Fujitsu Corporation

Fujitsu Limimited

Yutaka Awata

Nobukazu Koizumi

Seiji Miyoshi

Takashi Sasaki

Mitsuo Kakuishi

Hiroyasu Murata

Kazutomo Hasegawa

Yasuo Ohtomo

Hidetake Asahina

Norio Ueno

Masashi Sato

Misao Fukuda

Hiroaki Itokawa

Norio Murakami

Kazuhiko Hatae

Kazuo Murano

Minoru Hirahara

Toshitaka Tsuda

Shinji Ohta

Kazuyoshi Maruyama

Seiichi Yamato

Atsushi Manabe

Takuo Gotoda

Seiji Mikyoshi

Yuko Kurosaki

Kinji Kawada

A timing recovery circuit capable of enhancing the reliability of timing recovery in a receiver apparatus in a communication system that employs the scheme of modulating the amplitude of a carrier wave. In the receiver apparatus which receives a transmitted signal created by modulating the amplitude of the carrier wave, and which comprises an AD converter for converting the received signal into a digital signal by sampling the received signal at an n-times oversampling rate, the timing recovery circuit which recovers a clock signal by extracting timing information from the output of the AD converter is constructed by containing therein a decimation filter for decimating the output of the AD converter down to an m-times oversampling rate (where 1&#x3c;m&#x3c;n), a phase difference information calculator for calculating the phase difference information from the output of the decimation filter; a loop filter for averaging the output of the phase difference information calculator, and an oscillator for generating, based on the output of the loop filter, a clock signal for controlling the sampling performed by the AD converter.

Timing recovery circuit

A signal modulation method by an electronic device which includes a minimal reducing unit that minimally reduces an integrated signal returned to an adder from an integrator. The signal modulation method includes generating an added signal with the adder. The signal modulation method further includes generating a new integrated signal with the integrator by returning a previously self-generated and stored integrated signal to the adder, and by integrating the added signal generated by the adder. The signal modulation method further includes generating a new quantization signal with a quantizer by quantizing the new integrated signal generated by the integrator.

Signal modulation method, signal modulation apparatus, electronic device, and computer program product

A digital subscriber line communicating system having a central office and a remote terminal connected through a telephone line, the transmitting side comprising a sliding window transmitting unit for transmitting DMT symbols according to the sliding window through the telephone line to the receiving side, and the receiving side comprising a sliding window receiving unit for receiving DMT symbols according to the sliding window from the transmitting side, the sliding window indicating the phase of cross-talk condition due to a TCM-ISDN transmission at the receiving side, whereby TCM cross-talk can be reduced without largely departing from the standard system.

Digital subscriber line communicating system

A digital subscriber line transmission (xDSL), system includes a transmitting side which transmits training symbols by adding some data that is contained in a training symbol sequence onto at least one of the beginning and the end of this symbol sequence and then transmits the training symbol sequence. A receiving side removes the data that has been added onto the training symbol sequence and executes training processing. The length of the training symbol sequence and of a transmit symbol sequence at time of normal communication is set in such a manner that the symbol sequence will not fall within an interval in which effects of near-end crosstalk from a neighboring line are received. The data added to the training symbol sequence specifies an interval in which effects of the crosstalk are received.

Digital subscriber line transmission method, apparatus and system

A digital subscriber line communicating system having a central office and a remote terminal connected through a telephone line, the transmitting side including a sliding window transmitting unit for transmitting DMT symbols according to the sliding window through the telephone line to the receiving side, and the receiving side including a sliding window receiving unit for receiving DMT symbols according to the sliding window from the transmitting side, the sliding window indicating the phase of cross-talk condition due to a TCM-ISDN transmission at the receiving side, whereby TCM cross-talk can be reduced without largely departing from the standard system.

A digital subscriber line transmission (xDSL) system includes a transmitting side which transmits training symbols by adding some data that is contained in a training symbol sequence onto at least one of the beginning and the end of this symbol sequence and then transmits the training symbol sequence. A receiving side removes the data that has been added onto the training symbol sequence and executes training processing. The length of the training symbol sequence and of a transmit symbol sequence at time of normal communication is set in such a manner that the symbol sequence will not fall within an interval in which effects of near-end crosstalk from a neighboring line are received. The data added to the training symbol sequence specifies an interval in which effects of the crosstalk are received.

