Abstract: 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.

Abstract: 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.

Abstract: There is provided a method of reading information which makes it possible to suppress the size of hardware and a price thereof and to improve an S/N ratio of a reading signal and reading resolution, wherein even if depth of field for reading is enlarged or a concave/convex portion or a blurred portion is left on the reading face, reading precision can be improved. The method includes steps of acquiring from a medium 1, a signal containing binary digit information having a predetermined information length and a one-dimensional arrangement, extracting information concerning an elemental unit length of the information length of the binary digit information from the acquired signal, and reading a ratio of the binary digit information to the information length based on the extracted elemental unit length information.

Abstract: A power line carrier communication system can effectively reduce leak electromagnetic field generation. Transmission data is copied on a frequency axis, and vector multiplication of a finite-difference function is performed to insert either a zero signal or an inverted signal between original signals.

Abstract: Timing phase information is extracted from a power spectrum of a received signal whose amplitude is modulated per frame or sub-frame, and timing phase synchronization of the received signal is performed with the timing phase information. Also, a vector signal of the power spectrum is generated, the vector signal is multiplied by another vector signal to be rotated, a sign decision of the rotated vector signal is performed, a result of the sign decision is integrated to be outputted as the timing phase information, and a vector conversion is performed to the integrated value to be fed back as the other vector signal.

Abstract: A method of suppressing leakage electromagnetic fields on a communication line or a power line having reflected waves includes the steps of (a) transmitting a first impulse from a transmission end and (b) transmitting a second impulse from the transmission end after passage of a given period of time during which a reflected wave of the first impulse disappears before returning to the transmission end. Thereby, the leakage electromagnetic fields are minimized.

Abstract: In a method and an apparatus for a data transmission in transmission media which vary depending on noises from outside, connected apparatuses, connection methods such as multi-path, or the like, a Hadamard multiplexing/distribution, or a quadrature mirror filter multiplexing/distribution is performed. Also, data is multiplexed by using an orthogonal sequence, the multiplexed data is transmitted to a transparent transmission line, and the data received from the transparent transmission line is distributed by using the orthogonal sequence. Also, data is multiplexed by using the orthogonal sequence, the multiplexed data is interleaved on a frequency axis and a time axis, the interleaved multiplexed data is multiplexed by using the orthogonal sequence, the multiplexed data is distributed by using the orthogonal sequence, the distributed data is deinterleaved on the frequency axis and the time axis, and the deinterleaved data is distributed by using an orthogonal transform.

Abstract: In a noise canceling method and an apparatus therefor which notices the colored noise looked macroscopically, positively cancels the dominant noise component in the low frequency band, shifts the S/N value to plus, and can extract the reception signal buried in the low frequency band and having a comparatively high level, a signal in which a time axis, an amplitude, and a phase are specified or a zero-point signal is inserted into a transmission signal by an inserter, a noise component is interpolated by using the specified signal or the zero-point signal by a noise canceler, and an originally transmitted signal is regenerated by subtracting the noise component from the reception signal.

Abstract: The present invention is directed to preventing the generation of a jarring noise when a voice/data multiplexing modem is in a diverging condition. This is accomplished by the modem including an encoder section 14, where a voice signal encoded by mapping it to 63 codes out of the 64 codes that can be expressed with 6 bits. When the unused code is detected by a detector section 28, the reproduced voice signal is masked.

Abstract: In a coefficient update method for a time domain equalizer of a DMT system, an optimum coefficient is obtained even during a data period. The processing volume for the coefficient update is also decreased. A coefficient of the TEQ 32 is updated by the output of the time domain equalizer (TEQ 32) of the DMT system. Because of this, the transient of the sync symbol where a cyclic prefix is added during the data period can be removed, so the coefficient of the TEQ can be accurately updated even if sync symbols are used. Therefore, the coefficient of the TEQ is updated even during data communication, so the coefficient of the TEQ 32 can be updated according to the change in the characteristics even for a channel where the characteristics change. Since the output of the FFT (36) on the main path at a subsequent stage of the TEQ (32) is used, the processing volume of the FFT for the coefficient correction processing can be decreased.

Abstract: The invention relates to an eye pattern which is generated upon transmission and also to a modulation and demodulation method which employs the eye pattern. The eye pattern and the modulation and demodulation method are improved in that, by devising the arrangement of signal points, the timing jitter amount is minimized and a frequency offset can be followed up accurately. The eye pattern to be generated upon transmission is constructed such that the arrangement of signal points thereof is not symmetrical with respect to the origin on a signal point arrangement plane on which the signal points are arranged.

Abstract: An eye pattern display device for receiving and equalizing signals transmitted on a frequency-division multiplex basis to produce equalized output signals and displaying eye patterns of the equalized output signals is intended to check the eye patterns of the equalized output signals on multiple channels simultaneously. Level converters convert the signal levels of the equalized output signals output from channel demodulators. Offset adders add predetermined offset signals to level-converted equalized output signals so that they can be displayed on corresponding display areas of a display which are allocated to the respective channels. A selector selects output signals of the offset adders in sequence to display the eye patterns of the equalized output signals simultaneously on the display.

