Abstract: A method used in equalization processing is provided, in which a reference signal is received and a change point of transmission line characteristics is detected. A basic frequency signal of fluctuation period of the transmission line characteristics is extracted, and vectorized. The vector is adjusted such that vectors corresponding to two change points become symmetrical with respect to X axis. Then, fluctuation interval of transmission line characteristics is judged by comparing X component of the vector with a reference value. As a result, equalization processing is performed in accordance with the fluctuation.

Abstract: A data processing apparatus includes a decision section that determines a predetermined plurality of channels of original data and a predetermined channel of correction data based on data of received signals; an exclusive OR circuit that calculates an exclusive OR upon the channels of the decided data; a signal quality decision section that detects signal quality of received data on each channel; and a correction section that replaces a channel of data whose channel has a worst detection result as detected by the signal quality detection section with the result of the exclusive OR calculation when the result of the calculation is other than “0”. The signal quality detection section calculates a mean signal quality and an instantaneous signal quality that are used by the correction section to determine the worst channel.

Abstract: A canceling method and apparatus can achieve a fast communication by improving an S/N value by adaptively canceling a noise with respect to a frequency or band having a large noise by selecting noise canceling band in accordance with a condition of noise being generated. A reception signal contains a specific signal having a specified time position, amplitude and phase. A noise distribution of the specific signal is recognized so as to predict a noise by extracting a frequency band having a larger noise component from a pair of frequencies generated by the insertion of the specific signal. An original transmission signal is reproduced by canceling the predicted noise from the reception signal.

Abstract: The present invention is concerned with an error correction device and method for correcting errors in data items sent on a plurality of channels. An identification unit calculates an exclusive OR value for data items sent on the plurality of channels, and adopts the calculated value as data sent on a separate error correction channel. A signal quality detection unit detects the signal qualities concerning the plurality of channels. If the exclusive OR value is not equal zero, an identifying and processing unit replaces data on a channel whose signal quality is detected to be worst with an exclusive OR value for data items sent on channels other than the channel whose signal quality is worst.

Abstract: A configuration, comprising: a DEC section that employs an exclusive OR operation result upon a plurality of channels of data as a channel of correction data, receives data of signals modulated and thereafter sent, and performs decisions on a predetermined plurality of channels of original data and the predetermined channel of correction data, the decisions based on data of received signals; a XOR section that calculates an exclusive OR upon the channels of the decided data; a SQD section that detects signal quality of received data on each channel; and a correction section that replaces a channel of data whose channel has the worst detection result (according to detection results detected by the SQD section) with a result of exclusive OR operations upon the other channels of data when the result of the calculation of the XOR section is other than “0”. The SQD section calculates mean signal quality and instantaneous signal quality.

Abstract: The present invention is concerned with an error correction device and method for correcting errors in data items sent on a plurality of channels. An identification unit calculates an exclusive OR value for data items sent on the plurality of channels, and adopts the calculated value as data sent on a separate error correction channel. A signal quality detection unit detects the signal qualities concerning the plurality of channels. If the exclusive OR value is not equal zero, an identifying and processing unit replaces data on a channel whose signal quality is detected to be worst with an exclusive OR value for data items sent on channels other than the channel whose signal quality is worst.

Abstract: A canceling method and apparatus can achieve a fast communication by improving an S/N value by adaptively canceling a noise with respect to a frequency or band having a large noise by selecting noise canceling band in accordance with a condition of noise being generated. A reception signal contains a specific signal having a specified time position, amplitude and phase. A noise distribution of the specific signal is recognized so as to predict a noise by extracting a frequency band having a larger noise component from a pair of frequencies generated by the insertion of the specific signal. An original transmission signal is reproduced by canceling the predicted noise from the reception signal.

Abstract: A method used in equalization processing is provided, in which a reference signal is received and a change point of transmission line characteristics is detected. A basic frequency signal of fluctuation period of the transmission line characteristics is extracted, and vectorized. The vector is adjusted such that vectors corresponding to two change points become symmetrical with respect to X axis. Then, fluctuation interval of transmission line characteristics is judged by comparing X component of the vector with a reference value. As a result, equalization processing is performed in accordance with the fluctuation.

Abstract: Disclosed is a PLL control method of controlling a phase of a PLL for taking synchronism of a receiving signal in a data receiving apparatus. The phase of the PLL is synchronized with a phase when training irrespective of a line characteristic.

Abstract: A transmission system for transmitting a data signal with an analog passband signal through a analog transmission line. The data signal is transformed to a signal representing a descrete data signal point in a vector signal space. The analog passband signal is transformed to a base band signal, and the base band signal is superimposed on the signal representing a descrete data signal point. A signal representing the superimposed data signal point is modulated and transmitted through the analog transmission line. In a receiver, the data signal point is decided from the signal representing the superimposed data signal point, and the superimposed bass band signal is extracted by subtracting the decided result from the signal representing the superimposed data signal point. The base band signal is transformed to the analog passband signal. A portion of information carried by the analog passband signal may be converted to a digital signal, and the digital signal is multiplexed with the data signal.

