Abstract: In a synchronization method and apparatus in a data transmission using a transparent transmission line, a periodic amplitude modulation is applied, or a zero-point is inserted, as a synchronizing signal to a transmission signal point on a transmission side at a preceding stage of a transparent transmission line. Also, in case of a frame synchronization, a power value of a received signal is calculated on a reception side of the above-mentioned transparent transmission line and the synchronizing signal is vectorized using the power values whose phases are different from each other by 90 degrees on a time axis.

Abstract: An automatic gain control circuit includes a first portion which calculates a first error amount, and a second portion which calculates a second error amount. Both calculated error amount is sent to a determination module. Further, an integrator integrates an error amount, a difference between a power of an input signal and an average power of an eye pattern for example. The determination determines whether the integrated error amount exceeds a predetermined value or not, and output either of the first error amount and the second error amount based on the determination.

Abstract: A modem coupling circuit comprising: (a) a transformer 1 having a core 1a including a gap formed therein, primary windings N1a, N1b constituting a bifilar wound coil which is wound around the core 1a, forming a single layer and connected to power lines L1, L2, and a secondary winding N2 connected to a transmitting circuit 2 and a secondary winding N3 connected to a receiving circuit 3, the secondary windings N2, N3 holding the single layer of the primary windings between; (b) a coupling capacitor C1 connected to a middle point between first ends of the primary windings, the first ends being not connected to the power lines L1, L2; (c) current limiting resistances R1a, R1b connected to the primary windings N1a, N1b having a bifilar construction; (d) drive resistances R2a, R2b connected to the secondary winding for transmission N2; and (e) terminating resistances R3a, R3b connected to the secondary winding for reception N3.

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 data transmission apparatus is provided that enables accurate data regeneration using an A/D converter with a relatively narrow dynamic range for processing a signal having a large noise amplitude. To this end, the data transmission apparatus includes a receiving part having a multiplier that performs a spread spectrum process by multiplying an input signal by a PN sequence, an A/D converter that performs an analog-to-digital conversion process on the signal that has undergone the spread spectrum process, and a multiplier that performs an inverse spread spectrum process by multiplying the signal that has undergone the analog-to-digital conversion process by the same PN sequence.

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: In a noise elimination method and apparatus, a spread spectrum modulation signal having a data signal and an overlapping noise component at a signal point on a time axis and a noise component at a zero point on the time axis is received. A correlation of the received modulation signal to a spread spectrum code is generated by using a correlating filter. Zero is set at points of the modulation signal other than the signal point where the correlation becomes the maximum, so that the noise component at the zero point is extracted from the modulation signal. The noise component at the signal point is predicted by performing interpolation prediction based on the extracted noise component. The noise component at the signal point is removed from the modulation signal based on the predicted noise component.

Abstract: A transmission part produces a copy of a given narrow-band signal so as to obtain a number of same signals according to predetermined orthogonal sequence, and performs respective phase rotations on the thus-obtained signals according to the present invention orthogonal sequence. A reception part performs reverse phase rotation on the reception signals according to the predetermined orthogonal sequence, and then performs mutual addition thereon so as to restore the narrow-band signal.

Abstract: A polling communication system includes a main station and a plurality of sub stations connected to the main station. The main station includes an address control part and a polling control part. The address control part divides a predetermined polling cycle into a plurality of kinds of polling intervals each having a different number of times of polling, and holds addresses of polling target sub stations corresponding to the respective polling intervals. The polling control part switches the polling intervals and changes the addresses in the address control part according to states of the sub stations. Each of the sub stations includes another polling control part that sends a response when the sub station is polled by the main station.

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 synchronization method and apparatus in a data transmission using a transparent transmission line, a periodic amplitude modulation is applied, or a zero-point is inserted, as a synchronizing signal to a transmission signal point on a transmission side at a preceding stage of a transparent transmission line. Also, in case of a frame synchronization, a power value of a received signal is calculated on a reception side of the above-mentioned transparent transmission line and the synchronizing signal is vectorized using the power values whose phases are different from each other by 90 degrees on a time axis.

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: The n-bit data is converted to specific patterns of n+m-bit data when the data is written to the memory device. These specific patterns are those n+m-bit data patterns that have the more numbers of logic values that have the smaller amount of current consumed. Additionally, when the n+m-bit data is read, it is converted back to the original n-bit data. This process makes it possible to reduce the number of write/read operations for the logic values that consume the greater amount of electric current when writing/reading the data to/from the memory device, thereby reducing the amount of power consumed.

Abstract: The present invention is concerned with an error correction device and method for correcting errors in data items sent on a plurality of channels. An identification unit calculates an exclusive OR value for data items sent on the plurality of channels, and adopts the calculated value as data sent on a separate error correction channel. A signal quality detection unit detects the signal qualities concerning the plurality of channels. If the exclusive OR value is not equal zero, an identifying and processing unit replaces data on a channel whose signal quality is detected to be worst with an exclusive OR value for data items sent on channels other than the channel whose signal quality is worst.

Abstract: A data transmission method comprises the steps of: a) performing two-dimensional interleaving along a time axis and along a frequency axis; b) transmitting the thus-obtained data by a multi-carrier transmission form; and c) producing, by channel copy operation, data which is short for the number of channels required for fast inverse Fourier transform performed antecedent and subsequent to said step a).

Abstract: A canceling method and apparatus can achieve a fast communication by improving an S/N value by adaptively canceling a noise with respect to a frequency or band having a large noise by selecting noise canceling band in accordance with a condition of noise being generated. A reception signal contains a specific signal having a specified time position, amplitude and phase. A noise distribution of the specific signal is recognized so as to predict a noise by extracting a frequency band having a larger noise component from a pair of frequencies generated by the insertion of the specific signal. An original transmission signal is reproduced by canceling the predicted noise from the reception signal.

Abstract: A method used in equalization processing is provided, in which a reference signal is received and a change point of transmission line characteristics is detected. A basic frequency signal of fluctuation period of the transmission line characteristics is extracted, and vectorized. The vector is adjusted such that vectors corresponding to two change points become symmetrical with respect to X axis. Then, fluctuation interval of transmission line characteristics is judged by comparing X component of the vector with a reference value. As a result, equalization processing is performed in accordance with the fluctuation.

Abstract: A peak suppression method detects a peak value exceeding a threshold value of a transmitting signal, forms a peak value prediction signal which is limited to a noise cancelling frequency band of a receiving end, based on the detected peak value of the transmitting signal, and subtracts the peak value prediction signal from the transmitting signal.

Abstract: A limiter is connected with the output of a PLL to limit the amplitude of the output from the PLL. The output from limiter is supplied to a voltage-controlled oscillator (VCXO). The limiter determines the difference between the input signal and the output signal. If the difference exceeds a predetermined value, the change in the output from the limiter is limited to the predetermined value. If the difference does not exceed the predetermined value, the change in the output is considered to be a difference value.