Abstract: Methods, system, nodes and computer program for transmission of a synchronous data stream having a bitrate, over an asynchronous packet data network between a transmitter node and a receiver node comprising: packaging, by the transmitter node, the synchronous data stream into data packets, transmitting, by the transmitter node, the data packets onto the asynchronous packet data network with a fixed packet rate defined by a first clock frequency which corresponds to the average distance in time between two consecutive data packets transmitted onto the asynchronous packet data network, which is independent of the bitrate of the synchronous data stream, receiving, by the receiver node, the data packets from the asynchronous packet data network detecting, by the receiver node, the fixed packet rate, and based on the fixed packet rate, regenerating, by the receiver node, the first clock frequency by detection of the distance in time between two consecutive data packets received from the asynchronous packet data ne

Abstract: An optical system is provided comprising a first node and a channel drop add device. The first node is configured to transmit data onto an optical fiber in a first line direction. The channel drop add device (501) is adapted to receive and add channels onto the optical fiber thereby transmitting the data into the first and a second line direction. The network further comprises a second node configured to form a transmitter/receiver function. The second node is configured to receive data on said optical fiber from said first and second line directions. Further, the second node is adapted to synchronize received data from said first and second line directions by delaying the data signals seeing the shortest delay, by a delay device.

Abstract: Described are, among other things, a method and a receiver for receiving a management data signal in an optical transmission system where a traffic data signal is transmitted as a NRZ modulated signal. The traffic data signal has a management data signal superimposed thereon as a pulse width modulation of the symbols of the NRZ modulated signal. The NRZ modulated signal is received with the data signal superimposed thereon and the traffic data signal is recovered. The recovered traffic data signal in anti-phase is added to the received signal. The management data signal is detected from the added signals.

Abstract: In a data transmission system, a first node receives at least two sets of input data signals including at least two signals being based on different synchronization sources. The first node extracts a respective clock signal representing the embedded clock signals from the sources, samples and formats these signals for transmission according to a TDM structure. The TDM formatted signals are transmitted as at least one bit stream over a transmission medium to at least one second node, where the bit stream is demultiplexed into at least two sets of output data signals respective demultiplexed clock signals representing the sampled clock signals. A jitter attenuating mechanism reduces an amount of frequency jitter to below a predefined level to produce a respective clock signal having a synchronization quality superior to that of the demultiplexed clock signals. An interface module recombines each data signal with its associated clock signal.

Abstract: A sampling unit (110) receives an input clock signal (CLKin) having a varying period time, and samples the input clock signal (CLKin) based on a sampling clock signal (CLKsmpl) that has a frequency being substantially higher than an average frequency of the input clock signal (CLKin). The sampling unit (110) produces a respective period length value (PL) for each period of the input clock signal (CLKin). An averaging unit (120) receives a number of period length values (PL) from the sampling unit (110), and based thereon produces an average period length value (PLavg) representing an average period time for the input clock signal (CLKin) over an averaging interval including a number of periods equivalent to said number of period length values (PL). An output unit (151) produces a stabilized output clock signal (CLKout) based on the average period length value (PLavg) and the sampling clock signal (CLKsmpl).

Abstract: In a data transmission system, a first node (100) receives at least two sets of input data signals (d-in1, d-in2) including at least two signals being based on different synchronization sources. The first node (100) extracts a respective clock signal (CLKex1, CLKex2) representing the embedded clock signals from said sources, samples and then formats these signals (CLKsp1, CLKsp2) for transmission according to a TDM structure. The TDM formatted signals are transmitted as at least one bit stream (bs1, bs2) over a transmission medium (L1, L2) to at least one second node (201, 202), where the bit stream (bs1, bs2) is demultiplexed into at least two sets of output data signals (d-out1, d-out2, d-out3, d-out4) respective demultiplexed clock signals (CLKdm1, CLKdm2) representing the sampled clock signals.

Abstract: A sampling unit (110) receives an input clock signal (CLKin) having a varying period time, and samples the input clock signal (CLKin) based on a sampling clock signal (CLKsmpl) that has a frequency being substantially higher than an average frequency of the input clock signal (CLKin). The sampling unit (110) produces a respective period length value (PL) for each period of the input clock signal (CLKin). An averaging unit (120) receives a number of period length values (PL) from the sampling unit (110), and based thereon produces an average period length value (PLavg) representing an average period time for the input clock signal (CLKin) over an averaging interval including a number of periods equivalent to said number of period length values (PL). An output unit (151) produces a stabilized output clock signal (CLKout) based on the average period length value (PLavg) and the sampling clock signal (CLKsmpl).

Abstract: The invention concerns an arrangement for supervising and/or controlling the bit rate of data pulses that are transmitted from a transmitter (16) to at least one optical conduction path (22). The transmitter (16) has an input side (18) which receives electrical pulses from an electric connection (14) and an output side (20) from which light pulses are transmitted in response to the received electrical pulses. The arrangement comprises a supervising unit (24) with at least one input (26) which is suited to be connected to said electric connection (14). The supervising unit (24) is arranged to estimate or determine the bit rate of the pulses that are received at said input (26). The arrangement is arranged to carry out at least one measure which depends on the estimated or determined bit rate.

Abstract: The present invention relates to a system for optical transmission of information over a multiplexed logical ring structure comprising a number of nodes, of which at least one is a master node, as stated in the independent claim 1. Said ring structure is a combination of a number of logical optical rings on the same physical fiber ring. Possible embodiments are disclosed in the dependent claims.

