Abstract: The loop gain of an AGC circuit 7 and the loop gain of a clock regenerating circuit 6 are increased (the gain of an amplifier is increased, or the band of a loop filter is widened) until a synchronizing signal (a segment synchronizing signal or a field synchronizing signal) is detected. The loop gain of the AGC circuit 7 and the loop gain of the clock regenerating circuit 6 are decreased (the gain of the amplifier is decreased, or the band of the loop filter is narrowed) after the synchronizing signal is detected. Consequently, it is possible to make a reduction of a time period required until convergence processing is completed in the AGC circuit and the clock regenerating circuit compatible with an improvement of a ghost disturbance removal performance and accurate clock regeneration.

Abstract: An inexpensive synchronous detection module is disclosed for a sideband signal receiver that provides for flexibility in design of the tuner. The detection module is adaptable to detection of upper or lower sideband signals. One embodiment includes an analog-to-digital converter, a Hilbert transform filter, a sideband selection switch, a complex multiplier, a carrier recovery. loop, a matched filter, and a decimator. The analog-to-digital converter oversamples an intermediate frequency (IF) signal from the tuner, and the Hilbert transform filter generates a Hilbert transform of the digital IF signal. An analytic IF signal can be generated from the digital IF signal by multiplying the Hilbert transform of the digital IF signal by j(=sqrt(−1)), and adding the resulting imaginary-valued signal to the digital IF signal. The sideband selection switch can “flip” the analytic IF signal by inverting the imaginary-valued signal.

Abstract: An adjustable K-factor-improvement (KFI) filter having a sparse kernel composed of non-zero weighting coefficients of substantially equal amplitudes is included in a receiver for digital television signals or the like. The receiver includes apparatus for measuring the channel impulse response (CIR) or cepstrum of the signal as received. The respective polarities of the non-zero weighting coefficients in the sparse kernel of the adjustable KFI filter are adjusted responsive to the measured CIR. The differential delay between each successive pair of non-zero weighting coefficients in the sparse kernel of the adjustable K-factor-improvement filter is adjusted responsive to the measured CIR. The adjustment is such that the KFI filter response has a principal component with substantially more energy than any of its echo components. The KFI filter response is applied as input signal to subsequent adaptive equalization filtering in the receiver.

Abstract: Digital radio receivers for digital television signals often employ bandpass trackers in which the bandwidth of the automatic-frequency-and-phase-control (AFPC) loop is determined in the baseband by lowpass filtering after demodulating the intermediate frequency signal. If the I-F signal is vestigial-sideband in nature, and if baseband symbol code is designed to have a spectrum reaching at least substantially to zero-frequency, low-frequency modulation components tend to give rise to phase jitter in the AFPC loop. This is owing to the asymmetry of the modulation sidebands near carrier frequency. To reduce such phase jitter, a filter is introduced before the AFPC detector for reducing asymmetry of channel response in a narrow-frequency band including the pilot carrier signal.

Abstract: A radio receiver for receiving a selected digital HDTV signal, irrespective of whether it is a complex-amplitude-modulation (QAM) or a vestigial sideband (VSB) signal, using the same tuner. The tuner supplies a final IF signal in a 6 MHz frequency band, the lowest frequency of which is not appreciably more than 2.38 MHz. The final IF signal is digitized for synchrodyning to baseband, with the 2.375 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 symbol frequency by applying automatic frequency and phase control signals developed in the digital circuitry to a local oscillator of the tuner. The presence of the pilot carrier accompanying a selected VSB HDTV signal is detected for automatically switching the radio receiver for operation in a VSB signal reception mode.

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: A remodulator timing signal (35) is generated by a phase locked loop (33) which is coupled to a broadcast vestigial sideband signal (5). Within the signal (5) is highly accurate timing data which is coupled to a demodulator (31). Timing signals to the demodulator are provided by a variable frequency oscillator (32) which receives a correction signal from a phase locked loop (33) housed within the demodulator. The phase locked loop generates the correction signal by comparing the VFO output frequency (36) with the timing data embedded within the broadcast signal (5). A value register (203,303,403) maintains the recent average VFO frequency. A multiplexer (204,304,404) selects the value register data to control the VFO (32,220,320) in the absence of the broadcast timing data.

Abstract: Analog video tape recording (VTR) and video cassette recording (VCR) systems/apparatuses with novel converter of a frequency modulated signal into the pulse-frequency-modulated (PFM) signal during readback are described. The novel converter provides effective filtering function in itself and suppresses all carrier harmonics of the PFM signal. This reduces combination noise at the input to the PFM filter-demodulator by 20-25 db. Therefore, filtering requirements to PFM demodulator are greatly reduced and it can be of very simple design. The novel converter provides significant improvement in performance and reduces cost of analog VTR/VCRs.

