Abstract: A diversity receiver includes: a plurality of demodulating means for demodulating inputted OFDM signals, to output their demodulated signals; noise component calculating means provided for each demodulating means, for calculating noise components included in the demodulated signals outputted from corresponding demodulating means; channel profile calculating means provided for each demodulating means, for calculating channel profiles based upon the demodulated signals outputted from corresponding demodulating means; transmission channel decision means for determining transmission channel based upon the channel profiles; reliability information generating means for generating reliability information indicating reliability of the demodulated signals outputted from each demodulating means, based upon the noise components and the results of the determinations by the transmission channel decision means; a weighting factor calculating means for calculating, depending on the reliability information, weighting factors

Abstract: A diversity receiver includes: a plurality of demodulating means for demodulating inputted OFDM signals, to output their demodulated signals; noise component calculating means provided for each demodulating means, for calculating noise components included in the demodulated signals outputted from corresponding demodulating means; channel profile calculating means provided for each demodulating means, for calculating channel profiles based upon the demodulated signals outputted from corresponding demodulating means; transmission channel decision means for determining transmission channel based upon the channel profiles; reliability information generating means for generating reliability information indicating reliability of the demodulated signals outputted from each demodulating means, based upon the noise components and the results of the determinations by the transmission channel decision means; a weighting factor calculating means for calculating, depending on the reliability information, weighting factors

Abstract: A delay profile generating circuit 9 generates a delay profile signal. Concerning the delay profile signal, a ghost decision circuit 10 makes a decision as to the presence or absence of ghosts that will appear during traveling of a mobile vehicle in response to a transmission mode signal fed from a changeover switch 8. The delay profile signal and the decision signal about the presence/absence of the ghosts are delivered to a window control circuit 13 via an accumulator 11. The window control circuit 13 sets and controls the FFT window position of an FFT circuit 5 in response to a guard correlation signal fed from a guard correlation signal generating circuit 12 and a signal fed from the accumulator 11.

Abstract: The present invention relates to a OFDM signal receiver device that performs weighting for branch metrics based on average noise power or signal-to-noise power ratio and conducts Viterbi decoding based on the result of the weighting. In the present invention, based on a demodulated signal, electric power corresponding to a noise component contained in the demodulated signal is calculated. A noise power signal corresponding to the result of the calculation is output from a noise power-calculating unit 8. Based on the noise power signal and a transmission channel characteristic corresponding to a subcarrier component that is output from an interpolation filter unit, a weighing factor for a branch metric is calculated by a weighting factor-calculating unit 9, and based on the weighting factor, the demodulated signal is decoded by decoding unit 10.

Abstract: The present invention relates to a demodulation device and a demodulation method, and its object is to demodulate subcarrier components utilizing estimated delay profiles to control the timing for performing a Fourier transform and the pass band of an interpolation filter used in interpolating transmission channel characteristics along a frequency axis so as to suppress unnecessary noise components, whereby an error rate after the demodulation is reduced. To achieve the object, in a demodulation device according to the present invention, a Fourier transform unit 1 performs a Fourier transform according to a timing signal and an interpolation filter unit 18 sets a pass band of a frequency interpolation filter used for interpolation along the frequency axis based on a signal corresponding to a maximum delay time, whereby the frequency band of a transmission channel characteristic corresponding to a subcarrier component is restricted when it is output.

Abstract: A diversity receiver is provided with antennas (1a) and (1b) in a first branch and antennas (1c) and (1d) in a second branch each of which antenna gains is controlled so that the offset between the directions of directional radiation patterns for the first and second branches becomes approximately ?/2. Thereby, the diversity receiver can obtain a sufficient diversity gain even when it is incorporated into an indoor television with the antennas being built thereinto in close vicinity to one another.

Abstract: The value of a pilot signal extracted from the received signal is divided by the known value (sm,n) of the pilot signal to obtain a channel characteristic value (3), changes in the timing of the Fourier transform are detected (5), and on the basis of the detected result, interpolated data are generated (4) by selection or interpolation in the time direction, using the channel characteristic values as the original data. The decoding error rate after equalization when the timing of the Fourier transform changes is lowered, and receiving performance is improved.

