Abstract: A system and method for enabling an efficient Zero Phase Restart (ZPR) of a device. The structure is based on deploying normalized timing gradient (NTG) blocks (501 and 502) in pairs, each circuit employing an orthogonal phase error transfer function characteristic (having one TG circuit sample orthogonally in relation to the other), for example, PR4 and EPR4 modes ideal sampling instances of a preamble. An NTG block (501 or 502) is selected based on having a native timing sampling instance with a phase error that is closest to zero. Since there is an equal chance that either of the circuits in a circuit pair will be selected, if the circuit implementing the current non-native architecture is selected, a separate signal is generated. This signal adds the equivalent of 180° to the error value that is provided to the timing recovery circuit.

Abstract: The invention relates to a method for forming a training sequence in a communication system, in which information is transmitted at one or several carrier frequencies, the training sequence (T) being used at least as a synchronization signal. The training sequence (T) is composed of three or more training parts (103-106; 209-212) by any of the following methods. In the first method, at least two adjacent training parts (103, 104; 209, 210) in the training sequence (T) are formed substantially identical, and furthermore, at least one training part (105, 106; 211, 212) is formed substantially as a negation to said identical training parts (103, 104; 209, 210). In the second method, at least two adjacent training parts (103, 104; 209, 210) in the training sequence (T) are formed substantially identical, and furthermore, at least one training part (105, 106; 211, 212) is formed substantially different from said identical training parts.

Abstract: In a coding method and a coder for introducing a non-audible data signal into an audio signal, the audio signal is first transformed to a spectral range and the masking threshold of the audio signal is determined. A pseudo-noise signal and a data signal are provided and multiplied with each other so a to provide a frequency-spread data signal. The spread data signal is weighted with the masking threshold, and thereafter the audio signal and the weighted data signal are superimposed. In a method and a decoder for decoding a data signal introduced into an audio signal in non-audible manner, the audio signal is first sampled and thereafter the sampled audio signal is filtered in non-recursive manner. The filtered audio signal is subsequently compared to a threshold value so as to retrieve the data signal.

Abstract: An adaptive equalizer for use in a communication receiver that prevents equalizer operation divergence in response to slicer errors in a high noise communication application. The equalizer uses the difference between an equalized sample value and the nearest constellation point determined by the slicer both as the equalizer adaptation value and as a control value to selectively enable or minimize (disable) adaptation modifications. The difference is compared to a threshold value to determine whether the difference should be applied to the equalizer for adaptation purposes or a minimal value to prevent equalizer divergence in response to significant slicer errors. The threshold value is determined as a function of the ratio of the probability of correct slicer determinations and the probability of incorrect slicer determinations for a given sample value and a given signal to noise ratio.

Abstract: In an Asymmetric Digital Subscriber Loop (ADSL) Discrete Multi-Tone (DMT) system, ADSL DMT equipment includes an encoder that operates on a DMT input signal representing ƒ symbols/sec. to generate, for transmission, a DMT output signal representing Nƒ symbols/sec., where N>1, and where each symbol from the DMT input signal is generated in a redundant form in the DMT output signal. In one example of a redundant form, each symbol from the DMT input signal is repeated in N consecutive symbol intervals in the DMT output signal. In another example of a redundant form, every N DMT input symbol values are transmitted in 2N consecutive symbol intervals in the DMT output signal. These 2N consecutive symbols in the DMT output signal include 1) N symbols whose values equal the respective N DMT input symbol values and 2) N symbols whose values are a function of the respective N DMT input symbol values.

Abstract: A channel compensator for estimating and for compensating a phase change and a residual frequency offset of a despreaded signal, prior to synchronous demodulation in a DS-CDMA receiver. In the channel compensator, a first integrator accumulates input signals sampled at a given chip rate for a predetermined period and multiplies the accumulated value by a given gain. A shift register having a plurality of registers shifts the data output from the first integrator. A second integrator integrates the data generated at once from the respective registers of the shift register. A delay means delays the input signal for a predetermined time, and a multiplier multiplies the delayed input signal by an output of the second integrator in order to generate the compensated signal. The delay device delays the input signal by a time required for the input signal to reach a central register of the shift register through the first integrator.

