Abstract: A network node of a synchronous network, wherein said network node comprises a timing circuit which recovers a reference clock from a reception signal received by said network node from an upstream network node of said synchronous network and uses the recovered reference clock for a transmission signal transmitted by said network node to a downstream network node of said synchronous network; and a clock stability monitoring circuit which monitors internal control parameters (CP) of said timing circuit to detect an instability of the reference clock distributed within said synchronous network.

Abstract: A time aware device for a packet switched network comprising at least one time tag processing unit adapted to process time tag data of a predetermined time tag data field (TTDF) provided within a header of a tagged data packet (TDP) transported in said packet switched network to provide time related information reflecting a delay undergone by said tagged data packet (TDP) during its transport in said packet switched network.

Abstract: Disclosed are a device and a method for transmitting an optical data signal over an optical transmission channel, comprising a differential phase shift keying unit for differential phase shift keying of at least one serial data stream to generate a differential phase shift keying coded data stream; an amplitude shift keying unit for amplitude coding of at least two further serial data streams that can be selectively activated to generate an amplitude shift keying coded data stream; and a modulation unit for generating an optical data signal in accordance with a control signal that is, formed from the generated differential phase shift keying coded data stream and from the generated amplitude shift keying coded data stream.

Abstract: An optical line termination node has a first connection arrangement for connecting a working fibre, a second connection arrangement for connecting a protection fibre, a transceiver arrangement having first primary link and a first secondary link, and protection switching means configured for being switched either in a working operating state or in a protection operating state.

Abstract: The invention relates to a network comprising at least one host device having an interface card connected to a backplane of said host device, wherein said interface card comprises at least one cage for receiving a pluggable module which performs a traffic management of data transported via at least one optical fiber connected to said pluggable module.

Abstract: The invention relates to a method and an arrangement for measuring power for an optical user signal transmitted via an optical fiber by converting the transmitted optical user signal into a pulsed optical measurement signal, the pulse repetition rate of which is dependent on the power of the transmitted optical user signal, and evaluating the pulse repetition rate of the converted optical measurement signal in order to ascertain the power of the optical user signal transmitted via the optical fiber.

Abstract: The invention relates to a method of operating a first optical network element (100), particularly an optical network unit, ONU, wherein said method comprises the following steps: performing a coarse tuning process (2100) of at least one transmission wavelength which is used by said first optical network element (100) for transmitting an optical signal to a second optical network element (200), particularly an optical line terminal, OLT, and performing a fine tuning process (2200) of said at least one transmission wavelength, wherein said fine tuning process (2200) is preferably performed after said coarse tuning process (2100).

Abstract: The invention relates to a network comprising at least one host device having an interface card connected to a backplane of said host device, wherein said interface card comprises at least one cage for receiving a pluggable module which performs a traffic management of data transported via at least one optical fiber connected to said pluggable module.

Abstract: The invention relates to a fractional bit encoder (1) and a method for encoding a data stream into code word identifiers for a physical line encoder (13), wherein said fractional bit encoder (1) comprises a (1:K) demultiplexer (3) for a de-multiplexing a received data stream into a predetermined number (K) of bit streams, a first (K1:n) multiplexer (4) for re-multiplexing a first number (K1) of said K bit streams onto n parallel lines transporting n re-multiplexed bit streams and a second multiplexer (5) re-multiplexing a second number (K2) of said K bit streams (K2:1) onto a single line transporting one further re-multiplexed bit stream, wherein n=[ld(M)] and M being a configurable number of different code word identifiers, a class detector (7) which evaluates the first n re-multiplexed bit streams to determine a class of the respective bit combination and a word encoder (10) which encodes the respective bit combination depending on the determined class of the bit combination.

Abstract: The present invention encompasses a method for 1+1 protection of an optical transmission path comprising a working path and a protection path that connect a first and second terminal node. In a working mode, an optical transmission signal is transmitted via the working path from the first to the second terminal node. At the second terminal node, the optical transmission signal is split into two optical sub-signals, and one of the optical sub-signals is sent via the protection path to a protection-path connection node as a working-path control signal. In the case of an interruption of the signal transmission via the working path, the protection-path connection node detects the absence of the working-path control signal and switches the system from the working mode to a protection mode in which signal transmission is conducted via a separate protection path.

Abstract: It is described an optical amplification device for receiving an optical input signal and transmitting an amplified optical output signal on the basis of the optical input signal comprising an optical amplifier that comprises an input and an output. An optical gain control unit is connected to the output path of the optical amplifier and the optical gain control unit is connected to the input path of the optical amplifier. The optical gain control unit is configured to control the gain of the optical output signal. Additionally, an electrical gain control unit is connected to the output path of the optical amplifier. The electrical gain control unit is also connected to the input path of the optical amplifier. The electrical gain control unit is configured to control the gain of the optical output signal. By providing both an electrical gain control unit and an optical gain control unit, a control characteristic can be improved.

