronous circuit, causing the compared output voltage to provide negative-feedback to a second control terminal of the voltage-controlled oscillator, whereas, in the absence of the input signal, to the phase synchronous circuit, causing the frequency signal to be input to the second control terminal of the voltage-controlled oscillator.

Abstract: A multi-media system for transferring a single program transport stream and a method therefor are provided. A receiver is for receiving a transport stream. For the receiver to control recording and reproduction performed by a recording/reproducing device, the receiver selects one program to constitute a single program transport stream and transfers the single program transport stream to the recording/reproducing device. Here, a program number is transferred, by correcting program association table (PAT) information of the transport stream. Accordingly, the recording/reproducing device can recognize the program number within the single program transport stream to be recorded. Therefore, the receiver can perform remote control of the recording/reproducing device without the extra transfer of the program number. Also, the receiver provides an on-screen graphic (OSG) to the recording/reproducing device, resulting in an OSG of consistent appearance.

Abstract: A demodulator is able to demodulate a television signal and an FM broadcast signal by a common demodulator. Also, a receiver is able to output television video signal and audio signal and an audio signal of the FM broadcast signal by the common demodulator without using a second mixer for frequency-converting the FM broadcast signal to provide an audio intermediate frequency signal of 10.7 MHz when the FM broadcast signal is received. A demodulator includes a first input terminal, a second input terminal, a third input terminal and a change-over switch and wherein the change-over switch connects the first input terminal, a video detector and a video carrier generator to receive the television signal and the change-over switch connects the third input terminal, the video detector and the video carrier generator to receive the FM broadcast signal.

Abstract: A decision directed phase detector that uses the quantized data output from a slicer to aid the phase error detection process to determine a phase error of a complex signal such as a vestigial sideband (VSB) signal containing in phase (I) and quadrature phase (Q) components (I and Q signals). The phase detector comprises subtractor having one input coupled to the I signal and a second input coupled to the data output of the slicer representing the magnitude of a sample point within a symbol. The quantized signal is subtracted from the I signal to produce &Dgr;I signal. The Q signal is processed to determine its sign and magnitude. The sign and magnitude values are multiplied together and the result is multiplied with the &Dgr;I signal to produce the phase error between the I and Q signals. This phase error signal is used in a digital television receiver to extract a data signal from a VSB signal for demodulation.

Abstract: A television receiver includes a tuner for receiving either analog or digital signals. Separate analog and digital demodulators are selectively coupled to the tuner through an RF switch that is controlled by a sync detector in the output of the analog demodulator. The selected one of the demodulators develops an AGC signal that is coupled to the tuner through the RF switch. In one embodiment, a two pole RF switch is used with one pole switching the IF signal and the other pole switching the AGC signal In another embodiment, a single pole RF switch is used with the tuner signal and the AGC signal being multiplexed through the switch. This is accomplished by the provision of a high frequency path and a low frequency path between each of the RF switch and the tuner, the RF switch and the analog demodulator, and the RF switch and the digital demodulator.

Abstract: A radio receiver uses the same tuner for receiving a selected digital television (DTV) signal, irrespective of whether it is a quadrature-amplitude-modulation (QAM) or a vestigial sideband (VSB) signal. The tuner supplies a final IF signal in a 6-MHz-wide frequency band, the lowest frequency of which is not appreciably more than 2.69 MHz. The final IF signal is digitized at a rate that is a multiple of both the symbol frequencies of the QAM and VSB signals, for synchrodyning to baseband, with the 2.69 MHz difference between the carrier frequencies of QAM and VSB signals being taken into account in the digital synchrodyning circuitry. The carrier frequencies of the QAM and VSB final IF signals are regulated to be submultiples of the multiple of both the symbol frequencies of the QAM and VSB signals by applying automatic frequency and phase control signals developed in the digital circuitry to a local oscillator of the tuner.

Abstract: The present invention provides a tuner apparatus operating as a common tuner capable of receiving both satellite digital TV and terrestrial TV broadcasting. A tuner configured, according to the invention operates as follows. As it receives satellite TV broadcasting, intermediate-frequency signals SIF1 are supplied to its quadrature detector circuit where the SIF1 signals are demodulated into baseband signals SI and SQ by using oscillation signals supplied thereto from its oscillator. As it receives terrestrial TV or CATV broadcasting, terrestrial TV or CATV broadcast wave signals are supplied to its mixer circuit where these signals are frequency-converted into intermediate-frequency signals SIF1 that fall within the bandwidth of the satellite TV broadcasting SIF1 signals. The first intermediate-frequency signals SIF1 are supplied to the quadrature detector circuit where the SIF1 signals are frequency-converted into second SIF2 signals by using oscillation signals supplied thereto from the oscillator.

Abstract: A demodulator suitable for implementation in a single chip for demodulating digital video broadcast signals comprising data modulated on a multiplicity of spaced carrier frequencies, wherein an input broadcast signal is converted to a frequency sufficiently low to enable analog digital conversion of the signal, the demodulator comprising analog to digital conversion means (20) for converting the broadcast signal to a series of digital samples, real to complex conversion means (22) for converting each digital sample to a complex number value, Fourier transform means (24) for analyzing the complex number values to provide a series of signal values for each carrier frequency, frequency control means (9, 38), comprising means responsive to the output of said Fourier Transform means for producing a signal for controlling the frequency of the signal formed by said complex number values, and signal processing means for receiving the signal values and providing an output for decoding, the signal processing means incl

Abstract: A receiver circuit, which may be used in a leakage detector, includes an RF input, a narrow band filter, and a direct demodulator. The leakage detector in which the receiver circuit may be used is operable to measure leakage in a communication system, the communication system operable to transmit broadband communication signals comprising one or more radio frequency carrier signals modulated by one or more baseband communication signals, wherein each radio frequency carrier signal has a channel frequency. Essentially, the exemplary receiver circuit according to the present invention is operable to generate a baseband leakage signal. To this end, the RF input is coupled to a source of broadband communication signals and receives a broadband communication signal therefrom, the broadband comnunication signal including a first signal associated with a first channel frequency.

