Tellabs Oy

Coriant Oy

Other

Laamanen, Heikki

Hann, Kenneth

Gowda, Umesh

Heikki Laamanen

Kenneth Hann

Mikko Laulainen

Antti Holma

Jonas Lundqvist

Janne Väänänen

Petri Kohonen

Ian Leiman

Vesa Hokkanen

Umesh Gowda

Jännë Väänänen

Markus Hurme

Jonas Lunquist

A device and a method for generating a secondary timing signal that is synchronous with a primary timing signal are presented. The method comprises deriving () an auxiliary timing signal from an auxiliary signal received at a first site and correcting () the timing phase of the auxiliary timing signal so as to obtain the timing phase for the secondary timing signal. The timing phase is corrected with the aid of the following a) a constant phase shift between the auxiliary timing signal and another auxiliary timing signal derived in a second site where both the primary timing signal and the auxiliary signal are available and b) a dynamic phase shift between the other auxiliary timing signal and the primary timing signal at the second site.

Method and a device for generating a timing signal

Equipment including at least one plug-in unit and a body device for receiving the plug-in unit is presented. The plug-in unit includes a mechanical structure () enabling the plug-in unit to be locked in its operating position with respect to the body device with a fastening element () that can be, for example, a fastening screw. The plug-in unit further includes a sensor circuit () having first electrical properties when the fastening element is in the position locking the plug-in unit in the operating position and otherwise different electrical properties. The equipment includes a monitoring circuit () for generating a signal indicative of a difference between the prevailing electrical properties of the sensor circuit and the first electrical properties, the signal being indicative also of correctness of the installation of the plug-in unit. Thus, the correct installation of the plug-in unit can be electrically indicated and monitored.

Equipment and a plug-in unit of the equipment

Equipment including at least one plug-in unit () and a body device () for receiving the plug-in unit is presented. The equipment includes a circuit () including a test signal generator for supplying a test signal to a measurement circuit including galvanic contacts provided by electrical connectors between the body device and a plug-in unit so that the test signal belongs at least partly to a frequency band used in data transfer between the plug-in unit and the body device. The equipment includes a monitoring circuit for generating a signal indicative of a difference between a quantity responsive to the test signal and a reference. As the test signal belongs at least partly to the frequency band used in the data transfer, the quality of the galvanic contacts between the body device and the plug-in unit can be monitored concerning the behavior on the data transfer frequency band.

Equipment including at least one plug-in unit and a body device for receiving the plug-in unit is presented. The plug-in unit includes an electrically conductive structure () having at least one surface area capable of forming a capacitive coupling with a surface area of an electrically conductive part () of the body device when the plug-in unit is inserted in the body device. The equipment further includes a monitoring circuit () for generating a signal indicative of electrical properties of a measurement circuit including the capacitive coupling and at least one galvanic contact provided by electrical connectors of the plug-in unit and the body device. The generated signal is also indicative of correctness of the installation of the plug-in unit. Thus, the correct installation of the plug-in unit can be electrically indicated and monitored.

Equipment provided with one or more plug-in units

A device for controlling a clock signal generator includes a processor () for forming at least two mutually different control quantities on the basis of reception moments of timing messages such as time stamps, where the reception moments are expressed as time values based on a first clock signal and the timing messages are transmitted in accordance with a second clock signal. The processor also calculates a weighted sum of the control quantities, and controls the clock signal generator with the weighted sum so as to synchronize the first clock signal and the second clock signal. The control quantities may represent, for example, a filtered value of observed phase-errors, a phase-error corresponding to a minimum observed transfer delay, and phase-errors corresponding to a given portion of the delay distribution. Using the weighted sum of the mutually different control quantities improves the utilization of the information content of the timing messages.

Method and a device for controlling a clock signal generator

An arrangement for adjusting a clock signal in a network element of a communications network includes a processor device arranged to produce a control variable containing information about synchronization messages received from at least two other network elements. A situation in which the reception from a sending network element of synchronization messages of a good enough quality ceases will not significantly disturb the clock signal to be adjusted because only part of the control variable used for the adjustment depends on synchronization messages sent by an individual network element. In a preferred arrangement, the reference value of the control variable is changed in response to a situation where the reception from a sending network element of synchronization messages of a good enough quality ceases. Thus it is possible to reduce the change of the difference between the control variable and its reference value which further reduces disturbances caused in the clock signal to be adjusted.

Method and arrangement for adjustment of a clock signal

A method and arrangement for transferring synchronizing information in a data transmission system includes modem connections. The arrangement includes a modulator () arranged to generate an analog signal () modulated by synchronizing information, the frequency spectrum of the signal being located in a frequency range that falls outside the data transmission bands of the modem line connected to the network element. The arrangement includes a switching circuit () arranged to connect the analog signal to a data transmission cable () that forms part of the modem line connected to a network element. The arrangement includes a second switching circuit () arranged to receive the analog signal from a data transmission cable that forms part of the modem line connected to the second network element. The arrangement also includes a regenerator (-arranged to regenerate the synchronizing information from the analog signal.

Method and arrangement for transferring synchronizing information

A method and system for adjusting a clock signal in a network element of a data network adjusts the clock signal based on difference values formed by received synchronizing messages. Each difference value is a difference of a reception and transmission values of a received synchronizing message. The reception value depends on a cumulated number of periods of the clock signal at a moment of arrival of the synchronizing message. The transmission value depends on a position of the synchronizing message in a chronological transmission order of synchronizing messages. When adjusting, an adjusting effect of the difference values belonging to a lower part of a margin of fluctuation of the difference values is weighted more heavily than that of an upper part. Thus, for clock signal adjustment, that share of information represented by the received synchronizing messages that has the least interference is used, irrespective of the data network load.