Abstract: A diversity receiver includes: a plurality of demodulating means for demodulating inputted OFDM signals, to output their demodulated signals; noise component calculating means provided for each demodulating means, for calculating noise components included in the demodulated signals outputted from corresponding demodulating means; channel profile calculating means provided for each demodulating means, for calculating channel profiles based upon the demodulated signals outputted from corresponding demodulating means; transmission channel decision means for determining transmission channel based upon the channel profiles; reliability information generating means for generating reliability information indicating reliability of the demodulated signals outputted from each demodulating means, based upon the noise components and the results of the determinations by the transmission channel decision means; a weighting factor calculating means for calculating, depending on the reliability information, weighting factors

Abstract: The circuit size of a diversity receiver for an orthogonal frequency division multiplexing signal is reduced, and the diversity effect is increased, by providing a power ratio comparator that calculates a difference value as a ratio of powers derived from channel estimation results for subcarrier components received from two antennas (11), (21) and compares the calculated difference value with a predetermined threshold, and a selective/equal gain combining selector (33) that outputs one of the received demodulated signals when the comparison result indicates that the calculated difference value is greater than the threshold value.

Abstract: The present invention relates to a demodulation device and a demodulation method, and its object is to demodulate subcarrier components utilizing estimated delay profiles to control the timing for performing a Fourier transform and the pass band of an interpolation filter used in interpolating transmission channel characteristics along a frequency axis so as to suppress unnecessary noise components, whereby an error rate after the demodulation is reduced. To achieve the object, in a demodulation device according to the present invention, a Fourier transform unit 1 performs a Fourier transform according to a timing signal and an interpolation filter unit 18 sets a pass band of a frequency interpolation filter used for interpolation along the frequency axis based on a signal corresponding to a maximum delay time, whereby the frequency band of a transmission channel characteristic corresponding to a subcarrier component is restricted when it is output.

Abstract: The circuit size of a diversity receiver for an orthogonal frequency division multiplexing signal is reduced, and the diversity effect is increased, by providing a power ratio comparator that calculates a difference value as a ratio of powers derived from channel estimation results for subcarrier components received from two antennas (11), (21) and compares the calculated difference value with a predetermined threshold, and a selective/equal gain combining selector (33) that outputs one of the received demodulated signals when the comparison result indicates that the calculated difference value is greater than the threshold value.

Abstract: The present invention relates to a OFDM signal receiver device that performs weighting for branch metrics based on average noise power or signal-to-noise power ratio and conducts Viterbi decoding based on the result of the weighting. In the present invention, based on a demodulated signal, electric power corresponding to a noise component contained in the demodulated signal is calculated, A noise power signal corresponding to the result of the calculation is output from a noise power-calculating unit 8. Based on the noise power signal and a transmission channel characteristic corresponding to a subcarrier component that is output from an interpolation filter unit, a weighing factor for a branch metric is calculated by a weighting factor-calculating unit 9, and based on the weighting factor, the demodulated signal is decoded by decoding unit 10.

Abstract: An equalizer providing a filtered signal to a data decision unit calculates an amplitude error signal by comparing the filtered signal with the data signal output from the data decision unit, and calculates a squared envelope error signal from the filtered signal. These two error signals are separately weighted according to the absolute value of the amplitude error, the weight of the amplitude error signal decreasing and the weight of the squared envelope error signal increasing as the absolute value of the amplitude error increases. The weighted amplitude error signal and weighted squared envelope error signal are added to obtain an error signal used in updating filter coefficients in the equalizer. Rapid convergence of the filter coefficients is obtained, with small residual error.

Abstract: A phase error detector in a digital demodulator estimates phase error by dividing the difference between an in-phase demodulated signal and the transmitted data values included in the in-phase demodulated signal by the sum or difference of a quadrature demodulated signal and a product signal. The product signal is equal to the in-phase demodulated signal multiplied by a fixed gain constant. The phase error detector thereby obtains an error estimate that is substantially independent of the transmitted data values.

Abstract: It is an object to enlarge the phase range in which a phase error can be determined. An operating block (1) calculates a power of carriers from data DI and DQ. An ideal symbol estimating block (2a) outputs a plurality of ideal symbols which correspond to the power of carriers outputted from the operating block (1). A phase error tan(.theta.) calculating block (2b) calculates prediction phase errors between the ideal symbols and the symbol given by the data DI and DQ. A phase error determining block (3) determines a phase error from among the prediction phase errors outputted from the phase error tan(.theta.) calculating block and outputs the phase error.

Abstract: A motion detection circuit within MUSE decoder for reproducing a high definition television picture signal from a MUSE signal obtains one-interframe differential signal and preferably one-interfield differential signal from an interframe interpolation signal. The differential signals are passed through a vertical filter to limit the vertical frequency and through a horizontal filter or filters to obtain a high and a low frequency component signal. The judgment circuit judges the reliability of the high and low component signals on the basis of the levels of peak values thereof, and the selector selects an appropriate signal in accordance with the judgment. Horizontal and vertical width extenders and absolute value output circuits may be provided to improve the performance.