Abstract: The system for recovering symbol timing offset and carrier frequency error from an orthogonal frequency division multiplexed (OFDM) signal includes a receiver circuit for receiving an OFDM modulated signal representing a series of OFDM symbols, and providing a received signal to an output thereof. A peak development circuit is included for developing a signal having a plurality of signal peaks representing symbol boundary positions for each received OFDM symbol, where each of the signal peaks is developed responsive to an amplitude and phase correspondence produced between the leading and trailing portions of each of the received OFDM symbols. The system includes a circuit for enhancing the signal peak detectability, which includes a circuit for additively superimposing and then filtering the signal peaks, to produce an enhanced signal peak having an improved signal-to-noise ratio.

Abstract: A radio receiver for vestigial sideband digital modulation, such as used for transmitting digital television signals, employs real-only digital synchrodyne circuitry for synchrodyning a real digital carrier with digitized final intermediate-frequency signal to generate an in-phase synchronous detection signal. Digital filtering supplies a complex frequency response to the digitized final intermediate-frequency signal. Further digital synchrodyne circuitry synchrodynes this complex frequency response with a complex digital carrier to generate a quadrature-phase synchronous detection signal. This quadrature-phase synchronous detection signal is used in automatic frequency and phase control of a local oscillator used in the conversion of received signal to the final intermediate-frequency signal for digitization.

Abstract: An adaptive equalizer updates its tap coefficients with the aid of an error signal e(k)=sign[z(k)]*(RS−|z(k)|2) where sign[] is the sign function, z(k) is the equalizer output at symbol time k, || is the magnitude function and RS is a positive real constant, which is optimally defined as RS=E{|an|3}/E{|an|}, where E{} is the mathematical expectation function and an is the information symbol at symbol time n. A generalized equalizer error signal satisfies e(k)=sign[z(k)]*(RSp−|z(k)|p) where RSp is a positive real constant, which is optimally defined as RSp=E {|an|p+1}/E }|an|} and p is a positive integer. The equalizer conducts blind equalization of an Advanced Television Systems Committee-High Definition Television signal and any other one-dimensional modulation system.

Abstract: A bandpass phase tracker automatically samples at prescribed carrier phases when digitizing a vestigial-sideband intermediate-frequency signal, which VSB I-F signal is modulated in accordance with a baseband symbol code of a prescribed symbol frequency. Heterodyning circuitry mixes oscillations from a local oscillator with the VSB I-F signal received from the I-F amplifier to generate an analog low-frequency heterodyne signal offset from zero frequency. The heterodyne signal is digitized in accordance with a first sampling clock signal to supply input signal for digital demodulation circuitry that demodulates the VSB I-F signal to supply real and imaginary components of a demodulated signal at baseband. The real component of the demodulated signal is supplied to an equalizer and symbol decoded; the imaginary component controls the frequency and phase of the local oscillator.

Abstract: A technique for receiving and transmitting wireless telecommunications through use of a generic architecture is disclosed. The present invention mitigates the complexity of different transceiver operations by allowing a generic architecture to be used in a variety of situations with different channels and different telecommunications standards. An illustrative embodiment of the present invention comprises: receiving uplink analog RF signals at a base station; converting the uplink analog wide-band RF signals into IF uplink digital signals at an analog-to-digital converter; converting the IF uplink digital signals into a number of uplink channels; and demodulating selected narrow-band uplink channels from the total number of narrow-band uplink channels.

Abstract: A digital VSB transmission system that is able to send supplemental data along with MPEG image/sound data is enclosed. The system initially encodes the supplemental data symbol to generate a parity bit, and it multiplexes the parity bit with a predefined sequence and transmits the multiplexed data to a receiver. The system is compatible with the existing ATSC 8T-VSB receivers that are already on the market. It can have advantages over the other types of VSB transmission systems that transmit only the predefined sequence. In addition, the system according the to the present invention results an improved robustness against ghost and noise signals in a channel compared to systems using only the ½ rate convolutional encoding.