Abstract: A frequency modulation method and modem unit for a frequency modulation using a common filter which uses a large number of carrier frequencies include a frequency-shifting unit for subjecting an input data to a frequency shift corresponding to a binary data value, a filter for limiting an output obtained by the frequency-shifting unit to a common band, and a modulation unit for frequency-modulating an output obtained by the filter, by a carrier frequency having an intermediate value of the frequencies respectively corresponding to the binary data values.

Abstract: A frequency modulation method and modem unit for a frequency modulation using a common filter which uses a large number of carrier frequencies include a frequency-shifting unit for subjecting an input data to a frequency shift corresponding to a binary data value, a filter for limiting an output obtained by the frequency-shifting unit to a common band, and a modulation unit for frequency-modulating an output obtained by the filter, by a carrier frequency having an intermediate value of the frequencies respectively corresponding to the binary data values.

Abstract: A transmission system for transmitting a data signal with an analog passband signal through a analog transmission line. The data signal is transformed to a signal representing a descrete data signal point in a vector signal space. The analog passband signal is transformed to a base band signal, and the base band signal is superimposed on the signal representing a descrete data signal point. A signal representing the superimposed data signal point is modulated and transmitted through the analog transmission line. In a receiver, the data signal point is decided from the signal representing the superimposed data signal point, and the superimposed base band signal is extracted by subtracting the decided result from the signal representing the superimposed data signal point. The base band signal is transformed to the analog passband signal. A portion of information carried by the analog passband signal may be converted to a digital signal, and the digital signal is multiplexed with the data signal.

Abstract: A modem connected to a radio which compensates for the characteristics of the radio side to make them suitable for data transmission without changing the characteristics of the radio and thereby increase the transmission speed. Therefore, a transmission side modem is provided with a deemphasis filter for compensating for the characteristics of a preemphasis filter of the radio transmitter, and a receiving side modem is provided with an emphasis filter for compensating for the characteristics of the deemphasis filter of the radio receiver so as to compensate for the characteristics of the radio. Further, in the signal constellation when selecting a signal point of input data, redundant signal points are added to the outside of the constellation to enable emphasis of the in-phase components of the preceding and succeeding signal points.

Abstract: A transmitter has a power calculation unit for calculating the power of a signal. A maximum value detection circuit determines a maximum value of an output of the power calculation unit, and a floating point transformation circuit changes an output of the maximum value detection circuit into a floating point representation. A significant bit extracting circuit extracts significant bits from an output of the floating point transformation circuit and outputs the significant bits as the transmitting signal.

Abstract: A transmission apparatus applied as a modem connected to a private branch exchange discriminates coordinates of an analog signal inputted thereto on a two-dimensional coordinate plane and transmits the signal, whose coordinates have been discriminated, as a digital signal. The transmission apparatus includes a frequency shifting section for performing frequency shifting for the inputted analog signal so that a tone signal of a single frequency may be a dc signal, and a coordinate discrimination section for discriminating coordinates on the two-dimensional coordinate plane of the analog signal for which the frequency shifting by the frequency shifting section has been performed. By the transmission apparatus, a single tone signal is transmitted without suffering from deterioration of the S/N ratio and so forth.

Abstract: In a modem signal transmitting/receiving system which includes a modem signal transmitter and a modem signal receiver connected to each other via a transmission line, a modem signal transmitter is suitable to transmit by multiplexing an analog signal such as audio and a modem carrier with digital data. Analog signals and digital data can be multiplex-transmitted at a high rate by effectively using an analog signal line. The modem signal transmitter includes a modem transmitting unit, an analog/digital converting unit which converts an analog signal into a digital signal, a demodulating unit which demodulates the digital signal with a predetermined carrier frequency signal, a decimation processing filter which decimates the demodulated signal and a deciding unit which decides a coordinate on a two-dimensional plane for the output from the decimation processing filter and then inputs the decision result to the modem transmitting unit.

Abstract: A transmission apparatus such as a modem has a receiving unit which receives information and a clock-supplying unit which supplies a clock signal to the receiving unit. It further has an instantaneous dropout detection unit which detects the occurrence of an instantaneous dropout on the receiving circuit and a clock supply control unit which stops the supply of a clock to the receiving unit for a prescribed amount of time when the instantaneous dropout detection unit detects an instantaneous dropout, the stopping of the clock supply causing holding of receiving parameters and the restarting of clock supply causing restarting of the receiving operation.

Abstract: A transmission apparatus, connected via a hybrid circuit to a line, such as a modulator-demodulator which can perform stable echo cancellation, whether the level of the far-end echo is high or not, provided with a transmission unit which generates a transmission signal to be transmitted to the line via the hybrid circuit, a reception unit which receives the reception signal supplied from the line via the hybrid circuit, and a superimposing means for superimposing the reception signal applied to the hybrid circuit onto the transmission signal. The transmission signal onto which the reception signal is superimposed by the superimposing means is transmitted to the line via the hybrid circuit.

Abstract: An apparatus for recovering a timing signal from a received signal in a transmission apparatus includes an equalizer equalizing a processed signal which is provided by processing the received signal with a first signal and adjusting tap coefficients so as to eliminate distortion in the processed signal. A tap-power distribution detector detects a distribution of the tap coefficients adjusted in the equalizer. A phase control part controls a phase of the first signal according to the distribution of the tap coefficients detected in the tap-power distribution detector. In the apparatus, the phase of the first signal is controlled so as to be synchronized with a timing signal component in the received signal.