Abstract: In a condition where periodically varying noise is generated, multi-carrier transmission is efficiently performed. On a central office (XTU-C), a tone of tone generating portion is transmitted with controlling level by a clock synchronized with a noise. On a terminal (XTU-R), a clock period is detected by a clock detector. A pseudo random signal (including all carriers) is transmitted from a pseudo random signal generating portion on the side of central office. On the side of terminal, an SNR of carriers per previously detected clock period (noise period) is measured by an SNR measuring portion. According to a result of measurement, power/bit distribution of each carrier is derived by a power/bit distribution calculating portion to store as a demapping information upon down carrier transmission. Also, the power/bit distribution is also transmitted to central office to be stored in a mapping portion of the central office. By this, down transmission is performed.

Abstract: A DSL communication system including a DSL transmission unit at a central office (DTU-C) and a DSL transmission unit at a remote location (DTU-R) in communication over a communication link. DTU-C and DTU-R are capable of transmitting and receiving packets of data prior to synchronization or training. DTU-C transmits a discovery message to DTU-R and awaits receiving a discovery response message from DTU-R. After receiving the discovery response message, DTU-C transmits a probe message to DTU-R followed by a probe signal. DTU-R measures the line quality while receiving the probe signal. After receiving the probe signal, DTU-R transmits a probe signal to DTU-C, using which signal DTU-C measures the line quality. After transmitting the probe signal, DTU-R transmits a probe response message, including line quality measurements performed by DTU-R. DTU-C and DTU-R may negotiate a first data rate by transmitting data rate messages based on the line quality measurements.

Abstract: An arrangement to analyze the nonlinear properties of a communication channel that uses a test signal having a number of tones. The test signal is transmitted via the communication channel to be evaluated. For the individual tones of the test signal, equidistant tone frequencies are selected, some of these tone frequencies not being used for the test signal. By the use of frequency shifters in the form of digital modulators, which shift the frequency spectrum of the transmitted test signal to zero by in each case one tone frequency value that is not used, nonlinear interference can be determined with the aid of a low-pass filter.

Abstract: A method is presented for changing data rates in a communication connection between a transmitting device and a receiving device, in which communication connection—the information to be transmitted is in the form of bits grouped to code words and—bits are diagonally interleaved from code words into symbols, a predetermined number of consecutive symbols consituting a burst. The method comprises constructing the symbol according to a predetermined set of rules, wherein said predetermined set of rules are chosen according to the length of the code words.

Abstract: When multiplexing channels which conduct communication at various transmission rates, each communication is made capable of conducting communication processing, such as information reception, with a minimum required processing amount needed by itself. A plurality of communication channels are set in a predetermined band, and communication in each of the set channels is performed by using a multi-carrier signal having transmission symbols distributed among a plurality of subcarriers. Transmission symbols of each channel on a frequency axis are arranged at intervals of an Nth power of 2 (where N is an arbitrary positive number) with respect to a reference frequency interval for transmission. From the transmission signal, a signal component of a required channel is received.

Abstract: A service chip for use with a computer. The chip includes a CPU interface, a transceiver interface, an adaptive echo cancellation filter, a monitor, and first and second data synthesizers. The CPU interface receives a transmit sample sequence from a modem sample generator executing on a central processor of the computer, and presents a receive sample sequence to a modem sample receiver executing on the central processor. The transceiver interface presents data to a line interface, which includes digital-to-analog and analog-to-digital converters for converting samples to/from analog signals for transmission on a telephone line. The filter adapts in response to an echo correlation between data transmitted over a transmit channel of the modem and data received on a receive channel of the transceiver interface. The monitor monitors the transmit sample sequence for a data starvation condition.

Abstract: Correlation power at each timing is computed, a maximum value of the correlation power is obtained, time sequence is reversed by the time-reverse circuit from the timing at which the maximum value is detected by considering the timing corresponding to the maximum value as a tentative bit timing, correlation power is compared with a threshold value, and a timing at which the correlation power exceeds the threshold value is detected and outputted by a timing detecting circuit as the bit timing.