Abstract: A vestigial sideband (VSB) modulation minimum output energy (MOE) pre-equalizer operating on a received ATSC 8-VSB DTV signal includes one or more of an adaptive feed-forward filter and an adaptive feedback filter each utilizing only real adaptive coefficients, with the direct term for the overall filter constrained to unity to remove one degree of filter parameterization freedom. Adaptation of the filter(s) is based on minimizing a blind energy cost function, and is independent of adaptation of a conventional adaptive channel equalizer. The pre-equalized signal is passed to the conventional adaptive equalizer for channel equalization utilizing DFE, IIR-CMA, etc., resulting in performance improvements including faster convergence and greater robustness with relatively small implementation costs.

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: 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: Training sequences designed for N-VSB systems within the embodiment of an N-squared QAM receiver facilitate designing 8-VSB receivers using methodologies of 64-QAM receiver design. A receiver designed using such methodologies converts the received modulation into a signal which can be accepted by circuitry for decoding 64 level quadrature-amplitude modulation (64-QAM) signals. This process provides a better signal to noise ratio reception than the conventional I-channel only decoding circuitry of most 8-VSB receivers. This process also employs training and equalizing algorithms developed for 64-QAM receivers which are superior to equivalent algorithms for 8-VSB receivers. The invention can be generalized to N-VSB conversion into M-QAM where M=N2. Adaptive equalization algorithms for 8-VSB transmissions implemented within the context of the 64 QAM receiver are superior to present single-channel VSP processing receivers.

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 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: A process for transmitting mixed analog and digital signals. A composite signal is transmitted whose frequency spectrum is composed of a first analog spectrum representative of the amplitude of single-sideband modulation and of a second spectrum composed of multi-subcarriers. The two spectra occupy two disjoint frequency bands. The device may be used for simultaneous broadcast of the same program or its reception by analog or digital receivers.

Abstract: A VSB receiver and a method for processing a receiving signal in the same are disclosed, which is not subject to frequency offset. The VSB receiver includes an intermediate frequency signal generator generating an intermediate frequency band signal from a received signal; a demodulator generating a complex base band signal consisting of an I channel signal and a Q channel signal using the intermediate frequency band signal and at least one local carrier wave signal; and a complex base band matched filter filtering at least one of the I channel signal and the Q channel signal. In the VSB receiver, since a complex signal responds to a required channel of the I channel and the Q channel, it is possible to prevent performance of the system from being deteriorated by frequency offset.

Abstract: A solid-state gyroscope in a closed flight-control loop produces a DSSC QAM body angular-rate output signal and a drive current, which is converted to a demodulation reference signal. The frequency of the demodulation reference signal drifts slowly. A digital complex AM demodulator must demodulate the rate-output signal and correct the phase shift with as little delay as possible. This demodulator employs three elemental Hilbert transformers (EHT), one for direct current (d.c.) blocking and two for phase shifting. The gains of these Hilbert transformers shift with the drive frequency. In order to hold signal-path delays to a minimum, the gains of the Hilbert transformers are held to unity by means of a simple Least Mean Squared (LMS) adaptive loop whose output feeds the gain multiplier of all three Hilbert transformers. Automatic phase-shift correction is also included by adaptively rotating the demodulator reference phase in order to decorrelate the outputs of the demodulator.

Abstract: An adaptive CAP filter includes a clock-controlled A/D converter for converting an input signal, a digital level-control circuit, an adaptive controlled reception filtering system with two parallel filters and a downstream decision maker for outputting reconstructed signal coordinates. The digital level-control circuit and the adaptive reception filtering system are decoupled by virtue of the fact that either an adjustment of the digital level-control circuit or a coefficient adjustment of the adaptive reception filtering system is active. A method for controlling a cap receiver is also provided.

Abstract: A method of estimating pilot signal phase embedded in a wideband digital signal modulating a RF signal that is down converted to an intermediate frequency and digitized includes the steps of summing a block of the signal samples for removing the modulation data and generating data values representative of vector locations of the pilot signal with each data value representing an angular rotation of the pilot signal vector, and calculating the phase of the pilot signal by determining the arc tangent of the data values. The method produces a computationally efficient narrow band filter generated at the pilot signal frequency by simple addition of the digital data values. The method is usable in a software based 8-VSB digital television demodulation system.

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; FIG. 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: A method and system are provided for the transmission and reception of a composite radio-frequency (RF) signal including a supplemental signal, preferably representing encoded digital information, together with an analog signal which represents monophonic analog audio in the AM-band. The analog monophonic component of the composite signal may be received by conventional AM-band audio receivers. In certain embodiments, the analog signal is a single-sideband large-carrier or vestigial-sideband large-carrier signal, and the composite RF signal includes a digital signal whose spectrum is substantially confined in one inner sideband. In other embodiments, a baseband digital signal is combined with an analog monophonic audio signal and transmitted in upper inner and lower inner sidebands using nonlinear compatible quadrature amplitude modulation (NC-QAM). Additional digital signals' spectrum occupies the lower outer and upper outer sidebands.