Abstract: A roll off filter portion for an input transmission point signal executes a roll-off filtering process and an interpolation process with a multiple of two at the same time. The roll-off filtering process is adapted to form a frequency spectrum characteristic in a cosine roll-off shape for the input signal. An interpolator portion, connected to the roll-off filter portion, executes an interpolation process with a multiple of two. This process is a filtering process for forming a frequency spectrum characteristic in a cosine roll-off shape for an input signal. Depending on what multiple of the original sampling frequency a transmission point signal is interpolated, a corresponding number of the interpolator portions are connected in a cascade shape.

Abstract: A modulator and demodulator apparatus for use with a network is provided. The modulator and demodulator apparatus comprises a modulation section which includes a timing phase discrimination section for receiving, as an input signal thereto, a demodulation vector signal sampled into a digital value and discriminating to which one of a plurality of regions of a discrimination plane the phase of the input signal belongs. The timing phase discrimination section supplies, as an input to a next processing stage, a rotation vector obtained by rotating an input vector, moves the rotation vector to a quadrant which includes a reference discrimination region of the discrimination plane and performs, when the vector after the movement is not in the reference discrimination region, a predetermined calculation. When the vector after the movement comes to the reference discrimination region, another calculation is performed. This discriminates a timing phase of the input vector from the result of the calculation.

Abstract: A demodulation and roll-off filter apparatus comprises a demodulation portion, a decimation portion, a demodulation and roll-off filter portion, and a modulation portion. The demodulation portion converts a pass-band signal received from an A/D converter into a base-band signal. The decimation filter portion lowers the sampling frequency of the base-band signal into a frequency four times higher than the frequency of a demodulation carrier used for the demodulation and roll-off filter portion. The modulation portion converts a base-band signal received from the decimation filter portion into a pass-band signal. The demodulation and roll-off filter portion performs a simplified demodulation and roll-off filter process for the pass-band signal.

Abstract: A modulation and demodulation system suitable for use with a modem (modulator and demodulator apparatus) of a first polling type. The system allows reproduction of a signal necessary for initialization of a reception section of a modulator and demodulator apparatus with certainty in a short training time. The modulation and demodulation system is constructed such that, upon transmission of data, training data of a particular pattern are modulated and transmitted prior to transmission of the data, and such training data are demodulated by demodulation means and initialization of a reception section of the modulation and demodulation system is performed using the demodulation training data. The pattern of the training data to be transmitted includes an arrangement of signals wherein signals having phases different by 180.degree. from each other are arranged alternately, and a signal having the same phase as the last signal is arranged intermediately.

Abstract: A numerical value (Y-X).multidot.0.5 indicative of a phase angle .theta..sub.1 in the first quadrant is calculated on the assumption that a quadrant of an input vector signal (x+jy) is judged and the signal is rotated into the first quadrant by a rotational vector signal (a+jb) and the phase angle of 0 to .pi. is expressed by 0 to +2 and the phase angle of .pi. to 2.pi. is expressed by -2 to 0 as a prerequisite. Further, a numerical value c indicative of an offset phase angle .theta..sub.2 to return the vector signal into the original signal and the phase number indicative of each of the (N) divided phase regions of the phase plane is directly obtained as bit data.

Abstract: An automatic gain control circuit which is provided in a demodulation section of a modem to adjust the loop gain so that the level of a band-limited receive signal may have a predetermined reference value and to output the receive signal to an automatic equalization section of the modem. The automatic gain control circuit is improved in that, even when a disturbance of the circuit such as a gain hit or a drop-out occurs, regular communication can be continued without requiring a data mode leading-in operation.

Abstract: The invention provides a frequency offset dealing modulator and demodulator apparatus which modulates and demodulates transmission/reception data and is improved in that it can reproduce an accurate impulse when data are transmitted. The modulator and demodulator apparatus includes a modulator for modulating data, and a demodulator for demodulating a receive signal to reproduce such data. The demodulator includes a demodulation processing unit, a roll-off filter, a receive level adjustment unit, an equalizer, a carrier frequency offset removing correction signal generation unit, a normalizer, a multiplier and a sum calculation unit.

Abstract: A device for removing a frequency offset in modem reception signals includes a sampling part for sampling signals, a carrier phase control (CAPC) part to compute and correct a frequency offset value .theta..sub.1, an automatic equalizer, a determining circuit, and a frequency offset computing part disposed between the automatic equalizer and the determining circuit to separately compute the frequency offset value .theta..sub.2 from a vector signal sampled in the sampling part. The frequency offset value .theta..sub.2 is compared with the frequency offset value .theta..sub.1 computed by the carrier phase control part, and when the net error .DELTA..theta. exceeds a predetermined value, a renewing part forcibly substitutes the first frequency offset value .theta..sub.1 in the carrier phase control part with the second frequency offset value .theta..sub.2.