Method and system for synchronizing clock signals

A method and equipment for obtaining routing data for a data transfer packet is presented. The data transfer packet is associated with information indicating a quality-of-service class of the data transfer packet and is related to protocol data associated with a data transfer protocol being used. The method using the protocol data as an input quantity for reading basic data and a reduction rule that are compatible with a routing table and the protocol data, using the information indicating the quality-of-service class as an input quantity of the reduction rule for obtaining auxiliary routing data, and obtaining the routing data on the basis of the basic data and the auxiliary routing data. The reduction rule connects auxiliary data to each quality-of-service class in such a way that each auxiliary data is associated with at least two different quality-of-service classes in order to reduce the amount of required storage capacity.

Method and equipment for making a routing decision dependent on a quality-of-service class

The invention relates to determining a quantity to be measured from a communication system, such as a transmission delay or the phase difference of clock times. Measurement messages are transmitted () between the two areas of the communication system in both transmission directions. Values of the time difference are calculated () for the measurement messages transmitted in at least one of the transmission directions, each of which values is the difference between the instant of reception measured at the reception and the instant of transmission measured at the transmission of the measurement message. The values of the time difference are used to calculate () an estimate of the distribution of the time difference, on the basis of which an estimate of the minimum value of the time difference is calculated ().

Method and equipment for measurements

The objective of the invention is to devise a method for establishing a subscriber connection and a system applying the method. According to the method, a digital subscriber connection consisting of a composition of an optical fiber and a metallic pair cable is implemented by transporting a digital information stream in two directions over an optical fiber () between a central site and equipment () which is connected to the metallic pair cable () of each subscriber. According to the invention, the information streams transmitted and received over the pair cables are multiplexed onto the optical fiber by using a multiplexing method of optical signals, whereby the information streams originating from different subscribers are combined onto the fiber by means of passive optical elements and whereby the information streams transmitted from the central site are distributed to each subscriber-specific optical-to-electric conversion element () by means of passive optical elements. Thus the multiplexing and demultiplexing need no active multiplexing/demultiplexing electronics common to all subscribers, but rather the active electronics of the conversion elements () of each subscriber operates independently without being dependent on the state of operation of other subscriber's conversion elements. Hence the operating power for said electronics can be fed from the respective subscriber through the subscriber's pair cable.

Method for establishing a subscriber connection and a system utilizing the method

The present invention concerns adjustment of tap coefficients of a Tomlinson-Harashima precoder in a digital communications path during a data transmission state. According to the invention, the tap coefficients of the Tomlinson-Harashima precoder are adjusted based on content values of a delay line of the Tomlinson-Harashima precoder and on an error variable associated with a receive. Synchronization between the error value and the content values of the delay line is performed according to line frame synchronization information.

Method and apparatus for implementing a channel correction in a digital data link

The invention relates to a method for implementing adaptive Tomlinson-Harashima precoding using a digital data communications link. According to the method, the outgoing bit stream is coded into symbols, channel distortion is corrected by precoding (TML) the symbols, the precoded symbols are sent over a data communications channel (, CHN), in which case the symbols, which have passed through the channel (, CHN) and signal processing means for the receiver are reconstructed to form a bit stream. According to the invention, updated precoder coefficient parameter values are formed with the aid of an error variable (e), which is dependent on the symbol decisions (S') of the receiver, the output signal of a decision-feedback equalizer, and a signal (Q) that is formed from the received signal by compensating the effect of the precoder transfer function of the received signal with an inverse precoder transfer functions.

Method and apparatus for implementing adaptive tomlinson-harashima precoding in a digital data link

The invention relates to a method and apparatus for improving the quality of receiver synchronization on QAM- or CAP-modulated modem connections having an adaptive linear equalizer. The invention is based on the finding that in a QAM- or CAP-modulated data transmission system where the symbol rate and the average carrier frequency are in fixed relationship with each other, the vector formed by the In-phase and the Quadrature component of the detector input signal rotates with the timing phase shift of the receiver. The quality of receiver synchronization is improved by utilizing information extracted from the vector rotation.

Method and apparatus for increasing the quality of the receiver synchronization of QAM or CAP modulated modem connection

The invention relates to a method and system for implementing a digitally controlled sample and timing clock in a system performing analog and digital signal processing. According to the method, as the timing clock of the digital signal processing is used a clock with a controllable frequency such that said digital signal processing can have a function suited for controlling the frequency of said timing clock, and the conversion of the signal is performed in synchronism with the timing clock of the digital signal processing operation when a delta-sigma converter or a switched-capacitor filter device is employed. According to the invention, the timing and sample clocks are generated by dividing a fixed-frequency clock operating at a frequency substantially higher than that of said timing/sample clock by a digital divider of an integer division factor whose division factor is controlled by means of an at least second-order delta-sigma modulator capable of delivering an output signal of two values so that one of the modulator output signal values selects the division factor to be N while the other value selects the division factor to be N+1, and, further, the delta-sigma modulator controlling the integer-factor divider is adapted to be clocked by the timing signal generated by said integer-factor divider.

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Espoo, Finland

Heikki Laamanen