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Now showing items 1 - 16 of 29

  • Method for synchronizing clocks in a communication network

    A method for synchronizing clocks in a communication network includes a first clock of a first network element which is a master element is used for synchronizing second clocks of one or more second network dements which are slave elements. A first sequence of first messages transmitted from the first network element to the second network element and/or a second sequence of second messages transmitted from the second network element to the first network element is recorded. First messages and/or second messages out of those sequences are identified by using an appropriate threshold function with respect to the transmission delays of those messages. Those identified messages have the same constant minimum delay, and based on those messages clock synchronization between the first clock and the second clock is performed.
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  • Method for time synchronization in a communication network

    A method for time synchronization in a communication network comprising a multiplicity of network nodes, wherein synchronization messages are transmitted in the communication network and the synchronization message received in a slave node contains synchronization information for synchronizing the slave time of the slave node with the master time, i.e., synchronization messages are transmitted in a closed ring or line topology and the slave node receives first and second synchronization messages from different transmission directions, and wherein the slave node synchronizes a first time with the synchronization message from one transmission direction and a second time with the synchronization message from the other transmission direction.
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  • Method, park controller and program element for controlling a wind farm

    The disclosure relates to a method for controlling a wind farm, the wind farm includes at least two wind turbines, the method includes determining the required power, determining fatigue load versus power curves for each wind turbine, and based on the determined fatigue load versus power curves attributing different power settings to the wind turbines such that sum of the power settings of all wind turbines is equal to the required power. Furthermore, the invention concerns a park controller for controlling a wind farm and a program element for controlling a wind farm.
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  • Method and device for determining a quality of a clock signal

    Method, device and system for detecting a disturbance, e.g., at least one short mechanical impact (shock or vibration) on a clock of a slave device by detecting a non-typical variation of a tracking error, i.e., a tracking error having a deviation that exceeds a predetermined threshold, wherein such a non-typical variation can be determined by the deviation from a statistical measure, e.g., a variance or a standard deviation, such that the determination of the quality of a clock signal is advantageously allowed and thus suitable counter-measures are provided. The method, device and system are applicable for all kinds of technical systems comprising slave devices that have a clock, e.g., devices in industrial and automation systems. The method, device and system are also applicable in communication systems that use a protocol to synchronize the clocks of its devices, e.g., Profinet.
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  • Method for transmitting synchronization messages in a communication network

    A method for transmitting synchronization messages in a communications network including a plurality of nodes having a first node and at least one second node, wherein in order to take into account differences in a reference clock frequency of a reference clock and an internal clock frequency of an internal clock of the at least one second node, a compensation interval, with which the second clock count state is adjusted on measurement of a delay time, is subdivided into smaller compensation timespans, and the smaller compensation timespans are used to determine a compensated time value for the delay time with a high degree of accuracy, where the compensated time value is then used to update the time information in the synchronization message.
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  • Method for time synchronization in a communications network

    A method for time synchronization in a communications network having multiple nodes, wherein the nodes comprise a first node and at least one second node, where the first node generates first cycle counter states according to a reference clock frequency and the second node or nodes each generate second cycle counter states according to an internal clock frequency, where a time synchronization is carried out in sequential synchronization cycles, in which synchronization messages originating from the first node are sequentially transmitted from one node to another node, and a synchronization message transmitted by a node contains information used for time synchronization in the at least one second node receiving the synchronization message such that a time synchronization is performed in a given second node based on an estimation of a first cycle counter state and a compensation factor in combination with a linear quadratic regulator.
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  • Time synchronization in a communications network with a plurality of network nodes

    One or a plurality of sub-networks are defined in the communications network. Each of the sub-networks includes a plurality of network nodes from the communications network. One or a plurality of the sub-networks represent pre-determined sub-networks, in which respective pre-determined network nodes have both the function of a global slave node and the function of a local master node. The one or the other network nodes of the respective pre-determined sub-networks are local slave nodes. In addition to global synchronization using the global master node and the global slave nodes, local synchronization is also performed in the pre-determined sub-networks using the local master node and the local slave nodes. Thus, in the event of an error outside a pre-determined sub-network, the local synchronization may be continued, whereas the global synchronization is aborted. It is thus avoided that an erroneous synchronization is propagated into corresponding sub-networks.
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  • System and method for time synchronization in a communication network

    A system and method for time synchronization in a communication network. The communication network includes a plurality of network nodes each having a respective internal clock, and a reference node having a reference clock and each configured transmits synchronization messages within the communication network. At least one network node is configured to determine an estimated reference clock time discretely upon arrival of a synchronization message at the at least one network node. To that end, the at least one network node includes a controller for determining a controlled time comprising a time-continuous estimate of the discreetly estimated reference clock time. The controller is configured to determine the controlled time based on an input that is extrapolated to an execution time instant of the controller, where the execution time instant is separated from the time instant of arrival of the synchronization message by a delay (Δtdelay).
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  • Device and method for time synchronization in a communication network

    A device and method for time synchronization in a communication network, wherein a virtual clock is produced by a controller in each network node based on the PROFINET-Standard and/or the Precision Transparent Clock Protocol. In contrast to known methods for estimating the time, the time of the virtual clock does not undergo sudden changes. The virtual clock includes a controlled, continuous path. As a result, the virtual clock is particularly suitable for time-critical applications. Here, the estimation of the time of a reference clock is improved by 18-35%. Accordingly, a markedly greater number of network nodes may be synchronized with a predetermined level of accuracy for the time synchronization.
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  • Method for synchronizing clocks in a communication network

