Abstract: A sampling phase synchronizing apparatus includes a received signal memory for storing a received signal partially including training codes, a channel response calculator for calculating the time response of a channel (to be referred to as a channel response hereinafter) unique to the reception time using a partial sequence of the training codes included in the received signal stored in the received signal memory, a power ratio calculator for calculating the ratio between the power of the channel response calculated by the channel response calculator, and the power of a portion of the channel response, a power ratio memory for storing the power ratio calculated by the power ratio calculator, and a sampling phase deciding section for determining a sampling phase using the power ratio stored in the power ratio memory. The apparatus samples the received signal with reference to the sampling phase determined by the sampling phase deciding section.

Abstract: A sampling phase synchronizing apparatus includes a received signal memory for storing a received signal partially including training codes, a channel response calculator for calculating the time response of a channel (to be referred to as a channel response hereinafter) unique to the reception time using a partial sequence of the training codes included in the received signal stored in the received signal memory, a power ratio calculator for calculating the ratio between the power of the channel response calculated by the channel response calculator, and the power of a portion of the channel response, a power ratio memory for storing the power ratio calculated by the power ratio calculator, and a sampling phase deciding section for determining a sampling phase using the power ratio stored in the power ratio memory. The apparatus samples the received signal with reference to the sampling phase determined by the sampling phase deciding section.

Abstract: A maximum likelihood sequence estimation capable of reducing an amount of real time calculations involved and improving a high speed follow up characteristic. N-dimensional vectors corresponding to all possible transmission sequence candidates of a prescribed length, which are pre-calculated according to a prescribed definition, are stored in a memory. Then, an estimated received signal for each one of the branches at the present sampling time is obtained by calculating an inner product of one of the N-dimensional vectors stored in the memory corresponding to each transmission sequence candidate resulting from each one of the branches reaching to each state at the present sampling time with the N-dimensional received signal vector for the present sampling time obtained from at least N received signals for at least N previous sampling times. The maximum likelihood sequence can be estimated as a survivor path for each state at the present sampling time according to this estimated received signal as usual.

Abstract: A carrier phase synchronous type maximum likelihood decoder for estimating a maximum likelihood sequence of data sequence includes N memories for memorizing N partial series of data sequence; N carrier phase adjust loop, each provided correspondingly to N memories, each for adjusting a carrier phase of received data series on the basis of a partial series memorized in corresponding memory; N likelihood function calculate parts, each provided correspondingly to N memories and N carrier phase adjust parts, each for calculating likelihoods of partial series by utilizing partial series memorized in corresponding memory and an output of corresponding carrier phase adjust loop, a compare and modulation part for comparing N calculated likelihoods and for selecting partial series having a maximum likelihood from memory, thereby, the satisfactory operation in the low S/N ratio can be realized and the satisfactory phase tracking characteristics can be obtained.

Abstract: A ghost canceller includes a ghost canceling circuit having a transversal filter for receiving a television input signal and a tap gain holding circuit for holding tap gains of the filter, a ghost detector, and a means for writing tap gain data into the tap gain data holding circuit in response to the ghost detector to permit a ghost component in an output signal of the ghost canceling circuit to be canceled out. In order to prevent the disturbance of a TV screen due to a transient response which occurs upon writing tap gain data into the tap gain data holding circuit, an output means is provided for permitting a signal other than the output signal of the ghost canceling circuit to be selectively taken out during a first time period including an interval in which tap gain data is written into the tap gain holding circuit and for permitting an output signal of the ghost canceling circuit to be selectively taken out during a second time period other than the first time period.

Abstract: An automatic equalizer comprises a waveform equalizer having a transversal filter connected to receive an input signal having a linear distortion, and having controllable tap gains; and a tap gain correcting means for successively correcting the tap gains of the transversal filter to take from the transversal filter an output signal from which the linear distortion is removed. In order to maintain the good convergency of tap gain correction control and prevent the excessive increase of the residual distortion, the tap gain correcting means is arranged to add a small leak to the correction control of tap gains. The magnitude of this leak is increased or decreased depending upon the sum of absolute values of the differences between the tap gains and their predetermined values to be set when the input signal contains no distortion.

Abstract: The input video signal including a ghost signal is supplied to a first transversal filter weighted by a first weighting signal. The output of the first transversal filter is supplied to a difference circuit to detect the ghost signal component which is supplied to a second transversal filter weighted by the second weighting signal derived from the input video signal. The output of the second transversal filter is supplied to a circuitry which includes a sign detecting circuit and a tap gain memory to produce the first weighting signal.

Abstract: An automatic equalizer comprises a transversal filter connected to receive an input signal such as a television signal in which a predetermined periodic reference signal is present and having variable tap gains, and a correlator for forming the correlation between the input and output signals of the transversal filter and correcting the tap gains of the transversal filter to cancel out distortion components such as ghost component contained in the input signal. For the purpose of preventing the slow convergence and fluctuation of tap gains of the transversal filter due to non-periodic noise components contained in the input signal, a circuit is further provided to integrate a predetermined portion of the waveform of the reference signal contained in the input signal. An output signal of the waveform integrator circuit is correlated with the output signal of the transversal filter by the correlator.