Abstract: A digital demodulation apparatus is provided for automatically controlling gain based on a state of receiving a digital modulated signal.

Abstract: In a clock recovery circuit for DTV using a VSB modulation method, if the frequency of the symbol clock is fs, since the frequency difference between the fs/2 component signal of the VSB signal and the pilot signal is constant at fs/2, it is possible accurately to detect the phase error from their differential signal. Furthermore there is no distortion of the clock signal frequency of the VSB signal, even when the symbol data is distorted by multi-pass distortion or the like, since clock signal regeneration is performed by frequency domain processing. By employing this type of principle and performing phase error detection for each symbol at a time, it is possible to ensure a high speed tracking performance for clock signal regeneration.

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: A vestigial sideband/quadrature amplitude modulation (VSB/QAM) receiver, which receives both VSB and QAM signals and restores a carrier wave with a restored symbol clock after restoring a symbol timing in a front portion of a carrier wave restoration unit.

Abstract: An adaptive equalizer for use in a digital transmission receiver includes Q-channel regeneration. A equalization filter produces complex valued equalized signal samples representative of a digital transmission signal. A slicer produces ideal real component values of the equalized signal samples. A Q-regeneration filter produces ideal imaginary component values of the equalized signal samples from the ideal real component values. The ideal real and imaginary component values are combined with the component values of the equalized signal samples to produce a complex valued error signal. The error signal is fed back to scale update values for updating coefficient values of the equalization filter. Delays in the equalizer provide storage to synchronize various equalizer signal and component values with the Q-regeneration filter output.

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: A receiver for processing a VSB modulated signal containing terrestrial broadcast high definition television information and a pilot component includes a carrier recovery network (22; FIG. 3) that produces a demodulated baseband signal. The carrier recovery network additionally responds to a locally generated control signal (Ph. Offset; 360) representing an unwanted phase offset of the pilot signal due to multipath distortion, for example. The control signal is used to compensate for the pilot phase offset before the demodulated signal is equalized. The control signal is produced by correlating received sync values with both a reference sync value (362) and a Hilbert transform of the reference sync value (363). The output of the carrier recovery network signal is phase compensated twice.

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: 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 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: A vestigial sideband VSB receiver for receiving signals which are transmitted by being modulated in a vestigial sideband method and a carrier wave restoring method are disclosed, in which the VSB receiver includes a digital processing part for selecting a desired channel frequency via an antenna and converting the desired channel frequency to an intermediate frequency to digitalize a predetermined band of the intermediate frequency, a carrier wave restoring part for extracting pilot components from a signal of the digitalized pass band to restore carrier waves, and a demodulator for separating components I and Q from signal of the digitalized pass band and multiplying the components with a complex carrier wave, which is restored in the carrier wave restoring part, wherein the carrier waves are restored by extracting the pilot signals from the pass band and the symmetrical errors of the carrier wave frequency is detected, so that the carrier wave may be stably obtained and pursued with relation to the both pos

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: A remote control apparatus for a digital cable television system and a method thereof which are capable of inserting and transmitting a control data into each channel of a head end (HE) which is an output unit of a transmitting unit and modulating a state checking data of a receiving unit for a VSB/QAM receiving unit based on a QPSK method, thus upwardly transmitting the date, whereby it is possible to remotely control and monitor a VSB/QAM receiving unit without additionally allocating a frequency band width.

Abstract: An apparatus efficiently performs symbol timing recovery of sampled data included in a vestigial sideband (VSB) signal. Each of the sampled data is first filtered to output a positive and a negative band edge filtered components thereof. Thereafter, the negative band edge filtered component is processed to obtain a conjugate complex component; and the positive band edge filtered component is multiplied by the conjugate complex component to provide a multiplied component as symbol timing information. Finally, each of the sampled data is corrected based on the symbol timing information to generate interpolated data thereon as the timing recovered data.

Abstract: A broadcast receiving apparatus provides multifunctionality to cope with analog modulated input signals as well as digital input signals modulated by various types of modulation schemes. The apparatus comprises a detector for detecting the modulation scheme of input signals, and a switch for switching one or more of the characteristic of a filtering section, an amplifying section, and a detection section, depending upon the detected modulated scheme.