Abstract: The invention provides a method and a system for localizing an attenuation change location in an optical waveguide, wherein the attenuation change location can be determined depending on a time difference (?T) between signal power change instants of optical signals having different wavelengths (?1, ?2) that are transmitted via the optical waveguide.

Abstract: The invention relates to a data transmission unit for high bit-rate optical data signals, in particular, high bit-rate optical data signals with a backplane, which has a line structure connecting several plug-in positions for several receiver or transceiver cards to each other and/or to one or more additional data processing cards, with the cards, each held in one of the plug-in positions and each having at least one input port for a high bit-rate data signal. Each card also has at least one output port, to which the relevant one or more high bit-rate data signals can be fed, and each of these output ports is connected via a serial data line between the plug-in position holding the relevant receiver or transceiver card and an input port of a central selection unit with the relevant input port. The output ports connect serially to the central selection unit.

Abstract: A system and method comprise a first buffer having a first capacity and a first threshold level adapted to store data frames having the lowest priority, a second buffer having a second capacity greater than the first capacity and a second threshold level greater than the first threshold level adapted to store data frames having a medium priority, a third buffer having a third capacity greater than the second capacity and a third threshold level greater than the second threshold level adapted to store data frames having the highest priority. The system further includes means for differentiating a data frame as having lowest, medium or highest priority and storing the data frame in the respective first, second or third buffer, and discarding the data frame in response to the first, second or third buffer reaching the respective threshold level.

Abstract: The invention relates to a method for monitoring an optical amplifier, in particular, an optical fiber amplifier which has an optical input port and an optical output port. The optical pumping power of the amplifier is presumed to be directly proportional to the electrical pumping current, with a proportionality constant that decreases over time due to degradation. The functional dependence of the optical pumping power on the optical input signal power or the optical output signal power is determined at least for the predetermined nominal value of the optical gain. These relationships may be combined with certain measured values to determine the instantaneous optical pumping power, the instantaneous proportionality constant, and the maximum values for the optical input and output signal powers. These calculated parameters may be used to ensure that an increase of input power will not reduce the optical gain.

Abstract: Systems and methods for monitoring a data transmission link, especially an optical, bidirectional data transmission link, in which a digital transmit signal is transmitted on a first transmission path from a local end of the data transmission link toward a remote end of the data transmission link. A portion of the power of the transmit signal sent at the local end is transmitted, delayed by a non-zero delay time on a second transmission path as a control signal toward the remote end of the data transmission link. Both signals are received at the remote end and are tested for the presence of events of a predetermined type. A conclusion can be reached on the quality of the transmission link as a function of a time correlation and frequency of the appearance of events in the received transmit signal and in the received control signal.

Abstract: A system coupled between at least one input port and at least one output port comprises at least one queue, each queue being identified by a QID and operable to receive and buffer data in at least one service flow from the at least one input port. The system further comprises a predetermined at least one token allocated to each queue, each token indicative whether a predetermined amount of data may be dequeued from a queue and transmitted to the output port. The system comprises at least one group of queues where each queue in the group has a subordinate QID identifying a subordinate queue in the group having a lower priority for reallocating unused tokens. The at least one output port receives at least one output flow comprising the dequeued data from the at least one queue.

Abstract: A circuit for transmitting signals in a network node, particularly for a channel card for an optical WDM signal transmission device, with a first holding device assigned to the local side of the network node, which can be freely equipped by means of a local-side transceiver unit and which has an internal transmitting port connection and an internal receiving port connection which, in case first holding device is equipped with local-side transceiver unit, are connected to the respective transmitting or receiving ports of local-side transceiver unit, with two additional holding devices assigned to the remote side of the network node having similar ports. A controllable signal switching unit is provided with novel construction to configure connections between the respective internal ports.

Abstract: The invention relates to an optical circuit structure for realizing a higher-order node in an optical transmission network with a number N of bidirectional remote ports, wherein an optical receive wavelength division multiplexed signal with a set of optical receive channels can be fed to each remote port and wherein an optical transmit wavelength division multiplexed signal with a set of optical transmit channels can be output from each remote. The optical drop channel means and the optical add and cross-connect means include exclusively optical splitter units, optical demultiplexing units, and optical add units, wherein for generating each transmit wavelength division multiplexed signal for a certain remote port, the receive wavelength division multiplexed signals of several or all of the other remote ports are guided as cross-connect wavelength division multiplexed signals toward the certain remote port.

Abstract: A method for monitoring an optical transmission line in which digital optical signals are transmitted bidirectionally between a first and a second end point of the transmission line. At the first end point of the transmission line the digital optical signal to be transmitted to the second end point is amplitude-modulated with a preset frequency, with the modulation amplitude being small relative to the amplitude of the digital signal. At the second end point of the transmission line a small fraction of the power of the received digital signal is overcoupled passively on the optical transmission line in the direction towards the first end point and is transmitted to the first end point together with the digital signal to be transmitted from the second end point to the first end point of the optical transmission line. At the first end point the amplitude-modulated component of the received digital signal is detected.