Abstract: A data transmission/reception system made up of a transmission device for transmitting data according to a transmission clock signal and a reception device for receiving the data according to a reception clock signal. On receiving synchronization data representing the transmission clock signal from the transmission device, the reception device generates the reception clock signal which is synchronous to the transmission clock signal using a PLL circuit, and notifies the transmission device of an input voltage applied to a VCO in the PLL circuit on completing PLL processing. The transmission device adjusts a frequency of the transmission clock signal based on the notified input voltage so that the reception clock signal will be synchronized to the transmission clock signal at a median frequency in a synchronous range of the VCO in the PLL circuit.

Abstract: An interconnection interface for transmitting digital data between a sending module and a receiving module connected to one another through point-to-point serial links, forming a global data link. Each of the modules are provided, firstly, with a multiplexing unit associated with each of the serial links disposed in the module's physical layer, so as to distribute data transmitted through the global link at a speed determined by the sending module to a given number of parallel links, with each of these parallel links conveying a part of the transmitted data at a speed higher than the sending module data speed; and secondly, with a demultiplexing unit associated to the parallel links conveying received data parts, so as to synchronously and integrally reconstitute these received data parts at a speed accepted by the receiving module.

Abstract: A method is taught for improving the transmission of information signals in a communications system having a base station and a remote station. First and second transmission links are established with the remote station. An information signal is encoded to provide an encoded information signal having more bits than the information signal. First and second transmission signals are provided wherein each transmission signal has bits selected from the encoded information signal. Each of the first and second transmission signals is transmitted to the remote station by way of a respective one of the first and second transmission links. The remote station receives and combines the first and second transmission signals transmitted by the remote station to provide a combined encoded signal. The combined encoded signal is decoded by the remote station to provide the information signal.

Abstract: In a bidirectional data channel between a central station and a multiple of remote stations, a method for equalizing interference over a synchronized packet or frame based baseband transmission system wherein the crosstalk on the system is cyclostationary or periodic with a period equal to a symbol interval, the method comprising the steps of synchronizing the transmitters and receivers using the uncorrelated transmit signals; generating the cyclostationary NEXT and FEXT interference along with ISI using the uncorrelated symbols at the synchronized transmitters at one or more remote stations and the centrally station; using cascaded Fractionally Spaced Linear Equalizer (FSLE) and Decision Feed back Equalizer (DFE) for both interference suppression and equalization to minimize excess bandwidth at central receivers at the central station; increasing the receiver's FSLE filter taps (NT) to maximize Signal to noise ration; combining FSLE/DFE and proper phase sampling adjustments, enabling use of the spectral

Abstract: A method and apparatus for driving the DC output of a precoder in the transmitter of a data communication system to zero after the end of a scheduled transmission of data include the use of a DC canceling circuit in a feedback arrangement with the precoder to drive the DC output of the precoder and of the transmitter circuits associated therewith to zero.

Abstract: According to the present invention a transmitter for the wireless transmission of information data for example according to the OFDM system is provided. The transmitter comprises a random orthogonal transform (9) for random orthogonal transforming (ROT) of blocks of data to be transmitted by a multiplication of a symbol vector (26) comprising the data of one block, with a matrix (29). Furthermore up conversion element for transmission of data originating from the ROT (9) for random orthogonal transforming (ROT) are provided. According to the invention, the matrix operation uses a matrix (29) comprising n orthogonal columns, wherein n is the number of data samples comprised in one of said blocks, for example the number n used for the following IFFT procedure (10). The number of rows of said matrix (29) is larger than the number of said columns of said matrix (29). According to a further aspect of the present invention, a plurality of mutually orthogonal matrices are used in one base station.

Abstract: A DSL communication system including a DSL transmission unit at a central office (DTU-C) and a DSL transmission unit at a remote location (DTU-R) in communication over a communication link. DTU-C and DTU-R are capable of transmitting and receiving packets of data prior to synchronization or training. DTU-C transmits a discovery message to DTU-R and awaits receiving a discovery response message from DTU-R. After receiving the discovery response message, DTU-C transmits a probe message to DTU-R followed by a probe signal. DTU-R measures the line quality while receiving the probe signal. After receiving the probe signal, DTU-R transmits a probe signal to DTU-C, using which signal DTU-C measures the line quality. After transmitting the probe signal, DTU-R transmits a probe response message, including line quality measurements performed by DTU-R.