Abstract: A sampling timing phase error detector in a VSB modulation signal which can realize a high speed transmission. The sampling timing phase error detector for detecting a timing phase error of a sampling from a discrete time sequence obtained by sampling, by a frequency n.multidot.fs (n is a positive integer), a multivalue VSB modulation signal in which transmission symbol sequence of real numbers is processed by a VSB modulation at a symbol frequency fs obtains the timing phase error on the basis of signals obtained by detecting the discrete time sequence at frequencies around a Nyquist frequency fs/2 as a center.

Abstract: A QAM/VSB digital television (DTV) receiver of plural conversion type uses the same circuitry up to a penultimate IF amplifier for receiving DTV signals no matter whether they use QAM or VSB modulation. The converter used for generating final IF signals when QAM modulation is received and the converter used for generating final IF signals when VSB modulation is received have respective mixers and respective local oscillators with separate automatic frequency and phase control. The use of such separate converters avoids a lock-out from VSB reception mode that otherwise can occur during the reception of DTV signals with VSB modulation.

Abstract: Methods, apparatus and system for transmitting signals in QPSK, QAM and other similar modulation formats as single sideband (SSB) signals. An exemplary SSB-QPSK transmitter receives an in-phase data signal and a quadrature-phase data signal. The in-phase data signal and a Hilbert transform of the quadrature-phase data signal are modulated onto a cosine carrier signal, the quadrature-phase data signal and a Hilbert transform of the in-phase data signal are modulated onto a sine carrier signal, and the modulated sine and cosine carrier signals are combined to provide a modulated SSB-QPSK signal. The in-phase and quadrature-phase data signals are time-aligned signals which are interpolated prior to modulation so as to include zero values at alternating instants of time. Their corresponding Hilbert transforms therefore also exhibit alternating zero values.

Abstract: Time dispersion of a signal that has been received from a channel is measured by utilizing metrics to determine the energy inside an equalizer window and outside of the equalizer window. In one embodiment, the estimate of the energy outside the window is a difference between residual interference estimates. In another embodiment, the estimate of the energy outside the window is a difference between residual impulse response power estimates.

Abstract: A multi-carrier radio system in which pairs of subcarriers are positioned in frequency such that each subcarrier in a pair is the image of the other subcarrier in the pair. By making each subcarrier the image of another subcarrier, the radio system of the present invention permits highly integrated low-IF transceiver implementation. In an exemplary embodiment, a multi-carrier transceiver includes an integrated receiver comprising a first mixer for mixing an input signal with a local oscillator signal to produce an in-phase downconverted signal. Additionally, a first phase shifter phase-shifts the local oscillator signal to produce a quadrature local oscillator signal, and a second mixer mixes the input signal with the quadrature local oscillator signal to produce a quadrature downconverted signal. Thereafter, a second phase shifter phase-shifts, or rotates, the quadrature downconverted signal to produce a rotated quadrature downconverted signal.

Abstract: A phase detection circuit detects a phase of a phase detection signal output from a complex multiplication circuit. A frequency error detection circuit detects a frequency error of a phase-detected signal, with the first frequency error detection characteristic in which a first frequency domain is defined as a detection range. An average circuit converts a signal having the detected frequency error into a signal having a second frequency error detection characteristic in which a second frequency domain other than the first frequency domain is defined as a detection range. After the average circuit calculates an average of frequency error signals for each period of time, it converts an average signal into a signal having the original first frequency error detection characteristic and outputs it to an AFC loop filter.

Abstract: A Vestigal Sideband (VSB) demodulator having a clock generator for generating a clock signal based on a symbol frequency of the VSB signal; an A/D converter for converting the VSB signal into a digital signal based on the clock signal of the clock generator; a first multiplier for multiplying the digital signal by a first value sequence and generating a first multiplier output signal; a second multiplier for multiplying the digital signal by a second value sequence and generating a second multiplier output signal; a complex type filter for shaping and VSB demodulation of the multiplier output signals and generating Inphase and Quadrature data output signals; a decimating circuit for decimating the Inphase and Quadrature data output signals and generating decimated signals; a complex multiplier for multiplying the decimated signals by a predetermined value and generating multiplied output signals; an error detector for detecting a frequency deviation and a phase deviation from the multiplied output signals and

Abstract: A frequency and phase regulating circuit, particularly for a digital complex-value vestigial sideband signal or Nyquist flank-filtered signal, with a regulating loop having a filter device which generates, from the signal to be regulated, a symmetrical double sideband signal band-delimited to a reference frequency. This regulating circuit is particularly suitable for a digital TV demodulator.