Abstract: An ADSL modem apparatus including an IFFT unit that performs an inverse fast Fourier transform on transmission data, an FFT unit that performs a fast Fourier transform on reception data, and a processor that performs an initialization sequence according to a protocol, is provided. During the initialization sequence, the processor maintains and enables an interleave memory to be employed. After data transmission is initiated, the processor instructs a switch controller so that an interleave unit and de-interleave unit can use the interleave memory.

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: 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: 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 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.

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: An ADSL modem apparatus including an IFFT unit that performs an inverse fast Fourier transform on transmission data, an FFT unit that performs a fast Fourier transform on reception data, and a processor that performs an initialization sequence according to a protocol, is provided. During the initialization sequence, the processor maintains and enables an interleave memory to be employed. After data transmission is initiated, the processor instructs a switch controller so that an interleave unit and de-interleave unit can use the interleave memory.