Abstract: Disclosed are method and apparatus which measure signal level of an RF signal. The measured RF signal includes a baseband signal modulated onto a first carrier signal having a first frequency and the baseband signal includes program information and control information. The method and apparatus digitize the RF signal which includes the baseband control information and determine a signal level measurement from the baseband control information in the digitized RF signal. Furthermore, method and apparatus are disclosed which determine from the digitized RF signal whether a tagging signal is present in the RF signal.

Abstract: The tuner in a digital TV receiver converts received signal to a penultimate intermediate-frequency signal. Penultimate local oscillations are supplied in a first phasing and in a second phasing in quadrature therewith, for heterodyning with the penultimate IF signal in first and second mixers respectively to generate real and imaginary components of an ultimate intermediate-frequency signal. The first and second mixers are of a switching type, switching in respective response to the penultimate local oscillations as supplied in first and in second phasing. First analog-to-digital conversion circuitry containing a number N of analog-to-digital converters digitizes the real component of the ultimate IF signal on an N-phase basis, N being at least one. Second analog-to-digital conversion circuitry, which contains a number N of analog-to-digital converters, digitizes the imaginary component of the ultimate IF signal on an N-phase basis.

Abstract: An N-VSB (vestigial sideband) modulation signal is converted into an M-QAM (quadrature amplitude modulation) signal, where M=N2, by shifting the symbol rate frequency of a received N-VSB modulation signal to center the waveform spectrum about zero Hertz prior to complex demodulation so that data symbols will alternately appear on demodulated I and Q channels. A pilot tone of the received N-VSB modulation signal is removed to eliminate any bias in the both I and Q channels. Symbol timing between I and Q channels is offset, and quadrature amplitude demodulation of the I and Q channel signals generate alternating I and Q channel data symbols. Alternating inversion of the alternating I and Q channel data symbols recovers the N-VSB symbol data.

Abstract: At the transmitter side, carrier waves are modulated according to an input signal for producing relevant signal points in a signal space diagram. The input signal is divided into, two, first and second, data streams. The signal points are divided into signal point groups to which data of the first data stream are assigned. Also, data of the second data stream are assigned to the signal points of each signal point group. A difference in the transmission error rate between first and second data streams is developed by shifting the signal points to other positions in the space diagram. At the receiver side, the first and/or second data streams can be reconstructed from a received signal. In TV broadcast service, a TV signal is divided by a transmitter into, low and high, frequency band components which are designated as a first and a second data stream respectively.

Abstract: In a digital frequency phase locked loop (FPLL) for a grand alliance (GA) HDTV receiver using a vestigial sideband (VSB) modulation transmission system, the digital FPLL for a VSB transmission system having a VCO and a plurality of NTSC carrier eliminating filters for eliminating interference of NTSC adjacent channels includes a filter for eliminating high-frequency components by converting a digital signal output from one of the plurality of NTSC carrier eliminating filters, a delay for delaying the high-frequency-component-eliminated signal by a predetermined width so that its frequency-versus-phase characteristics are changed linearly, symbol inverter for inverting the symbol of the digital signal output from another of the plurality of NTSC-carrier eliminating filters, a switch for selectively outputting the symbol-inverted signal and the digital signal output from another filter, a second filter for limiting the selectively output signal to a predetermined frequency band, a digital-to-analog (D/A) conver

Abstract: An HDTV receiver includes an AGC system that develops an RF AGC voltage that is derived on an analog basis and an IF AGC voltage that is derived on a digital basis. The digital voltage is developed from an error signal that comprises the most significant bits of a continuously operated large accumulator that is supplied with the algebraically combined output of the digital signal and an AGC reference number.

Abstract: A receiver for processing a VSB modulated signal containing terrestrial broadcast high definition television information and a pilot component includes an input analog-to-digital converter (19) for producing a datastream which is oversampled at twice the received symbol rate, and a digital demodulator (22; FIG. 3) with a data reduction network (330, 332) in a phase control loop. A segment sync detector (24; FIGS. 4, 5) uses an abbreviated correlation reference pattern to recover a twice symbol rate sampling clock for the digital converter (19). A DC offset associated with the pilot component is removed (26; FIG. 6) from the demodulated signal before it is applied to an NTSC interference detection network (30; FIG. 7). The interference detection network includes a comb filter network (710, 718) responsive to a twice symbol rate sampled data datastream, and exhibits a sample delay dimensioned to avoid aliasing in the combed frequency spectrum (FIG.

Abstract: An HDTV receiver is disclosed including a tuning portion for selecting one of a plurality of RF signals received, and converting a selected RF signal into an intermediate frequency signal; a demodulator/FPLL for demodulating the intermediate frequency signal output from the tuning portion into a baseband signal in which the frequency and phase are locked, and outputting an AFC signal; a first local oscillator for forming a frequency signal which can be varied from a reference frequency to a specific frequency, and outputting the thus-formed frequency signal to the demodulator/FPLL; and a VSB filter for VSB-filtering the baseband signal output from the demodulator/FPLL.