Abstract: The present disclosure encompasses establishing and maintaining a routing protocol based on a measured link metric p, such as for a smart grid communication system. A link between a first node such as a router A and a neighbouring second node B of a communication path from a source to a destination in a packet oriented communication network is selected wherein the two nodes are connected via first and second communication links. An updated link metric p(t+1) at a point in time t+1 of the first communication link is determined. The first or the second communication link is selected for transmitting a further packet from node A to node B by comparing the updated link metric p(t+1) to a threshold pthr.

Abstract: A method and system are provided for determining a length quantity of a power transmission line, which connects a first location with a second location. A first signal having a first carrier frequency is provided at the first location. The first signal is transmitted from the first location to the second location via the power transmission line. A second signal having a second frequency is provided at the second location. A first phase difference between the first signal and the second signal is measured at the second location, and the length quantity is calculated from the measured phase difference. In the system, a second receiver at the second location is configured to receive the first signal having the first carrier frequency from the first location. A frequency generator creates the second signal having the second frequency at the second location.

Abstract: Exemplary embodiments of a communication system for a power electronic converter with a plurality of converter modules includes controllable power semiconductor switches and individually mountable onto a converter cabinet or frame. The communication system includes unguided transmission of optical signals between optical elements arranged on a converter module and on the converter cabinet, respectively. The communication system provides a free-space optical signal transmission between two distinct parts of the converter that combines the flexibility offered by radio transmission and the data rate and reliability of optical communication, while at the same time avoiding the complex and expensive cabling of optical fiber solutions.

Abstract: A method and arrangement are provided for time synchronization between two geographically separated stationary clocks, such as first and second clocks located respectively at first and second ends of an AC power line. A first representation of an oscillating power line quantity is produced by measuring or recording the power line quantity at the first end of the power line, and time-stamping the first representation by the first clock. A second representation of the same oscillating power line quantity is produced by measuring the power line quantity at the second end of the power line, and time-stamping the second representation by the second clock. The first and second representations are compared to determine a clock offset between the first and second clocks. Based on the comparison, one or both of the first and second clocks are adjusted to reduce the determined clock offset.

Abstract: The present disclosure relates to highly available communication networks, e.g., for industrial or utility applications such as substation automation. The devices are connected to two redundant lines through two independent transceivers and bus controllers, i.e. the physical layer and the link layer of the corresponding protocol stack is duplicated. For seamless operation, a sender sends frames simultaneously over both lines and a receiver accepts whichever frame of a pair comes first and ignores the late frame. An exemplary method is disclosed for discarding duplicate frames at the link layer without considering the higher protocol layers, based on a counter inserted in the frame and an algorithm for rejection, with a corresponding means to detect which frames operate according to the redundancy protocol.

Abstract: A flame detector is disclosed for monitoring a flame during a combustion process, comprising a camera and a carrier tube, wherein the camera is arranged at a front end of the carrier tube such that an optical access of the camera is directed toward the flame when the front end of the carrier tube is mounted in the vicinity of a burner nozzle aperture.

Abstract: A method for controlling a plurality of power converters connected to a power supply network is described. Each power converter includes high-power semiconductor devices. Control signals are sent between a controller and a wireless node of one or more of said plurality of power converters using a wireless communication system. The control signals are transmitted to a local wireless node of one or more of a plurality of power converters. The data transmissions include data packets including control information such that a clock of the local wireless node can be synchronized using time synchronization information of the wireless communication system. In other aspects of the invention a system employing the method and a computer program for carrying out the method are described.

Abstract: A method and system are provided for determining a length quantity of a power transmission line, which connects a first location with a second location. A first signal having a first carrier frequency is provided at the first location. The first signal is transmitted from the first location to the second location via the power transmission line. A second signal having a second frequency is provided at the second location. A first phase difference between the first signal and the second signal is measured at the second location, and the length quantity is calculated from the measured phase difference. In the system, a second receiver at the second location is configured to receive the first signal having the first carrier frequency from the first location. A frequency generator creates the second signal having the second frequency at the second location.

Abstract: Time synchronization of two clocks is disclosed herein, such as two stationary clocks. A global time signal from a global time reference or common time source can be used to calculate a common view based clock offset between the two clocks. In parallel, a network based clock offset between the two clocks can be calculated based on messages exchanged over a communication network interconnecting the two clocks, without reverting to the global time reference. Two recent values (e.g., the two most recent values) of the common view clock offset and the network based clock offset can be combined or superposed in a seamless way to produce a final time offset estimate. The combination of independently calculated common view and network based clock offsets can be a weighted average of the two values, involving respective weights based on quality estimates of the latter.

Abstract: The present invention is concerned with a method to encrypt OFDM modulation, by multiplying its underlying QAM symbols by a complex-valued generalized key stream sequence. Performing encryption on the physical layer ensures that all services and applications running over the OFDM modem will be protected against eavesdropping. It is also proposed to include in the encryption any training symbols used for synchronization and channel estimation. Only the legitimate receiver knowing the encryption key is hence able to synchronize and correctly demodulate the received signal. Attackers will not even be able to acquire the encrypted signal.

Abstract: Time synchronization of two clocks is disclosed herein, such as two stationary clocks. A global time signal from a global time reference or common time source can be used to calculate a common view based clock offset between the two clocks. In parallel, a network based clock offset between the two clocks can be calculated based on messages exchanged over a communication network interconnecting the two clocks, without reverting to the global time reference. Two recent values (e.g., the two most recent values) of the common view clock offset and the network based clock offset can be combined or superposed in a seamless way to produce a final time offset estimate. The combination of independently calculated common view and network based clock offsets can be a weighted average of the two values, involving respective weights based on quality estimates of the latter.

