Panasonic Communications Co., Ltd.

Matsushita Graphic Communication Systems, Inc.

Panasonic Corporation

Nobuhiko Noma

Mikio Mizutani

Keiichi Tomita

Mitsuhiro Araki

Tatsuo Imai

Genzo Takagi

Osamu Noguchi

Eizo Katayama

Toshiyuki Ougi

Tsukasa Sakai

Hiroyuki Nemoto

Yoshihiko Noguchi

Kazuo Kurita

Hisao Koga

Nobutaka Kodama

Yoshihiro Noguchi

Taisuke Konishi

Shigeo Yoshida

Genzou Takagi

Sei Matsumoto

Keiji Egashira

Yumi Katayama

Sakae Miyamoto

Zhi Jian Dai

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.

Communication apparatus, communication method, and integrated circuit

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.

DSL communication apparatus, and download method of DSL communication program

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.

ADSL modem apparatus and ADSL modem communication method

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.

ADSL modem apparatus and re-initialization method for ADSL modem apparatus

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.

Communication control method, communication control apparatus, and ADSL communication apparatus

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.

ADSL modem apparatus

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.

Modulator and demodulator (MODEM)

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.

Modem apparatus, communication apparatus and communication control method

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.

Modem apparatus, image communication apparatus and communication control method

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.

Adaptive equalizer training circuit, modem apparatus and communication apparatus

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.

It is decided whether or not the reception is performed with respect to signals of 1650 Hz, 1750 Hz and 185O Hz passed through band pass filter (BPF) up to and processed for the energy calculation in energy calculating circuit up to respectively. Low speed signals that are processed for the energy calculation in energy calculation circuit up to respectively are added in adding section At this time, a timer in decision circuit starts. When a predetermined time passes in the timer in decision circuit with a predetermined energy level of signals of 1650 Hz, 1750 Hz and 1850 Hz kept, the signals are identified as EOP signal that comes after PIX signal. Thereby the apparatus is controlled to shift to the low speed signal reception mode.

Communication speed switching device

When carrying out pre-processing of image signal transmission using the control channel of a full-duplex modem and switching image signal transmission to the primary channel of a half-duplex modem, the answer modem stops the transmission carrier upon confirmation that all &ldquo;1&rdquo; signals with 40 bit or more have been received from the calling modem, restarts the reception of all &ldquo;1&rdquo; signals after the elapse of a certain period of time, confirms the end of all &ldquo;1&rdquo; signals and switches to the primary channel.

Modem control method

When the present modem control apparatus detects that the receive level of a probing signal in phase 2 of the pre-communication procedure or a tone signal with a specific frequency in phase 2 of the pre-communication procedure is lower than a prescribed value, it sets the transmission rate of the control channel to a low rate of 1200 bps. In this case, the modem control apparatus sets the transmission rate to 1200 bps through a prescribed bit of the MPh signal in the communication control procedure and performs the setting that will not permit communications with the answer modem at different transmission rates, through the second prescribed bit of said MPh signal, and notifies those settings to the answer modem, thus carrying out communications at a lower transmission rate.

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Yokohama, Japan

Nobuhiko Noma