Abstract: The invention relates to a method for conveying management information in a WDM system from a number of wavelength converters to a central management unit, wherein a management information signal is superimposed on the WDM signal from the respective wavelength converter. A fraction of the optical signal in the common optical transmission line is tapped off to a detector and the different management information signals are recovered by a receiver unit which is connected to the detector. The invention also relates to a WDM system and a pluggable WDM wavelength converter.

Abstract: The invention concerns a transmitter circuit comprising a light source (20) and arranged to operate said light source (20) to transmit optical communication signals in response to balanced electric input signals from a first (11) and a second (12) circuit point. The transmitter circuit comprises a first (21) and a second (22) circuit branch which extend from said first (11) and second (12) points, respectively. The light source (20) is connected between the circuit branches (21, 22). The components which are positioned on the circuit branches (21, 22) are selected such that the transmitter circuit is formed with a symmetry which is such that, under normal operation conditions, a balanced drive voltage is the case between the connection points (13, 15) of the light source (20) on the circuit branches (21, 22) and such that the modulation current which drives the light source (20) essentially only depends on the voltage difference between said connection points (13, 15).

Abstract: The invention concerns a transmitter-receiver device (A, B) which comprises a receiver unit (RXA) arranged to receive light and optical signals from a transmitter unit (TXA) arranged to transmit light and optical signals. The device also comprises a supervising unit (CUA) which prevents the transmitter unit (TXA) from continuously transmitting light when the supervising unit (CUA) detects that the receiver unit (RXA) does not receive light. The supervising unit (CUA) is arranged to, when it detects that the receiver unit (RXA) does not receive light, change to a test mode where the transmitter unit (TXA) is controlled to intermittently transmit short light pulses the supervising unit has an output (109) where a status signal indicates whether the transmitter-receiver device is in said test mode. The invention also concerns a communication system which comprising at least two such transmitter-receiver devices.

Abstract: The invention concerns a transmitter-receiver device (A, B) which comprises a receiver unit (RXA) for receiving optical signals and transmitter unit (TXA) for transmitting optical signals. Furthermore, the transmitter-receiver device (A, B) comprises a supervising unit (CUA) which supervises the functions of the receiver unit (RXA) and the transmitter unit (TXA). Furthermore, the transmitter-receiver device (A, B) comprises a transmitter circuit which transmits optical communication signals in response to a balanced electric input signal. The invention also concerns a communication system comprising two transmitter-receiver devices (A, B). Through the structure of the invention is by relatively simple means a well functioning device achieved, which, inter alia, makes it possible to supervise the status of the two transmitter-receiver devices (A, B) in an advantageous manner.

Abstract: The invention concerns a method of connecting a subscriber unit (12) to a fiberoptic communication network (14) via a fiberoptic interface device (30) adapted to function as an interface device (30) in a coarse wavelength division multiplex (CWDM) system. The interface device (30) comprises an electric circuit arrangement (32) and a first (34) and a second (36) receiving section adapted to receive transceiver modules (24, 70). According to the method, an opto-electric transceiver module (24) is arranged in said first receiving section (34) and connected to said fiberoptic communication network (14). A first electric transceiver module (70) is provided and arranged in said second receiving section (36). The interface device (30) is connected, via said electric transceiver module (70), to said subscriber unit (12) via electrical conduction paths (82, 86). The invention also concerns a method of testing the function of said interface device (30).

Abstract: The invention concerns an interface device for a fiberoptic communication network. The interface device comprises an electric circuit arrangement 32, a first receiving section 34 for receiving a first transceiver module 24 and a second receiving section 36 for receiving a second transceiver module 26. The interface device also comprises a switching unit 54 for switching said electric circuit arrangement between at least a first and a second state. Furthermore, the interface device includes a controller 56 arranged to automatically control the switching unit 54 in response to at least one control signal such that said first or second states are selected depending on whether at least one control signal is received indicating either that no transceiver module 26 is attached to said second receiving section 36 or that no optical signal above a certain signal level is received by a transceiver module 26 attached to said second receiving section 36.

Abstract: The invention concerns an amplifier circuit for receiving an optical signal. The circuit comprises a light sensitive member (301) which delivers an electric signal in response to an optical signal. Furthermore, the amplifier circuit comprises an amplifier unit (302) with a first input (304) which receives an electric signal from the light sensitive member (301). The amplifier unit (302) is of the kind which does not have any special input intended for controlling the amplification. A filter unit (310) prevents a possible direct current from the light sensitive member (301) from reaching the first input (304). A control unit (314) is connected to the first input (304) for controlling the amplification of the circuit. The invention also concerns an optical communication system comprising an amplifier circuit of the above-described kind. The invention also concerns a method of controlling the amplification in an optical input stage.

Abstract: The invention concerns an amplifier circuit which comprises an amplifier unit (210) arranged to receive an input signal, to influence the amplification of this input signal and to transmit an output signal. The amplifier circuit also comprises a first control unit (210) and a second control unit (220). Those control units receive said output signal. Furthermore, the amplifier circuit comprises a selector unit (240) which is arranged to receive first and second control signals from the control units (310, 220). The selector unit (240) is arranged to control the amplification of the amplifier unit (201) in accordance with that one of said first and second control signals which gives the lowest amplification.

Abstract: The invention concerns a contact device that comprises a carrier member (10), a receiving unit (12) for receiving at least one optical fibre (14), a control circuit (16) that includes a converter for converting optical signals to electrical signals and vice versa and a first contact member (18) connected to the control circuit (16) and designed such that a second contact member may be connected to the first contact member (18) for conducting electrical signals from and to the first contact member (18). The receiving unit (12), the control circuit (16) and the first contact member (18) are fixed relative to the carrier member (10). The contact device is designed to be fixable at a structural element (20) in a room (22) or other part (22) of a building. The invention also concerns a use of the contact device.