Abstract: A communication apparatus is connected to a transmission channel for transmitting data to another communication apparatus. The communication apparatus includes: a communication frame generator which generates a communication frame for storing the data; and a controller which controls to insert a pilot symbol into the communication frame based on a state of the transmission channel.

Abstract: A host manages a ROM that stores a handshake program for executing a handshake sequence and an initialization program for executing an initialization sequence. During the handshake sequence, the handshake program is retrieved from the ROM to download the program to a non-resident memory of a program area. Upon completing the handshake sequence, the initialization program is retrieved from the ROM, to download the program to the non-resident memory, replacing the handshake program.

Abstract: A communication apparatus is connected to a transmission channel for transmitting data to another communication apparatus. The communication apparatus includes: a communication frame generator which generates a communication frame for storing the data; and a controller which controls to insert a pilot symbol into the communication frame based on a state of the transmission channel.

Abstract: The present invention provides a management table that uses only specific symbols for upstream signals and other symbols for downstream signals, within a hyperframe (ADSL communication unit). Communication is performed by switching streams between the upstream and downstream, in accordance with the symbols stored in the management table. Upon transmitting a predetermined number of hyperframes, a processor transmits a SEGUE signal instead of a REVERB signal in the beginning of the next hyperframe.

Abstract: The present invention monitors communication status during a data communication, determines whether the current communication status needs a re-initialization, requests a re-initialization of an opposing ADSL modem apparatus by transmitting ClearEOC when a re-initialization is needed, receives a response to a re-initialization request from the opposing ADSL modem apparatus, and performs a re-initialization after a predetermined time period.

Abstract: A communication control method detects whether an opposing apparatus is capable of performing an abbreviated procedure during a handshake step, declares an initiation of the abbreviated procedure if the opposing apparatus is capable of performing the abbreviated procedure, omits a negotiation prior to transmitting a MEDLEY signal, allows a remote side to transmit capacity information and reception result once to a center side after exchanging the MEDLEY signal, and further allows the center side to transmit the final capacity and transmission speed information to the remote side, in order to complete the initialization sequence.

Abstract: A control monitors communication status during a data communication and determines a re-initialization is necessary in the current communication status. If the re-initialization is necessary, a pre-selected sub-carrier topology is inverted to request the re-initialization to an ADSL modem apparatus, which is installed by a central system. Upon receiving a reply to the re-initialization request from the ADSL modem apparatus, the re-initialization is performed after an expiration of a predetermined time period.

Abstract: A MODEM can shorten the processing time of an interface disposed between a data terminal equipment (DTE) and the MODEM. The MODEM stores an object program of a procedure in a memory and switches an operational mode of the MODEM automatically corresponding to the prescribed procedure thereby executing the procedure corresponding to the current operational mode. The MODEM further comprises a timer which monitors the transits time between a completed procedure and the next procedure, and the MODEM starts the process of a specified operational mode based on a mode-setting-instruction of the procedure as well as monitoring the transitions time by using the timer, and executing a next specified operational mode when the timer times out, thereby allowing the MODEM to perform the various operational mode switches.

Abstract: The present invention calculates a difference between present sampling data and sampling data one data unit ahead, cumulatively adds up difference values calculated for every sampling by going back to the time point ahead by the number of samples of a cyclic prefix signal inserted into an initializing signal and confirms the position of the cyclic prefix signal from the sample number for which this cumulative value indicates a minimum value.

Abstract: After establishing a connection between an ATU-C and an ATU-R and having a state where data communication is enabled, the ATU-R checks a packet that flows through a network at the user side. When there is no packet addressed to the ATU-R for a predetermined time period, the ATU-R transmits, to the ATU-C, a request to transition to an energy-save mode. The ATU-C and AUT-R determines a parameter to be used for the energy save mode, the parameter enabling a number of carriers and/or transmission power to be decreased compared to the ones in a normal mode. Using the determined parameter, a state in which data communication is enabled is maintained.