A digital subscriber line communicating system having a central office and a remote terminal connected through a telephone line, the transmitting side comprising a sliding window transmitting-unit for transmitting DMT symbols according to the sliding window through the telephone line to the receiving side, and the receiving side comprising a sliding window receiving unit for receiving DMT symbols according to the sliding window from the transmitting side, the sliding window indicating the phase of cross-talk condition due to a TCM-ISDN transmission at the receiving side, whereby TCM cross-talk can be reduced without largely departing from the standard system.

A digital subscriber line transmission (xDSL)-, system includes a transmitting side which transmits training symbols by adding some data that is contained in a training symbol sequence onto at least one of the beginning and the end of this symbol sequence and then transmits the training symbol sequence. A receiving side removes the data that has been added onto the training symbol sequence and executes training processing. The length of the training symbol sequence and of a transmit symbol sequence at time of normal communication is set in such a manner that the symbol sequence will not fall within an interval in which effects of near-end crosstalk from a neighboring line are received. The data added to the training symbol sequence specifies an interval in which effects of the crosstalk are received.

A digital subscriber line communicating system for communicating between a transmitting side and a receiving side tough a communication line, the system including a hyperframe counter for periodically counting a predetermined number of continuous transmitting data symbols constituting a hyperframe synchronized with a timing signal, and a decoder for discriminating, based on the count value of the hyperframe counter, whether a transmitting data symbol belongs to a FEXT, or a NEXT. A sequencer is provided for initializing the status during an initialization period before starting usual communication. The initialization period includes an activation and acknowledgement sequence, a transceiver training sequence, a channel analysis sequence, and an exchange sequence. According to a single bitmap mode, the initialization is carried out by transmitting modulated symbols through only inside of the sliding window. According to a dual bitmap mode, the initialization except for an S/N measuring sequence in the channel analysis sequence is carried out by transmitting modulated symbols through only inside of the sliding window, and the S/N measuring sequence is carried out by transmitting modulated symbols through both inside and outside of the sliding window.

Digital subscriber line communicating system and a transceiver in the system

A digital subscriber line communicating system having a central office and a remote terminal connected through a telephone line, the transmitting side having a sliding window transmitting unit for transmitting DMT symbols according to the sliding window trough the telephone line to the receiving side, and the receiving side having a sliding window receiving unit for receiving DMT symbols according to the sliding window from the transmitting side, the sliding window indicating the phase of cross-talk condition due to a TCM-ISDN transmission at the receiving side, whereby TCM cross-talk can be reduced without largely departing from the standard system.

A digital subscriber line communicating system having a central office and a remote terminal connected through a telephone line, the transmitting side including a sliding window transmitting unit for transmitting DMT symbols according to the sliding window through the telephone line to the receiving side, and the receiving side including a sliding window receiving unit for receiving DMT symbols according to the sliding window from the transmitting side, the sliding window indicating the phase of cross-talk condition due to a TCM-ISDN transmission at the receiving side, whereby TCM cross-talk can be reduced

Digital subscriber line communicating system determining signal-to-noise ratios

A digital subscriber line communicating system for communicating between a transmitting side and a receiving side through a communication line, comprising a hyperframe counter for periodically counting a predetermined number of continuous transmitting data symbols constituting a hyperframe synchronized with a timing signal, and a decoder for discriminating, based on the count value of the hyperframe counter, whether a transmitting data symbol belongs to a FEXTor a NEXT. A sequencer is provided for initializing the status during an initialization period before starting usual communication. The initialization period includes an activation and acknowledgement sequence, a transceiver training sequence, a channel analysis sequence, and an exchange sequence. According to a single bitmap mode, the initialization is carried out by transmitting modulated symbols through only inside of said sliding window. According to a dual bitmap mode, the initialization except for an S/N measuring sequence in the channel analysis sequence is carried out by transmitting modulated symbols through only inside of said sliding window, and the S/N measuring sequence is carried out by transmitting modulated symbols through both inside and outside of said sliding window.

A digital subscriber line communicating system having a central office and a remote terminal connected through a telephone line, the transmitting side having a sliding window transmitting unit for transmitting DMT symbols according to the sliding window through the telephone line to the receiving side, and the receiving side having a sliding window receiving unit for receiving DMT symbols according to the sliding window from the transmitting side, the sliding window indicating the phase of cross-talk condition due to a TCM-ISDN transmission at the receiving side, whereby TCM cross-talk can be reduced without largely departing from the standard system.

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Yokohama, Japan

Yutaka Awata