Abstract: A flame detector is disclosed for monitoring a flame during a combustion process, comprising a camera and a carrier tube, wherein the camera is arranged at a front end of the carrier tube such that an optical access of the camera is directed toward the flame when the front end of the carrier tube is mounted in the vicinity of a burner nozzle aperture.

Abstract: A method is proposed for operating a system according to TDMA (Time Division Multiple Access) with a multiplicity of wireless sensors and/or actuators as nodes (S.1 . . . S.n) and a base station (BS), said system being installed in a machine or installation, such as industrial robots or an automated manufacturing or production unit, whereby cyclical TDMA data transmission blocks are transmitted and each TDMA data transmission block is composed of consecutive time slots. Each time slot is allocated to a specific node. The uplink signals (UL.1 . . . UL.n) can be transmitted from the different nodes (S.1 . . . S.n) to the base station (BS) simultaneously on two, three or more different frequencies (f1, f2, f3) whereas the. downlink signals (DL) are transmitted from the base station (BSA) to the different nodes (S.1 . . . S.n) on only one frequency, which differs from the uplink frequencies. The time slots and the different uplink frequencies of the different nodes are defined once and are thereafter retained.

Abstract: A method of message authentication in communication networks with multicast-enabled routers or switches is disclosed. The latter are tasked to support the packet source authentication: On reception of a multicast packet, the router attests the authenticity of the sender of the packet, and adds corresponding authentication information to the packet, before forwarding it in the normal multicast manner. Any receiver of the multicast packet then uses the authentication information collected by the packet while traversing the network to verify the original packet source.

Abstract: The present disclosure relates to highly available communication networks, e.g., for industrial or utility applications such as substation automation. The devices are connected to two redundant lines through two independent transceivers and bus controllers, i.e. the physical layer and the link layer of the corresponding protocol stack is duplicated. For seamless operation, a sender sends frames simultaneously over both lines and a receiver accepts whichever frame of a pair comes first and ignores the late frame. An exemplary method is disclosed for discarding duplicate frames at the link layer without considering the higher protocol layers, based on a counter inserted in the frame and an algorithm for rejection, with a corresponding means to detect which frames operate according to the redundancy protocol.

Abstract: A method is proposed for operating a system according to TDMA (Time Division Multiple Access) with a multiplicity of wireless sensors and/or actuators as nodes (S.1 . . . S.n) and a base station (BS), said system being installed in a machine or installation, such as industrial robots or an automated manufacturing or production unit, whereby cyclical TDMA data transmission blocks are transmitted and each TDMA data transmission block is composed of consecutive time slots. Each time slot is allocated to a specific node. The uplink signals (UL.1 . . . UL.n) can be transmitted from the different nodes (S.1 . . . S.n) to the base station (BS) simultaneously on two, three or more different frequencies (f1, f2, f3) whereas the. downlink signals (DL) are transmitted from the base station (BSA) to the different nodes (S.1 . . . S.n) on only one frequency, which differs from the uplink frequencies. The time slots and the different uplink frequencies of the different nodes are defined once and are thereafter retained.

Abstract: The present invention is concerned with a method to encrypt OFDM modulation, by multiplying its underlying QAM symbols by a complex-valued generalized key stream sequence. Performing encryption on the physical layer ensures that all services and applications running over the OFDM modem will be protected against eavesdropping. It is also proposed to include in the encryption any training symbols used for synchronization and channel estimation. Only the legitimate receiver knowing the encryption key is hence able to synchronize and correctly demodulate the received signal. Attackers will not even be able to acquire the encrypted signal.

Abstract: A signal transmission method according to the principle of quadrature/amplitude modulation, in which digital data occurring at a time interval T are formed into a transmit signal with the aid of pulse shapers (3a, 3b) having a given unit pulse response r(t) in a transmitter (4), the transmit signal is transmitted by means of a carrier oscillation via a channel (5) having a channel unit pulse response h(t), when an additive white noise w(t) is superimposed on it, so that a receive signal y(t) is present in a receiver (10), and in which the receive signal y(t) is preprocessed by channel-matched filters (7 a, 7b) in the receiver (10), has channel-matched filters (7a, 7b) which are matched to a filter cascade H(t) formed by pulse shapers (3a, 3b) and channel (5) as a whole. The channel-matched filters f(7a, 7b) are preferably transverse filters the data points of which are at a time interval .DELTA.T which is small in relation to the time interval T of the digital data.

Abstract: During a signal transmission process, digital data are reproduced in a transmitter in accordance with a given process for the continuous phase modulation of a carrier wave (CPM) in a time-dependent envelope curve, the envelope curve is transmitted by the carrier wave via a channel with a given unit pulse response, an additive, white Gaussian noise being superimposed, the digital data are sent through a channel-specific filter and sampled in a receiver, and a sequence of estimated symbols is determined with an optimization algorithm.

Abstract: A method for transmitting digital data wherein the data are transmitted in several transmission sections (I-IV) which in each case contain several symbols (1-6). In the transmitter, the phase of a carrier wave is modulated by n different phase angles and their frequency is suddenly changed at the beginning or at the end of each transmission section. So that the individual transmission sections (I-IV) can be synchronized in the receiver, at least one symbol from each transmission section is additionally transmitted by the transmitter in another transmission section as synchronization information. In the receiver, the phases of the carrier wave within the individual transmission sections, that is to say the block phases, are first determined independently of each other by means of an estimating method directly from sections of the carrier wave modulated with the respective data, apart from a phase uncertainty of n-times.