Abstract: In an ATU-R having established a connection with an ATU-C and being in a state where data communication is enabled, the ATU-R being located at a user's home, a voltage detection circuit detects a connector voltage of a connector to which a network cable of a user side is connected. When the connector voltage is decreased below a predetermined value in a state where power is supplied to an ADSL circuit of the ATU-R, the power supply to the ADSL circuit is stopped while maintaining a function related to detecting the connector voltage and controlling the power supply. The connector voltage is monitored even after the power supply is stopped. When the detected connector voltage becomes greater than the predetermined value, the power supply to the ADSL circuit is resumed.

Abstract: When a communication is started through a control channel in a half-duplex communication compliant with the Recommendation V.34, the modem apparatus of the present invention demodulates reception symbols subjected to quadrature amplitude modulation and thereby finds their coordinates on a signal space diagram. Then, the modem apparatus calculates a cross product of two vectors from the origin to the coordinates of two consecutive symbols and identifies a control signal from a polarity array configured by polarities of the calculation result arrayed over a span of a plurality of consecutive symbols.

Abstract: A training circuit for training a tap coefficient of an adaptive equalizer that performs error calculations in a training process and updating of the tap coefficient in a time area and thereby makes the tap coefficient converge stably in a short time.

Abstract: The present invention calculates a product of the present sampling data by the sampling data one data unit ahead through a multiplier, adds up product values calculated for every sampling by adding product values calculated from previous samples occurring one data unit in advance through an adder and detects a reference timing with regard to a CP (cycle prefix) signal using the addition value.

Abstract: A processor executes an initialization sequence that exchanges predetermined signals prior to data communication. A complex operation circuit multiplies transmission data of a sub-carrier by gain compensation data and phase angle compensation data, which are prepared for the same sub-carrier. Therefore, modulation is done so that the multiplication results are simultaneously transmitted, by an IFFT unit, in a plurality of sub-carriers. In addition, the transmission data of a sub-carrier, during the data communication, is multiplied by gain compensation data and phase angle compensation data, which are prepared for the same sub-carrier.

Abstract: A DSL modem apparatus provided at a transmission side in an upstream performs upstream communication using carrier indexes of the same range as a downstream. During an echo canceller learning period, a transmission signal is outputted to a line, via notch filters that cut the signal at a frequency location of a PILOT signal of the downstream. An echo signal is received via notch filters and a coefficient is set by calculating from the training signal of its own apparatus and the echo signal.

Abstract: The present invention provides a communication control method between DSL modem apparatuses mutually connected via a metallic cable. One of the DSL modem apparatuses transmits transmission data using a plurality of sub-carriers simultaneously, while the other DSL modem apparatus decodes the transmission data in the plurality of sub-carriers. The both sides of DSL modem apparatuses exchange data signals by mutually synchronizing and alternatively sharing transmission timeslots and reception timeslots, using the same range of sub-carriers. In addition, the upstream (data transmission from a remote side to a center side) uses the same range of carrier indexes that are used in the downstream (data transmission from the center side to the remote side).

Abstract: An ADSL modem apparatus is provided that accurately obtains a communication distance to an opposing ADSL modem apparatus, and that enables ADSL communication in an area exceeding the communication distance conventionally used. In the ADSL modem apparatus, a transmitter-receiver transmits and receives a carrier specified by a communication standard in a handshake procedure, and a processor estimates a communication distance to an opposing ADSL modem apparatus in accordance with a reception level of the carrier.

Abstract: A processor of a transceiver estimates a communication distance to an opposing ADSL modem apparatus by detecting a reception level of a communication distance detecting signal in accordance during an initialization sequence with the ITU-T regulated G.992. 1 or G. 992.2. The communication distance detecting signal is used to detect a communication distance to an opposing ADSL modem apparatus and has comb-shaped frequency characteristics. Based on the estimated communication distance, and by referring to a table showing attenuation of signal energy (stored in a RAM), the signal energy in a high frequency band (among the signal energy assigned to transmitting signals) is concentrated into a low frequency band during the communication.

Abstract: A processor of a transceiver estimates a communication distance to an opposing ADSL modem apparatus by detecting a reception level of a REVERB signal in accordance with the ITU-T regulated G.992.1 or G. 992.2. Based on the estimated communication distance, and by referring to a table showing attenuation of signal energy (stored in a RAM), the signal energy in a high frequency band (among the signal energy assigned to transmitting signals) is concentrated into a low frequency band during the communication.