    The invention refers to a method for synchronizing clocks in a communication network, wherein a first clock of a first network element (MA) which is a master element is used for synchronizing second clocks of one or more second network elements which are slave elements. According to the method of the invention, a first sequence of first messages transmitted from the first network element to the second network element and/or a second sequence of second messages transmitted from the second network element to the first network element is recorded. First messages and/or second messages out of those sequences are identified by using an appropriate threshold function with respect to the transmission delays of those messages. Those identified messages have the same constant minimum delay, and based on those messages clock synchronization between the first clock and the second clock is performed. The invention has the advantage that clock synchronization is possible even if an intermediate switch causing an unknown delay is located in the transmission path between the first and the second network element. This is because most of the messages are transmitted within a minimum constant delay via such an intermediate switch and, by identifying those messages, a line delay between the first network element and second network element can be estimated and used for synchronizing the second clock with the first clock. The synchronization method of the invention is preferably used for synchronizing clocks in a DECT network. Furthermore, in a preferred embodiment, the first and second messages are messages according to the standard IEEE 1588.
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  • Method for transmitting synchronization messages in a communication network

    There is described a method for transmitting synchronization messages in a communication network, the communication network comprising a plurality of network nodes communicating with one another, each containing an internal clock, which is timed with a node clock frequency assigned to the respective network node. The synchronization messages transmitted in the communication network serve to synchronize the times of the internal clocks of the network nodes and contain the pulse counter status of a synchronization clock operating at a predefined synchronization clock frequency. The pulse counter status is estimated by each network node and updated in the synchronization message. Changes in the synchronization clock frequency are taken into account when estimating the pulse counter status. Precise determination of the pulse counter status is achieved with the aid of an approximation of the change over time in the pulse ratio between synchronization clock frequency and node clock frequency by means of a function, with the result that the pulse ratio on transmission of a new synchronization message can be predicted and a precise current pulse counter status can be determined on the basis of the predicted pulse ratio. The method is particularly suitable for use in a communication network of an industrial automation system, whose components communicate with one another for example according to the Profinet standard.
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  • Wind turbine controller and method for controlling a power production of a wind turbine

    A wind turbine controller for controlling power production of a wind turbine is provided. The wind turbine is arranged within a wind farm coupled to a public power network via a point of common coupling. The wind turbine controller has a receiving unit for receiving a measured value of a property of the wind farm taken at the point of common coupling and for receiving a reference value for the property, and a control unit for controlling the power production of the wind turbine by regulating a local property of the wind turbine based on the received measured value and the received reference value such that the measured value of the wind farm taken at the point of common coupling corresponds to the reference value. Further, a wind turbine having such a controller, a wind farm and a method for controlling a power production of a wind turbine are provided.
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  • Fusion of Map and Sensor Data in a Modern Car Navigation System

    Dragan Obradovic   Henning Lenz and Markus Schupfner  

    The main tasks of car navigation systems are positioning, routing, and guidance. This paper describes a novel, two-step approach to vehicle positioning founded on the appropriate combination of the in-car sensors, GPS signals, and a digital map. The first step is based on the application of a Kalman filter, which optimally updates the model of car movement based on the in-car odometer and gyroscope measurements, and the GPS signal. The second step further improves the position estimate by dynamically comparing the continuous vehicle trajectory obtained in the first step with the candidate trajectories on a digital map. This is in contrast with standard applications of the digital map where the current position estimate is simply projected on the digital map at every sampling instant.
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  • Fusion of Map and Sensor Data in a Modern Car Navigation System

    Dragan Obradovic   Henning Lenz   Markus Schupfner  

    The main tasks of car navigation systems are positioning, routing, and guidance. This paper describes a novel, two-step approach to vehicle positioning founded on the appropriate combination of the in-car sensors, GPS signals, and a digital map. The first step is based on the application of a Kalman filter, which optimally updates the model of car movement based on the in-car odometer and gyroscope measurements, and the GPS signal. The second step further improves the position estimate by dynamically comparing the continuous vehicle trajectory obtained in the first step with the candidate trajectories on a digital map. This is in contrast with standard applications of the digital map where the current position estimate is simply projected on the digital map at every sampling instant
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  • Method for locating a frequency deviation in a communication network, and corresponding communication network

    Locating a frequency deviation in a communication network is provided. A node clock frequency is assigned to each internal clock of each network node. Messages are transmitted synchronizing the internal clocks. The synchronization messages are transmitted from one node to another in succession based on a reference clock frequency predefined by a reference clock. The synchronization messages include a reference clock count state of the reference clock. Synchronization deviations are calculated at predefined intervals of time. If the synchronization deviation of the middle network node exceeds a threshold value, a change in the reference clock frequency is detected if the synchronization deviations of adjacent nodes. Otherwise, a change in the node clock frequency of the middle network node is detected.
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  • Troubleshooting in GSM Mobile Telecommunication Networks Based on Domain Model and Sensory Information

    Dragan Obradovic   Ruxandra Lupas Scheiterer  

    Mobile cellular telecommunication networks are complex dynamic systems whose troubleshooting presents formidable challenges. Typically, the network performance analysis is carried out on a network cell basis and it is based on the traffic information obtained from various sensors such as the number of requested calls, number of dropped calls, number of handovers, etc. This paper presents a novel troubleshooting system, which provides likelihood of different user-specified root causes of performance degradation based on the observed sensory information and the underlying domain model. This domain model has a form of a Causal Network whose structure is appropriately chosen. The novelty of the herein presented approach is that the domain model is initially based on expert knowledge and later on refined via supervised learning with the data gathered during system operation.
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